Obesity has become a serious global medical and social problem. In my country, the prevalence of overweight and obesity, according to WHO standards, rose from 14.6% to 21.8% between 1992 and 2002. In 2006, obesity affected the health of over 200 million Chinese people, and the obese population is projected to rise rapidly in the coming decades. Obesity is a major risk factor for diseases such as hyperlipidemia, type 2 diabetes, fatty liver, hypertension, cardiovascular disease, and cancer, causing approximately 3 million deaths globally each year. Clinically available weight-loss drugs have not seen significant progress compared to 10 years ago due to the discovery of serious adverse reactions. For the foreseeable future, "controlling your diet and increasing physical activity" will remain the best way to lose weight.
Currently, the only FDA-approved weight-loss drugs for long-term use are the lipase inhibitor orlistat, the 5-HT2C receptor agonist lorcaserin (newly launched in 2012), and the combination weight-loss drug Qsymia (a sustained-release formulation containing phenbutylamine and topiramate). Four new drugs submitted to the FDA in 2010 were rejected due to safety concerns. Therefore, safety has become the biggest challenge in weight-loss drug development and a crucial hurdle that must be overcome.
Currently, there are two main categories of weight-loss drugs on the market: pancreatic lipase inhibitors and appetite suppressants that act on the central nervous system. Appetite suppressants are restricted due to their potential to cause adverse nervous system reactions. Orlistat, a pancreatic lipase inhibitor, inhibits pancreatic lipase activity, thereby inhibiting the breakdown and absorption of fat from food, leading to weight loss. However, it can cause steatorrhea and lead to deficiencies in fat-soluble vitamins. Recent reports also indicate that it can cause liver damage. Although lorcaserin and Qsymia, central nervous system appetite suppressants, became the first weight-loss drugs approved by the FDA in 13 years, safety uncertainties regarding the central nervous system and cardiovascular system remain. Currently, the selection of weight-loss drugs on the market is extremely limited. If a weight-loss drug with good efficacy and low adverse reactions were to emerge, its market would expand significantly.
The difficulty in developing weight-loss drugs has resulted in very few new drugs being launched for many years. Although lorcaserin and Qsymia were approved after years of research and repeated FDA reviews, they still face challenges in terms of drug safety. Currently, several weight-loss drugs are undergoing clinical trials or experimental studies.
