STABLE REMDESIVIR FORMULATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS:

This application claims priority to Indian Application No. 202021046615, filed 26 ^th October, 2020 and entitled “STABLE REMDESIVIR FORMULATIONS” which is incorporated herein in its entirety.

FIELD OF INVENTION:

The invention is directed to stable formulations of nucleotide analogue prodrug, in particular Remdesivir in the form of cyclodextrin-free ready-to-use solution and ready-to-dilute concentrates for the treatment of COVID-19.

BACKGROUND AND PRIOR ART:

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease of potential zoonotic origin. Severe acute respiratory syndrome (SARS) corona virus- 2, (SARS-CoV-2), the etiological agent of COVID-19, can cause a serious or lifethreatening disease or condition, including severe respiratory illness. The public health concerns caused by the outbreak of COVID-19 was declared as a “public health emergency of international concern” on 31 January and “pandemic on 11 March 2020 by World Health Organization. Impacts of the COVID-19 pandemic are currently ‘skyrocketing’ across the globe, causing enormous public health havoc and a colossal economic crisis.

The spread of COVID-19 is so accelerating that it needed 67 days from the first diagnosed case to reach the first 100,000 cases, 11 days for the second 100,000 cases, 4 days for the third 100,000 cases, 3 days for the fourth 100,000 cases and just extra 7 days for additional 400,000 cases around the globe. A similar pattern has been seen in the fatality as it required 17 days from the first death reported on 11 January 2020 to reach the first 100 deaths, 30 days for the 1,000 deaths, 61 days for the 5,000 deaths and 68 days for 10,000 deaths and just 9 additional days for additional 20,000 deaths. By 1 April 2020, the number of confirmed cases skyrocketed to approximately 823,000 and 40,598 deaths from 205 countries and territories around the globe. In the single day of 31 March, there were approximately 72,700 new confirmed cases and 4,193 deaths reported across the world. The reported mortality rate for COVID-19 is around 3% and the mortality rates vary depending on geographical regions, age distributions and co-morbidities. With the advent of the devastating pandemic, many clinical trials have been initiated, and couple of them are pursuing already known drugs and evaluating whether such known drugs could be re-purposed towards alleviating and/ or treating the symptoms associated with COVID-19 patients.

Remdesivir was discovered by Gilead Sciences Inc., however, Gilead Sciences originally developed this drug to eliminate Ebola virus and Marburg virus infection. In vitro tests have shown that Remdesivir is not only effective against Ebola virus and other filoviruses, but also against respiratory syncytial virus, coronavirus, Nipah virus, Hendra virus, and atypical pneumonia (SARS-CoV) and Middle East Respiratory Syndrome (MERS-CoV) virus pathogens.

Remdesivir has been the only drug which is approved by FDA for use in adult and pediatric patients 12 years of age and older and weighing at least 40 kilograms (about 88 pounds) for the treatment of COVID-19 requiring hospitalization.

Remdesivir is available as VEKLURY for injection, 100 mg, is a sterile, preservative-free lyophilized powder that is to be reconstituted with 19 mL of Sterile Water for Injection and further diluted into 0.9% sodium chloride infusion bag prior to administration by intravenous infusion and is also available as VEKLURY (remdesivir) injection 100 mg/20 mL (5 mg/mL) that is to be diluted into 0.9% sodium chloride infusion bag prior to administration by intravenous infusion.

The inactive ingredients of both these formulations contain Betadex Sulfobutyl Ether Sodium also known as sulfobutylether-P-cyclodextrin sodium salt (SBECD), water for injection and may include hydrochloric acid and/or sodium hydroxide for pH adjustment.

Because remdesivir has limited water solubility, the intravenous preparation contains the solubilizer, SBECD. SBECD is a large, cyclic oligosaccharide that is predominantly excreted through glomerular filtration with a ti/2 elimination of 2 hours in patients with normal kidney function. Animal studies have associated SBECD accumulation with liver necrosis and renal tubule obstruction, which occurred in animals at doses 50- to 100-fold higher than expected for a 5- to 10-day remdesivir course.

Each 100 mg of lyophilized powder and solution of remdesivir contain 3g and 6g of SBECD respectively which maintains remdesvir in solution form thus avoiding precipitation of the drug during its shelf life and in-use storage.

Although the approved formulations may seem to contain higher quantity of SBECD, the quantity of SBECD is well below the maximum recommended safety threshold dose of 250 mg/kg per day of SBECD. In spite of this, remdesivir is not recommended in adults and pediatric patients (>28 days old) with eGFR less than 30 mL per minute or in full-term neonates (>7 days and <28 days old) with serum creatinine >1 mg/dL.

Further, each 100 mg of lyophilized powder as well as solution of remdesivir requires dilution with 0.9% sodium chloride solution requiring multiple solution transfer prior to intravenous administration. Also, the diluted solution needs to be prepared under aseptic conditions and on same day as administration. Further, the reconstituted product needs to be used immediately to prepare the diluted drug product. Any unused portion remaining in the reconstituted vial needs to be discarded since after a diluted solution is prepared the product contains no preservative. Any unused portion of a single-dose VEKLURY vial also needs to be discarded. Hence, there is a need to develop a formulation of Remdesivir which is safe for administration to all categories of patients as well as which is cost effective, which can be produced by simple manufacturing techniques, exhibits better or improved bioavailability, which can be stored for a longer period of time and moreover which provides patient compliance as well as is free of side effects.

OBJECT OF THE INVENTION:

An object of the invention is to provide stabilized, ready -to-use, remdesivir compositions.

Another object of the invention is to provide stabilized, ready -to-dilute, remdesivir compositions.

Yet another object of the invention is to provide stabilized, ready-to-use and/or ready -to-dilute, remdesivir compositions free of Betadex Sulfobutyl Ether Sodium (SBECD).

Another object of the invention is to provide ready-to-use and/or ready-to-dilute composition comprising remdesivir or its pharmaceutically acceptable salts, surfactants and optionally pharmaceutically acceptable excipients.

Another object of the invention is to provide a process for preparing stabilized, ready-to-use, remdesivir compositions.

Yet another object of the invention is to provide a process for preparing stabilized, ready-to-dilute, remdesivir compositions.

Another object of the invention is to provide a process for preparing stabilized, ready-to-use and/or ready-to-dilute, remdesivir compositions free of Betadex Sulfobutyl Ether Sodium (SBECD).

One another object of the present invention is to provide safe, efficacious and easy to use compositions of remdesivir.

Another object of the present invention to provide a method of treating COVID-19 by administering stable ready-to-use and ready-to-dilute parenteral compositions of remdesivir. SUMMARY OF THE INVENTION:

In some embodiments, the compositions of the present invention do not include Betadex Sulfobutyl Ether Sodium (SBECD) or any cyclodextrin compounds. In an embodiment, the compositions of the present invention are in the form of ready -to- use solution and/or ready-to-dilute concentrates.

According to some embodiments of the present invention the ready-to-use and/or ready-to-dilute composition comprising remdesivir or its pharmaceutically acceptable salts, surfactants and optionally pharmaceutically acceptable excipients is provided.

According to some embodiments, the composition can be a composition of remdesivir, ready for direct introduction into an infusion bag.

According to some embodiments, the composition can be a ready-to-use composition of remdesivir that can be directly administered to patient without first combining with a pharmaceutically acceptable diluent.

Also disclosed herein are processes for preparation of ready-to-use and/or ready-to- dilute formulations of remdesivir.

Also disclosed herein are method for treating COVID-19 by parenterally administering ready-to-use and/or ready-to-dilute composition of remdesivir.

DETAILED DESCRIPTION OF THE INVENTION:

The antiviral nucleotide analogue prodrug, in particular remdesivir, chemically referred as (S)-2-ethylbutyl 2-(((S)-(((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,l- f][l,2,4]triazin-7-yl)-5-cyano-3,4-dihydroxytetrahydrofuran- 2- yl)methoxy)(phenoxy) phosphoryl)amino)propanoate, referred to herein as Compound 1, is a viral RNA polymerase inhibitor and is known to exhibit antiviral properties against Arenaviridae, Coronaviridae, Filoviridae, and Paramyxoviridae viruses as described in Warren, T. et al, Nature (2016) 531 :381-385, and antiviral activities against Flaviviridae viruses as described in co-pending International Publication No. WO2016/069826 and WO 2017/184668. The CAS Registry Number for Compound 1 is 1809249-37-3.

[Compound 1]

A composition comprising the antiviral nucleotide analogue prodrug, in particular remdesivir would otherwise have experienced issues such as insolubility and relative chemical instability in aqueous media that are attributed to remdesivir, however, a suitable pharmaceutical composition is disclosed in a PCT application viz. WO2019014247 which provides a parenteral composition of remdesivir which comprises cyclodextrins whereby the composition exhibits improved solubility, improved usability for parenteral administration, and sufficient room-temperature and elevated temperature stability to avoid the use of cold-chain for transport and/or storage. However, beta-cyclodextrin derivatives are known to have certain physiological effects on kidneys.

The WO2019014247 application acknowledges that certain solubilizers may be used to improve the solubility of a compound to form a composition capable of being administered parenterally, however such solubilizers may have certain undesirable effects (Stella, et. al. Toxicologic Pathology (2008), Vol 36, Number 1, pages 30-42). For example, a formulation including polysorbate 80 may have potential hemodynamic effects, tubing limitations, extractables and leachables from tubing, limitations on stoppers, potential for precipitation upon dilution, or issues with adaptability for pediatric use. As another example, beta-cyclodextrin derivatives are known to have certain physiological effects on kidneys, thus there is also a need to limit the amount of such solubilizers in a pharmaceutical formulation. This application also explored pre -concentrate formulations comprising a surfactant and organic solvents. A solution formulation comprising Remdesivir present in about 30 mg/ mL in 25 % TWEEN® 80, 50 % PEG 300, and 25 % water was evaluated, but showed precipitation upon lOx and lOOx dilution in normal saline. Other explored formulations included solution formulations comprising Remdesivir present in about 5 mg / mL in 25 % Tween 80, 25 % PEG 300, 50 % water and another solution formulation comprising Compound 1 present at about 5 mg / mL in 25 % TWEEN® 80, 75 % water. These other formulations did not exhibit precipitation upon dilution in normal saline but would require larger amounts of TWEEN® 80 which could be associated with toxicity.

Given the shortcomings in the existing approach and to overcome the toxic and side effects, the inventors of the present invention have developed stable pharmaceutical composition comprising remdesivir along with pharmaceutically acceptable excipients which is safe for administration to all categories of patients, exhibits better or improved bioavailability, can be stored for long period of time, provides patient compliance as well as are free of side effects.

In particular, the inventors of the present invention have developed a stable remedesivir formulation by optimizing the concentrations of certain excipients, wherein the formulation remedesivir remains stable without exhibiting any precipitation as well as would render the said formulation safe for administration. As used in this specification, whether in a transitional phrase or in the body of the claim, the terms “comprise(s)” and “comprising” are to be interpreted as having an open-ended meaning. That is, the terms are to be interpreted synonymously with the phrases “having at least” or “including at least”. When used in the context of a process, the term “comprising” means that the process includes at least the recited steps, but may include additional steps. When used in the context of a compound or composition, the term “comprising” means that the compound or composition includes at least the recited features or components, but may also include additional features or components.

As used in this specification, the singular forms “a,” “an” and “the” specifically also encompass the plural forms of the terms to which they refer, unless the content clearly dictates otherwise.

The term “about” is used herein to mean approximately, in the region of, roughly, or around. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 20%.

It will be well appreciated that the term “Remdesivir” as used herein is denoted in broad sense to include not only “Remdesivir” per se but also its pharmaceutically acceptable derivatives thereof. Suitable pharmaceutically acceptable derivatives include pharmaceutically acceptable salts, pharmaceutically acceptable solvates, pharmaceutically acceptable hydrates, pharmaceutically acceptable anhydrates, pharmaceutically acceptable enantiomers, pharmaceutically acceptable esters, pharmaceutically acceptable isomers, pharmaceutically acceptable polymorphs, pharmaceutically acceptable prodrugs, pharmaceutically acceptable tautomers, pharmaceutically acceptable complexes etc.

As used herein, the term " Remdesivir " refers to the above referred Compound 1 as discussed above which is incorporated herein by reference. This term may relate either to the free form of remdesivir or to any pharmaceutically acceptable salt thereof.

The term "treating" or "treatment" as used herein refers to relieving, reducing or alleviating at least one symptom in a subject or effecting a delay of progression of a disease. For example, treatment can be the diminishment of one or several symptoms of a disorder or complete eradication of a disorder, such as cancer. Within the meaning of the present invention, the term "treat" also denotes to arrest, delay the onset (i.e., the period prior to clinical manifestation of a disease) and/or reduce the risk of developing or worsening a disease.

The term "pharmaceutically acceptable salt" refers to a charged species of the parent compound and its counter ion, which is typically used to modify the solubility characteristics of the parent compound and/or to reduce any significant irritation to an organism by the parent compound, while not abrogating the biological activity and properties of the administered compound. Examples, without limitation, of pharmaceutically acceptable salts include salts comprising an anion such as a carboxylate or sulfate anion, and/or a cation such as, but not limited to, ammonium, sodium, potassium, and the like. Suitable salts are described in, e.g., Birge et al. [J Pharma Sci 1977, 66: 1-19],

The term "pharmaceutical composition" or “pharmaceutical formulation” or similar term combination refers to a formulation of remdesivir described herein with pharmaceutically acceptable carriers and excipients.

The term "pharmaceutically acceptable carrier" refers to a carrier, adjuvant, or a diluent that does not cause significant irritation to an organism and does not abrogate the biological activity and properties of the administered compound.

The term “excipient(s)" refers to an inert substance added to a pharmaceutical composition to further facilitate administration of an active ingredient. Examples, without limitation, of excipients include surfactants, isotonicity agents, pH adjusters, buffers, preservatives, various sugars and types of starch, cellulose derivatives, gelatin, vegetable oils, and polyethylene glycols.

The disclosed formulations of the present invention are particularly suited for injection, but it will be understood that the solutions may have alternative uses. Injectable formulations may be administered via any route including intramuscular, intravenous, or subcutaneous.

The formulations can be in the form of liquid concentrates, ready -to-dilute and/or ready-to-use solutions. The ready-to-dilute and ready-to-use formulations may be packaged within a conventional sterile vial or other container. Alternatively, the formulations may be packaged in a sterile syringe already fitted with a needle for injection.

The term “ready-to-use” refers to any preparation of remdesivir which can be administered to patient directly without any further dilution or processing. The concentration of remdesivir in the ready-to-use formulation is about 1 mg/mL

The term “ready-to-dilute” refers to a formulation which can be directly combined with a diluent (e.g., dextrose solution, saline solution, or any other infusion medium) and then administered to a patient. In some embodiments, the ready-to- dilute formulation may be provided as a single vial containing the remdesivir formulation. In other embodiments, the ready-to-dilute formulation may be accompanied by a pharmaceutically acceptable diluent in a separate container (i.e., a dual vial formulation). The concentration of remdesivir in the ready-to-dilute formulation is about 5 mg/mL

The term “ready-to-dilute” is distinguished from lyophilized products that require two steps, a first step of reconstitution to form a preconcentrate and then a second step where the preconcentrate is subjected to dilution with an aqueous infusion fluid. The ready- to- dilute parenteral formulation according to the present invention avoids the inconvenience of reconstituting a concentrated parenteral formulation into infusion diluents prior to infusion, as well as eliminates the risk of any potential calculation or dilution error as well as risk of microbiological contamination during handling. The volume of the aqueous drug solution according to the present invention is large i.e. when the end use container used in ‘ready-to-dilute’ parenteral dosage form is a prefilled syringe, then the volume of the aqueous solution may be about 50 ml to 100 ml. When the end use container is infusion bag, the volume of the aqueous solution may be about 100 ml to 500 ml.

The term "stable formulations" refers that remdesivir formulations of present invention are physically as well as chemically stable as demonstrated by compliance to acceptable specification when the formulation is stored at convenient temperature, such as between about 0°C and about 60°C, for a commercially reasonable period of time, such as at least about 1 day, at least about 1 week, at least about 1 month, at least about 3 months, at least about 6 months, at least about 1 year, or at least about 2 years. For purposes of the present invention, “long term storage' shall be understood to include at least time periods which are in excess of those observed when currently available lyophilized remdesivir formulations are reconstituted. Suitably, the solution of remdesivir of present invention remains physically stable, with no precipitation or crystallization or color change upon storage and the value of percentage transmittance of the solution remaining greater than 90%, preferably greater than 95% for the shelf life period of 18-24 months when stored at room temperature.

According to the present invention, there is provided a pharmaceutical composition administered by injection comprising remdesivir along with one or more pharmaceutically acceptable carriers as defined hereinabove.

The pharmaceutical compositions of the invention may optionally comprise one or more pharmaceutically acceptable excipients, such as a pH adjusting agent, buffer, osmotic agent, surfactant, antioxidant, preservative, and/or isotonicity agent. The use of said pharmaceutically acceptable excipients in appropriate amounts or quantity can be readily determined by any person with ordinary skill in the art.

The pharmaceutical compositions of the present invention have a pH of about 3 to about 7. The pH may be adjusted by the addition of one or more pharmaceutically acceptable acids. Examples of suitable pharmaceutically acceptable acids include inorganic acids, such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, and phosphoric acid, and combinations thereof. Examples of other suitable pharmacologically acceptable acids include organic acids, such as ascorbic acid, citric acid, malic acid, maleic acid, tartaric acid, succinic acid, fumaric acid, acetic acid, formic acid, and/or propionic acid or other than acid variants which comprises sodium hydroxide. In one embodiment, the pH is adjusted with IN hydrochloric acid or sodium hydroxide. In another embodiment, the pH is adjusted with one or more organic acids selected from citric acid, ascorbic acid, fumaric acid and acetic acid.

The pharmaceutical compositions of the present invention may optionally include a buffer. General and biological buffers in the pH range of about 2.0 to about 8.0 include, but are not limited to, acetate, borate, citrate, collidine, formate, maleate, Mcllvaine, phosphate, Prideaux-Ward, succinate, citrate -phosphate -borate buffers. Suitable osmotic adjusting agents that may be used include, but are not limited to, sodium chloride, dextrose, sucrose and mixtures thereof. Other osmotic adjusting agents may also include, but are not limited to, mannitol, glycerol, propylene glycol and mixtures thereof.

The pharmaceutical compositions can include one or more pharmaceutically acceptable surfactants. Suitable surfactants include anionic, cationic, amphoteric and non-ionic surfactants, Pharmaceutically acceptable surfactant for this application include, but are not limited to, polysorbate or polyethoxylated castor oil, Polyoxyl 20 stearate, Polyoxyl 35 castor oil, pol oxamer, polyoxyethylene sorbitan monoisostearate, polyethylene glycol 40 sorbitan diisostearate, Polyoxyl 40 Hydrogenated castor oil, Polysorbate, Polysorbate 20, Polysorbate 40, Polyoxyl 60 stearate, Polysorbate 85, Polysorbate 60, poloxamer 331, polyoxyethylene fatty acid esters, Polyoxyl 40 castor oil, poloxamer 188, polyoxyethylene poly oxypropylene 1800, oleic acid, Sodium desoxy cholate, Sodium lauryl sulfate, Sorbitan monolaurate, Sorbitan monooleate, Sorbitan monopalmitate, Sorbitan trioleate, N-Carbamoyl methoxypolyethylene glycol 2000-1,2-distearol, myristic acid, Steareth, Stearic acid, Polyoxyl 40 stearate, Sucrose stearate, Tocopherol, polyoxyl castor oil, Triglyceride synthetic, Trimyristin, Tristearin, magnesium stearate, lecithin, lauryl sulfate, Vitamin E, egg yolk phosphatides, docusate sodium, Polysorbate 80, dimyristoyl phosphatidylglycerol, dimyristoyl lecithin, Capryol 90 (propylene glycol monocaprylate), Capryol PGMC (propylene glycol monocaprylate), deoxycholate, cholesterol, Cremophor EL, Propylene glycol alginate, Croval A- 10 (PEG 60 almond glycerides), Labrafil 1944 (oleoyl macrogol-6 glycerides), Labrafil 2125 (linoleoyl macrogol-6 glycerides), Labrasol (capryl ocaproyl macrogol-8 glycerides), Lauroglycol 90 (propylene glycol monolaurate), Lauroglycol FCC (propylene glycol laurate), calcium stearate, Lecithin Centromix E, Lecithin Centrophase 152, Lecithin Centrol 3F21B, POE 26 glycerin, Olepal isosteariques (PEG-6 isostearate), Plurol diisostearique (polyglycerol-3-diisostearate), Plurol Oleique CC, POE 20 Sorbitan trioleate, Tagat TO (polyoxyethylene glycerol trioleate), or Solutol (macrogol-15 hydroxystearate). Preferably, the surfactant included in composition of present invention is Polysorbate 80.

In some ready-to-dilute (pre concentrate) embodiments, the surfactant can be present in an about 5% to about 30% of the total weight of the formulation, preferably from about 6% to about 25% of the total weight of the formulation, more preferably from about 7% to about 20% of the total weight of the formulation and most preferably from about 8% to about 12% of the total weight of the formulation. In some ready -to-administer/use (RTU) embodiments, the surfactant can be present in an about 1% to about 6% of the total weight of the formulation, preferably from about 1.5% to about 4% of the total weight of the formulation, more preferably from about 1.5% to about 3% of the total weight of the formulation and most preferably from about 1.5% to about 2.5% of the total weight of the formulation.

Formulation containing high concentration of surfactant in the formulation did not exhibit precipitation upon dilution in normal saline but these formulations contained large amounts of Polysorbate 80 which could be associated with toxicity. In formulation containing low or no Polysorbate 80 concentration, the formulation had tendency for precipitation of remdesivir during storage. Hence, appropriate concentration of surfactant was necessary to maintain remdesivir in solution state during shelflife of the product and in-use period while limiting the daily intake well within the level of Polysorbate 80 approved in the other marketed products is necessary.

The pharmaceutically acceptable co-solvent system may comprise at least one pharmaceutically acceptable, water miscible organic solvents. In some embodiments, the compositions can include ethanol, isopropyl alcohol, benzyl alcohol, propylene glycol, polyethylene glycol, glycerol, dimethylacetamide, N- methylpyrrolidone, dimethylsulfoxide (DMSO), diethylene glycol monoethyl ethers, capryl ocaproyl polyoxyl-8 glycerides, glycofurol, or mixtures thereof.

In some embodiments, the co-solvent can be present in an about 3% to about 80% of the total weight of the formulation, preferably from about 3% to about 50% of the total weight of the formulation, more preferably from about 3% to about 30% of the total weight of the formulation and most preferably from about 3% to about 25% of the total weight of the formulation.

The co-solvent is preferably selected from the group consisting of alcohol, polyethylene glycols, propylene glycol and mixtures thereof. Preferably, the polyethylene glycol has a molecular weight in the range from 200 to 600. More preferably, the polyethylene glycol has a molecular weight of about 300 (PEG 300). In some ready-to-dilute (pre-concentrate) embodiments, the co-solvent can be present in an about 5% to about 70% of the total weight of the formulation, preferably from about 10% to about 50% of the total weight of the formulation, more preferably from about 15% to about 30% of the total weight of the formulation and most preferably from about 20% to about 25% of the total weight of the formulation. In some ready -to-administer/use (RTU) embodiments, the co-solvent can be present in an about 0% to about 10% of the total weight of the formulation, preferably from about 2% to about 7% of the total weight of the formulation, more preferably from about 3% to about 6% of the total weight of the formulation and most preferably from about 4% to about 5% of the total weight of the formulation. Formulation containing high concentration of co-solvent resulted in high viscosity of the solution, while formulations having low concentration had tendency for precipitation of remdesivir during storage. Hence, appropriate concentration of cosolvent is necessary to maintain remdesivir in solution state during shelf life of the product and in-use period while avoiding the high viscous solution. The formulations may include one or more buffering agents. In certain embodiments, the buffering agent comprises a Cl-6alkyl carboxylic acid, for instance formic acid, acetic acid, 1 -propionic acid, 2-propionic acid, n-butyric acid, t-butyric acid, isobutyric acid, or sec-butyric acid. In some embodiments, the buffering agent comprises a hydroxy substituted-carboxylic acid or polycarboxylic acid, e.g., a compound having two or more carboxylic acid functional groups. Such compounds include, for instance, lactic acid, glycolic acid, 3 -hydroxypropionic acid, hydroxylbutyric acid, malonic acid, succinic acid, malic acid, tartaric acid, citric acid, fumaric acid, muramic acid, gluconic acid and glucuronic acid.

The acid buffering agent or acidifying agents may be present in an amount in the range from about 0.01% to about 2% of the total weight of the formulation.

Generally, the formulations disclosed herein will not contain any cyclodextrin compounds. As used herein, the term “cyclodextrin” refers to any cyclic compound composed of multiple carbohydrate (e.g., glucopyranoside) units. Remdesivir in formulations disclosed herein has substantially the same solubility and pharmacokinetic behavior as remdesivir complexed with cyclodextrin.

The pharmaceutical composition of present invention further comprises antioxidant. Suitable antioxidants include those, although not limited to , monothioglycerol, L-cysteine and thioglycolic acid, selected from the group comprising of acetyl cysteine, butylated hydroxy toluene, butylated hydroxy anisole, DL-tocopherol, sodium metabisulfite, sodium formaldehyde sulfoxylate, EDTA and its derivatives, methionine, ascorbic acid, citric acid and its pharmaceutically acceptable salt, sodium sulfite and its derivative and the like.

The antibacterial preservatives, that can be included in the present invention are, but not limited to, one or more of phenylmercuric nitrate, thiomersal, benzalkonium chloride, benzethonium chloride, phenol, cresol, chlorobutanol, benzyl alcohol, parabens and combination thereof.

According to the present invention, there is provided a process of preparing a pharmaceutical composition comprising remdesivir with one or more pharmaceutically acceptable excipients.

According to preferred embodiment of the present invention, the pharmaceutical composition may involve dissolution of remdesivir in suitable excipients like surfactants, co-solvents mixture containing buffering agent followed by other excipients osmolality agents and pH adjusting agents and making up of the volume with suitable solvent and filling in suitable containers like ampoule or vials or plastic bags. The containers may or may not require any form of sterilization.

According to the invention, there is provided a pharmaceutical composition comprising remdesivir with one or more pharmaceutically acceptable excipients for the treatment of infection caused COVID-19.

It may be well appreciated by a person skilled in the art that the pharmaceutical composition comprising remdesivir may require specific dosage amounts and specific frequency of administrations specifically considering their individual established doses, the dosing frequency, patient adherence and the regimen adopted. As described herein, considering that there are various parameters to govern the dosage and administration of the composition as per the present invention, it would be well acknowledged by a person skilled in the art to exercise caution with respect to the dosage, specifically, for special populations associated with other disorders. In order that this invention be more fully understood, the following preparative and testing methods and examples are set forth. The following examples are for the purpose of illustration of the invention only and are not intended in any way to limit the scope of the present invention.

EXAMPLES

Screening experiments:

Preliminary screening experiments (Table 1) were performed to understand the solubility of Remdesivir in the co-solvent and surfactant combinations.

Table 1. Preliminary screening trials

These experiments (Formula - 1 and Formula - 2) indicated that a stable composition can be formulated which does not exhibit precipitation upon further dilution with 0.9% saline solution. The limitation/drawback of these formulations are usage of higher amounts of Polysorbate 80.

Considering the maximum daily dose of 200 mg Remdesivir, the above compositions (Formula -1 & Formula 2) with 26% Polysorbate 80 would corresponds to a daily intake of about 10.4 g of Polysorbate 80. An intake of <4.5g/day is preferred considering the level of Polysorbate 80 approved in the marketed products.

Effect of Surfactant concentration:

Set of experiments were designed and to study the effect of polysorbate 80 concentration on stability of formulation to maintain Remdesivir in solution state without precipitation during storage and in-use period upon dilution using 0.9% saline solution.

Table 2. Effect of surfactant concentration

Formula 3 experiment was conducted to understand the effect of additional cosolvent i.e. propylene glycol in absence of surfactant, polysorbate 80. Precipitation was observed within 24 hours. This experiment highlights the need of presence of effective concentration of Polysorbate 80 for formulating stable composition.

These experiments highlight the significance of surfactant concentration in the formulation stability. Maintenance of adequate surfactant concentration is necessary to stabilize the formulation and to avoid precipitation. Formulations up to 6.5% w/v polysorbate have a precipitation tendency during storage. It was surprisingly observed that a stable Remdesvir formulations can be achieved even with lower level of Polysorbate 80 when maintained at about 10% w/v & about 20% w/v, the formulations are stable during storage, without any precipitation tendency even after dilution with saline solution.

These experiments demonstrate that the optimal concentration of surfactant, polysorbate 80 is required for maintaining the stability of Remdesivir formulation and manifests that solubilization of Remdesivir is mainly through micellar solubilization.

Effect of co-solvent and buffer concentration:

Set of experiments were conducted to understand the role of co-solvent, i.e. Polyethylene glycol 300 concentration and buffering agent, Citric acid concentration on stability of formulation.

Table 3. Effect of co-solvent and buffer concentration

These experiments (Formula 8 and Formula 9) indicated that appropriate level of cosolvent concentration and buffering/ pH adjusting agent (to maintain pH) is necessary to maintain stability of Remdesivir in solution state during storage.

From the above set of experiments, the formula 6 is found to be promising and considered as a prototype formula and is detailed below.

READY-TO-DILUTE (RTD) FORMULATION

Table 4. Prototype formula (Formula 6)

Considering the maximum daily dose of 200 mg Remdesivir, the prototype formula (Formula 6) with 10% polysorbate 80 would corresponds to a daily intake of about 4.0 g of Polysorbate 80. An intake of <4.5g/day is preferred considering the level of Polysorbate 80 approved in the marketed products (Amiodarone Injection 50mg/mL &Docetaxel injection 20mg/mL) Hence, the optimized concentration of polysorbate 80 and other excipients are well within the level used in other approved formulations. Manufacturing Process:

1) Polyethylene glycol and Polysorbate 80 were mixed followed by addition of Citric acid to obtain a clear solution.

2) Remdesivir was added to the solution obtained in step (1) and mixed for NLT 1 hour to obtain a clear solution.

3) Volume was made up using Water for Injection to 95% batch volume.

4) The pH was adjusted to 3.0 to 4.5 using sodium hydroxide and/or hydrochloric acid and finally volume is made up to batch volume using Water for Injection to yield a 5 mg/ml solution of Remdesivir.

5) The solution was filtered through 0.2p PES filters and filled in 20 mL USP Type 1 glass vials, stoppered using butyl rubber stopper and sealed using aluminum flip-off seals.

Stability evaluation of prototype formulations:

Batches were manufactured with Formula - 6 composition and pH was varied to understand the effect of pH of the formulation. The batches were loaded onto long term (2°-8°C) and accelerated (25°C/60%RH) storage conditions. The stability of the formulations were compared with a typical formulation containing Cyclodextrin as solubilizer, similar to Reference product, Veklury.

Reference product information (Formulation containing Cyclodextrin)

The Reference Listed Drug (RLD) is Veklury (Remdesivir) 100mg/20mL (5mg/mL), which was approved on Oct 22, 2020 in United States and application holder is Gilead sciences INC. Inactive ingredients in Veklury injection are 6 g betadex sulfobutyl ether sodium, Water for Injection, USP, and may include hydrochloric acid and/or sodium hydroxide for pH adjustment. Betadex sulfobutyl ether sodium (Cyclodextrin) acts as solubilizer in this formulation. Recommended storage condition of Veklury is “Store at refrigerated temperature (2°C to 8°C)”. The following Table provides comparative stability of the prototype formula - 6 at different solution pH and a formulation manufactured using quantitative formula provided in label of Reference product, Veklury® at room temperature conditions. Table 5. Comparative Stability data of Cyclodextrin- free formulations at room temperature conditions (25°C/60%RH) in inverted orientation

Based on 6 months data at room temperature condition (25°/60%RH), it can be inferred that prototype cyclodextrin free formulation, especially the formulation at pH about 4 exhibits comparable or improved stability when compared to current cyclodextrin formulations indicating pH dependent stability of the formulation.

Stability evaluation at long term refrigeration (2°-8°C):

Further, the comparative stability of the prototype formulation at long term refrigeration storage condition (2°-8°C) is provided in Table 6.

Table 6. Comparative Stability data of Cyclodextrin- free formulations at refrigeration storage conditions (2°C to 8°C) in inverted orientation

Based on 6 months data at long term refrigeration storage condition (2°-8°C), it was observed that the prototype cyclodextrin-free formulation exhibits comparable or improved stability when compared to formulation containing cyclodextrin. The proposed prototype formulation is found to be accommodate longer exposure to room temperature storage conditions during in-use or during transportation.

Ready to use (RTU) Formulations

Based on the observations/learnings from Ready to dilute (RTD) concentrate formulations, a cyclodextrin-free ready-to use (RTU) formulation was developed, which saves time during administration at hospital setup and reduces dosing errors. In ready to use formulation, the prototype formula (Formula 10) is designed to yield 1 mg/mL of Remdesivir. Appropriate quantity of sodium chloride or dextrose can be added to maintain isotonicity.

Table 7. Prototype Cyclodextrin- free Ready to use (RTU) formulation

Manufacturing Process:

1) Polyethylene glycol and Polysorbate 80 were mixed followed by addition of Citric acid to obtain a clear solution.

2) Remdesivir was added to the solution obtained in step (1) and mixed for NLT 1 hour to obtain a clear solution.

3) Volume was made up using Water for Injection to 95% batch volume and sodium chloride (when applicable) was added and mixed to obtain a clear solution.

4) The pH was adjusted to 3.0 to 4.5 using sodium hydroxide and/or hydrochloric acid and finally volume is made up to batch volume using Water for Injection to yield a 1 mg/ml solution of Remdesivir.

5) The solution was filtered through 0.2p PES filters and was filled in 100 mL USP Type 1 glass vials, stoppered using butyl rubber stopper and sealed using aluminum flip-off seals

The stability of the formulation at room temperature conditions (25°C/60%RH) at inverted orientation was evaluated and is provided in Table 8.

Table 8. Stability data of ready to use (RTU) formulation

# Clear, colorless to yellow solution essentially free particles

@ Testing not performed

Based on 3 months data at 25°C/60%RH, all physico-chemical test parameters are within the specified limits. It can be inferred that cyclodextrin free ready to use formulation is stable that could potentially support an extended in-use and transportation at room temperature conditions.