Topical formulations of rhein and its process for preparation

Abstract

The present invention relates to topical formulations of Rhein. The present invention specifically relates to a Rhein transferosomal gel formulation. The present invention specifically relates to a Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents or thickening agents, pH adjusting agents and anti-foaming agents. The present invention specifically relates to use of Rhein transferosomal gel formulation for treatment of Osteoarthritis. The present invention also relates to the process for the preparation of Rhein transferosomal gel formulation.

Description

[0001] TOPICAL FORMULATIONS OF RHEIN AND ITS PROCESS FOR PREPARATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to topical formulations of Rhein.

[0004] The present invention specifically relates to a Rhein transferosomal gel formulation.

[0005] The present invention specifically relates to a Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents, thickening agents, pH adjusting agents and anti-foaming agents.

[0006] The present invention specifically relates to use of Rhein transferosomal gel formulation for treatment of Osteoarthritis.

[0007] The present invention specifically relates to Rhein transferosomal gel formulation, wherein the formulation exhibits Tmaxin a range of 10 mins to 150 mins, Cmaxin a range of 1 to 100 ng / mL and AUC0_ , in a range of 100 to 2000 ng / ml*min in the plasma when the Rhein transferosomal gel is applied topically.

[0008] The present invention also relates to the process for the preparation of Rhein transferosomal gel formulation.

[0009] BACKGROUND OF THE INVENTION

[0010] Osteoarthritis is the most common global chronic joint disease. The disease may affect single or multiple joints and even be generalised. Osteoarthritis is a chronic arthropathy affecting the entire joint, involving the cartilage, joint lining, ligaments, and underlying bone. In osteoarthritis, cartilage loss, osteophyte formation (bone spurs), and subchondral bone sclerosis leads to pain, disability, and a reduction in quality of life. Structural changes, visible by radiography, include narrowing of the joint space, osteophyte formation and bone remodelling around the joints. Osteoarthritis can arise in any synovial joint in the body but is most common in the large joints (knees and hips), hands, and spine.

[0011] Inflammation is the body's immediate response to damage to its tissues and cells by pathogens, noxious stimuli such as chemicals or physical injury. Acute inflammation is a short-term response that usually results in healing: leukocytes infiltrate the damaged region, removing the stimulus and repairing the tissue. Chronic inflammation, by contrast, is a prolonged, dysregulated and maladaptive response that involves active inflammation, tissue destruction and attempts at tissue repair.

[0012] Rhein is used as hepatoprotective, nephroprotective, anti-inflammatory, antioxidant, anticancer, antimicrobial agent and for treating osteoarthritis.

[0013] Rhein is a lipophilic anthraquinone extensively found in medicinal herbs Rheum palmatum L., Cassia tora L., Polygonum multiflorum Thunb and Aloe barbadensis Miller. Rhein is commonly found as a glycoside such as rhein-8- glucoside or glucorhein. Rhein was first isolated in 1895. It is found in rhubarb species like Rheum undulatum and Cassia reticulata. The chemical name of Rhein is 9,10- dihydro-4,5-dihydroxy-9,10-dioxo-2-anthracene carboxylic acid. Rhein has a chemical formula of Ci5H8O6and a molecular mass of 284.22 g / mol. It has a structural formula of:

[0014] Diacerein is also known as diacetyl Rhein, is a slow acting medicine of the class anthraquinone used to treat joint diseases, such as Osteoarthritis. It works by inhibiting interleukin- 1 beta. Diacerein works by blocking the actions of interleukin- 1 beta a protein involved in the inflammation and destruction of cartilage that play a role in the development of symptoms of degenerative joint diseases. The chemical name of Diacerein is 4,5- diacetyloxy-9,10-dioxo-anthracene-2-carboxylic acid. Diacerein has a chemical formula of Ci9Hi2O8and a molecular mass of 368.29 g / mol. It has a structural formula of:

[0015] Diacerein is a pro-drug of rhein widely used as an anti-inflammatory agent in the treatment of osteoarthritis, which acts by inhibiting the interleukin- 1 (IL-1) signalling pathway. Diacerein capsules are available in the market as 50 mg strength with different brand names in different countries, including ART 50®, Artrodar® etc.

[0016] In the treatment of osteoarthritis, generally rhein is administered orally as its pro-drug Diacerein and where Diacerein is entirely converted into rhein before reaching the systemic circulation. However, the converted rhein is not completely absorbed from the gastro-intestinal tract (GIT) and hence the oral bioavailability of Diacerein was reported to be approximately 40-60%. In the lower part of the GIT, the unabsorbed rhein causes undesirable side effects such as diarrhoea or soft stools.

[0017] Since the bioavailability of Diacerein through oral route of administration is less and the unabsorbed rhein is showing laxative effect in the lower part of GIT, these problems can be overcome by applying the formulation containing Diacerein through topical route at the site of osteoarthritis. However, clear reports are not available on conversion of Diacerein to its active form rhein, at the arthritic site or within the blood circulation.

[0018] WO 2009 / 133430 discloses topical composition comprising rhein or Diacerein, salts or esters or prodrug thereof and one or more pharmaceutically acceptable excipients selected from emulsifiers, wetting agents or surfactants, chelating agents, solvents, antioxidants, gelling agents, thickening agent or viscosity-enhancing agent waxes, penetration enhancers, solubilizing agents, buffering agents, emollients, bases, coloring agents, flavoring agents and preservatives. It also discloses process for the preparation of a topical composition comprising rhein or Diacerein, salts or esters or prodrug thereof, the process comprising dissolving or suspending rhein or Diacerein, or salts or esters or prodrugs thereof in one or more solvents or bases; and mixing with one or more pharmaceutically acceptable excipients. This application does not disclose the Rhein transferosomal gel formulation. The examples and its manufacturing process provide preparation conventional creams and gels which are completely different from the present invention formulation and process.

[0019] WO 2017 / 004319 discloses topical composition comprising a therapeutically effective amount of a compound selected from the group consisting of Diacerein, rhein, monoacetyl rhein, and salts or esters or prodrugs thereof, and one or more pharmaceutically acceptable excipients, wherein the composition is in the form of ointment, cream, or gel, and at least about 90% by volume of the compound has a particle size of about 0.5 to 35 pm. This application does not disclose the Rhein transferosomal gel formulation. The examples and its manufacturing process provide preparation conventional creams, ointments and gels which are completely different from the present invention formulation and process.

[0020] None of the above prior art reference disclose or enable the Rhein transferosomal gel formulation of the present invention. The inventors of present invention have developed novel Rhein transferosomal gel formulation with enhanced bioavailability and reduced side effects when compared to existing products. The inventors of present invention also provide specific process for the preparation of Transferosomal gel formation comprises the steps of dissolving, adding and mixing. The transferosomes gel formulations of the present invention has maximum transdermal permeation and improved bioavailability of the Rhein which gives maximum therapeutic effect to the patient.

[0021] OBJECTIVE OF INVENTION

[0022] The main objective of the present invention is to provide topical formulations of Rhein.

[0023] Another objective of the present invention is to provide a Rhein transferosomal gel formulation.

[0024] Another objective of the present invention is to provide a Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents, thickening agents, pH adjusting agents and anti-foaming agents.

[0025] Another objective of the present invention is to provide use of Rhein transferosomal gel formulation for treatment of Osteoarthritis.

[0026] Another objective of the present invention is to provide a Rhein transferosomal gel formulation, wherein the formulation exhibits Tmaxin a range of 10 mins to 150 mins, Cmaxin a range of 1 to 100 ng / mL and AUC0_, in a range of 100 to 2000 ng / ml*min in the plasma when the Rhein transferosomal gel applied topically.

[0027] Another objective of the present invention is to provide a process for the preparation of Rhein transferosomal gel formulation.

[0028] SUMMARY OF INVENTION

[0029] Accordingly, the present invention provides topical formulations of Rhein.

[0030] In one embodiment, the present invention provides a Rhein transferosomal gel formulation.

[0031] In one embodiment, the present invention provides a Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents, thickening agents, pH adjusting agents and anti-foaming agents.

[0032] In one embodiment, the present invention provides use of Rhein transferosomal gel formulation for treatment of Osteoarthritis.

[0033] In another embodiment, the present invention provides a Rhein transferosomal gel formulation comprising: a) 0.1% to 10% w / w of Rhein, b) 0.1% to 10% w / w of Vesicle forming lipids, c) 50% to 90% w / w of buffering agents, d) 1% to 15% w / w of emulsifying agents, e) 1% to 15% w / w of penetration enhancers, f) 1% to 20% w / w of humectants, g) 0.1% to 5% w / w of gelling or thickening agents, and h) 0.01% to 1% w / w of pH adjusting agents.

[0034] In another embodiment, the present invention provides a Rhein transferosomal gel formulation comprising: a) 0.1% to 10% w / w of Rhein, b) 0.1% to 10% w / w of Soya Lecithin, c) 0.1% to 10% w / w of Cholesterol, d) 50% to 90% w / w of Phosphate buffer, e) 1% to 15% w / w of Span-60, f) 1% to 15% w / w of Diethylene glycol monoethyl ether, g) 1% to 20% w / w of Glycerol, h) 0.1% to 5% w / w of Carbopol, and i) 0.01% to 1% w / w of Triethanolamine.

[0035] In another embodiment, the present invention provides a Rhein transferosomal gel formulation comprising: a) 0.1% to 10% w / w of Rhein, b) 0.1% to 10% w / w of Soya Lecithin, c) 0.1% to 10% w / w of Cholesterol, d) 50% to 90% w / w of Phosphate buffer, e) 1% to 15% w / w of Span-60, f) 1% to 15% w / w of Diethylene glycol monoethyl ether, g) 1% to 20% w / w of Glycerol, h) 0.01% to 2% w / w of Simethicone 30% emulsion, i) 0.1% to 5% w / w of Carbopol, and j) 0.01% to 1% w / w of Triethanolamine.

[0036] In another embodiment, the present invention is to provide a Rhein transferosomal gel formulation, Rhein in a plasma exhibits Tmaxin a range of 10 mins to 150 mins, Cmaxin a range of 1 to 100 ng / mL and AUC0- , in a range of 100 to 2000 ng / ml*min when the Rhein transferosomal gel applied topically. In another embodiment, the present invention provides a process for the preparation of Rhein transferosomal gel formulation.

[0037] In yet another embodiment, the present invention provides process for preparing topical formulations in the form of gel, wherein the process comprising the steps of: a) heating solvent upto temperature in the range of 45°C to 55°C and adding anthraquinone compound slowly with continuous stirring until the active ingredient is solubilised completely, b) adding penetration enhancer and humectant by maintaining the temperature at 45°C to 55°C, c) adding gelling or thickening agent to step (b) slowly under stirring and some portion of water (about 40-60%) is added intermittently upon maintaining the temperature at 45 °C to 55 °C, d) dissolving preservatives in small portion of water (about 20-40%) and adding obtained solution to step (c), e) adjusting the pH of formulation to alkaline pH with a base, and f) adding quantity sufficient of purified water and mixing the medium until homogeneous gel is formed.

[0038] In another embodiment, the present invention provides a process for the preparation of Rhein transferosomal gel formulation, wherein the process comprising the steps of: a) adding emulsifying agents to buffer and stirring at 50 - 60°C, b) adding rhein to above step a) and mixing for 1 hour at 50°C to 60°C until dissolved, c) adding vesicle forming lipid and buffer to step b) and mixing for 3 hours at 50 - 60°C until dissolved, d) adding penetration enhancers and humectants to above step c) and stirring continued for 2 hours, e) adding gelling agents to step d) and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 buffer, f) adding pH adjusting agents step e) and stirring until a uniform and consistent gel was formed, and g) adjusting to batch size and stirring until uniform transferosomal gel was obtained.

[0039] In another embodiment, the present invention provides a process for the preparation of Rhein transferosomal gel formulation, wherein the process comprising the steps of: a) weighing and melting emulsifying agent at 60°C to 70°C, b) adding rhein followed by vesicle forming lipid to step a) and mixing for 1 hour at 60°C to 70°C until dissolved, c) adding pre-heated phosphate buffer and anti-foaming agents to above step b) and mixing for 3 hours at 60°C to 70°C until dissolved, d) adding penetration enhancers and humectants to above step c) and stirring continued for 2 hours, e) adding gelling agents to step d) and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 buffer, f) adding pH adjusting agents step e) and stirring until a uniform and consistent gel was formed, and g) adjusting to batch size and stirring until uniform transferosomal gel was obtained.

[0040] In another embodiment, the present invention provides a process for the preparation of Rhein transferosomal gel formulation, wherein the process comprising the steps of: a) adding Span 60 to 80% quantity of pH 7.4 to phosphate buffer and stirring at 50 - 60°C, b) adding rhein to above step a) and mixing for 1 hour at 50°C to 60°C until dissolved, c) adding lecithin and cholesterol to step b) and mixing for 3 hours at 50 - 60°C until dissolved, d) adding Transcutol and glycerol to above step c) and stirring continued for 2 hours, e) adding Carbopol (Acrypol - 956) to step d) and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 phosphate buffer, f) adding triethanolamine step e) and stirring until a uniform and consistent gel was formed, and g) adjusting to batch size and stirring until uniform transferosomal gel was obtained.

[0041] In another embodiment, the present invention provides a process for the preparation of Rhein transferosomal gel formulation, wherein the process comprising the steps of: a) weighing and melting Span 60 at 60°C to 70°C, b) adding rhein followed by lecithin and cholesterol and stirring for 1 hr at 60 °C to 70°C until dissolved, c) adding pre-heated phosphate buffer and simethicone to above and stirring continued for 3 hrs at 60°C to 70°C until dissolved, d) adding Diethylene glycol monoethyl ether and glycerol to above and stirring continued for 2 hours, e) homogenizing the above solution for 20 mins at 60 °C with using Homogenizer, f) adding Carbopol (Acrypol 956) to above and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 buffer, g) adding triethanolamine and stirring until a uniform and consistent gel was formed, and h) adjusting to batch size and stirring until uniform transferosomal gel was obtained. BRIEF DESCRIPTION OF THE FIGURES

[0042] Figure 1: Comparative in-vivo diffusion of Diacerin Vs Rhein Transferosomal gel Vs Rhein conventional gels.

[0043] Figure 2: SEM Image of Rhein Transferosomes and SEM Image of Rhein Transferosomal gel.

[0044] Figure 3: Picture of normal smooth cartilage (untreated left knee joint).

[0045] Figure 4: Picture of Denudation and complete loss of articular cartilage in femur and increased subchondral space (OA induced right knee joint).

[0046] Figure 5: Picture of Cyst in the subchondral bone (triangle), collapse of subchondral area and loss of articular cartilage (OA induced right knee joint).

[0047] Figure 6: Picture of Diacerein treated - Re-appearance of cartilage tissue (less thickened) and normal subchondral bone (right knee joint).

[0048] Figure 7: Picture of Rhein treated - Re-appearance of cartilage tissue (less thickened) in the femur and normal subchondral bone (right knee joint).

[0049] DETAILED DESCRIPTION OF THE INVENTION

[0050] The term "comprising", which is synonymous with "including", "containing", or "characterized by" here is defined as being inclusive or open-ended, and does not exclude additional, unrecited elements or method steps, unless the context clearly requires otherwise.

[0051] The present invention provides topical formulations of Rhein.

[0052] The present invention provides a Rhein transferosomal gel formulation.

[0053] The present invention provides a Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents, thickening agents, pH adjusting agents and anti-foaming agents.

[0054] The term “active ingredient” of the present invention is used to relieve osteoarthritis and inflammation. Preferably used active ingredient is Rhein.

[0055] The concentration of the Rhein used in the formulations of the present invention is in the range of 0.1% to 10% w / w. Rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid), the active component of Rhubarb, has been shown to have multiple functions, such as antibacterial, antioxidant, anticancer, anti-angiogenic, anti-inflammatory effects and also used in treatment of osteoarthritis.

[0056] Rhein is the main effective ingredient isolated from Rheum palmatum L. Radix et Rhizoma. It is the dried root and rhizome of R. palmatum L., R. tanguticum Maxim, ex Balf., or R. officinale Baill. of the family Polygonaceae, whose major active constituents are anthraquinone derivatives. The root bark of rhein belongs to the Ranunculaceae family.

[0057] The transfersome term was first introduced by Cevc (Transfersomes, a trademark of IDEA AG, Munich, Germany), and it represents the first generation of ultradeformable vesicles. The skin permeation and penetration of these elastic vesicles result from a synergic mechanism among the carrier properties and the access enrichment ability. Transfersomes are ultradeformable lipid bundles of aggregates in supramolecular form constructed with a minimum of one interior aqueous segment encircled by a lipid bilayer exhibiting adapted properties, which are appropriate under the presence of surfactants in the vesicular membrane (edge activator (EA)). Even if it is generally accepted that the permeation usually, liposomes is limited to the outer layer of the stratum corneum, thus providing a drug or cosmetic localizing effect within the skin, transfersomes are claimed to infuse as intact vesicles through the skin layers to the complete circulation.

[0058] The Vesicle forming lipids used in the present invention are selected from and not limited to phospholipid, examples of specific phospholipids are, soya lecithin, L-a- (distearoyl) lecithin, L-a-(diapalmitoyl) lecithin, L-a-phosphatide acid, L- a- (dilauroyl)-phosphatidic acid, L-a (dimyristoyl) phosphatidic acid, L- a(dioleoyl)phosphatidic acid, DL-a(dipalmitoyl) phosphatidic acid, L-a(distearoyl) phosphatidic acid, and the various types of L-a-phosphatidylcholines prepared from egg yolk and soybean.

[0059] The concentration of Vesicle forming lipids used in the formulations of the present invention is in the range of 0.1% to 10% w / w. The buffering agents used in the present invention are selected from and not limited to citrate buffers, phosphate buffers, acetate buffers, carbonate buffers, ammonia buffers, borate buffers, lactate buffers, Cholesterol, ethanolamine buffers, glycine buffers, methionine buffers, glutamate buffers, and succinate buffers.

[0060] The concentration of buffering agents used in the formulations of the present invention is in the range of 50% to 90% w / w.

[0061] Cholesterol acts as a "buffer" at higher and lower temperatures and prevents the collapse of the plasma membrane during thermical pressures. Cholesterol-rich domains in the bilayer are called lipid rafts.

[0062] The “emulsifying agents” or “surfactants” used in the present invention are selected from and not limited to polawax, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, Span 60. Polysorbates are a series of partial fatty acid esters of sorbitol and its anhydrides copolymerized with approximately 20, 5 or 4 moles of ethylene oxide for each mole of sorbitol and its anhydrides. Polysorbates may function as an emulsifying agent or solubilizing agent. "Span 60" refers to sorbitan monostearate and is a series of mixtures of partial esters of sorbitol and mono- or dianhydrides with fatty acids.

[0063] The concentration of emulsifying agents used in the formulations of the present invention is in the range of 1% to 15% w / w.

[0064] The penetration enhancers used in the present invention are selected from but not limited to propylene glycol, glycerine, isopropyl palmitate, isopropyl myristate, laurocapram, oleic acid, oleyl alcohol, ethoxydiglycol, alkanecarboxylic acids, Azone®, adipic acid derivatives, ethanol, urea, polyethylene glycol (PEG), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone, diethylene glycol monoethyl ether, calcipotriene, detergents, emollients, ethoxy diglycol, triacetin, benzyl alcohol, sodium laureth sulfate, dimethyl isosorbide, medium chain triglyceride oil (MCT Oil), menthol, isopropyl isostearate, propylene glycol monostearate, lecithin, diisopropyl adipate, diethyl sebacate, ethyl oleate, glyceryl oleate, caprylic / capric triglyceride, propylene glycol dicaprylate / dicaprate, laureth 4, oleth-2, oleth-20, propylene carbonate, nonoxynol-9,2-n-nonyl-l,3-dioxolane, C7to Ci4-hydrocarbyl substituted 1,3 -dioxolane, 1,3-dioxane, or acetal and nonoxynol-15.

[0065] The concentration of penetration enhancers used in the formulations of the present invention is in the range of 1% to 15% w / w.

[0066] The humectants used in the present invention are selected from but not limited to glycerol, sorbitol, maltitol, polydextrose, triacetin, propylene glycol, polyethylene glycol (PEG) esters including PEG-20 stearate, PEG-40 stearate, PEG- 150 stearate, PEG- 150 distearate and PEG- 100 stearate, alkoxylated alcohols including laureth-12, ceteareth-20, laureth-23, glycereth-7, glycereth-12, glycereth-26, PEG-4, PEG-6, PEG-8, PEG-12, PEG-32, PEG-75, PEG-150, dipropylene glycol, polypropylene glycol, pantothenol, gluconic acid salts.

[0067] The concentration of humectants used in the formulations of the present invention is in the range of 1% to 20% w / w.

[0068] The gelling agents or thickening agents used in the present invention are selected from but not limited to Carbopol (Acrypol - 956), hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, methyl cellulose, acacia, alginic acid bentonite, polyvinyl pyrrolidone, magnesium aluminium silicate, carbomer, microcrystalline cellulose, carboxymethylcellulose calcium or sodium, cetostearyl alcohol, ethylcellulose, guar gum, maltodextrin, polyvinyl alcohol, povidone, propylene carbonate, propylene glycol alginate, sodium alginate, sodium starch glycolate, starch, tragacanth, stearic acid and xanthan gum.

[0069] The concentration of gelling agents or thickening agents used in the formulations of the present invention is in the range of 0.1% to 5% w / w.

[0070] The pH adjusting agents used in the present invention are selected from but not limited to triethanolamine (TEA), citric acid monohydrate, amine base tromethamine, tetrahydroxypropyl ethylenediamine, diethanolamine, aminomethyl propanol and sodium or ammonium hydroxide.

[0071] The concentration of pH adjusting agents used in the formulations of the present invention is in the range of 0.01% to 1% w / w. The antifoaming agents used in the present invention includes but not limited to Simethicone 30% emulsion, dimethicone, polydimethylsiloxane and combinations thereof.

[0072] The concentration of antifoaming agents used in the formulations of the present invention is in the range of 0.01% to 2% w / w.

[0073] The solvents used in the present invention includes but not limited to polyols and polyglycols such as propylene glycol (1,2-propanediol), glycerin (glycerol), glycol furol, 1,2-phenol-hexanetriol, sorbitol solution, esters and polyesters such as polyoxyethylene sorbitan monoesters (e.g., Tween® 60) and polyoxy ethylene sorbitan polyesters (e.g., Tween® 20), ethers and polyethers such as polyethylene glycol monocetyl ether (cetomacrogol 1000) and polyethylene-polypropylene glycols (pluronics), dimethyl sulfoxide, alcohol, castor oil, diisopropyl adipate, ethoxylated alcohol, ethyl alcohol, fatty alcohol citrate, glycerin, 1,2,6-hexanetriol, hexylene glycol, isopropyl alcohol, isopropyl myristate, isopropyl palmitate, mineral oil, phosphoric acid, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 1450, polyethylene glycol 8000, polyethylene glycol monostearate, polyethylene glycol 400 monostearate, polyethylene glycols, polyoxyl 20 cetostearyl ether, polyoxypropylene 15-stearyl ether, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, polysorbates, propylene carbonate, purified water, SD alcohol 40, triglycerides of saturated fatty acids.

[0074] Other additives used in the preparations to the formulations of this invention, the following can be used and there were no limitations: base, corrigent, suspending agent, antioxidant, preservatives, wetting agent, refrigerative agent, sugar coating agent, isotonizing agent, softener, anti-frothing agents, dispersing agent, fragrance, desiccant, antiseptics, and solubilizing agents.

[0075] The topical pharmaceutical composition having the above properties provides systemic bioavailability equal to or better than orally administered Diacerein and hence, useful in the treatment of osteoarthritis effectively without side effects observed with oral Diacerein. The following examples describes the nature of the invention and are given only for the purpose of illustrating the present invention in more detail and are not limitative and relate to solutions, which have been particularly effective on bench scale and prepared by the process of the present invention.

[0076] Example 1: Composition of Rhein Transferosomal Gel

[0077] Manufacturing process

[0078] Step 1: Dispensed quantity of span-60 was added to 80% quantity of pH 7.4 phosphate buffer and stirred at 50 - 60°C,

[0079] Step 2: To step 1, dispensed quantity of Rhein was added and mixed for 1 hour at 50 - 60°C until dissolved,

[0080] Step 3: To step 2, lecithin and cholesterol were added and mixed for 3 hours at 50 - 60°C until dissolved, Step 4: To step 3, Transcutol and glycerol were added and stirred for 2 hours,

[0081] Step 5: To step 4, Carbopol (Acrypol - 956) was slowly added and stirred continuously until completely swelled and volume was made up with remaining portion of pH 7.4 phosphate buffer, Step 6: To step 5, dispensed quantity of triethanolamine was added and stirred continuously until a uniform and consistent gel was formed,

[0082] Step 7: weight was adjusted to batch size and stirred until uniform transferosomal gel was obtained, Step 8: above Transferosomal gel filled in to specified tubes.

[0083] Example 2: Composition of Rhein Transferosomal Gel

[0084] Manufacturing process Step 1: Dispensed quantity of span-60 was added to a vessel and heated with stirring at 60 - 70°C,

[0085] Step 2: To step 1, dispensed quantity of Rhein, lecithin and cholesterol were added and mixed for 1 hour at 60 - 70°C until dissolved,

[0086] Step 3: To step 2, 60% phosphate buffer pre-heated to about 60° C and simethicone were added and mixed for 3 hours at 60 - 70°C until dissolved,

[0087] Step 4: To step 3, Transcutol and glycerol were added and stirred for 2 hours, Step 5: To step 4, Carbopol (Acrypol - 956) was slowly added and stirred continuously until completely swelled and volume was made up with remaining portion of pH 7.4 phosphate buffer,

[0088] Step 6: To step 5, dispensed quantity of triethanolamine was added and stirred continuously until a uniform and consistent gel was formed,

[0089] Step 7: weight was adjusted to batch size and stirred until uniform gel was obtained,

[0090] Step 8: Above Transferosomal gel filled in to specified tubes. Example 3: Composition of Rhein Gel

[0091] Manufacturing process

[0092] Step 1: Dispensed quantity of DMSO was taken in a beaker and was heated to 50 °C - 60 °C and then Rhein API was added and stirred to dissolve, Step 2: On other hand, a known portion of pH 7.4 phosphate buffer was heated up to 70 °C and to it dispensed quantities of methylparaben and propylparaben were added and cooled to room temperature, Step 3: To step 2, dispensed quantity of carbomer was slowly added and stirred continuously until completely swelled,

[0093] Step 4: Step 2 contents were added to step 3 and mixed well,

[0094] Step 5: To step 4, remaining portion of pH 7.4 phosphate buffer was added and stirred for about 2 hours to endure uniform mixing,

[0095] Step 6: To step 5, dispensed quantity of triethanolamine was added and stirred continuously until a uniform and consistent gel was formed.

[0096] Example 4: Composition of Diacerein Transferosomal Gel

[0097] Manufacturing process

[0098] Step 1: Dispensed quantity of span-60 was added to 80% quantity of pH 7.4 phosphate buffer and stirred at 50 - 60°C,

[0099] Step 2: To step 1, dispensed quantity of Diacerein was added and mixed for 60min at 50 - 60°C until dissolved,

[0100] Step 3: To step 2, lecithin and cholesterol were added and mixed for 3h at 50 - 60°C until dissolved,

[0101] Step 4: To step 3, Transcutol and glycerol were added and stirred for 2h, Step 5: To step 4, Carbopol (Acrypol - 956) was slowly added and stirred continuously until completely swelled and volume was made up with remaining portion of pH 7.4 phosphate buffer,

[0102] Step 6: To step 5, dispensed quantity of triethanolamine was added and stirred continuously until a uniform and consistent gel was formed.

[0103] Certificate of Analysis (CoA) for Optimized Rhein Transferosomal Gel IQmg / gm

[0104] Certificate of Analysis (CoA) for Optimized Rhein Conventional Gel - IQmg / gm

[0105] Certificate of Analysis (CoA) for Optimized Diacerein Transferosomal Gel - lOmg / gm Comparative In-Vivo Skin Permeability Studies of Optimized formulations of

[0106] Rhein Transferosomal gel Vs Rhein Conventional Gels Vs Diacerein Transferosomal gel:

[0107] Pharmacokinetics of Proposed drug in blood from topical gel formulations in rats were checked

[0108] Pharmacokinetic Study of Proposed drug products in blood in Rats:

[0109] 1. Use three groups of rats each containing 6 animals

[0110] 2. Group-I of animals should be applied with Rhein Transferosomal formulation

[0111] 3. Group II of animals should be applied with Rhein Conventional Gel formulation 4. Group III of animals should be applied with Diacerein Transferosomal Gel formulation 5. Weigh required amount of topical formulations on watch glasses and note the total weight of each formulation

[0112] 6. Apply the topical formulation (200mg) on the dorsal site of the Rat (approximately 2cm2) and note the time (each group with different formulation).

[0113] 7. Weigh the watch glass and note the exact quantity of formulation applied for each Rat.

[0114] 8. Keep the Rat in holding cage for collection of blood

[0115] 9. Collect the blood from orbital sinus of the Rat at O(pre-dose), 15min, 30min, 45min, 60min, 90min, 120min and 180min (from six rats in each group) after application of the formulation into the tube containing anti-coagulant (K2EDTA solid).

[0116] 10. Centrifuge the blood and collect the plasma

[0117] 11. Store the plasma sample at -20°C until analysed.

[0118] 12. Plasma samples of Group - 1& II ((To which rhein formulation is applied) shall be estimated for the presence of Rhein at each time point

[0119] 13. Plasma samples of Group - III ((To which diacerein formulation is applied) shall be estimated for the presence of Diacerein and Rhein at each time point.

[0120] Results of Group -I: Rhein Transferosomal gel - Trend of penetrated drug plasma concentrations in male wistar rats

[0121] Results of Group-II: Rhein Conventional gel - Trend of penetrated drug plasma concentrations in male wistar rats Results of Group-Ill: Diacerein Transferosomal gel - Trend of penetrated drug plasma concentrations in male wistar rats

[0122]

[0123] Estimation of Pharmacokinetic Parameters

[0124] Upon applying Diacerein Transferosomal gel to rats, Diacerein was found to be unstable and was completely converted to Rhein in-vivo and hence Diacerein concentrations were not observed in plasma when tested in male wistar rats. However, average plasma concentration of rhein from diacerein gel was (1.34ng / mL) less than the average plasma concentration of Rhein from Rhein Transferosomal gel (3.1ng / mL).

[0125] It was also observed that the plasma concentration of rhein from transferosmal gel was found to be higher than conventional gel (3.1ng / mL vs 1.89ng / mL). Calculated Cmaxvalue of rhein from Transferosomal gel was found to be higher than remaining formulations. Relative bioavailability of rhein Transferosomal gel was found to be 1.73 times higher than conventional gel and 1.43 times higher than diacerein gel. Hence, from the above results, it was observed that Rhein Transferosomal gel has shown better penetrability than Diacerein transferosomal and Rhein conventional gels.

[0126] Comparative in-vivo diffusion of Diacerin Vs Rhein Transferosomal gel Vs Rhein conventional gels is given in Figure 1.

[0127] Surface Morphology of Rhein Transferosomal Gel by Scanning Electron Microscopy:

[0128] Surface morphology of optimized formulation of Rhein Transferosomes and Transferosomal gel was done by Scanning Electron Microscopy (SEM Analysis). Images of both Rhein Transferosomes and Transferosomal gel are depicted in Figure 2. It was observed that clear transferosomes and their lamellarity were not seen by SEM and however, the size of individual vesicles was found to be below 20p.

[0129] Determination of Partition Coefficient and pKa of Rhein:

[0130] The partition coefficient of Rhein API was determined by measuring the drug distribution between organic solvent and (octanol) and aqueous solvent (7.4pH buffer) and dissociation constant of Rhein API was determined by half-neutralization method.

[0131] Values obtained are represented in below table.

[0132] IN-VIVO PHARMACOLOGICAL EFFICACY EVALUATION OF TOPICAL RHEIN TRANSFEROSOMAL GEL FORMULATION IN IODOACETATE- INDUCED OSTEOARTHRITIC RATS

[0133] This study is to evaluate the effect of Rhein Transferosomal gel topical application on mono sodium lodoacetate (MIA) induced osteoarthritis model. Male Sprague Dawley (SD) rats were injected with 2 mg of mono sodium lodoacetate (MIA) into right knee joint. One week after injection, randomization was carried out based on body weight and grouped into 3 groups each containing 8 animals. One group was administered with diacerein 15mg / kg / day and another group with topical application of Rhein Transferosomal gel 12mg / kg / day initiated from 1 week after MIA injection to week 12 (week 2 to week 12). The control group animals were dosed with vehicle / placebo gel application.

[0134] Animals were anaesthetized with isoflurane and blood sample were collected on 7th day from application / administration and on final day study termination. After blood collection on final day of termination, 50% animals were sacrificed for synovial fluid and joint cartilage collection and another 50% animals were terminated for femorotibial joint collection for histopathological evaluation. Diacerein oral administration and Rhein Transferosomal gel topical application was well tolerated without any abnormal clinical signs. MIA injected right knee joint in control group animals showed significant increase in histopathology score whereas left knee joint did not show any osteo arthritic disease related pathological findings.

[0135] The diagrammatic effect of Placebo Vs Diacerein oral administration Vs Rhein transferosomal gel improvement / amelioration of MIA is shown in Figures 3-7.

[0136] Diacerein oral administration and Rhein transferosomal gel topical application had shown -29% and - 23% reduction respectively in total histopathology score when compared to control group. Diacerein suspension oral administration at 15mg / kg / day showed -24% increase and topical application of Rhein Transferosomal gel at 12mg / kg / day showed - 94 % increase in articular cartilage Chondroitin sulfate levels compared to control group. On day 7 and final day of application, plasma Rhein levels measurement Ihr after diacerein administration showed -732 nM and ~1093nM whereas Rhein transferosomal gel topical application showed -540 nM and -2109 nM levels. The trend towards improvement / amelioration of MIA induced histopathological changes were comparable between the Diacerein po administration at 15 mg / kg / day and Rhein gel topical application at 12mg / kg / day.

[0137] Topical application transferosomal of Rhein gel at 12mg / kg / day is well tolerated in MIA induced osteoarthritis rat model and the trend towards improvement in histopathology of knee joint and augmentation of chondroitin Sulfate is comparable with Diacerein po administration at 15 mg / kg / day.

Claims

I / WE CLAIM:

1. A Rhein transferosomal gel formulation comprising pharmaceutically acceptable excipients selected from Vesicle forming lipids, buffering agents, emulsifying agents, penetration enhancers, humectants, gelling agents, thickening agents, pH adjusting agents and anti-foaming agents.

2. The formulation as claimed in claim 1, wherein said vesicle forming lipids are selected phospholipids, soya lecithin, L-a-(distearoyl) lecithin, L-a-(diapalmitoyl) lecithin, L-a-phosphatide acid, L- a- (dilauroyl) -pho sphatidic acid, L-a (dimyristoyl) phosphatidic acid, L-a(dioleoyl)phosphatidic acid, DL-a(dipalmitoyl) phosphatidic acid, L-a(distearoyl) phosphatidic acid, and the various types of L-a- phosphatidylcholines prepared from egg yolk and soybean.

3. The formulation as claimed in claim 1, wherein said buffering agents selected from citrate buffers, phosphate buffers, acetate buffers, carbonate buffers, ammonia buffers, borate buffers, lactate buffers, Cholesterol, ethanolamine buffers, glycine buffers, methionine buffers, glutamate buffers, and succinate buffers.

4. The formulation as claimed in claim 1, wherein said emulsifying agents are selected from polawax, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, Span 60.

5. The formulation as claimed in claim 1, wherein said penetration enhancers are selected from propylene glycol, glycerine, isopropyl palmitate, isopropyl myristate, laurocapram, oleic acid, oleyl alcohol, ethoxydiglycol, alkanecarboxylic acids, Azone®, adipic acid derivatives, ethanol, urea, polyethylene glycol (PEG), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone, diethylene glycol monoethyl ether, calcipotriene, detergents, emollients, ethoxy diglycol, triacetin, benzyl alcohol, sodium laureth sulfate, dimethyl isosorbide, medium chain triglyceride oil (MCT Oil), menthol, isopropyl isostearate, propylene glycol monostearate, lecithin, diisopropyladipate, diethyl sebacate, ethyl oleate, glyceryl oleate, caprylic / capric triglyceride, propylene glycol dicaprylate / dicaprate, laureth 4, oleth-2, oleth-20, propylene carbonate, nonoxynol-9,2-n-nonyl-l,3-dioxolane, C7 to C14-hydrocarbyl substituted 1,3 -dioxolane, 1,3-dioxane, or acetal and nonoxynol-15.

6. The formulation as claimed in claim 1, wherein said humectants are selected from glycerol, sorbitol, maltitol, polydextrose, triacetin, propylene glycol, polyethylene glycol (PEG) esters including PEG-20 stearate, PEG-40 stearate, PEG- 150 stearate, PEG- 150 distearate and PEG- 100 stearate, alkoxylated alcohols including laureth- 12, ceteareth-20, laureth-23, glycereth-7, glycereth-12, glycereth-26, PEG-4, PEG-6, PEG-8, PEG-12, PEG-32, PEG-75, PEG-150, dipropylene glycol, polypropylene glycol, pantothenol, gluconic acid salts.

7. The formulation as claimed in claim 1, wherein said gelling agents or thickening agents are selected from Carbopol (Acrypol - 956), hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, methyl cellulose, acacia, alginic acid bentonite, polyvinyl pyrrolidone, magnesium aluminium silicate, carbomer, microcrystalline cellulose, carboxymethylcellulose calcium or sodium, cetostearyl alcohol, ethylcellulose, guar gum, maltodextrin, polyvinyl alcohol, povidone, propylene carbonate, propylene glycol alginate, sodium alginate, sodium starch glycolate, starch, tragacanth, stearic acid and xanthan gum.

8. The formulation as claimed in claim 1, wherein said pH adjusting agents are selected from but not limited to triethanolamine (TEA), citric acid monohydrate, amine base tromethamine, tetrahydroxypropyl ethylenediamine, diethanolamine, aminomethyl propanol and sodium or ammonium hydroxide.

9. The formulation as claimed in claim 1, wherein said antifoaming agents are selected from Simethicone 30% emulsion, dimethicone, polydimethylsiloxane and combinations thereof.

10. A Rhein transferosomal gel formulation, wherein the formulation exhibits Tmaxin a range of 10 mins to 150 mins, Cmaxin a range of 1 to 100 ng / mL and AUC0_, in a range of 100 to 2000 ng / ml*min in the plasma when the Rhein transferosomal gel applied topically.

11. The process for the preparation of formulation as claimed in claim 1, wherein said process comprising steps of: a) adding emulsifying agents to buffer and stirring at 50 - 60°C, b) adding rhein to above step a) and mixing for 1 hour at 50°C to 60°C until dissolved, c) adding vesicle forming lipid and buffer to step b) and mixing for 3 hours at 50 - 60°C until dissolved, d) adding penetration enhancers and humectants to above step c) and stirring continued for 2 hours, e) adding gelling or thickening agents to step d) and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 buffer, f) adding pH adjusting agents step e) and stirring until a uniform and consistent gel was formed, and g) adjusting to batch size and stirring until uniform transferosomal gel was obtained.

12. The process for the preparation of formulation as claimed in claim 1, wherein said process comprising steps of: a) weighing and melting emulsifying agent at 60°C to 70°C, b) adding rhein followed by vesicle forming lipid to step a) and mixing for 1 hour at 60°C to 70°C until dissolved, c) adding pre-heated phosphate buffer and anti-foaming agents to above step b) and mixing for 3 hours at 60°C to 70°C until dissolved,d) adding penetration enhancers and humectants to above step c) and stirring continued for 2 hours, e) adding gelling agents to step d) and stirring continuously until completely swelled and volume making up with remaining portion of pH 7.4 buffer, f) adding pH adjusting agents step e) and stirring until a uniform and consistent gel was formed, and g) adjusting to batch size and stirring until uniform transferosomal gel was obtained.

13. A method of treating osteoarthritis in a mammal by topical application of the therapeutically equivalent amount of rhein transferosomal gel formulation.

14. The method of treatment as claimed in claim 13, wherein said therapeutic amount of Rhein in Transferosomal gel is from 30 mg to 300 mg twice daily.

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