HYDERABAD, India, Feb 22 (Reuters) - Indian drugmakers aiming to grab a slice of the burgeoning weight-loss treatment sales pie, both at home and abroad, have begun developing their own versions of Novo Nordisk's wildly in demand Wegovy.

With some analysts predicting a weight-loss market reaching $100 billion a year or more by the end of the decade, executives at Sun Pharma, Cipla, Dr Reddy's and Lupin -- some of the world's largest generic drugmakers -- all said they have started work on Wegovy versions.

Novo Nordisk has been unable to produce enough Wegovy to meet demand in more than half a dozen countries where it has already launched, amid record global obesity rates and people looking for easier alternatives to diet and exercise. U.S. rival Eli Lilly likewise has been unable to meet demand for its weight-loss drugs Zepbound and Mounjaro.

Novo has not provided a clear timeline for introducing Wegovy globally, but told Reuters it aims to launch in India in 2026.

The move by Indian drugmakers could go a long way toward improving global access to weight-loss drugs and make them far more affordable, analysts said.

"We expect volume expansion to increase multi-fold by the time patent expires, which is a few years from now," Systematix analyst Vishal Manchanda said. "They will also be available at a much lower price by generic drugmakers."

Industry insiders agreed.

"There is big potential in India... given the lifestyle choices," Cipla Global CEO Umang Vohra said in a post-earnings call in January.

India has high obesity rates, especially among women, and has the world's second highest number of people with type 2 diabetes, trailing only China. Around 11% of adults in India will be obese by 2035, according to the World Obesity Federation Atlas.

Novo's patents for Wegovy, given as a weekly injection, expire in China in 2026, in Japan and Europe in 2031, and in the U.S. in 2032, according to its annual report.

The Danish drugmaker is the sole patent holder of semaglutide, the active ingredient in Wegovy and diabetes treatment Ozempic, which are not yet approved in India. It declined to comment on when its patent would expire in India.

"We want to market this product on time in all the markets as (Novo's) patent expires," Dr Reddy's CEO Erez Israeli said of semaglutide in a media call last month.

Novo did not comment on when it expects to see competition from Indian drugmakers but told Reuters it "welcomes new treatment options" for people living with obesity.

DEVELOPING A MARKET

Sun Pharma is working on its own experimental drug to treat type 2 diabetes and obesity. Others are taking a more traditional generic drug path.

"Dr. Reddy's and Cipla are making a copy of the innovator drug more like a generic version, while Sun is working on its own innovator drug. So, Sun will have to do clinical trials. Its drug will be novel and patented," Manchanda said.

The Indian market for diabetes drugs alone was estimated at 316 billion rupees ($3.81 billion) in 2023 and is projected to hit 1.2 trillion rupees ($14.48 billion) in the next decade, according to Expert Market Research.

Wegovy in clinical trials helped patients lose up to 15% of their body weight, while Eli Lilly drug trial participants lost even more. Their medicines belong to a class of therapies known as GLP-1 receptor agonists originally developed to control blood sugar in type 2 diabetes patients. They also slow digestion, helping people feel full longer.

Data showing the class of drugs may also delay progression of chronic kidney disease and lower heart disease risks are likely to further increase demand.

Despite the home turf advantage for companies like Cipla, cracking the price-sensitive Indian market won't be easy.

"In India, the requirement is to develop a market for anti-obesity (drugs)," said DAM Capital analyst Nitin Agarwal, "unlike in other countries where drugmakers can just take a share of existing market."

($1 = 82.8700 Indian rupees) (Reporting by Rishika Sadam; Editing by Dhanya Skariachan and Bill Berkrot)