Sanofi-Aventis is expected to launch Ambien CR (zolpidem extended-release) in the next few weeks following FDA approval of the sleep agent, announced Sept. 6.

Sanofi Senior Exec VP-Science & Medical Affairs Gerard Le Fur reiterated the firm's planned launch of the Ambien successor by the end of the summer during an Aug. 31 earnings presentation, ahead of the drug's approval.

Ambien CR is approved "for the treatment of insomnia, characterized by difficulties with sleep onset and/or sleep maintenance (as measured by wake time after sleep onset)," labeling states.

Labeling contains no limitation on duration of use. However, labeling notes that "clinical trials performed in support of efficacy were both three weeks in duration, although the final formal assessments of sleep latency and maintenance were performed after two weeks of treatment."

Labeling for immediate-release Ambien states that the sleep agent is indicated for "short-term treatment of insomnia."

The maintenance indication for the successor product will likely be a central feature of Sanofi's marketing plans, particularly in light of new and forthcoming competition in the sleep category.

Takeda's Rozerem (ramelteon), which is expected to launch this month, received FDA approval July 22 for the "treatment of insomnia characterized by difficulty with sleep onset" (¹ Also see "Takeda's Rozerem To Launch In September Following FDA Approval" - Pink Sheet, 22 July, 2005.).

Sepracor's Lunesta (eszopiclone) debuted in April, taking share from immediate-release Ambien (² Also see "Lunesta Has "Encouraging" Debut, Sepracor Says" - Pink Sheet, 25 April, 2005.).

Pfizer/Neurocrine's insomnia agent indiplon is under review at FDA (³ Also see "Takeda’s Sleep Aid Rozerem Could Avoid Controlled Substance Scheduling, Firm Says" - Pink Sheet, 12 July, 2005.).

Sanofi's Ambien CR features a controlled-release, biphasic formulation that includes "one layer that releases its drug content immediately and another layer that allows a slower release of additional content," labeling states.

Ambien labeling states that immediate-release zolpidem showed a small, yet statistically significant, decrease in performance for next-day residual effect observed in the Digit Symbol Substitution Test compared with placebo.

In contrast, Ambien CR labeling states that "no significant decrease in performance was observed eight hours after a nighttime dose" in neurocognitive tests.

"Next day somnolence was reported by 15% of the adult patients who received 12.5 mg Ambien CR versus 2% of the placebo group," labeling states. "Next day somnolence was reported by 6% of the elderly patients who received 6.25 mg Ambien CR versus 5% of the placebo group."

The recommended dose in adults is 12.5 mg before bedtime; recommended dose for elderly or debilitated patients, or those with hepatic insufficiency, is 6.25 mg.

Labeling for both Ambien formulations contains identical warnings and slight differences in commonly reported adverse events.

The most common adverse events for Ambien CR are headache, somnolence and dizziness, while common adverse events for Ambien are drowsiness, dizziness and diarrhea.

- Christopher Hollis

Ambien CR Gets FDA Approval; Launch Expected In Mid-September

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