Takeda Pharmaceuticals North America has reported data showing its Rozerem drug is an effective treatment for transient insomnia, reduced time to fall asleep with no evidence of next-day residual effects.

The data add to the profile surrounding Rozerem (ramelteon), which has made a strong start in the marketplace as the first hypnotic drug to be approved that is not classified as a scheduled drug. Analysts have predicted sales of up to $900 million for the drug.

In the trial, 289 healthy adults were randomised to receive either Rozerem 8mg, 16mg, or placebo 30 minutes before bedtime. The data, presented at the 20th anniversary meeting of the Associated Professional Sleep Societies, revealed that Rozerem reduced the time taken to fall asleep without any residual psychomotor or memory effects.

Patients taking the lowest dose of the drug experienced a significant decrease in time taken to fall asleep, in comparison with placebo (12.7 minutes versus 19.7 minutes). The higher dose of the drug did bring about a reduction in the time to sleep, but the difference was not statistically significant.

Rozerem was not associated with any next-day memory or motor impairment, following a series of memory assessments and the digit symbol substitution test. Adverse events occurred at a rate of 12.4% for the 8mg cohort and 13.3% for the 16mg group, compared with 6.4 % in the placebo group.

Rozerem was approved in the USA just under a year ago, and has been positioned in the marketplace as a better-tolerated alternative to the two biggest sellers, Sanofi-Aventis’ Ambien (zolpidem) and Sepracor’s more recent entrant Lunesta (eszopiclone), which was cleared by the US Food and Drug Administration in December 2004.

Ambien achieved sales of more than 1.5 billion euros in 2005, 1.3 billion of which came from the USA alone, but is due to lose patent protection later this year. And while the entrance of low-cost generic zolpidem could hold back Rozerem’s growth, Takeda has just got good news on the competition front as one potential rival, Neurocrine Biosciences/Pfizer’s indiplon, looks likely to be delayed for some time after the US regulator said it required a new clinical trial to support approval.

Meanwhile, the next competitor scheduled to reach the market is Merck & Co’s gaboxadol, but this is not expected to be launched until 2008.