WO2021216022A1

WO2021216022A1 - Gel formulation comprising etodolac nanosuspension

Info

Publication number: WO2021216022A1
Application number: PCT/TR2021/050314
Authority: WO
Inventors: Alptug Eren KARAKUCUK; Serdar Tort; Fatma Nevin CELEBI
Original assignee: Gazi Universitesi Rektorlugu
Priority date: 2020-04-22
Filing date: 2021-04-06
Publication date: 2021-10-28

Abstract

A lyophilized etodolac nanosuspension comprising PVP K30 or Poloxamer 188 as a stabilizer was prepared and dispersed in a Hydroxyethylcellulose or Hydroxypropylmethyl cellulose gel system comprising 2-phenoxyethanol, and a gel formulation was obtained.

Description

GEL FORMULATION COMPRISING ETODOLAC NANOSUSPENSION

Technical Field

It relates to the preparation of gel formulation comprising etodolac nanosuspensions prepared by wet grinding technique in the presence of surfactants or polymers as stabilizers.

State of the Art

Dermal application of the active pharmaceutical ingredients is limited as low water solubility causes to low bioavailability. Biopharmaceutical Classification System (BCS) Class II and IV drug molecules are compounds exhibiting low water solubility. Increasing the solubility of these molecules poses difficulties in the formulation development phase.

Nanosuspensions are a successful approach to increase the solubility and dissolution of lipophilic drug molecules. The term nanocrystal was first defined in the early 1990s and Rapamune®, the first commercial product, was introduced to the market in 2000. Nanosuspensions are pure active pharmaceutical ingredients having a particle size of less than 1000 nm and in stabilization of which surfactants and/or polymers are used. Particle size reduced in nanometer size provides an increase in surface area which allows to increase the solubility. The stabilizers used provide electrostatic and steric stabilization in the nanosuspension system. In this way, stability problems such as crystal growth, aggregation and sedimentation are avoided.

In the preparation of nanosuspensions, the bottom-up technique, which is a method of precipitating of the dissolved drug molecules in a nanometer size, and the top-down technique, which allows the micrometer-sized drug particles dispersed in a dispersion medium to be reduced to the nanometer size, is being widely used. The most common top-down methods are high pressure homogenization and wet grinding methods. The high pressure homogenization method can be divided into two subgroups namely microfluidization and piston-gap homogenization. In the wet grinding technique, which is one of the most common methods, grinding beads of zirconium, ceramic or stainless steel rotate at a certain speed in the grinding chamber together with a coarse suspension and provide grinding. The volume and size of the grinding bead, grinding speed and time, physicochemical properties and ratio of the drug substance, the type and ratio of the stabilizer, affect the quality of the resulting nanosuspensions. After the nanosuspensions are obtained, these can be processed into dosage forms such as tablets, capsules, parenteral lyophilized powders, gels etc. making them a powdered solid by lyophilisation or spray drying methods.

Etodolac (ETD) is a NSAID drug (Selective COX-2 inhibitor) which is a pyranocarboxylic acid derivative, used as an anti-inflammatory and analgesic in the treatment of rheumatoid arthritis, osteoarthritis, rheumatoid arthritis in young people. It is a BCS Class II a drug substance; it has the low solubility and high permeability properties. Continuous use of etodolac can cause side effects such as ulcers, gastric or intestinal bleeding, and chest pain which may even cause death. This situation can be avoided by preparing different dosage forms, especially dermal formulations, or by delaying the release of etodolac.

Summary of the invention

Etodolac nanosuspensions (NS) were prepared by wet grinding technique. Polyvinylpyrrolidone (PVP K30) or Poloxamer 188, suitable for dermal use, was used as a stabilizer.

Different concentrations of PVP K30 or Poloxamer 188 were dissolved in distilled water and different concentrations of etodolac were dispersed in this solution. To carry out the wet grinding, the 20 ml. coarse suspension was transferred to the zirconium grinding chamber.

In the wet grinding technique, zirconium grinding medium of 0.5 mm, grinding speed of 400 rpm and grinding time of 2 hours were used. The ratio of grinding medium volume to the coarse suspension volume is 1 :1.

After the grinding process was completed, the grinding medium was separated from the nanosuspensions by filtration.

The resulting nanosuspensions were dispersed in Natrosol 250 HHX or HPMC K100M gels to contain 2% etodolac which were dried by lyophilization process, and were turned into dosage forms (NS-HEC gel, NS-HPMC gel). The stability of the gel formulations was achieved using 1% (w/v) 2-phenoxyethanol. Detailed description of the invention

To improve the low solubility properties of etodolac, the BCS Class II drug substance, and to prepare an effective dermal formulation, nanosuspensions were developed and dispersed in the gel. Wet grinding method was used in the preparation of etodolac nanosuspensions. The stability of the nanosuspensions was achieved using Polyvinylpyrrolidone (PVP K30) or Poloxamer 188. Lyophilization process was performed in order to increase the stability of the nanosuspensions and to make dermal dosage forms.

Nanosuspensions were dispersed in a gel system prepared with Natrosol 250 HHX (Hydroxyethylcellulose, HEC), with a viscosity of 3,400-5,000 cps) or HPMC K100M (Hydroxypropylmethyl cellulose, 2% aqueous solution viscosity of 100,000 cP, HPMC) and stabilized with 2-phenoxyethanol, and were turned into dosage forms suitable for dermal use.

To prepare the gel formulation, firstly, HPMC K100M (2%) or Natrosol 250 HHR (2.5%) were mixed in the distilled water comprising 1% (w/v) 2-phenoxyethanol (Optiphen™300) at an appropriate speed and time until the gelling agents swollen.

The lyophilized powder of ETD nanosuspension was dispersed in the gel with continuous stirring. The volume is completed by adding the appropriate amount of distilled water. The gel formulation contains approximately 2% (w/w) etodolac.

Lyophilized Etodolac nanosuspension

The particle size and particle size distribution of nanosuspensions were measured by dynamic light scattering method and the zeta potential was measured by electrophoretic light scattering methods. Scanning electron microscope, X-ray powder diffraction and differential scanning calorimetry were used to characterize the nanosuspensions. By performing the solubility studies of nanosuspensions, pH measurement, rheology, bioadhesion, permeation studies through membrane and rat skin and in vivo pharmacodynamics studies were completed in nanosuspension-based gel formulations.

As a result, nanosuspensions with approximately 190 nm particle size, 0.160 particle size distribution and 15 mV zeta potential values were obtained. The thermal and crystalline properties of etodolac were maintained after the nanosuspensions were prepared. Homogeneously distributed and spherical particles were obtained. Nanosuspension-based gels achieved successful permeation through membrane and skin, and showed higher analgesic and anti-inflammatory activity compared to the coarse powder.

The amount of ETD in lyophilized nanosuspensions is 1 -5% (weight/weight). Preferably, the ETD ratio is 5% by weight (w/w).

The amount of PVP K30 in lyophilized nanosuspensions can be between 1 -10%. Preferably, the amount of PVP K30 is 4-5%, more preferably 4.6%.

In the wet grinding technique, grinding medium of 0.1 - 1 mm can be used. Preferably, diameter of the grinding medium is 0.5 mm.

In the wet grinding technique, a grinding speed of 100 - 600 rpm can be used. Preferably, the grinding speed is 400 rpm.

In the wet grinding technique, a grinding time of 30 minutes - 4 hours can be used. Preferably, the grinding time is 2 hours.

In the preparation of nanosuspension-based gel formulations, Natrosol 250 HHX or HPMC K100M is 0.5 - 4% (w/v). Preferably, the amount of Natrosol 250 HHX is 2% and the ratio of HPMC K100M is 2.5% (w/v).

In the preparation of nanosuspension-based gel formulations, the amount of 2- phenoxyethanol is 1%.

Example 1 Obtaining Etodolac Nanosuspension by Wet Grinding

ETD nanosuspensions were prepared by wet grinding technique. Poloxamer 188 or PVP K30 stabilizers of between 1% and 5% were dissolved in distilled water. 5% of ETD was dispersed in stabilizer solution. The coarse suspension was taken into a 50 ml. zirconium grinding chamber in a 20 ml. volume, and 20 ml. zirconium grinding medium with a 0.5 mm diameter was added. The grinding process was carried out at 400 rpm for 2 hours. The grinding medium was separated from the nanosuspensions by using a sieve with an appropriate scale.

Lyophilization of nanosuspensions The lyophilization process was performed to increase the stability of nanosuspensions and to be easily dispersed in the gel formulation. Approximately 2 mL of nanosuspension was frozen at -80°C for 2 hours. Freeze drying was performed at -50°C at a pressure of 0.021 mbar for 40 hours using Christ Alpha 1 -2 LD Freeze Dryer.

Solubility studies

For solubility studies, the excess of etodolac, physical mixtures (PM) and nanosuspensions were dispersed in distilled water. It was stirred for 72 hours and analyzed by UV spectrophotometry. (Figure 1).

In vitro/ ex vivo permeation studies

Permeation studies were performed using dialysis membrane and the skins of Wistar albino rats. Franz diffusion cells with a diffusion area of 1 cm² and a receptor volume of 2.5 mL were used. Permeation experiments were performed in ETD nanosuspension- based HPMC K100M or Natrosol 250 HHX gels placed between the membrane or the skin receptor and the donor compartments. The experiments were completed in three parallel in a water bath with a temperature of 37±0.5 °C for 24 hours. The experimental results were analyzed using validated HPLC method. (Figure 2-3).

In vivo pharmacodynamics studies

In vivo pharmacodynamics studies were carried out with the approval of Gazi University Animal Experiments Local Ethics Committee (G.U.ET- 66332047-604.01.02/18.025).

In order to evaluate the anti-inflammatory activity, a paw edema model created with l type 1 carrageenan (1% w/v) dissolved in physiological saline (SF) was used. Freshly prepared carrageenan suspension (1 mg/0.01 ml/paw) was intraplantarly injected into the right paw of each rat. For each rat's own control, the same volume (0.01 ml/paw) of SF was intraplantarly injected into the left hind paw. The difference in volume between the right and left paw was considered as "edema". Edema volume in the paw was measured with a plethysmometer before and at 0, 1 , 3, 4, 6, 8 and 24 hours after the application of the carrageenan, and the inhibition of edema was calculated. (Figure 4).

The tail-flick method was used to evaluate the analgesic effect. The formulations were applied to the tails of rats such that the amount of ETD was 20 mg/kg. The measurements were carried out using an analgesiometer. The tails of the rats were placed on the temperature-controlled plate and the measurement was repeated at 30, 60, 180 and 240 minutes after application of the formulations. (Figure 5).

Description of the drawings:

Figure 1. Solubility of coarse powder of Etodolac, physical mixtures and nanosuspensions in distilled water

A = coarse powder of ETD

B= physical mixture of ETD and Poloxamer 188

C= physical mixture of ETD and PVP K30

D = nanosuspension stabilized with Poloxamer 188

E = nanosuspension stabilized with PVP K30

Figure 2a. Cumulative amount of ETD permeated through skin

PM-HPMC gel: = Physical mixture - HPMC gel

NS-HPMC gel: = Nanosuspension - HPMC gel

PM-HEC gel: = Physical mixture - HEC gel

NS-HEC gel: = Nanosuspension - HEC gel

Figure 2b. Cumulative amount of ETD permeated through skin at the first four hours

Figure 3a. Cumulative amount of ETD permeated through membrane

Figure 3b. Cumulative amount of ETD permeated through membrane at the first four hours

Figure 4. Effects of different formulations on the rat paw edema induced with carrageenan

Control = Control

HEC Blank gel = HEC Blank gel

PM-HEC gel = Physical mixture - HEC gel

NS-HEC gel = Nanosuspension - HEC gel

Figure 5. % analgesic effects of different formulation.

#p<0.05 significantly different from natrosol blank gel,

&<0.05 significantly different from gel group comprising physical mixture (PM).

HEC Blank gel = HEC Blank gel PM-HEC gel = Physical mixture - HEC gel NS-HEC gel = Nanosuspension - HEC gel

Claims

1. Gel formulation comprising etodolac, wherein lyophilized etodolac nanosuspension comprising PVP K30 or Poloxamer 188 as a stabilizer is dispersed in a Hydroxyethylcellulose or Hydroxypropylmethyl cellulose gel system comprising 2-phenoxyethanol.

2. Gel formulation according to the claim 1 , wherein the gel system comprises 0.5 - 4% (w/v), preferably 2.5% (w/v) Hydroxyethylcellulose.

3. Gel formulation according to the claim 2, wherein Hydroxyethylcellulose has a viscosity of 3,400-5,000 cps.

4. Gel formulation according to the claim 1 , wherein the gel system comprises 0.5 - 4% (w/v), preferably 2% (w/v) Hydroxypropylmethyl cellulose.

5. Gel formulation according to the claim 4, wherein the viscosity of aqueous Hydroxypropylmethyl cellulose 2% (w/v) solution is about 100000 cP (HPMC K100M).

6. Gel formulation according to claim 1 , wherein the Hydroxyethylcellulose or Hydroxypropylmethyl cellulose gel system comprises about 1% (w/v) 2- phenoxyethanol.

7. Gel formulation according to any of the preceding claims, comprises about 2%

(w/w) etodolac.

8. Gel formulation according to claim 1 , wherein the lyophilized nanosuspension has approximately 190 nm particle size, 0.160 particle size distribution and 15 mV zeta potential value.

9. Gel formulation according to the claim 1 , wherein the lyophilized nanosuspension comprises 1 -5% (w/w) etodolac.

10. Gel formulation according to the claim 9, wherein the lyophilized nanosuspension comprises 5% (w/w) etodolac.

11. Gel formulation according to the claim 1 , wherein the lyophilized nanosuspension comprises 1-10% (w/w), preferably 4-5% (w/w), more preferably 4.6% (w/w) by weight PVP K30.

12. Gel formulation according to the claim 1 , wherein the lyophilized nanosuspension is produced by wet grinding technique at the following parameters: diameter of grinding medium is 0.1 - 1 mm, preferably 0.5 mm, grinding speed is 100 - 600 rpm, preferably 400 rpm. grinding time is 30 minutes - 4 hours, preferably 2 hours.