Pharmaceutical formulations of tofacitinib and preparation method thereof

Abstract

Pharmaceutical formulations of tofacitinib and preparation method thereof ABSTRACT The present disclosure relates to novel pharmaceutical formulations containing tofacitinib or a pharmaceutically acceptable salt’s thereof for treating dermatological conditions, such as atopic dermatitis, psoriasis, and eczema and autoimmune disorders such as rheumatoid arthritis, wherein the formulation is a solid lipid nanoparticles (SLNs) based formulation.

Specification

Description:TITLE OF THE INVENTION
Pharmaceutical formulations of tofacitinib and preparation method thereof
FIELD OF THE INVENTION
The present invention relates to stable pharmaceutical compositions comprising Tofacitinib or a pharmaceutically acceptable salt thereof, surfactant, cholesterol, and optionally one or more pharmaceutical excipients. The present invention further relates to methods of preparing and administering such pharmaceutical compositions for treating autoimmune disorders, in particular rheumatoid arthritis and psoriasis.
BACKGROUND OF THE INVENTION
Tofacitinib Citrate is chemically known as (3R,4R)-4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino]-ß-oxo-1•piperidinepropanenitrile,2-hydroxy-1,2,3-propane tricarboxylate (1:1) and was approved by USFDA under the brand name XELJANZ to PFIZER for treating rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, Ulcerative Colitis in adults and Polyarticular Course Juvenile Idiopathic Arthritis in patients 2 years of age and older.
Tofacitinib is a Janus kinase (JAK) inhibitor, which was first disclosed in U.S. Pat. No. US7432370. US9937181 and US10639309 disclose tablet comprising Tofacitinib with specific excipients.
Oral administration of Tofacitinib citrate can present several challenges and limitations. Common gastrointestinal side effects such as diarrhea and nausea can impact patient compliance. Additionally, the risk of infections, neutropenia (a decrease in neutrophils), and hyperlipidemia are significant concerns that necessitate careful monitoring. Systemic exposure to the drug can lead to broader, unintended effects throughout the body. There's also an increased risk of major adverse cardiovascular events (MACE), such as heart attacks or strokes, which heightens the need for patient vigilance. First-pass metabolism in the liver reduces the bioavailability of Tofacitinib, and its metabolism and clearance from the body can vary widely among individuals, complicating dosage optimization and efficacy.
In view of the above side effects, it is therefore desirable to develop alternate dosage forms other than oral composition comprising Tofacitinib or a pharmaceutically acceptable salt thereof that are stable and having excellent bioavailability.
Alternate dosage forms includes topical formulations. Among those topical tofacitinib formulations with nano drug carriers include liposomal drug delivery systems, although successful in improving the pharmacokinetics and bioavailability of drugs, encounter challenges related to stability during storage, batch-to-batch consistency, and scalability.
Further, at times topical formulations prone for crystallization and precipitation that can significantly impact the stability and efficacy of the drug product. Crystallization can lead to the formation of solid particles within the formulation, which may affect the drug's bioavailability and uniformity. Precipitation can occur when the drug or other components become insoluble under certain conditions, leading to phase separation and reduced effectiveness. These issues can compromise the quality and performance of topical formulations, making it crucial to address them during the development and manufacturing process.
Hence, there remains a need to develop an alternate topical drug delivery system which provides maximum penetration of tofacitinib to treat various autoimmune disorders especially rheumatoid arthritis, atopic dermatitis and psoriasis.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
The present invention discloses a pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles, wherein said solid lipid nanoparticles consist of a lipid that is solid at room temperature, along with tofacitinib or it's salt thereof, and a surfactant in organic phase assisted by co-surfactants to stabilize the drug loaded lipid matrix in the aqueous phase, and optionally one or more pharmaceutically acceptable excipients.
The disclosed formulations of the invention are stable at room temperature for at least 6 months without any precipitation and crystallization.
The disclosed solid lipid nanoparticles of tofacitinib or pharmaceutical salt thereof are suitable for various routes of administration, including oral, parenteral, and topical routes.
The formulations of the present invention are topical formulations which are advantageous in treating autoimmune disorders that may include psoriasis, atopic dermatitis, vitiligo, epidermolysis bullosa acquisita, pemphigus vulgaris, IgA-mediated bullous dermatoses, systemic lupus erythematosus, alopecia areata, porphyria, scleroderma, multiple sclerosis and skin complication of Type I diabetes but not limited to rheumatoid arthritis.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1. illustrates drug release studies showing % cumulative drug release (CDR) of tofacitinib citrate gel and tofacitinib citrate SLN-Gel and kinetic model plots with drug release data of TCB SLNs-Gel; the chart showing the changes in paw volume in the groups of in vivo antiarthritic activity.

BRIEF DESCRIPTION OF THE INVENTION
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception, and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Definitions:

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated member, integer or step or group of members, integers or steps but not the exclusion of any other member, integer or step or group of members, integers or steps.

The terms "a" and "an" and "the" and similar reference used in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.
As used herein, the terms "composition(s)" and "formulation(s)" can be used interchangeably depending on the context in which they are used as would be appreciated by a person skilled in the art.
The term "room temperature" as used herein, means 20 °C to 25 °C. In an embodiment it is 20 °C. In an embodiment it is 21 °C. In an embodiment it is 22 °C. In an embodiment it is 23 °C. In an embodiment it is 24 °C. In an embodiment it is 25 °C.
As used herein, the term "gel", refers, inter alia, to a carrier or formulation or composition that is not flowable at room temperature, such that when subjected to normal gravity at room temperature, it will retain its form.
"Surfactant," "emulsifier," and "surface active agent," as used herein, do not include compounds which do not function effectively on their own to reduce surface tension between two substances or phases and stabilize an emulsion of water and oil, or two phases in the system.
As used herein, the term "emollient" refers to a material or agent that, when placed in contact with the human skin, is able to soften, smoothen, reduce scaling and itching, reduce inflammation, improve skin barrier function, and/or act as a carrier for active agents. Examples of emollients include but are not limited to avocado oil, isopropyl myristate, mineral oil, capric triglycerides, caprylic triglyceride, isopropyl palmitate, isopropyl isostearate, diisopropyl adipate, diisopropyl dimerate, maleated soybean oil, octyl palmitate, cetyl lactate, cetyl ricinoleate, tocopheryl acetate, acetylated lanolin alcohols, cetyl acetate, phenyl trimethicone, glyceryl oleate, tocopheryl linoleate, wheat germ glycerides, arachidyl propionate, myristyl lactate, decyl oleate, ricinoleate, isopropyl lanolate, pentaerythrityl tetrastearate, neopentylglycol dicaprylate/dicaprate, isononyl isononanoate, isotridecyl isononanoate, myristyl myristate, triisocetyl citrate, octyl dodecanol, unsaturated or polyunsaturated oils, olive oil, corn oil, soybean oil, canola oil, cottonseed oil, coconut oil, sesame oil, sunflower oil, borage seed oil, syzigium aromaticum oil, hempseed oil, herring oil, cod-liver oil, salmon oil, flaxseed oil, wheat germ oil, evening primrose oil, an essential oil, a silicone oil, dimethicone, cyclomethicone, polyalkyl siloxane, polyaryl siloxane, polyalkylaryl siloxane, a polyether siloxane copolymer, and poly(dimethylsiloxane)-(diphenyl-siloxane).
The term "Tofacitinib" as used herein includes the base, pharmaceutically acceptable salts, polymorphs, stereoisomers and mixtures thereof, the term "pharmaceutically acceptable salt" means a salt which is acceptable for administration to a patient, such as a mammal (e.g., salts having acceptable mammalian safety for a given dosage regime). Such salts can be derived from pharmaceutically acceptable inorganic or organic bases and from pharmaceutically acceptable inorganic or organic acids.
The term, "pharmaceutically acceptable excipients" as used herein refers to solubiliser, solvents, co-solvents, preservatives, wetting agents, thickening agents, rheology modifiers or thickening agent, antifoaming agents, stabilizers, an antioxidant, a chelating agent, an oil phase, an emulsifier, a penetration enhancer, a pH adjusting agent, a preservative, an antimicrobial agent, an opacifier, a fragrance, a colorant, a gelling agent, a moisturizer, a surfactant and the like. The pharmaceutical compositions of the present invention may be formulated in a conventional manner using one or more pharmaceutically acceptable excipients.
The term "Topical composition" or "pharmaceutical composition" or "dosage form" as used herein synonymously include topical dosage forms such as a solution, a suspension, a cream, an ointment, a lotion and a gel. Preferably, the topical formulation is a solution or a gel. More preferably, the topical formulation is a gel.
The term "stable" as used herein refers to formulations that substantially retain the label amount of the therapeutically active ingredient during storage for commercially relevant times, and the drug-related impurity contents in the formulations remain within acceptable limits.
As used herein the term "Solid Lipid Nanoparticles (SLNs)" are submicron-sized colloidal carriers, typically in the range of 50-1000 nm, composed of solid lipids that remain solid both at room and body temperatures. They serve as a drug delivery system that encapsulates therapeutic agents within a solid lipid matrix, which stabilizes the drug, enhances its bioavailability, and allows for controlled and sustained release. SLNs are known for their biocompatibility, low toxicity, and versatility, making them suitable for delivering both hydrophobic and hydrophilic drugs via various administration routes, such as oral, topical, and intravenous. Common lipids used in Solid Lipid Nanoparticles (SLNs) include: Glyceryl monostearate (GMS), Stearic acid, Glyceryl behenate (Compritol® 888 ATO), Glyceryl palmitostearate (Precirol® ATO 5), Cetyl palmitate, Tripalmitin, Trimyristin Tristearin. Surfactants used in the fabrication of SLNs include polysorbates such as Polysorbate 80 (also known as Tween 80). Poloxamers like Poloxamer 188 and Poloxamer 407 are also used as stabilizers and emulsifiers. Sodium dodecyl sulfate (SDS) and lecithin are other surfactants that help in the formulation. PEGylated surfactants such as PEG-40 stearate, along with bile salts like sodium cholate and sodium deoxycholate, are included as well.
Before undertaking the detailed description of the invention below it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise " as well as derivatives thereof mean inclusion without limitation; the term "or " is inclusive meaning and/or; the phrases "associated with" and "associated therewith " as well as derivatives thereof may mean to include be included within interconnect with contain be contained within connect to or with couple to or with be communicable with cooperate with interleave juxtapose be proximate to be bound to or with have a property of or the like; and the term .
In one embodiment, the present invention provides a stable pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles, wherein said solid lipid nanoparticles consist of a lipid that is solid at room temperature, surfactant in organic phase assisted by co-surfactants to stabilize the drug loaded lipid matrix and the aqueous phase, Tofacitinib or it's salt thereof and optionally one or more pharmaceutically acceptable excipients.
In the above mentioned embodiment, the disclosed solid lipid nanoparticles of tofacitinib or pharmaceutical salt thereof are suitable for various routes of administration, including oral, parenteral, and topical routes.
In any of the above mentioned embodiments, the disclosed formulation is a topical formulation and further comprises a carrier base and at least one emollient.
In any of the above mentioned embodiments of the invention, wherein the tofacitinib salt is a citrate salt, hydrochloride salt, hydrobromide salt, oxalate salt, nitrate salt, sulfate salt, phosphate salt, fumarate salt, succinate salt, maleate salt, besylate salt, tosylate salt, palmitate salt, tartrate salt, adipate salt, laurate salt, or myristate salt.
In any of the above mentioned embodiments of the invention, wherein the solid lipid matrix is enveloped by the surfactants and stabilized with other one or more pharmaceutically accepted formulation excipients embedding hydrophilic, lipophilic or amphiphilic drug molecules in the lipid matrix.
In any of the above-mentioned embodiments of the invention, the lipid is selected from the group consisting of fatty acids such as stearic acid, palmitic acid, and oleic acid; triglycerides such as tripalmitin, trilaurin, trimyristin, and tristearin; glycerides and glycerol esters such as glyceryl monostearate (GMS), glyceryl behenate (Compritol® 888 ATO), and glyceryl palmitostearate (Precirol® ATO 5); waxes such as cetyl palmitate, carnauba wax, and beeswax; solidified oils such as castor oil derivatives (like hydrogenated castor oil) and coconut oil (in solidified form); and phospholipids (used in combination with solid lipids) such as soy lecithin and egg lecithin."
In any of the above mentioned embodiments of the invention, lipid concentration is within a range of 80 mg to 150 mg.
In any of the above mentioned embodiments of the invention, wherein the lipid concentration ranges from 5% (w/w) to 30% (w/w) of the total formulation.
In any of the above mentioned embodiments of the invention, lipid-to-surfactant ratios ranges between 1:1 to 4:1.
In any of the above mentioned embodiments of the invention, wherein the surfactant concentration ranges between 30 mg to 200 mg.
In any of the above mentioned embodiment, the surfactant includes polysorbates, poloxamers, sodium dodecyl surfactant and lecithin.
In any of the above mentioned embodiments of the invention, the lecithin concentration is within a range of 30 mg to 100 mg.
In any of the above mentioned embodiments, the surfactant polaxomer 188 concentration is within a range of 100 mg to 200 mg.
In any of the above mentioned embodiments of the invention, the surfactant lecithin concentration is 30 mg to 80 mg and poloxamer 188 concentration is 100 mg to 200 mg.

In any of the above mentioned embodiments of the invention, the pharmaceutically acceptable excipients are charge inducers, organic solvents, aqueous carrier, viscosity modifier, co-surfactant, buffer and stabilizer.
In the above mentioned embodiment, the charge inducer is selected from the group consisting of dicetyl phosphate, dihexadecyl phosphate, lipoamine acid, stearyl amine, and cetylpyridinium chloride. Charge are included to alter the surface charge of the solid lipid nanoparticles
In any of the above mentioned embodiments, the stabilizer is selected from the group consisting of cholesterol, pluronic F-127, span-60, stearyl amine, Dicetyl phosphate tocopherol, polyethylene glycol, and sodium alginate.
In any of the above mentioned embodiments of the invention, the viscosity modifiers, is selected from the group consisting of carbopol® 940 and hydroxypropyl methylcellulose (HPMC), are used to adjust the viscosity of the formulation. These excipients such as charge inducers, stabilizers or viscosity modifiers are carefully selected based on the desired properties of the SLN formulation, such as particle size, surface charge, stability, and release profile.
In any of the above mentioned embodiment, the co-surfactant is butanol or ethanol.
In any of the above mentioned embodiment of the invention, the osmotic agents is glycerol or mannitol. The osmotic agents are used to maintain osmotic balance in the SLNs.
In any of the above mentioned embodiments of the invention, optionally the solid lipid nanaoparticle formulations comprises cryoprotectants and the cryoprotectant is sucrose or trehalose or like. These cryoprotectants are added to prepare tofacitinib within solid lipid nanoparticle for freeze-drying stability.
In yet another embodiment, the invention discloses a pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles (SLNs), wherein said SLNs consist of a 80 mg to 150 mg lipid, 30 mg to 80 mg soy lecithin, 100 mg to 200 mg poloxamer, 8 mg to 15mg Tofacitinib or it's salt thereof and optionally one or more pharmaceutically acceptable excipients wherein the SLNs have a particle size ranging from 50 to 1000 nm in formulation.
In the above mentioned embodiment, the disclosed formulation is a topical formulation.
In a furthermore embodiment of the invention discloses a topical pharmaceutical formulation of Tofacitinib-solid lipid nanoparticle (SLN) gel comprising:
a) tofacitinib or a pharmaceutically acceptable salt thereof SLNs;
b) gelling agent;
c) solvents/Co-solvents;
d) penetration enhancers;
e) pH adjusting agents;
f) preservatives;
g) humectants;
h) antioxidant; and
i) optionally comprising one or more pharmaceutically acceptable excipients selected from the group consisting of emollients, antioxidants, colorants, and fragrances.
In any of the above mentioned embodiments, the formulation is stable at room temperature without any agglomerates.
In any of the above-mentioned embodiment of the invention, the gelling agent is selected from the group consisting of Carbopol 934, 940, HPMC, Xanthan gum.
In any of the above-mentioned embodiment of the invention the solvents/Co-solvents is selected form the group consisting of water, ethanol, propylene glycol;
In any of the above-mentioned embodiment of the invention, the penetration enhancer is selected from the group consisting of ethanol, oleic acid, propylene glycol, dimethyl sulfoxide, urea, azone, isopropyl myristate, menthol, carbomer, SLS, lecithin, capsaicin, transcutol, polysorbate-80, and tween-20.
In any of the above-mentioned embodiment of the invention, the pH adjusting agent is triethanolamine,
In any of the above-mentioned embodiment of the invention, the preservative is selected from the group consisting of parabens, and phenoxyethanol.
In any of the above-mentioned embodiment of the invention, wherein the humectant is glycerine.
In some embodiments, the topical formulation comprises an antioxidant. Preferably, the antioxidant can be, for example, butylated hydroxyanisole, butylated hydroxytoluene, vitamin C, vitamin E, vitamin A, lutein, lycopene, retinyl palmitate, potassium metabisulfite, sodium metabisulfite, sodium thiosulfate pentahydrate, 3,4-dihydroxybenzoic acid, propyl gallate, alpha-lipoic acid, ascorbyl palmitate, sodium pyrosulfite, ubiquinone, selenium, or a combination thereof. More preferably, the antioxidant is butylated hydroxytoluene.
In any of the above-mentioned embodiment of the invention, the disclosed tofacitinib formulation is an oral or parenteral or topical formulation.
In any of the above-mentioned embodiment of the invention, the disclosed tofacitinib formulation is a gel, ointment or cream, lotion, pastes, patches, sprays, foams.
In any of the above-mentioned embodiment of the invention, the formulation has a pH between 4.5 to 6.5.
In any of the above mentioned embodiments of the invention, the particle size of tofacitinib or a pharmaceutically acceptable salt thereof is in the range of 50 nm to 1000 nm. More specifically 100 nm to 500 nm, and is 74.3 ± 3.42 to 244.2 ± 5.53 nm.
In any of the above mentioned embodiments of the invention, the disclosed formulations are stable at 22 ° C -25 ° C for a period of time includes at least one month.
In the above mentioned embodiment, the formulation is free of any agglomerates and crystallization.
In any of the above mentioned embodiments, the disclosed formulations are useful for the treatment of autoimmune disorders such as rheumatoid arthritis psoriatic arthritis, ulcerative colitis, poly articular course juvenile idiopathic arthritis, ankylosing spondylitis atopic dermatitis.
In an embodiment the present invention discloses, a topical pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles, wherein said solid lipid nanoparticles consist of 3 mg to 10mg of Tofacitinib or it's salt thereof; 80 mg to 150 mg lipid or lipid combinations, 30 mg to 100 mg of lecithin and 100 mg to 200 mg of poloxamer 188, and optionally one or more pharmaceutically acceptable excipients wherein the solid lipid nanoparticles have a particle size ranging from 100 to 1000 nm in the said formulation.

The invention specifically discloses tofacitinib or a pharmaceutically acceptable salt thereof solid lipid nanoparticles. The solid lipid nanoparticles possess qualities like enhanced stability, bio biodegradability, low toxicity, improved bioavailability, and can offer a controlled release of embedded drug, protection against drug leakage, can get imbibed in to skin layers easily and thereby enhance penetration of drug through the skin layers, and prolong their presence, thereby reducing systemic absorption. This can be advantageous in regulating drug effects within the body. When SLNs loaded gel is applied to the skin, that enhances the properties of the outermost skin layer by decreasing its water loss. Additionally, the occlusion and merging of SLNs with the skin elements will enhance the drug's thermodynamic activity gradient, affecting drug permeation.
The topical formulation as disclosed in the present invention has following advantages. First advantage is that, tofacitinib SLN formulations are stable as compared to nanoemulsions and liposomes. Tofacitinib loaded nanoemulsions showed visible coalescence, phase separation, and droplet growth within 30 days of preparation. In contrast, Tofacitinib-SLNs suspension remained stable for 180 days at low temp without any significant changes in the vesicles size, PDI, and zeta potentials. The amount of Tofacitinib was reduced to 98% at 45° C after 120 days of storage, whereas the Tofacitinib liposomes have shown a reduction in tofacitinib content by 89% after 120 days of storage at the same temperature.
The lipid nanoparticle delivery system offers several advantages for tofacitinib. It enhances bioavailability by ensuring more of the drug reaches its target site. The encapsulation within lipid nanoparticles improves drug stability, protecting it from degradation. This system also enhances targeting, enabling the drug to be delivered more precisely to the desired tissues. Moreover, it allows for controlled release, ensuring a sustained therapeutic effect over time. The use of biocompatible materials in lipid nanoparticles minimizes the risk of adverse reactions, improving overall biocompatibility. Consequently, this thus can reduce side effects, providing a safer and more efficient way to deliver tofacitinib.
The disclosed formulation of the invention delivers the drug in a sustained release manner. Improved drug release was observed in in vitro drug release studies conducted for Tofacitinib-SLNs over the free drug solution. 71.07% release was shown in first 8 hrs of release study from free drug solution whereas 100% was the release from Tofacitinib SLN in first 8hr, showing a sustained release and a complete release.
Tofacitinib-SLN gel formulation has shown an improved drug release and % cumulative drug release (CDR) in Invitro drug release studies of SLN gel and free drug gel were 84.5% and 40.2% respectively in the first 8 hrs.
The localized delivery system reduces systemic exposure and risk of serious side effects. Further, the localized drug delivery improves efficacy at the target site.
The disclosed formulations of the invention are more convenient and patient-friendly and allows for safer long-term use in managing chronic conditions.
The disclosed solid lipid nanoparticles of tofacitinib or pharmaceutical salt thereof are suitable for various routes of administration, including oral, parenteral, and topical routes.
Certain specific aspects and embodiments of the invention are more fully described by reference to the following examples. However, these examples should not be construed as limiting the scope of the invention in any manner.
Examples
Example 1: Preparation of TCB SLNs Formulation of SLNs
Tofacitinib citrate solid lipid nanoparticle were prepared by emulsion solvent evaporation method. The method is detailed below.
1. Organic phase preparation: Dissolve the lipid (glyceryl monostearate), soy lecithin, and drug (tofacitinib citrate) in a mixture of 6 ml chloroform and methanol (1:1 ratio) to form the organic phase.
2. Combination and homogenization:
o Add the organic phase dropwise into an aqueous solution containing Poloxamer-188.
o Homogenize the mixture at 1200 rpm for 20 minutes at 70°C.
3. High-Speed homogenization:
o Increase the speed and homogenize at 10,000 rpm for 20 minutes.
4. Probe sonication:
o Subject the homogenized mixture to probe sonication at 40% amplitude and 40°C.
o Set the pulse to "on" for 10 seconds and "off" for 5 seconds and sonicated for a stipulated period to obtain a solid lipid nanoparticle dispersion of uniform size.
This method ensures the formation of uniform solid lipid nanoparticles (SLNs) encapsulating tofacitinib citrate, suitable for drug delivery applications.
After a keen understanding of the influential factors in SLN preparation from the preliminary trials, the variable parameters that crucially affect the quality of SLNs were enlisted. Optimization studies were conducted by applying these factors in Box-Behnken Design (BBD) model developed using Design-Expert 13 software, which is an appropriate model in statistical validation techniques of quadratic Response surface methodology when more complexity of multiple factors and responses exit. The independent variables were the lipid GMS (glyceryl monostearate) concentration (A), soy lecithin concentration(B), Tofacitinib concentration (C), probe sonication time (D) and the dependent variables being particle size (nm):(Y1), polydispersity index:(Y2), and the entrapment efficiency:(Y3) as responses, studied in a total of 27 formulation batches suggested by the Design expert. An average of triplicate values of responses for each formulation batch were taken and proceeded for optimization data analysis.
Table 1 shows the responses of formulation batches.
Characterization of formulation batches
The formulation batches thus prepared were assessed for the responses comprehended as dependent variable constraints.
Particle size(PS) and Polydispersity Index (PDI)
PS, and PDI, could be analysed in one setting in Zeta sizer and zeta potential (ZP) in the other, and these parameters were assessed for the formulation batches using ZS 90 in a dynamic light scattering approach (Malvern instruments, UK).
Analytical method development
Quantification of tofacitinib at various instances during the evaluation was availed with the RP-HPLC method developed to plot the tofacitinib calibration curve. An isocratic mobile phase used was Methanol: Water in 70:30 ratio and using C18 column, a detection wavelength at 289 nm, peak retention time was 4.7 min.
Entrapment efficiency
An indirect method of estimation was used for finding the entrapment efficiency of formulated batches of SLNs wherein the trapped drug quantity of tofacitinib in the SLNs sediment was obtained by subtracting the quantity of unentrapped tofacitinib in supernatant solution, after centrifugation at 30,000 rpm for 45 min while the temperature was kept maintained at 4°C, from the amount of total drug added to the formulation and indicates the efficiency of delivery system to uptake and hold the drug into its constitution.
%Entrapment Efficiency = [(Total TCB-Free TCB in Supernatant) / (Total TCB)] × 100
Table 1: Results of evaluation parameters of formulation batches of Tofacitinib citrate SLNs

Factor 1 Factor 2 Factor 3 Factor 4 Response 1 Response 2 Response 3
Run A:GMS B:SL C:TC D:Sonication Time Particle Size PDI EE
Mg Mg Mg Min nm - %
1 120 70 9 7.5 207.8 0.44 93.3
2 110 55 9 7.5 137.1 0.4 84.7
3 110 70 8 7.5 155.4 0.42 78.9
4 110 70 9 5 244.2 0.48 79.2
5 110 40 9 5 230.7 0.54 72.7
6 120 55 9 5 159.3 0.42 78.5
7 100 55 10 7.5 111.4 0.36 77.2
8 110 55 9 7.5 130.2 0.31 84.9
9 110 55 8 10 80.4 0.28 90.5
10 110 55 9 7.5 133.4 0.26 80.4
11 110 55 8 5 240.1 0.51 73.8
12 110 70 10 7.5 189.2 0.44 95.5
13 100 55 8 7.5 140.9 0.29 70.1
14 100 55 9 5 241.4 0.61 71.7
15 120 55 10 7.5 115.1 0.48 94.1
16 100 70 9 7.5 110.1 0.39 78.7
17 100 40 9 7.5 199.8 0.42 71.7
18 110 55 10 10 95.5 0.49 90.4
19 120 40 9 7.5 81.9 0.48 89.9
20 110 40 8 7.5 189.4 0.46 79.2
21 110 55 10 5 194.9 0.46 89.2
22 110 40 10 7.5 89.2 0.36 78.4
23 120 55 9 10 89.2 0.27 94.2
24 110 40 9 10 84.3 0.35 77.8
25 100 55 9 10 74.3 0.26 68.9
26 120 55 8 7.5 95.5 0.48 78.8
27 110 70 9 10 110.2 0.29 94.7
Example 2 Stability of tofacitinib citrate-SLN formulation
The optimized formulation batch of Tofacitinib SLNs was assessed for physical and chemical stability according to ICH guidelines, at varied conditions of storage (2-8°C, 25 ± 2°C, 45 ± 2°C), in a humidity chamber, for three months and a regular monitoring for changes in size of particles and % of EE was carried out to assess the stability of the formulation.
Stability studies were conducted following a standard protocol, for a definite period. The results of assessed parameters did not show any significant changes, at low temperatures in 180 days of study period. SLNs suspension has shown stability with no significant difference in particle size and EE% when stored at cool temperature, and slight changes were observed in particle size and EE% has decreased in SLNs stored at 45 ± 2°C. Sedimentation and rise in particle size were observed, which could be because of particle aggregation, discharge of drug from SLN matrix, and also a decrease in EE%, sooner after three months of storage at 45 ± 2°C and later, at 25 ± 2°C.
Tofacitinib loaded nanoemulsions showed visible coalescence, phase separation, and droplet growth within 30 days of preparation. In contrast, Tcb-SLNs remained stable in 180 days at low temp without any significant changes in the vesicles size, PDI, and zeta potentials. The amount of Tcb was reduced to 99% at 25° C and 98% at 45 ± 2°C after 120 days of storage, compared to liposomes whose EE% was reduced to 89% on storing at 45 ± 2°C after 120 days. The higher stability of SLNs may be attributed to the presence of a right proportion of lipid and surfactant and the surfactants are both hydrophilic and lipophilic to enhance the integrity of lipid matrix and thereby reduce deterioration and degradation and prevents leakage.
Example 3: In Vitro release study of Tofacitinib SLNs
In vitro release studies were conducted using a dialysis sac technique for the SLN suspension and a Franz diffusion cell method for SLN gel. A 2 ml of tofacitinib citrate SLN suspension, equivalent to 1.6 mg of tofacitinib citrate was placed in the dialysis bag of nitrocellulose membrane, priorly tied on one side properly so as not to allow any leakage. The other end of the tubing was also tied and was kept submerged in the beaker containing release medium-PBS buffer (pH 7.4), maintained at 37 ± 1°C, and a stirring speed of 70 rpm. Samples were drawn at regular time intervals, for HPLC analysis, and replaced an equivalent quantity of fresh buffer for balancing the sink condition. The release data was interpreted in different mathematical models to understand the release profile of tofacitinib citrate from tofacitinib citrate -loaded SLN suspension to compare with that of the free- tofacitinib citrate drug solution examined in similar test conditions.
Example 4: Preparation and characterization of Tofacitinib citrate SLNs gel (TCB SLN gel)
Tofacitinib citrate SLN concentrate was obtained by centrifuging the suspension of SLN formulation for 30 min at 20,000 rpm and discarding the supernatant portion with unentrapped Tofacitinib citrate and the SLN concentrate thus obtained was resuspended into water. Carbopol 934 was the gelling agent used. A 1% hydrogel was prepared by dispersing a SLN concentrate along with the gelling agent into a relevant quantity of water, soaking and incubating for 6 hours while continuously mixing, and finally adjusting the pH using 0.5% triethanolamine. A visual inspection of the gel's colour and texture was conducted.
A digital pH meter (model CPH 102) was used to measure the pH of Tofacitinib citrate SLN gel after a predetermined amount of gel had been appropriately diluted in distilled water. Using a Brookfield Viscometer, spindle 64 (DV-III, USA), the viscosity of the produced gel was measured. 0.5 gm samples from different portions of the formulations were obtained and individually dissolved in PBS of pH 7.4 before being evaluated by HPLC to ascertain the percentage drug content and homogeneity.
Example 5: In vivo anti-arthritic activity of Tofacitinib citrate SLNs in oral suspension and topical gel
The induction of arthritis in male Wistar rats was accomplished using Freund's complete and incomplete adjuvant factor. For the study, five groups, each containing 6 animals were used, among which one group served as the normal control (group-1) (NC), and one was the disease control (group-2) (DC), three were treatment groups (TG). Arthritis was induced in three groups, except NC, with 0.1 ml of Freund's complete Adjuvant (FCA) injected in the sub-plantar region of the right hind paw and incomplete Freund's factor into the same paw as a booster dose on the 7th day. The NC group remained unimmunized. Development of arthritis was confirmed through visual observations, measurement of inflammation, joint and paw swelling, and estimation of arthritic score, indicating an established RA condition. The study continued with bis-in-die topical treatment in two animal groups using tofacitinib citrate free drug gel (group-3), tofacitinib citrate SLNs gel (group-4) and tofacitinib citrate SLNs orally with Tofacitinib rat dose equivalent to 0.2 mg of Tofacitinib for 14 days starting from the 14th day of disease inoculation with FCA. Throughout the study period, arthritic scores, paw volumes, and joint stiffness were regularly assessed. The disease control (DC) group and the treatment groups have shown an increase in the paw volume after the FCA inoculation. In treatment groups, the paw inflammation gradually reduced upon treatment with Tofacitinib citrate control gel, Tofacitinib SLN oral and Tofacitinib citrate SLNs gel, separately to the groups, and in the DC group, it was sustained throughout the study period. Changes in the paw volume are depicted in the chart in Figure 1.
Advantages of Tofacitinib SLNs and topical gel of Tofacitinib SLNs thereof:
Tofacitinib-loaded Solid Lipid Nanoparticles (SLNs) in a topical gel formulation offer multiple advantages:
1. Enhanced Drug Stability: SLNs protect tofacitinib from environmental degradation, improving stability and shelf life.
2. Localized Drug Delivery: The gel allows targeted delivery to affected skin areas, which is ideal for rheumatoid arthritis and other inflammatory skin conditions.
3. Reduced Systemic Side Effects: By delivering tofacitinib locally, systemic absorption is minimized, lowering the risk of systemic adverse effects commonly associated with oral administration.
4. Improved Skin Penetration: SLNs and the gel base improve skin permeability, allowing better penetration of tofacitinib into deeper skin layers and joints.
5. Controlled Drug Release: SLNs provide sustained release of tofacitinib, potentially extending its therapeutic effects and reducing the need for frequent application.
6. Enhanced Bioavailability: For poorly soluble drugs like tofacitinib, SLNs improve solubility, enhancing bioavailability at the target site.
This approach can improve treatment outcomes and patient comfort while minimizing adverse effects compared to systemic delivery.
, Claims:Claims
I/We claim

1. A pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles (SLNs), wherein said solid lipid nanoparticles consist of a solid lipid, surfactant(s), tofacitinib or it's salt thereof and optionally one or more pharmaceutically acceptable excipients.
2. The pharmaceutical formulation as claimed in claim 1, wherein the formulation is a topical or oral or parenteral formulation.
3. The pharmaceutical composition as claimed in claim 1, wherein the tofacitinib salt is a citrate salt, hydrochloride salt, hydrobromide salt, oxalate salt, nitrate salt, sulfate salt, phosphate salt, fumarate salt, succinate salt, maleate salt, besylate salt, tosylate salt, palmitate salt, tartrate salt, adipate salt, laurate salt, or myristate salt.
4. The pharmaceutical formulation as claimed in claim 1, wherein the lipid is selected from the group consisting of glyceryl monostearate (GMS), stearic acid, glyceryl behenate (Compritol® 888 ATO), glyceryl palmitostearate (Precirol® ATO 5), cetyl palmitate, tripalmitin, trimyristin, and tristearin.
5. The pharmaceutical formulation as claimed in claim 4, wherein the lipid concentration ranges from 5% (w/w) to 30% (w/w) of the total formulation.
6. The pharmaceutical formulation as claimed in claim 1, wherein the surfactant is selected from the group consisting of polysorbates, poloxamers, Sodium dodecyl sulfate (SDS), lecithin, PEGylated surfactants, and bile salts.
7. The pharmaceutical formulation as claimed in claim 1, lipid-to-surfactant ratios ranges between 1:1 to 4:1.
8. The pharmaceutical formulation as claimed in claim 1, wherein the lipid concentration ranges between 80 mg to 150 mg.
9. The pharmaceutical formulation as claimed in claim 1, wherein the surfactant concentration ranges between 30 mg to 200 mg.
10. The pharmaceutical formulation as claimed in claim 1, wherein the pharmaceutically acceptable excipients are charge inducers, organic solvents, aqueous carrier, buffer and stabilizer.
11. A pharmaceutical composition comprising tofacitinib or a pharmaceutically acceptable salt thereof within solid lipid nanoparticles, wherein said solid lipid nanoparticles consist of 3 mg to 10mg of Tofacitinib or it's salt thereof; 80 mg to 150 mg lipid or lipid combinations, 30 mg to 100 mg of lecithin and 100 mg to 200 mg of poloxamer 188, and optionally one or more pharmaceutically acceptable excipients wherein the solid lipid nanoparticles have a particle size ranging from 100 to 1000 nm in the said formulation.
12. The topical formulation as claimed in claim 1 or 11, wherein the formulation is stable at room temperature without any agglomerates.
13. A topical pharmaceutical formulation of tofacitinib solid lipid nanoparticles gel comprising:
a) therapeutically effective amount of Tofacitinib or a pharmaceutically acceptable salt thereof solid lipid nanoparticles;
b) gelling agent;
c) solvents/Co-solvents;
d) penetration enhancers;
e) pH adjusting agents;
f) preservatives;
g) humectants;
h) an antioxidant and
i) optionally comprising one or more pharmaceutically acceptable excipients selected from the group consisting of emollients, antioxidants, colorants, and fragrances.

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