The Indian Patent Office has granted patent to Aurobindo Pharma for its process for the preparation of its antiviral drug valacyclovir, which has been sold in US and other countries under the trade name Valtrex. Aurobindo’s invention is for an improved process for the preparation of the drug or pharmaceuticals acceptable salts.
Valacyclovir, which is marketed in the form of its hydrochloride salt, is an antiviral drug approved in the US and several other countries. Valacyclovir hydrochloride is used in the treatment of viral infections such as herpes zoster and genital herpes in humans.
It is a prodrug that is derived from acyclovir by esterification of the 3'-hydroxyl group of acyclovir with L-valine. Acyclovir is also an antiviral nucleoside that possesses activity against human herpes viruses. Valacyclovir has enhanced bioavailability, when compared to acyclovir, said the company in its patent specification submitted with the patent office.
It added that the product obtained by the process disclosed in one of the earlier patents contains a higher amount of impurities especially degradation products such as acyclovir and guanine. The product obtained through such a process would require several purification steps, which results in loss of yield, making the process infeasible for production at large scale.
The inventors from Aurobindo Pharma have developed a process for preparing pure valacyclovir hydrochloride suitable for use in the pharmaceutical composition, added the specification.
The patent office has granted the patent rights for a term of 20 years from March 3, 2016, which is the date of filing of the patent application.
It may be noted there has been a bitter fight between Indian drug major Ranbaxy and US pharma major GlaxoSmithKline (GSK) in connection with one of the latter’s patents on valacyclovir. GSK’s drug, branded Valtrex, according to earlier reports recorded a sales of $1.15 billion in US in 2006 and Ranbaxy filed a generic drug application triggering a fight between the patent owner and generic companies. Many generic firms followed Ranbaxy in applying for the generic drug.
In July 2007, Ranbaxy and GSK entered into an agreement related to the patent litigation, under which Ranbaxy said that it will enter the US market in late 2009 as the first generic version of the drug. This, according to the reports, has given an advantage to Ranbaxy for an exclusivity of 180 day in the market.
Aurobindo Pharma, in May, 2010, received final approval from the US Food and Drug Administration to manufacture and market valacyclovir hydrochloride tablets 500 mg (base) and 1g (base). The company then said that these are the generic equivalent of GSK’s Valtrex caplets 500 mg and 1g.
“Valacyclovir hydrochloride tablets falls under the Anti-infective therapeutic category and is indicated for the treatment of cold sores, genital herpes and shingles in adult patients and chicken pox in pediatric patients 2-18 years of age,” it said in a press release during the time. In 2010, the product had a market size of around $2 billion, it added.
