At long last, Eisai and Arena Pharmaceuticals have been given the go-ahead to launch their anti-obesity drug Belviq in the USA.

The US Food and Drug Administration approved Belviq (lorcaserin) last June chronic weight management in adults with a body mass index of 30 or greater, or adults with a BMI of 27 who have at least one weight-related condition such as hypertension, type 2 diabetes or high cholesterol.  However, the agency said at the time that Belviq be classified by the US Drug Enforcement Administration as a scheduled drug, ie its potential for abuse needed to be evaluated.

This has held up a launch but now the DEA has placed Belviq into Schedule IV of the Controlled Substances Act, which means that the treatment has a low potential for abuse. In 30 days time, Eisai will make the drug available and the launch will trigger a $65 million milestone payment to Arena.

Arena will manufacture Belviq at its facility in Switzerland, and sell finished commercial product to Eisai for a purchase price starting at 31.5% of the Japanese drugmaker's annual net product sales. The price increases on a tiered basis up to 36.5% exceeding $750 million and Arena is also eligible to receive $1.16 billion in purchase price adjustment payments.

Belviq can now compete against Vivus' Qsymia (phentermine/topiramate) which was launched in September but has had disappointing sales, hit by reimbursement issues. Qsymia is also classed as Schedule IV by the DEA.

The move is clearly very good news for Arena which last week withdrew its marketing application for Belviq this side of the Atlantic. The European Medicines Agency's Committee on Human Medicinal Products has expressed its concerns over potential cardiovascular risks and worries about tumours found in animal studies.