WO2019008472A1

WO2019008472A1 - Pharmaceutical compositions of lignocaine hcl

Info

Publication number: WO2019008472A1
Application number: PCT/IB2018/054729
Authority: WO
Inventors: Rangabhatla Gunneswara Subramanya VARA PRASAD; Rangabhatla SAI LAXMI APARNA; Harish TULASI; Ayalasomayajula RATNA PHANI
Original assignee: Shilpa Medicare Limited
Priority date: 2017-07-05
Filing date: 2018-06-27
Publication date: 2019-01-10

Abstract

The present invention relates to a topical composition for the treatment of pain and inflammation associated with lesions of skin or mucous membrane comprising lidocaine HC1, and sulfobutyl ether beta-cyclodextrin and the process for preparation thereof. Preferably the topical compositions are in the form of gel or spray dosage forms, which has superior transdermal flux properties.

Description

PHARMACEUTICAL COMPOSITIONS OF LIGNOCAINE HCL

FIELD OF THE INVENTION The present invention relates to pharmaceutical topical compositions for the treatment of pain and inflammation associated with lesions of the skin or mucous membrane. The present invention relates to the topical compositions for the treatment of i) damaged skin caused by harmful effects of radiation therapy such as used in the treatment of cancer, exposure to sun, as well as open sores such as bed sores, wounds, abrasions, skin ulcers and burns including chemical burns, and diaper rash; and ii) oral lesions (ulcers) within the oral cavity. The present invention further relates to the topical compositions of lignocaine (lidocaine) or pharmaceutically acceptable salt thereof and sulfobutyl ether beta-cyclodextrin and the process for preparation thereof. The most preferable topical compositions of the present invention are gel or spray dosage form, which are free of phosphate buffer.

BACKGROUND OF THE INVENTION Anesthesia is a process commonly used to block the perception of pain. Anesthetic agents are used in procedures carried out on various tissues and organs to alleviate pain. The use of topical or dermal medicaments has long been utilized in the practice of medicine. In particular, topical anesthetics are commonly administered prior to painful medical procedures such as injections, biopsies and the application of laser energy for cutaneous procedures such as removal of hair, tattoos, minor superficial surgeries.

Several topical anesthetic formulations have been extensively used by the medical field to obtain local anesthesia. Local anesthetics have been used in gels or spray for many years. These products are known to be effective as topical anesthetics; however, a long onset time, which is the time between the administration of the topical anesthetic and the commencement of the anesthetic effect, are a common limitation of conventional topical anesthetics. To enhance skin penetration of conventional topical anesthetics, it is often recommended that skin having anesthetic applied thereto be covered with an occlusive dressing. Typically, the onset of action for conventional topical anesthetics varies over a range of time, for example from 30 to 90 minutes. This variability in length of onset time leads to delays in the commencement of medical procedures and, because of the very wide variation in onset time, can lead to the premature commencement of procedures and the infliction of unnecessary pain on the patient. The problem with the penetration of the drug or chemical is due to physio-chemical properties of both drug and the formulation base it is used.

One particular topical anesthetic used to suppress or eliminate pain is lignocaine (lidocaine). Lignocaine alters signal conduction in neurons by blocking the fast voltage-gated Na⁺ channels in the neuronal cell membrane responsible for signal propagation. With sufficient blockage, the membrane of the postsynaptic neuron will not depolarize and will thus fail to transmit an action potential. This creates the anesthetic effect by not merely preventing pain signals from propagating to the brain, but by stopping them before they begin. Careful titration allows for a high degree of selectivity in the blockage of sensory neurons, whereas higher concentrations also affect other modalities of neuron signaling. Lignocaine is about 95% metabolized (dealkylated) in the liver mainly by CYP3A4 to the pharmacologically active metabolites monoethylglycmexylidide (MEGX) and then subsequently to the inactive glycine xylidide. MEGX has a longer half-life than lignocaine, but also is a less potent sodium channel blocker. The volume of distribution is 1.1 -2.1 1/kg, but congestive heart failure can decrease it. About 60- 80% circulates bound to the protein alpha] acid glycoprotein. The oral bioavailability is 35% and the topical bioavailability is 3%. Lignocaine HC1 is used in dental and topical applications. Local anesthetics reversibly blocks impulse conduction in any part of the nervous system and in all nerves, including sensory, motor and automatic types, providing a transient loss of sensation in a circumscribed area of the body without causing a general loss of consciousness. This action is used to block the pain sensation to the areas where it is applied, hence it is used to prevent pain in dental manipulations, burns, injury and diseases.

One particular topical anesthetic marketed in USA is known by the trade name EMLA© which contains prilocaine lignocaine (lidocaine) and as the active ingredients. This product is known to be effective as a topical anesthetic; however, EMLA® has a very long onset time, which can range from 45 to 90 minutes and, in some instances, can take even longer. The variability in length of onset time leads to delays in the commencement of medical procedures and, because of the very wide variation in onset time, can lead to the premature commencement of procedures, thereby inflicting unnecessary pain on the patient. EMLA® must also be covered with an occlusive dressing to enhance penetration. Another disadvantage of EMLA® is that one of its two active ingredients, prilocaine, causes vasoconstriction, and so cannot be used before procedures such as IV placement, blood drawing.

Accordingly, it would be advantageous and desirable to develop a topically applied, anesthetic formulation of lignocaine (lidocaine) for use before painful procedures of dental use (dental injections, dental impressions, x-ray photography, removal of calculus, seating or adjustment of dentures), oral surgery (especially in cancer patients for removing or cleaning tumors), otorhinolaryngology (puncture of the maxillary sinus and minor surgical procedures in the nasal cavity, pharynx and epipharynx), obstetrics (during the final stages of delivery and before episiotomy and perineal suturing as supplementary pain control), introduction of instruments and catheters into the respiratory tract and digestive tract, laser hair removal and skin resurfacing, giving injections, starting IVs, drawing blood, biopsies and minor superficial surgeries, treatment of burns, which has a more rapid onset time, has less variability in the onset time, does not require occlusion, does not interfere with laser energy penetration into the skin, does not cause vasoconstriction and lastly, permits enhanced penetration of the medicament.

Therefore, there exists a need to develop stable pharmaceutical compositions like gel or spray formulations for dental or topical applications with enhanced penetration properties for faster action.

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of the prior art by providing topical compositions of lidocaine HC1 comprising sulfobutyl ether beta- cyclodextrin for use before painful procedures of dental use (dental injections, dental impressions, x-ray photography, removal of calculus, seating or adjustment of dentures), oral surgery (especially in cancer patients for removing or cleaning tumors), otorhinolaryngology (puncture of the maxillary sinus and minor surgical procedures in the nasal cavity, pharynx and epipharynx), obstetrics (during the final stages of delivery and before episiotomy and perineal suturing as supplementary pain control), treatment of pain and inflammation associated with lesions, that display a better drying time, increased transdermal flux, and greater pharmacokinetic absorption in vivo when compared to previously marketed compositions. Moreover, the present topical compositions adhere well to the skin, spread easily, dry quicker, and show greater in vivo absorption in comparison to previously marketed compositions. The present invention provides a pharmaceutical topical composition for the treatment of pain and inflammation associated with lesions of skin or mucous membrane comprising lidocaine HC1 and sulfobutyl ether beta-cyclodextrin.

In one aspect the present invention provides a topical composition for the treatment of pain and inflammation associated with lesions of skin caused by harmful effects of radiation therapy such as used in the treatment of cancer, exposure to sun, as well as open sores such as bed sores, wounds, abrasions, skin ulcers and burns including chemical burns, and diaper rash, comprising lidocaine HCl, and sulfobutyl ether beta-cyclodextrin. In another aspect the present invention provides a topical composition for the treatment of pain and inflammation associated with mucous membrane (oral lesions or ulcers) of oral cavity comprising lidocaine HCl and sulfobutyl ether beta-cyclodextrin. In embodiments of the invention, the invention provides a topical composition comprising lidocaine HCl, sulfobutyl ether beta-cyclodextrin, chitosan, crosslinked polyacrylic acid, polyvinylpyrrolidone, polysorbate 80, polyethylene glycol 400 and pharmaceutical excipient(s).

In a specific embodiment, the invention provides a topical composition comprising of about 1 wt% to about 10 wt% of lidocaine HCl, about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin, about 0.1 wt% to about 1% wt of chitosan. about 0.5 wt% to about 2 wt% of crosslinked polyacrylic acid, about 0.5 wt% to about 2 wt% of polyvinylpyrrolidone, about 0.5 wt% to about 2 wt% of polyethylene glycol 400, about 0.5 wt% to about 2 wt% of polysorbate 80 and pharmaceutical excipient(s).

In a more specific embodiment, the present invention provides a topical composition comprising of about 2 wt% of lidocaine HCl, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinylpyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s).

In embodiments of the invention, the topical composition is applied to lesions in the oral cavity by taking an effective amount of the composition (gel dosage form) into the mouth, swishing around the oral cavity, holding for about two minutes and expectorating. In embodiments of the invention, the topical compositions are applied to topically lesions of the skin caused by harmful effects of radiation therapy such as used in the treatment of cancer, exposure to sun, as well as open sores such as bed sores, wounds, abrasions, skin ulcers and burns. More specifically, the present invention provides an aqueous gel or spray formulation which comprises, consists essentially of, or consists of, water, lidocaine HQ, and sulfobutyl ether beta-eyel odextri n . The formulation may also contain a pH adjusting agent or a product produced as a result of pH adjustment. Advantageously, the gel or spray formulation is free of phosphate buffer. The aqueous gel or spray formulation of the invention is targeted for application to various tissues or organs (internal or external).

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a pharmaceutical topical composition for the treatment of pain and inflammation associated with lesions of skin or mucous membrane comprising lidocaine HCl and sulfobutyl ether beta-cyclodextrin.

The term "topical administration' is used herein to generally include the delivery of a substance, such as a therapeutically active agent, to the skin or a localized region of the body.

The term '"transdermal administration' is used herein to generally include administration through the skin. Transdermal administration is often applied where systemic delivery of an active is desired, although it may also be useful for delivering an active to tissues underlying the skin with minimal systemic absorption.

In one embodiment, the present invention provides a topical composition for the treatment of pain and inflammation associated with lesions of skin caused by harmful effects of radiation therapy such as used in the treatment of cancer, exposure to sun, as well as open sores such as bed sores, wounds, abrasions, skin ulcers and bums including chemical burns, and diaper rash, comprising lidocaine HCi, and sulfobutyl ether beta-cyclodextrin.

In another embodiment, the present invention provides a topical composition for the treatment of pain and inflammation associated with mucous membrane (oral lesions or ulcers) of oral cavity comprising lidocaine HCI and sulfobutyl ether beta-cyclodextrin.

In a further embodiment, the present invention provides a topical composition (aqueous gel or spray) comprising water, lidocaine HCI and a solubilizing agent, wherein the aqueous gel or spray formulation free of phosphate buffer.

In accordance with the invention, the topical compositions of the present invention contain preferably of about 1 wt% to about 10 wt% lidocaine HCI. Lidocaine HCI may be present preferably in a range of approximately such as 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0% wt%, more preferably of about 1 wt% to about 5 wt% lidocaine HCI, and most preferably of about 2 wt% lidocaine HCI. The topical compositions of the present invention comprise sulfobutyl ether beta- cyclodextrin as a solubilizing agent. Sulfobutyl ether beta-cyclodextrin is preferably used in the present topical composition (aqueous gel or spray) in the range of about 0.5 wt% to about 5 wt%, more preferably in the range of about 0.1 wt% to about 1 wt%, and most preferably of about 0.5 wt%.

The topical compositions (aqueous gel or spray) contains permeation enhancers such as skin permeation enhancers/mucosal permeation enhancers, e.g., glycols (polyethylene glycol 400, polyethylene glycol 800), surfactants (polysorbate 80, sodium lauryl sulfate, Triton-X). Preferable glycol used in the present invention is polyethylene glycol 400 (PEG 400). In one embodiment of the invention PEG 400 is used in the range of about 0.5 wt% to about 5 wt%, more preferably in the range of about 0.5 wt% to about 2 wt% and most preferably of about 1 wt% based on the total weight of the composition. Preferable surfactant used in the present invention is polysorbate 80. In another embodiment of the invention polysorbate 80 is used in the range of about 0.5 wt% to about 5 wt%. more preferably in the range of about 0.5 wt% to about 2 wt% and most preferably of about 1 wt% based on the total weight of the composition

The topical compositions of the present invention further comprise a viscoelastic polymer. Suitable viscoelastic polymer includes hydroxypropylmethylcellulose, methylcellulose, sodium carboxymethyl cellulose, ethylene oxide/propylene oxide copolymers, alginates and crosslinked polyacrylic acid. Preferably, the viscoelastic polymer is crosslinked polyacrylic acid. In the embodiments of the invention cross-linked polyacrylic acid is present in the range of about 0.5 wt% to about 2 wt% and most preferably of about 1.5 wt% based on total weight of the composition.

The topical compositions of the present invention further comprise a thickener. Thickener used in the present invention is polyvinylpyrrolidone (PVP K30). In the embodiments of the invention polyvinylpyrrolidone is present in the range of about 0.5 wt% to about 2 wt% and most preferably of about 1 wt% based on total weight of the composition.

The topical composition of the present invention further comprise (aqueous gel or spray) mucoadhesive polymer and penetration enhancer selected from group consisting of tamarind seed polysaccharide and chitosan (low molecular weight). The most preferred mucoadhesive polymer is chitosan. In the embodiments of the invention chitosan is present in the range of about 0.1 wt% to about 2 wt%, more preferably of about 0.1 wt% to about 1 wt% and most preferably of about 0.5 wt% based on the total weight of the composition.

The topical composition (aqueous gel or spray) have a suitable pH ranging from about 5.0 to about 7.5, preferably, from about 6.0 to about 7.0. The pH is adjusted to minimize local, focal point irritation. The topical composition (aqueous gel or spray) may use an acid or base used to adjust the pH, or any reaction product formed as a result of pH adjustment. Preferable base used for the adjustment of pi I is triethylamine or sodium hydroxide. In embodiments of the invention, the present invention relates to a topical composition comprising lidocaine HCl, sulfobutyl ether beta-cyclodextrin, chitosan, crosslinked polyacrylic acid, polyvinylpyrrolidone, polysorbate 80, polyethylene glycol 400 and pharmaceutical excipient(s).

The pharmaceutical excipient(s) used in the present invention are selected from group comprising chelating agents, colouring agents, preservatives, flavoring agents, sweeteners and purified water.

The topical composition comprises the chelating agent EDTA sodium (ethylene diamine tetra acetic acid sodium), colouring agents selected from FD&C Blue, preservatives selected from benzalkonium chloride, 2-phenoxyethanol, phenylethyl alcohol, thimerosal, phenol crystals, benzethonium chloride, m- cresol, phenyl mercuric nitrate, benzyl alcohol, chlorobutanol, methylparaben, and propylparaben etc, flavoring agents selected from banana flavor, lemon flavor, strawberry etc and sweeteners selected from sucralose, saccharin sodium etc.

In embodiments, the invention provides a topical composition comprising of about 1 wt% to about 10 wt% of lidocaine HCl, about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin, about 0.1 wt% to about 1% wt of chitosan, about 0.5 wt% to about 2 wt% of crosslinked polyacrylic acid, about 0.5 wt% to about 2 wt% of polyvinylpynOlidone, about 0.5 wt% to about 2 wt% of polyethylene glycol 400, about 0.5 wt% to about 2 wt% of polysorbate 80 and pharmaceutical excipient(s).

In another embodiment, the invention provides a topical composition comprising of about 1 wt% to about 10 wt% of lidocaine HCl, about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin, about 0.1 wt% to about 1% wt of chitosan, about 0.5 wt% to about 2 wt% of crosslinked polyacrylic acid, about 0.5 wt% to about 2 wt% of polyvinylpyrrolidone, about 0.5 wt% to about 2 wt% of polyethylene glycol 400, about 0.5 wt% to about 2 wt% of polysorbate 80 and pharmaceutical excipient(s), wherein the composition has a pH of about 6.0 to about 7.0. In a further embodiment of the invention, the present invention provides a topical composition comprising of about 2 wt% of lidocaine HCl, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinylpyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s).

In another specific embodiment of the invention, the present invention provides a topical composition comprising of about 2 wt% of lidocaine HCl, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinylpyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s), wherein the composition has a pH of about 6.0 to about 7.0.

In a further embodiment, the invention provides a topical composition consisting of about 1 wt% to about 10 wt% of lidocaine HCl, about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin, about 0.1 wt% to about 1% wt of chitosan, about 0.5 wt% to about 2 wt% of crosslinked polyacrylic acid, about 0.5 wt% to about 2 wt% of polyvinylpyrrolidone, about 0.5 wt% to about 2 wt% of polyethylene glycol 400, about 0.5 wt% to about 2 wt% of polysorbate 80 and pharmaceutical excipient(s).

In a further embodiment of the invention, the present invention provides a topical composition consisting of about 2 wt% of lidocaine HCl, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinylpyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s). In an another embodiment of the invention, the present invention provides a topical composition consisting of about 2 wt% of Iidocaine HQ, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinylpyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s), wherein the composition has a pi I of about 6.0 to about 7.0.

In embodiments of the invention, upon topical administration of the aqueous gel or spray formulation of the invention to the tissue or organ, anesthesia onsets within 5 minutes, e.g., within about 15 seconds to about 3 minutes of administration, particularly within about 5 seconds to about 1 minute of administration, or more particularly within about one second to about 30 seconds of administration. The onset time is independent of the concentration of the anesthesia.

In certain embodiments of the invention, upon transdermal administration of the present invention comprising lidocaine HC1 applied to the skin has a drying rate and transdermal flux greater than a comparative marketed gel formulation. In some aspects, the transdermal flux is 2 or more greater than a comparative gel formulation as determined by Franz cell procedure. More preferably, the flux is at least 2 times greater than the flux of the marketed gel formulation, and most preferably at least 3 times greater than the flux of the marketed gel formulation.

Anesthesia induced on the tissue or organ after administration of the aqueous gel or spray formulation lasts up to 30 minutes or more. The embodiments of the invention possess advantageous properties including rapid onset of topical anesthesia and prolonged anesthetic activity, enabling various medical and surgical procedures to proceed without undesirable intervention.

Advantageously, the time to onset of anesthetic activity is dependent on concentration of the anesthetic and further can be enhanced by permeation enhancers. The duration of anesthetic activity can be controlled by controlling the concentration of the anesthetic. Advantageously, the aqueous gel formulation of the invention contains the anesthetic, penetration enhancer and the viscoelastic polymer in a dissolved molecular state, thereby permitting quick and constant rate of release of the anesthetic over time. The aqueous gel formulation of the invention is contemplated for use on procedures carried out on various tissues and organs, e.g., in bronchoscopy, colonoscopy, GI procedures, intubation, dentistry, ear, nose, and throat (ENT), urology, and gynecology or any other intended use.

The aqueous gel formulation of the invention can be filled in any suitable size container, using aseptic techniques.

The following examples, while illustrative individual embodiments are not intended to limit the scope of the described invention, and the reader should not interpret them in this way.

EXAMPLE- 1

Gel Composition:

12 Banana flavour 0-0.1

13 FD&C Blue 0-0.05

14 Distilled Water Q.s

15 Triethyl amine NaOH pll 6.0 to 7.0

This Example illustrates method for preparing various types of aqueous gel formulation comprising Lignocaine hydrochloride

1. Dental Gel

0.5-2% of crosslinked polyacrylic acid was dispersed in required quantity of water and stirred to obtain the uniform dispersion. To the above dispersion, 2-10% of Lignocaine HCl was added and the pH was adjusted in b/w 6.0 to 7.0 with Triethyl amine/Sodium hydroxide to form the gel. To the above pH adjusted gel 0.5-5% of PEG-400, 0.5- 5% of Polyvinyl Pyrrolidone, 0.5-5% of Polysorbate-80, 0.5-5% of Sulphobutyl β- cyclodextrin sodium,0.01-0.2% EDTA sodium, 0.1 -2% chitosan low mol wt 2 wt% solution, 0-0.2% sucralose, 0-0.1% banana flavour, 0-0.05% FD&C blue was added and stirred to form a homogenous clear dental gel.

2. Burn Gel

0.5-2% of crosslinked polyacrylic acid and 0-5% of tamarind seed polysaccharide was dispersed in required quantity of water and stirred to obtain the uniform dispersion. To the above dispersion, 2-10% of Lignocaine HCl was added and the pH was adjusted in b/w 6.0 to 7.0 with Triethyl amine/Sodium hydroxide to form the gel. To the above pH adjusted gel 0.5-5% of PEG-400, 0.5- 5% of Polyvinyl Pyrrolidone, 0.5- 5% of Polysorbate-80, 0.5-5%o of Sulphobutyl β-cyclodextrin sodium, 0- 1% of benzalkonium chloride and 0.01-0.2%) EDTA sodium was added and stirred to form a homogenous burn gel. EXAMPLE-2

Spray Composition:

This Example illustrates method of preparing an aqueous spray formulation comprising Lignocaine hydrochloride

0.5-2% of cross-linked polyacrylic acid was dispersed in required quantity of water and stirred to obtain the uniform dispersion. To the above dispersion, 2-10% of Lignocaine HCl was added and the pH was adjusted in b/w 6.0 to 7.0 with Triethyl amine/Sodium hydroxide to form the gel. To the above pH adjusted gel 0.5-5% of PEG-400, 0.5- 5% of Polyvinyl Pyrrolidone, 0.5-5% of Polysorbate-80, 0.5-5%) of Sulphobutyl β-cyclodextrin sodium and 0.01-0.2% EDTA sodium was added and stirred to form a homogenous clear solution. EXAMPLE-3

Gel Composition:

3 Polyvinylpyrrolidone (PVP 30) ig 1%

4 EDTA Sodium 0.15g 0.15%

5 PEG 400 ig 1 %

6 Polysorbate 80 i g 1%

Crosslinked polyacrylic acid 1.5g

7 1.5%

(carbomer 980)

8 Chitosan (low mol wt 2 wt% solution) 0.5g 0.5%

9 FD&C Blue 0.03g 0.03%

10 Sucralose 0.15g 0.15%

1 1 Banana flavour 0.082g 0.082%

12 Distilled Water 90g 90%

Q.s pH 6.0

13 Tri ethyl amine/N aOH

to 7.0

Process for Preparation:

1. Required quantity of distilled water weighed into clean glass beaker to which Carbomer 980 will be added slowly under continuous stirring under overhead stirrer.

2. The above mixture will be allowed to mix for 30min under continuous stirring at 500RPM until the Carbomer 980 dispersed uniformly without any lumps or agglomerates.

3. Lignocaine Hydrochloride will be added under continuous stirring and will be allowed to mix for 30 min.

4. Above obtained mixture pH adjusted to 6.0 - 7.0 range by adding Triethyl amine/NaOH drop by drop.

5. PEG 400 and chitosan were added and mixed for lOmin then add PVP K30 and mixed for lOmin.

6. Add Polysorbate 80, EDTA sodium, Sucralose, banana flavour and finally FD&C blue-1 with interval of lOmin continuous stirring after addition of each ingredient.

7. Finally, obtained gel mixed for 30min as final mixing. Example 4: In vitro permeation studies

In vitro skin permeation studies were performed on a Franz diffusion cell with an effective diffusional area of 0.636 cm² and 4 niL of receiver chamber capacity using pig buccal mucosa. The automated transdermal diffusion cell sampling system (SFDC6, Logan Inst, Avalon, NJ) was used for these studies. The full thickness pig buccal mucosa was excised from the oral cavity of pig. Mucosa was wiped with isopropyl alcohol to remove adhering fat. The cleaned mucosa was washed with distilled water and stored in the deep freezer at -21°C until further use. The mucosa was brought to room temperature and mounted between the donor and receiver compartment of the Franz diffusion cell. Initially the donor compartment was empty and the receiver chamber was filled with phosphate buffered saline (PBS) pH 7.4 The receiver fluid was stirred with a magnetic rotor at a speed of 600 rpm, and the assembled apparatus was placed in the Logan transdermal permeation apparatus and the temperature maintained at 32°C ± 1 °C. All the PBS was replaced every 30 minutes to stabilize the buccal mucosa. After complete stabilization 1 gm of reference (LOX-2% Gel- LP- Neon Laboratories Limited) and inventive composition gel as disclosed in example 3 was placed into each donor compartment and sealed with paraffin film to provide occlusive conditions. Samples were withdrawn at regular intervals and analysed for drug content by HPLC. The results are disclosed in Table-1.

Table-l

6 Hours 309.5 1 155.8

24 Hours 1015.1 3692.8

The inventive gel composition of present invention (Example 3) has higher penetration compared to the marketed formulation by which has cumulative average release of drug (flux) of at least 3 times at 24 Hours greater than the marketed gel formulation.

Claims

We Claim

1 . A topical composition for the treatment of pain and inflammation associated with lesions of skin or mucous membrane comprising lidocaine HQ, and sulfobutyl ether beta-cyclodextrin.

2. A topical composition of claim 1 , wherein the composition comprises of about 1 wt% to about 10 wt% of lidocaine HQ.

A topical composition of claim 1 , wherein the composition comprises about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin.

A topical composition comprising lidocaine HQ, sulfobutyl ether beta- cyclodextrin, chitosan, crosslinked polyacrylic acid, polyvinyl pyrrolidone, polysorbate 80, polyethylene glycol 400 and pharmaceutical excipient(s).

A topical composition of claim 4, wherein the composition comprises of about 1 wt% to about 10 wt% of lidocaine HQ, about 0.1 wt% to about 1 wt% of sulfobutyl ether beta-cyclodextrin, about 0.1 wt% to about 1 % wt of chitosan, about 0.5 wt% to about 2 wt% of crosslinked polyacrylic acid, about 0.5 wt% to about 2 wt% of polyvinyl pyrrolidone, about 0.5 wt% to about 2 wt% of polyethylene glycol 400 and about 0.5 wt% to about 2 wt% of polysorbate 80.

A topical composition of claim 4, wherein pharmaceutical excipient(s) are selected from group comprising chelating agents, colouring agents, preservatives, flavoring agents, sweeteners, pH adjusting agents and purified water.

7. A topical composition of claim 4, wherein the composition has a pH of about 6.0 to about 7.0.

8. A topical composition comprising of about 2 wt% of lidocaine HCI, about 0.5 wt% of sulfobutyl ether beta-cyclodextrin, about 0.5 wt% chitosan, about 1.5 wt% of crosslinked polyacrylic acid, about 1 wt% of polyvinyl pyrrolidone, about 1 wt% of polysorbate 80 and about 1 wt% of polyethylene glycol 400 and pharmaceutical excipient(s).

9. The topical composition of claim 8, wherein pharmaceutical excipient(s) are selected from group comprising chelating agents, colouring agents, preservatives, flavoring agents, sweeteners, pH adjusting agents and purified water.

10. A topical composition of claim 8, wherein the composition has a pH of about 6.0 to about 7.0.