New Delhi: A warning by India’s drug regulator that anti-diabetic medication rosiglitazone poses a risk for heart patients will dampen sales of the drug, according to initial reactions by doctors.

Rosiglitazone is sold by GlaxoSmithKline Pharmaceuticals Ltd and generic versions are made by Sun Pharmaceuticals Ltd, Dr Reddy’s Laboratories Ltd and Torrent Pharmaceuticals Ltd, among 30 other firms. GlaxoSmithKline sells the drug as Avandia overseas and Windia here.

Dangerous dose: Drug controller general Surinder Singh says a warning has been issued against the drug but it has not been banned altogether. Madhu Kapparath / Mint

For other drug makers, such as Merck Sharp and Dohme Pharmaceuticals Pvt. Ltd and local units of Eli Lilly and Co. and Sanofi Aventis SA, which are active in the oral anti-diabetics space and have competing diabetes-control products, the impact may be positive.

The news could even lend pace to the smaller but steadily growing insulin market, which has players such as Novo Nordisk AS, Eli Lilly, Shreya Life Sciences Pvt. Ltd and Biocon Ltd.

The warning, issued as a directive to drug firms by the drugs controller general of India (DCGI) on Wednesday to print a warning on the drug’s label cautioning its risks if used by heart patients, does not cover pioglitazone, which is marketed in India by Ranbaxy Laboratories Ltd, Cipla Ltd, Cadila Healthcare Ltd (popularly known as Zydus Cadilla), Biocon, Lupin Ltd and others.

The Economic Times newspaper first reported the DCGI’s action.

In October, the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD), in their new guidelines for the treatment of so-called type II diabetes or a diabetes disorder occurring in adults, advised against the use of rosiglitazone.

“Reports have shown that rosiglitazone increases the incidence of heart attack. So, we are putting a warning on it, though it’s not being banned altogether," drug controller general Surinder Singh said.

The US Food and Drug Administration (FDA) had issued a boxed warning against rosiglitazone in May 2007, which was strengthened in November last year after a study linked the medicine to a 43% higher risk of heart attack.

A doctor said he had stopped prescribing rosiglitazone earlier but “the drug’s sales seemed to have been affected little". “When rosiglitazone was launched, I must have prescribed the drug to thousands of my patients," recalls Vipin Mishra, senior consultant, endocrinology, at a Fortis Healthcare Ltd hospital in New Delhi.

Dr Mishra said he stopped prescribing the drug to 95% of his patients after they reported severe side effects such as signs of cardiac failure, weight gain and swelling in the feet. “But," he adds, “marketing activity for the drug kept it going." The most effective drug, recommends Mishra, after the glitazone class of drugs is insulin.

The updated guidelines for treatment of diabetics, widely followed by doctors in India as well, yet again place emphasis on the use of insulin as a blood sugar lowering agent, owing to its efficacy and also because insulin, being the oldest medication in the market, comes with the most clinical experience. But the market for this intravenous drug has seen slow growth in India owing primarily to fear of injections. While the share of oral anti-diabetic drugs is 70%, insulin has captured just 30%.

With few other options available while global studies are being conducted before bringing more oral forms of insulin into the market, the balance could change. The growth of insulin sales is 24% as against the 19% growth of oral anti-diabetics and the entire anti-diabetic market growing at 21% from January to September this year, according to ORG-IMS, a pharma-focused market research service.

“You could replace rosiglitazone with pioglitazone but the most potent intervention for diabetics is insulin. This is the only substance that will lower your blood sugar level as much as you like," says Viktor Jorgens, executive director, EASD.

Ram Shelat, director, domestic business, Shreya Life Sciences, which earlier this month launched oral insulin spray called Oral Recosulin, says there is a need to provide an alternative that can avoid the insulin injection. “With this new product, we hope to capture 10% of the insulin market in the next three years," says Shelat. Biocon is also in the process of developing oral insulin in India.

Late last year, Pfizer Inc. withdrew Exubera, an inhaled insulin product, after reporting poor sales.

Currently, besides oral anti-diabetic drugs such as metformin (marketed as Riomet by Ranbaxy) and sulfonylurea (marketed as Amaryl by Sanofi Aventis), all others lack adequate post-market clinical data about long-term safety and efficacy.

Still, the warning against rosiglitazone may help sitagliptin, a drug marketed by Merck Sharp and Dohme under the brand name Januvia, said Dr Jorgens. Januvia was launched in India in April. It reported global sales of at least $660 million (Rs3.280 crore today) in 2007.

More recently, a relatively new anti-diabetic drug came under FDA’s scrutiny after two reported deaths in the US. In August, FDA issued an alert against another injectable anti-diabetic drug exenatide, marketed as Byetta by Amylin Pharmaceuticals Inc. and Eli Lilly. Byetta was launched in India late last year. It, however, still remains a recommended option by ADA and EASD over newer drugs.