WO2019161470A1 - Pharmaceutical composition in the form of an aqueous suspension and use of a pharmaceutical composition in the form of an aqueous suspension - Google Patents

Abstract

The present invention relates to pharmaceutical compositions in the form of an aqueous suspension for the transmucosal administration of melatonin, comprising a drug-solubilization system and a polymeric system comprising a gelling agent and a suspension agent with thixotropic properties. The compositions are of use for treatment or relief in combating sleep disorders, particularly primary insomnia.

Description

PHARMACEUTICAL COMPOSITION IN THE WATER SUSPENSION FORM AND USING A PHARMACEUTICAL COMPOSITION IN THE WATER SUSPENSION FORM

The present invention relates to pharmaceutical compositions in aqueous suspension form for mucosal administration of melatonin comprising a drug solubilization system and a polymeric system comprising a gelling agent and a thixotropic suspending agent. The compositions are useful for treating or aiding in combating sleep disorders, particularly for primary insomnia.

Primary insomnia is characterized by difficulty in initiating or maintaining sleep (poor sleep quality) and the feeling of not having restful sleep for a period of not less than one month.

Melatonin is a neurohormonium, secreted by the pineal gland, responsible for controlling the synchronization of body rhythms with night and day cycles and thus can be used to improve sleep quality and latency, and even alleviate time zone effects. and other disorders arising from sleep imbalance. The most accepted hypothesis for the mechanism of action of melatonin would be through its probable action on receptors in peripheral blood vessels, resulting in vasodilation and consequent activity in the sleep and wake centers of the hypothalamus, causing a reduction in body temperature.

In addition to its effects on circadian rhythm, melatonin is considered a powerful antioxidant. There is evidence in the literature that melatonin decreases free radicals (hydroxyl and peroxyl), presenting direct and indirect activity on these substances (Bonnefont-Rousselot .; Collin, 2010).

Studies have shown that serum melatonin concentrations significantly decrease with advancing age, accompanied by a higher frequency of sleep disorders. Thus, chronic sleep disorders mainly affect the elderly. Melatonin's soporific and chronobiotic properties make it a great candidate for the treatment of these disorders. In different studies, melatonin (administered at night, in doses ranging from 0.3 to 12 mg) significantly improved subjective and / or objective sleep parameters in patients suffering from insomnia (reduced sleep latency, increased sleep time). total sleep and sleep effectiveness).

Currently in the international market there are different products marketed with melatonin, from medicines to food supplements. Most are for oral administration, which in turn has some disadvantages in therapy, such as low bioavailability and quite variable absorption rates. Neurohormonium Tmax when administered orally in humans is reached approximately one hour after administration and achieves a relative bioavailability of approximately 15%.

The low bioavailability of melatonin after oral administration is due to its low oral absorption, its first pass metabolism or the combination of both factors. In order to overcome the disadvantages presented by oral administration of melatonin, one of the possibilities is the administration of the drug by a second route that does not present first pass hepatic metabolism in an area with high vascularization, making it a promising strategy to increase it. absorption of the drug and consequently improves bioavailability. In this context, a transmucosal route of administration is inserted as an alternative for improving the drug delivery system.

The transmucosal route of administration presents interesting factors for melatonin administration, since the passage of the drug occurs by diffusion through the mucosa, which are relatively permeable and highly vascularized membranes. In this way rapid absorption can be achieved which, together with the absence of first pass hepatic metabolism, can achieve high bioavailability, while avoiding the harsh environment of the stomach.

For example, the study by Van Den Berg et al. (2004) compares nasal administration of a melatonin solution with intravenous administration in rats and has been shown to be bioequivalent. Other studies show that absorption of melatonin after nasal administration is extremely fast, with Tmax of 10 min. In addition, the same amount of melatonin absorbed after nasal administration of 0.2 mg is equivalent to oral administration of 2.5 mg. Although nasal doses of 0.2 mg and 0.4 mg were much lower than the oral dose of 2.5 mg, they produced maximum plasma concentrations (Cmax), which were about 5 and 11 times, respectively, higher than those resulting from oral dose (Merkus, 1999).

Similarly, the sublingual route is considered as a convenient, easily accessible and generally well-accepted route for drug administration. These facts have already been proven, as in the study by Bartoli et al. , (2012) that when evaluating sublingual administration of melatonin presented promising results, with absorption and Cmax found about 1.8 and 1.5 times higher, respectively, when compared to oral route.

However, several challenges are encountered in the process of developing a new formulation for transmucosal application. These challenges relate to the transmucosal drug administration itself as well as the intrinsic characteristics of the molecule.

For transmucosal administration, the obstacles are related to ensuring the deposition, application and effective adhesion of the formulation to the mucosa, taking into account the permeation / diffusion processes by the physical mucus barrier and local irritation. Thus, the development rationale should ensure that the formulation is distributed and in contact with the mucosa long enough for drug absorption without causing irritant processes.

The intrinsic characteristics of the melatonin molecule also directly impact the desired performance of the formulation. Melatonin has low solubility in water due to its lipophilic character, as well as being easily oxidized and sensitive to the presence of light, making development even more complex. Solubility is considered a critical factor for mucosal drug application as it may directly impact the pharmacokinetics of the drug, including absorption and bioavailability, as well as formulation stability. In addition, while melatonin oxidation highlights its potential antioxidant effect and has beneficial health effects, it becomes a major challenge to ensure the stability of the product under development. In the study by Xiang-Rong et al. , (2009), demonstrated that the oxidation reaction of melatonin can be catalyzed by UV exposure showing greater degradation when at higher pH. Within this context, avoiding the melatonin oxidation process becomes an additional challenge in developing a stable formulation.

The prior art already reports some approaches for transmucosal administration of lipophilic active ingredients, such as melatonin. Several strategies are described as nasal drug delivery using sprays, pumps and gels, while oral mucosa delivery is described using mucoadhesive tablets, fast dissolving tablets and solid tablet formulations, among others.

For example, WO1996030013 describes transmucosal melatonin release system 0.05 to 5 mg in mucoadhesive matrix, particularly a polymeric resin matrix for frequency reduction or prevention of migraine. Examples of the document disclose a patch system for oral mucosa administration.

In 1980, Japanese patent JP55057563 described intranasal compositions comprising 100 mg melatonin dissolved in 10 ml 5% ethanol solution, but there were serious side effects. The document also disclosed a composition in which propylene glycol was used instead of ethanol.

Another attempt to develop a nasal formulation with 1.7 mg administration of melatonin in ethanol has been described by Vollrath, et al. (1981), however, this formulation was considered inappropriate for clinical use due to serious local irritation and painful administration.

In an attempt to prevent nasal toxicity due to the use of solvents, CN1969814 describes a nasal administration preparation containing 0.1 to 100 mg melatonin and at least one type of polyethylene glycol. However, the study of melatonin in PEG solution demonstrated moderate to high irritation after nasal administration in two healthy subjects (Bechgaard E et al ., Int J Pharm 1999).

US6007834 also describes a nasal formulation containing melatonin which uses cyclodextrin or glycerol for solubilization. In particular, the document describes an aqueous solution or melatonin powder for human sleep induction. However, nasal solutions do not have adequate viscosity for adhesion and permanence on mucosal surfaces. The high viscosity of nasal mucus prevents drug diffusion, while rapid nasal mucociliary clearance reduces contact time with the epithelium. In addition, the inventors have found that US6007834 nasal solutions cause burning at the site of application, poor sleep induction and shorter duration of pharmacological effect.

International application WO2007123955 describes a hydroalcoholic spray composition comprising an active pharmaceutical agent; solvent; and a viscosity modifying agent.

WO2008141264 describes compositions for the treatment of insomnia in oral spray form comprising zolpidem, water and solvent, particularly propylene glycol or ethanol. The composition includes a taste masking or flavoring and propelling agent. US20150352038 describes a dosage form for buccal transmucosal administration of an active ingredient for accelerated sleep induction and / or treatment of sleep disorders, wherein the active ingredient is lipophilic or amphiphilic and is present in a hydroalcoholic solution. comprising ethanol and water.

Low molecular weight alcohols are commonly employed to increase the solubility of lipophilic drugs. However, use of alcohols, such as ethanol, may cause burning or irritation when in contact with sensitive mucous membranes such as nasal or sublingual, including possible irreversible effects on the nasal mucociliary membrane.

Thus, there is still a need for melatonin delivery formulations with uniform drug delivery, increased mucosal adhesion, rapid absorption and immediate onset of action without causing irritation at the site of application, and ensuring high bioavailability via the transmucosal pathway. .

In seeking solutions to the problems reported above, the inventors have surprisingly and unexpectedly found that aqueous suspension formulations for melatonin delivery through the mucosae comprising a drug solubilization system and a polymeric system comprising a gelling agent and a Thixotropic suspending agents have excellent results in drug solubility, system performance and stability, as well as excellent adhesion of the formulation to mucous membranes such as nasal and sublingual mucosae.

Summary of the Invention

The present invention aims to develop a stable transmucosal pharmaceutical composition which ensures melatonin solubility while ensuring a safe dose, effective distribution and adhesion of the formulation to the mucosae, rapid absorption without causing irritation at the site of application and consequently dose reduction required for sleep induction compared with formulations described above or available on the international market.

To this end, the inventors have developed an aqueous suspension formulation for mucosal administration of melatonin comprising a drug solubilization system and a polymeric system comprising an in situ gel-forming gelling agent and a suspending agent with thixotropic characteristics capable of ensuring system stability and formulation adherence in mucous membranes, particularly nasal and sublingual mucosa.

The compositions of the present invention are particularly suitable for spraying through a nasal or sublingual spray or other metered / accurate dose delivery device.

Additionally, the compositions according to the present invention are useful for treating or aiding in the fight against sleep disorders, such as circadian rhythm disorders and insomnia in general, particularly for primary insomnia.

Picture Listing

Figure 1: Mean plasma melatonin concentration following administration of 0.2 mg melatonin equivalent to 2 applications of the test drug nasal suspension or 1.75 mg of Melatonin Pura® equivalent to 10 drops of the oral solution of test drug 3.

Figure 2: Mean plasma melatonin concentration after administration of 0.5mg Melatonin equivalent to 1 sublingual spray application (Test 4) or 1.75mg Melatonin equivalent to 10 drops of oral solution (Test 3).

The aqueous suspensions of the present invention are suitable for mucosal administration of melatonin and comprise a drug solubilization system and a polymeric system comprising a gelling agent and a thixotropic suspending agent.

The transmucosal route includes oral, buccal, labial, sublingual, gingival / palatal, nasal, vaginal, urethral, esophageal, gastric, intestinal, olfactory, bronchial, endometrial mucosa. Particularly, the route of administration is the oral, buccal, labial, sublingual, gingival / palatal, or nasal mucosa; more particularly, the sublingual and nasal routes.

Although melatonin has significant pharmacological properties, its use is limited due to the low solubility of the compound in water. Thus, the first challenge for formulation development was the solubilization of melatonin.

In this context, the compositions according to the present invention contain a solubilizing system capable of ensuring solubility and stability and thus contributing to uniformity and increased absorption of the drug. The solubilizing system according to the invention acts as a vehicle of the drug (melatonin).

In a particular alternative of the invention, the melatonin solubilizing system is an emulsified system. This alternative is particularly suitable for the preparation of a suspension for nasal administration of melatonin.

Emulsions are biphasic systems defined as dispersions in which the dispersed phase (discontinuous or internal) consists of small droplets of liquid distributed in a vehicle (continuous or external phase) in which they are immiscible. In an emulsion, the mixture of the two constituent phases is stabilized by the action of one or more hydrophilic and / or lipophilic surfactant emulsifiers and may be of liquid or semi-solid consistency.

The emulsified system according to this alternative of the invention is composed of an aqueous external phase and an oily dispersed or internal phase, thus being an oil in water (O / W) emulsion. The drug melatonin is solubilized in the internal (oily) phase of the emulsified system.

To compose the oil phase of the emulsified system of the present invention, melatonin may be solubilized in different oils and solubilizing agents. Examples of suitable oils and solubilizing agents for this function are: caprylic caprylic acid triglyceride oil, diethylene glycol monoethyl ether, medium chain mono-diglyceride, castor oil, polyethylene glycol 400, Acconon CCG, monoglyceride, glycerol 99%, mineral oil , refined sesame oil, coconut oil, oleic acid, medium chain triglycerides (Miglyol), or a mixture thereof. Alternatively, melatonin is solubilized in diethylene glycol monoethyl ether. Preferably, melatonin is solubilized in a mixture of caprylic caprylic acid triglyceride oil and diethylene glycol monoethyl ether.

The surfactants (emulsifiers) used in stabilizing the emulsions of the present invention were chosen from the EHL (hydrophilic / lipophilic balance) required by the oil to form a stable system.

Surfactants may be natural (saponins, cholesterol, lecithin, lanolin, gums) or synthetic, which are subdivided into: anionic (sodium stearate, sodium oleate, sodium lauryl sulfate); cationics (benzalkonium chloride, cetylpyridine chloride); nonionic (sorbitan esters, alkyl sorbitan esters); and amphoteric (amino acid) surfactants. Nonionic surfactants selected from sorbitan monooleate 80 (Span 80), PEG-40 (Kolliphor RH40), polysorbate 80 (Tween 80), propylene glycol and sorbitan monostearate (Span 60) are preferred.

In a particular context of the invention, it may be necessary to use a combination of surfactants according to the EHL required by the oil phase and for proper stabilization of the emulsified system.

In this context, the following surfactant pairs are suitable: sorbitan monooleate 80 / PEG-40, polysorbate 80 / propylene glycol, sorbitan monostearate / polysorbate 80, sorbitan monooleate 80 / polysorbate 80. Preferably, the compositions of the present invention comprise sorbitan 80 (Span 80) and hydrogenated castor oil PEG-40 (Kolliphor RH40).

In particular, the intermediate phase of the handling process of the present invention specific to the formation of an emulsified system has a droplet size distribution of the internal phase of the colloidal dispersion in the range of 20 to 200 nm, particularly with an average diameter of 100 nm.

In a second alternative embodiment of the invention, a solubilizing agent is used to ensure melatonin solubilization. In that particular context, the compositions comprise a solubilizing agent. This alternative is particularly suitable for preparing a suspension for sublingual administration of melatonin.

The solubilizing agent according to this alternative of the invention is one selected from polyethylene glycol, propylene glycol, glycerol and mineral oil. Preferably, the solubilizing agent is polyethylene glycol 400.

In any of the possible alternatives to formulations, melatonin is present in an amount of 0.1-10%, preferably 0.1-1.5%, by weight / weight of the composition.

In addition to the solubilizing system, it is necessary to obtain a system that ensures deposition, distribution and effective adhesion of the formulation to the mucosae. Accordingly, the compositions of the present invention further comprise a polymeric system comprising a gelling agent and a suspending agent having thixotropy characteristics.

The first component of the polymeric system is the gelling agent, which acts as a gelled matrix that ensures deposition, application distribution and effective adhesion of the formulation to mucosal surfaces. In particular, the gelled matrix contains a gelling agent capable of forming a gel in situ .

In the context of the invention, gelling agent is defined as a biocompatible polymeric agent having adhesion and gelling ability in situ . The in situ gelation process, that is gelation when in contact with mucosal surfaces, is interesting because it allows the formulation to easily spray through a delivery device, such as through a spray valve, and disperse more easily before forming a gel and when in contact with the mucosal surface, viscosity gain occurs, ensuring formulation adherence and the desired effect.

Addition of the gelling agent in situ increases the residence time of the formulation in the mucosae and enables diffusion and increased absorption of the drug. This property has been exploited for sustained drug delivery, generally as matrix devices that have the ability to form gel. The in situ gelation strategy has been demonstrated in several studies for oral and ophthalmic application using polymers for this purpose, but there are still few studies regarding its use in nasal and sublingual mucosae.

The gelling agents according to the present invention are mucoadhesive polymers selected from natural or semi-natural polymers such as chitosan, gums, pectins and the alginate or derivatives thereof such as sodium alginate and calcium alginate; or synthetic polymers such as cellulose derivatives being carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, methylcellulose, poly (oxyethylene), polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, carbopol, polycarbofil. Preferably, the gelling agent is selected from pectin or sodium alginate.

The purpose of incorporating melatonin into a polymer blend was to ensure the physicochemical stability of the system by forming a continuous phase extended web which makes it highly viscous, keeping the formulation in suspension when at rest.

However, from a technical point of view for applications such as mucosal administration via a delivery device such as a spray, it is necessary that the viscosity be low to ensure uniform dose when administered. For such a mechanism this agent must exhibit the intrinsic characteristic of thixotropy which in turn highlights the behavioral mechanism of this innovative invention.

In that context, the polymeric system of the compositions of the present invention further comprises a second polymeric component to ensure performance, system stability and adhesion of the formulation to mucosal surfaces. The addition of the second polymeric component is important because the gelling agent forms a gel only when in contact with mucosal surfaces. Thus, it is necessary to add a second polymer to help stabilize the system when at rest by increasing viscosity. In the context of the invention, the second polymeric component is a thixotropic suspending agent.

A thixotropic fluid is characterized by being time dependent, ie its viscosity increases with time during a decrease in shear rate (rest formulation), however, this change in viscosity is easily reversible with increasing shear rate (agitation). ). The thixotropic effect of the compositions of the present invention is advantageous compared to the state of the art as it simultaneously provides: stability of the composition by viscosity gain, rapid fluid formation with uniformity suitable for mucosal administration and superior mucoadhesive properties. Thixotropic suspending agent is one capable of providing the rheological characteristics necessary for formation of a thixotropic system.

The thixotropic suspending agent according to the present invention may be selected from: agar, carrageenan, carboxymethylcellulose, microcrystalline cellulose, colloidal silicon dioxide, xanthan gum, gelatin gum or a mixture thereof. The mixture of carboxymethylcellulose (CMC) and microcrystalline cellulose is preferred.

The final pharmaceutical form of the invention is a suspension, due to the presence of insoluble suspending agent particles in the aqueous medium. Suspension is understood to be formulation containing solid particles dispersed in a liquid carrier in which the particles are not soluble.

In particular, the final suspension obtained in the handling process of the present invention has a particle size distribution in the range of 5 to 50 µm, particularly with an average diameter of between 10.0 - 15.0 µm with 90% <30%. µm.

The thixotropic effect of the compositions of the present invention is even more advantageous as it facilitates the manufacturing process of the medicament, especially during the product filling phase in the pharmaceutical manufacturing area. With agitation provided to the system, the formulation becomes fluid with easy flow assisting transport and transfer between tanks during the process.

In addition, the use of a thixotropic suspending agent assists in the process of adhesion of the formulation to the mucosae. The polymer is easily dispersed in water, resulting in a high initial drug release rate, but after dispersion forms a viscous liquid extending the retention time of the formulation at the site of action. Mucoadhesion of the suspending agent occurs after polymer hydration (polymer-mucus mixture). For these reasons, the use of this agent may contribute to better absorption and increased bioavailability.

Moreover, the performance of the invention is even more surprising because, by incorporating the melatonin solubilization system into a mucoadhesive gelled matrix, thereby obtaining a suspension, the skilled artisan would expect to find a reduction in the rate of absorption of the drug, as that it is necessary to break the viscous barrier of the polymeric network and thus allow the permeation of the drug. Thus, the gelled matrix when in close contact with the mucosa forms a physical barrier which would modulate the pharmacokinetics of the drug. However, surprisingly, excellent pharmacokinetic parameters were observed when compared with the state of the art.

The compositions of the present invention have a final viscosity of 5.0 - 250.0 centipoise (cp), preferably a nasal suspension has a viscosity of 15.0 - 25.0 cp and a sublingual suspension has a viscosity of 190.0 - 230, 0 cp.

The compositions of the present invention further comprise a preservative system for ensuring microbial control, thereby ensuring the stability and functionality of the developed formulation.

In that context, the compositions of the present invention may comprise the use of a microbiological preservative. Examples of microbiological preservatives that may be incorporated into the composition are benzalkonium chloride, benzoic acid, phenylethyl alcohol, bronopol, benzyl alcohol, methylparaben, propylparaben, paraben mixture, thymol, sodium benzoate and potassium sorbate, or a mixture thereof. Preferably the composition comprises the following preservatives, methylparaben, propylparaben, sodium benzoate and potassium sorbate, or a mixture thereof.

The compositions of the present invention optionally comprise an antioxidant system to prevent melatonin oxidation process, thereby ensuring the stability and functionality of the developed formulation.

In this context, in a particular alternative, the antioxidant system comprises the use of the nitrogen technique, which consists of the use of nitrogen conditioning an inert system in the handling steps until the formulation is filled in order to avoid product exposure and minimal contact. of the drug with atmospheric oxygen, which is responsible for the oxidation reaction.

In a second particular alternative, the antioxidant system comprises the use of photoprotective primary packaging, ensuring as much as possible controlling the exposure of the product to UV radiation and avoiding catalysis of the oxidation reaction. In this alternative, the packages may be composed of aluminum, PET, HDPE or amber glass, preferably in the HDPE package.

In a third alternative, the antioxidant system comprises an antioxidant agent in the formulation which may retard the oxidative reaction of melatonin, that is, acts by "preventing oxidation of another chemical and oxidizing", thereby ensuring the stability of the main drug. Suitable antioxidants suitable for use according to the invention include: Tocopherol in alpha, gamma and beta form; Ascorbic acid; ascorbyl palmitate; butylated hydroxytoluene; erythorbic acid; fumaric acid; malic acid; methionine, monothioglycerol; metabisulfite and bisulfite; N-acetylcysteine; propionic acid; sodium ascorbate; sodium formaldehyde sulfoxylate; sodium sulfite; sodium thiosulfate; sulfur dioxide; thymol and polyethylene glycol succinate of vitamin E, or a mixture thereof.

Particularly preferred is the use of tocopherol at a concentration of 0.001-0.05%, metabisulfite at a concentration of 0.01-1.0%, N-acetylcysteine at a concentration of 0.05-0.2%, or a mixture thereof.

Additionally, the compositions of the present invention may contain pH regulators, tonicity agents, sweeteners, emollients.

Within a particular embodiment, the compositions contain an emollient agent to ensure mucosal hydration and thus to prevent dryness and irritation upon application of the formulation. Suitable emollient agents for this purpose may be selected from D-panthenol, silicone, glycerol, vitamin E, sorbitol, allantoin, hyaluronic acid, or a mixture thereof. Preferably, D-panthenol is present in the composition acting as an emollient.

In a particular alternative, the compositions of the present invention further comprise sweeteners for improving the organoleptic characteristics of the invention. Suitable sweeteners are selected from sucralose, sodium cyclamate, saccharin, aspartame, citric acid, sweetening solutions with menthol, peppermint, mint, strawberry, grape, green apple, raspberry, banana and a mixture thereof, as well as colorants.

Thus it can be stated that the results were achieved due to the differential of several strategies adopted together in the development of the innovative formulation as: (1) formulation composition which ensured the solubility of the drug; (2) mucosal adhesion by in situ gel formation and (3) stability and (4) the thixotropic characteristic promoted by the addition of the suspending agent.

The compositions of the present invention are suitable for administration to the mucous membranes in the form of drops, jet, aerosol or by a nebulizer or spray by a nebulization process. Preferably, the compositions are suspensions for administration as a spray or jet or other metered / accurate dose delivery device. More particularly, the final pharmaceutical form of the invention is an aqueous nasal or sublingual spray suspension.

Nasal or sublingual administration with a metering valve device ensures spreadability, increased contact surface and improved mucosal absorption ensuring greater ease and uniformity and spreadability of the product when sprayed.

• Adequada solubilidade da melatonina em sistema final aquoso.
• Formulação com capacidade de gelificação in situ.
• Formulação com características tixotrópicas que garantem maior adesão às mucosas nasal ou sublingual, estabilidade do produto, além de maior facilidade e uniformidade durante a aplicação pela válvula dosadora (por exemplo, spray).
• A formulação desenvolvida apresenta alta biodisponibilidade para administração nasal ou sublingual.
• Quando comparada à via de administração oral, permite o uso de dose baixa atingindo altas concentrações séricas após administração nas mucosas, particularmente mucosa nasal e sublingual.
• Rápida absorção com início da ação imediato, aproximadamente em 4 minutos pela via de administração nasal e 5 minutos pela via de administração sublingual.
• A formulação não apresenta desconforto significativo após administração nas mucosas.

The compositions according to the present invention provide the following advantages:

• Adequate solubility of melatonin in aqueous final system.
• Formulation with gelability in situ .
• Formulation with thixotropic characteristics that ensure greater adhesion to the nasal or sublingual mucosae, product stability, as well as greater ease and uniformity during application by the dosing valve (eg spray).
• The developed formulation presents high bioavailability for nasal or sublingual administration.
• When compared to the oral route of administration, it allows the use of low dose reaching high serum concentrations after mucosal administration, particularly nasal and sublingual mucosa.
• Rapid absorption with immediate onset of action, approximately 4 minutes by nasal administration route and 5 minutes by sublingual administration route.
• The formulation shows no significant discomfort after mucosal administration.

The aqueous melatonin suspensions of the invention are suitable for the treatment or aid in combating sleep disorders and circadian biological rhythms.

Included in the context of the invention are various types of insomnia and circadian biological rhythm disorders, such as primary insomnia, delayed phase insomnia, sleep-wake cycle with periods other than 24h, prolonged sleep latency, sleep fragmentation, sleep behavioral disorders. REM, sleep corrections of the elderly, desynchronization between the sleep-wake cycle and day and night, and jet lag disorders.

The compositions are particularly useful for treatment for primary insomnia.

Except where otherwise defined, all technical and scientific terms used in the present invention have the meaning commonly understood by one of ordinary skill in the art to which it belongs.

Except where otherwise noted, percentage refers to the percentage by weight (ie,% weight / total weight of the composition).

The invention is illustrated in the following examples without imposing any limitations on the scope of the invention:

Examples Example 1:

		2mg / ml (0.2mg / dose)	4mg / ml (0.4mg / dose)	2mg / ml (0.2mg / dose)	10mg / ml (1.0mg / dose)	30mg / ml (3.0mg / dose)	50mg / ml (5.0mg / dose)
Ingredient	Function	%Ex. 1a	%Ex. 1b	%Ex. 1c	%Ex. 1- D	%Ex. 1 AND	%Ex. 1 F
Melatonin	Active principle	0.2	0.4	0.2	1	3	5th
Oil beaver	Oily Phase			1.75			2.75
Caprylic Capric Acid Triglycerides	Oily Phase	1.75	1.75		1.75	2.75
Glycerol	Oily Phase		0.7	0.7		1.7	1.7
Diethylene glycol monoethyl ether	Oily Phase	1.05	1.05	1.05	1.05	1.05	1.05
Sorbitan Monooleate 80	Emulsifier (Nonionic)	2	2	3.95	2	2	2
D- Panthenol		Emollient	2	5th			5th	2
PEG-40 Hydrogenated Castor Oil	Emulsifier (Nonionic)	3	3	1.05	3	3	3
Benzalkonium chloride	Preservative		0.02			0.02
Methylparaben	Preservative	0.05	0.05	0.033	0.05	0.05	0.05
Propylene glycol	Preservative	10			10
Pectin	Gelling Agent	1	1	1.5	1	1	1
Microcrystalline Cellulose / Sodium Carboxymethylcellulose	Thixotropic Suspending Agent	0.5 *	0.5 *	0.5 *	0.5 *	0.5 *	0.5 *
Purified water	Water phase	78.45	84.53	89.267	74.65	82.93	82.95
0.1N sodium hydroxide	PH corrector	Qsp.	Qsp.	Qsp.	Qsp.	Qsp.	Qsp.
0.1N hydrochloric acid	PH corrector	Qsp.	Qsp.	Qsp.	Qsp.	Qsp.	Qsp.

* equivalent to 0.075% Sodium Carboxymethylcellulose and 0.425% Microcrystalline Cellulose

The compositions of Example 1-A are prepared as follows:

In a container of suitable capacity add the hydrogenated castor oil PEG-40 and pectin and mix to a homogeneous mass. Prepare a solution of water and D-panthenol and pour over the mixture of pectin and hydrogenated castor oil PEG-40 under stirring and heating until complete solubilization of pectin in water. Prepare a solution of propylene glycol and methylparaben and pour over the container containing the pectin solution under stirring and heating. In a container of suitable capacity, add: caprylic capric acid triglycerides, diethylene glycol monoethyl ether, sorbitan monooleate 80 and melatonin under stirring and heating to complete solubilization. Pour the aqueous phase over the hot oil phase under stirring. In a container of suitable capacity add water and Microcrystalline Cellulose / Carboxymethylcellulose, homogenize under stirring. Pour the gel obtained in this step over the emulsion previously obtained under stirring.

The remaining examples 1-B to 1-F are prepared by equivalent process.

Example 2:

		5mg / ml (0.5mg / dose)	10mg / ml (1mg / dose)	10mg / ml (1mg / dose)	30mg / ml (3mg / dose)	50mg / ml (5mg / dose)
Ingredient	Function	%Ex. 1a	%Ex. 1b	%Ex. 1c	%Ex. 1-D	%Ex. 1 AND
Melatonin	Drug	0.5	1	1	3	5th
Polyethylene glycol 400	Solubilizing agent	20	20	16.5	16.5	16.5
Glycerin	Solubilizing agent	-	-	3.5	-	3.5
Sodium benzoate	Preservative	0.1	0.1	-	0.1	-
Potassium Sorbate	Preservative	0.1	0.1	-	0.1	-
Methylparaben	Preservative	-	-	0.18	-	0.18
Propylparaben	Preservative	-	-	0.02	-	0.02
Sodium Alginate	Gelling Agent	1.5	1.5	1	1.5	1
Microcrystalline Cellulose / Sodium Carboxymethyl Cellulose	Suspension Agent	0.5 *	0.5 *	0.5 *	0.5 *	0.5 *
Sweetening Solution	Sweetener	0.275	0.275	0.25	0.25	0.25
Sucralose	Sweetener	0.3	0.3	0.2	0.2	0.2
Anhydrous Citric Acid	Sweetener	0.3	0.3	0.035	0.035	0.035
Yellow Dye # 10	Dye	0.002	0.002	0.002	0.002	0.002
Purified water	Vehicle	76,423	75,923	76,813	77,813	72,813
0.1N sodium hydroxide	PH corrector	Qsp.	Qsp.	Qsp.	Qsp	Qsp
0.1N hydrochloric acid	PH corrector	Qsp.	Qsp.	Qsp.	Qsp	Qsp

* equivalent to 0.075% Sodium Carboxymethylcellulose and 0.425% Microcrystalline Cellulose

The compositions of Example 2-A are prepared as follows:

In a container of suitable capacity add polyethylene glycol 400 and add under stirring and heating to melatonin until complete solubilization. In another container, add water and sodium alginate until complete solubilization and uniform gel formation. In another container add water, sodium benzoate and potassium sorbate until complete homogenization. Pour the final solution obtained onto the alginate gel under agitation. In a container of suitable capacity to add water and under stirring, Microcrystalline Cellulose / Carboxymethylcellulose, homogenize under agitation. Pour Microcrystalline Cellulose / Carboxymethylcellulose gel onto the sodium alginate gel under stirring for 10-30 minutes. At the end of the mixture pour the melatonin solution on the mixture with stirring. In another container add water, and the other excipients until complete solubilization. At the end, pour the finished solution onto the agitated gel.

The remaining examples 2-B to 2-E are prepared by equivalent process.

Example 3:

The inventors conducted a comparative pilot study to evaluate the pharmacokinetic behavior of Melatonin present in three formulations, Test 1 - Melatonin 2mg / mL as nasal spray solution (formulation equivalent to US6007834), Test 2 - Melatonin 2mg / mL in the form of nasal spray suspension of the present invention and Test 3 - Pure Melatonin 1.9 mg oral drops (ESI spa) in healthy and fasting healthy research participants using quantification techniques of plasma concentration by High Performance Liquid Chromatography coupled to Mass Spectrometry (LC / MS). Male research participants aged 18 to 35 years were selected. The study was completed with 5 (five) participants.

In each period the research participants received a 0.2 mg dose of Melatonin equivalent to 2 applications of the nasal spray solution of test drug 1, 1 in each nostril or 0.2 mg of Melatonin equivalent to 2 applications of Nasal Spray suspension. of test drug 2 or 1.75 mg of Melatonin equivalent to 10 drops of the oral solution of test drug 3, as randomized, along with 200mL of water after a period of at least 8 hours of fasting.

Pharmacokinetic parameters are shown in Table 3.

Table 3  - Pharmacokinetic parameters pilot study:

Pharmacokinetic parameters after administration of treatments A, B and C (mean ± SD)
Parameter	A (US6007834 Patent Nasal Spray Solution)	B (Nasal Spray Suspension of the invention)	C (Oral Solution)
C max (pg / mL)	2506.1 ± 523.4	2761.7 ± 790.8	1656.7 ± 887.0
AUC (pg.h / ml)	1874.6 ± 490.2	1739.9 ± 321.8	1877.6 ± 584.8
Tmax (h)	0.15 ± 0.03	0.12 ± 0.03	0.53 ± 0.27
T1 / 2 (h)	1.13 + 0.26	1.56 + 0.77	1.08 + 0.35
Average residence time (h)	1.13 ± 0.08	1.16 ± 0.13	1.3 ± 0.12
Bioavailability (pg.h / ml.dose)	9373.0 ± 2451.1	8699.4 ± 1608.8	1073 ± 334.2
Cmax: maximum plasma concentrationAUC: area over curveTmax: time to reach CmaxT1 / 2: elimination half-lifeTreatment A: US6007834 Patent Nasal Spray (Test 1) Treatment B: Inventive Nasal Spray (Test 2) Treatment C: Solution oral treatment (Test 3)

The results found for parameters Cmax, AUC, Tmax, T1 / 2, mean residence time and bioavailability of nasal spray suspension are surprisingly better when compared to the results found for the oral solution already marketed.

The tested formulation, developed according to the present invention, is in aqueous suspension pharmaceutical form and contains in its manufacturing process an emulsion formed by the oil phase to ensure the solubilization of the hydrophobic drug. Like glycerol, used in Example 2 of US6007834, the oil phase of the emulsion promotes improved drug absorption compared to the oral solution. The incorporation of the final emulsion into a matrix with in vitro gelling properties makes it mucoadhesive, in addition to the addition of the thixotropic suspending agent that defined the formulation as a suspension. At the points presented, it was expected to observe a reduction in the rate of absorption of the drug, as it is necessary to break the viscous barrier of the water-soluble polymeric gel network and thus allow drug permeation. The gelled matrix in close contact with the nasal mucosa as a physical barrier would modulate the pharmacokinetics of the drug. Thus, the Cmax, AUC, Tmax results found were surprisingly similar to the values for the nasal solution referred to in US6007834. Additionally, the mucoadhesive gelled matrix nasal spray suspension had a longer half-life than the US6007834 nasal solution, about 30 minutes, considered a sustained release for nasal administration.

Nasal burning evaluation for the nasal formulations Test 1 (Nasal Spray Solution) and Test 2 (Nasal Spray Suspension) was performed immediately after the application of the medication by the nursing team by completing the Visual Analog Scale - VAS being 0 ( zero) for total absence of burning and 10 (ten) for intense burning.

The results obtained are described in Table 4 below:

Table 4  - Nasal burning reported by visual analog scale (VAS) questionnaire.

Subject	Treatment Nasal Spray Solution		BSuspension nasal spray treatment		Oral Solution Treatment
	Scale	ranking	Scale	ranking	Scale	ranking
1	5th	Moderate	3	Moderate	-	-
2	5th		Moderate	2	Light	-	-
4	4	Moderate	2	Light	-	-
5th	5th	Moderate	2	Light	-	-
6th	8th	Intense	3	Moderate	-	-
Minimum	4	Moderate	2	Light	-	-
Median	5th	Moderate	2	Light	-	-
Maximum	8th	Intense	3	Moderate	-	-

By analyzing the data in Table 5, it was found that the median nasal burning reported by participants is Mild for nasal spray suspension formulation and Moderate for US6007834 nasal spray solution formulation.

Thirty (30) minutes after drug administration, participants answered the following question: "How do you rate your sleep level after taking the study drug?" The data obtained are described in Table 5 below.

Table 5th  - Drowsiness reported in a questionnaire applied after the administration of the evaluated treatments.

Subject	Treatment Nasal Spray Solution US6007834		BSuspension nasal spray treatment of the invention		Oral Solution Treatment
	Period	ranking	Period	ranking	Period	ranking
1	3	Little sleep	2	Little sleep	1	Little sleep
2	2	Little sleep	3	Very sleepy	1	No sleep
4	1	Little sleep	3	Little sleep	2	Very sleepy
5th	2	Little sleep	1	Very sleepy	3	Little sleep
6th	1	Little sleep	2	Very sleepy	3	Little sleep
Minimum		Little sleep		Little sleep		No sleep
Median	-	Little sleep	-	Very sleepy	-	Little sleep
Maximum		Little sleep		Very sleepy		Very sleepy

By analyzing the data in Table 5, it was found that the median sleepiness reported by participants was “Little sleep” for the US6007834 nasal spray solution formulation, “Very sleepy” for the nasal spray suspension formulation and “ Little sleep ”for oral solution formulation.

Example 4:

In the same previous study, the inventors evaluated the pharmacokinetic behavior of the present invention compared to a commercial oral melatonin formulation, with Test 2 - Melatonin 2 mg / mL as a nasal suspension (formulation of the present invention) and Test drug. 3 - Pure Melatonin 1.9 mg in the form of oral drops (ESI spa).

The objective was to describe the pharmacokinetic profile of Melatonin present in Test 2 and Test 3 formulations when administered in a fasted state.

Melatonin 0.2 mg equivalent to 2 applications of the nasal suspension of Test 2 or 1.75 mg of Melatonin Pure equivalent to 10 drops of oral solution of Test 3 was administered.

To ensure the use and tolerability of the developed formulation, research participants were asked about the discomfort at the time of formulation application via the nasal route. And at the end of the administration, no adverse events were observed by the medical team, including symptoms related to the nasal cavity of each participant, demonstrating that there are no indications of the irritative process and discomfort after application, a fact of paramount importance for drugs with application. nasal.

The results obtained for mean plasma concentration were plotted in the graph of Figure 1. It can be observed the rapid absorption of the drug administered by the nasal route, with Tmax around 7.3 minutes. It was also found that nasal absorption of melatonin was greater than oral solution.

The results suggest that an even lower dose of nasal product is required to achieve the same plasma level compared to the oral product. Moreover, in the questions made to the research participants, the results obtained showed no discomfort and no indicative of irritative process after administration, thus ensuring that the administration of the nasal formulation was safe and effective. It can be concluded that the results of the pilot study proved that the mean plasma melatonin concentration was significantly high and Tmax as desired. Thus, the results ensure immediate action, a relevant advantage when compared to oral administration, which requires a period of 1-2 hours after administration for the desired effect.

Example 5:

Additionally, the inventors conducted a pilot study to evaluate the pharmacokinetic behavior of Melatonin present in two formulations, Test 4 - Melatonin 5mg / mL suspension as a sublingual spray according to the present invention, and Test 3 - Melatonin Pure 1, 9 mg oral drops (ESI spa) in healthy and fasting healthy research participants using plasma chromatographic high performance liquid chromatography (LS / MS) quantified plasma concentration quantification techniques. Male research participants aged 18 to 35 years were selected. The study was completed with 6 (six) participants.

In each period the research participants received either a 0.5mg dose of Melatonin equivalent to 1 application of the sublingual spray (treatment B - Test 4) or 1.75mg of melatonin equivalent to 10 drops of oral solution (treatment A - Test 3). ), according to the randomization list, together with 200mL of water after a period of at least 8 hours of fasting.

The pharmacokinetic parameters of the study are shown in Table 6:

Table 6 - Study pharmacokinetic parameters:

PPES003 / 17
Pharmacokinetics
Pharmacokinetic parameters after administration of treatments A and B
(mean ± SD)
Parameter	A (Oral Solution)	B (Sublingual Spray)
C max (pg / mL)	4428.2 ± 3680.9	3483.3 ± 2629.7
AUC (pg.h / ml)	5450.8 ± 3883.2	4150.3 ± 2865.9
Tmax (h)	0.46 ± 0.16	0.43 ± 0.3
T1 / 2 (h)	0.99 ± 0.29	1.5 ± 1.19
Average residence time (h)	1.27 ± 0.14	1.29 ± 0.27
Bioavailability (pg.h / ml.dose)	3114.7 ± 2219	20751.3 ± 14329.3
Cmax: maximum plasma concentration
AUC: area over the curve
Tmax: time to reach Cmax
T1 / 2: elimination half-life
Treatment A: Pure Melatonin Oral Solution (Test 3)
Treatment B: Sublingual Spray according to the Invention (Test 4)

The results obtained for mean plasma concentration were plotted in the graph in Figure 2. Overall, the results of the study found that the maximum plasma melatonin concentrations were significantly high and reached rapidly. Therefore the present invention has been surprisingly effective, having high absorption and bioavailability. The results demonstrate that even at low administered concentrations, the developed formulation showed higher bioavailability than the oral formulation.

The results obtained are mainly related to the composition of the formulation which ensured the solubility of the drug, adhesion in the sublingual mucosa by in situ gel formation caused by sodium alginate and the high stability aided by the addition of carboxymethylcellulose / microcrystalline cellulose. The spray system itself also helped to further increase the contact surface and enabled more efficient mucosal absorption.

Given these facts, the formulation can be considered effective and with better action when compared to the oral formulations available in the international market, besides presenting the convenience and ease of application by sublingual route.

The above examples demonstrate that the compositions of the present invention have shown promise with rapid absorption, increased bioavailability and immediate onset of action and are considered effective in treating primary insomnia as compared to oral formulations available on the international market.

Claims (25)

1. Pharmaceutical composition in aqueous suspension form for mucosal administration of melatonin, comprising:
   - a melatonin solubilization system
   a polymeric system comprising a gelling agent and a thixotropic suspending agent.
2. Composition according to Claim 1, characterized in that the melatonin is present in an amount of 0.1-10.0%, preferably 0.1-1.5% by weight of the composition.
3. Composition according to Claim 1, characterized in that the solubilising system is an emulsified system comprising an aqueous external phase, an oil internal phase, and at least one emulsifier.
4. Composition according to Claim 1, characterized in that the solubilising system comprises a solubilizing agent selected from polyethylene glycol 400, propylene glycol, glycerol and mineral oil, preferably polyethylene glycol 400.
5. Composition according to Claim 1, characterized in that the gelling agent is selected from chitosan, gums, pectins, alginate, sodium alginate, calcium alginate, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, poly (oxyethylene), polypyrpyrrolidone, polyacrylic acid, carbopol, polycarbophil.
6. Composition according to Claim 5, characterized in that the gelling agent is selected from pectin or sodium alginate.
7. Composition according to Claim 1, characterized in that the thixotropic suspending agent is selected from agar, carrageenan, carboxymethylcellulose, a mixture of microcrystalline cellulose and carboxymethylcellulose, colloidal silicon dioxide, xanthan gum, gelatin gum. , or a mixture of these.
8. Composition according to Claim 7, characterized in that the thixotropic suspending agent is a mixture of carboxymethylcellulose and microcrystalline cellulose.
9. Composition according to Claim 3, characterized in that the oil phase comprises one or more oils selected from: caprylic caprylic acid triglyceride oil, diethylene glycol monoethyl ether, medium chain mono-diglyceride, castor oil, polyethylene glycol 400, monoglyceride, 99% glycerol, mineral oil, refined sesame oil, coconut oil, oleic acid, medium chain triglycerides, or a mixture thereof.
10. Composition according to Claim 9, characterized in that the oil phase comprises a mixture of caprylic caprylic acid triglyceride oil and diethylene glycol monoethyl ether.
11. Composition according to Claim 3, characterized in that at least one emulsifier is selected from sorbitan monooleate 80, PEG-40, polysorbate 80, propylene glycol, sorbitan monostearate, alone or in combination.
12. Composition according to Claim 11, characterized in that it comprises a combination of emulsifiers selected from sorbitan monooleate 80 / PEG-40, polysorbate 80 / propylene glycol, sorbitan monostearate / polysorbate 80, sorbitan monooleate 80 / polysorbate 80.
13. Composition according to Claim 1, characterized in that it further comprises a preservative system.
14. Composition according to Claim 13, characterized in that it comprises a selected microbiological preservative benzalkonium chloride, benzoic acid, phenylethyl alcohol, bronopol, benzyl alcohol, methylparaben, propylparaben, mixture of parabens, thymol, sodium benzoate and potassium sorbate. or a mixture thereof, preferably methylparaben, propylparaben, sodium benzoate and potassium sorbate, or a mixture thereof.
15. Composition according to Claim 1, characterized in that it optionally comprises an antioxidant system.
16. Composition according to Claim 15, characterized in that the antioxidant system comprises the use of the nitrogen technique.
17. Composition according to Claim 15, characterized in that the antioxidant system comprises the use of photoprotective primary packaging composed of aluminum, PET, HDPE or amber glass, preferably in the HDPE packaging.
18. Composition according to Claim 15, characterized in that the antioxidant system comprises an antioxidant agent selected from tocopherol in alpha, gamma and beta form, ascorbic acid, ascorbyl palmitate, butylated hydroxytoluene, erythorbic acid, fumaric acid, malic acid, methionine, monothioglycerol, metabisulfite and bisulfite, N-acetylcysteine, propionic acid, sodium ascorbate, sodium formaldehyde sulfoxylate, sodium sulfite, sodium thiosulfate, thymol and polyethylene glycol succinate of vitamin E, or a mixture thereof .
19. Composition according to Claim 18, characterized in that it comprises tocopherol at a concentration between 0.001-0.05%, metabisulfite at a concentration between 0.01-1.0%, N-acetylcysteine at a concentration between 0.05-0, 2%, or a mixture of these.
20. Composition according to any one of Claims 1 to 19, characterized in that it additionally comprises an emollient agent selected from D-panthenol, silicone, glycerol, vitamin E, sorbitol, allantoin, hyaluronic acid, or a mixture thereof.
21. Composition according to any one of Claims 1 to 19, characterized in that it further comprises sweeteners selected from sucralose, sodium cyclamate, saccharin, aspartame, citric acid, menthol, mint, strawberry, grape flavored sweetening solutions. , green apple, raspberry, banana and mix of these.
22. Composition according to any one of Claims 1 to 21, characterized in that the size of the suspended particles has an average diameter of 5.0 - 50.0 µm, particularly between 10.0 - 15.0 µm. 90% <30 µm.
23. Composition according to any one of Claims 1 to 22, characterized in that it is suitable for administration to the oral, buccal, labial, sublingual, gingival / palatal, or nasal, preferably nasal or sublingual mucosa.
24. Composition according to any one of Claims 1 to 23, characterized in that it is for administration in the form of drops, jet, aerosol or through a nebuliser or spray, preferably spray or jet or other metered / accurate dose delivery device. .
25. Use of a pharmaceutical composition in the form of aqueous suspension as defined in any one of claims 1 to 24, characterized in that it is for the treatment or aid in combating sleep disorders and circadian biological rhythms such as: primary insomnia, delayed phase, sleep-wake cycle with periods other than 24h, prolonged sleep latency, sleep fragmentation, REM sleep behavioral disorders, the elderly's sleep corrections, sleep-day and night-time dyssynchronization, and disorders caused by jet lag, preferably for the treatment of primary insomnia.

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