Elinzanetant and menopausal sleep: an early gain that faded on polysomnography

Design

Phase 2, randomised, placebo-controlled

Population

110 postmenopausal women with moderate-to-severe vasomotor symptoms and disturbed sleep

Primary outcome

Polysomnographic wakefulness after sleep onset

Effect

Week 4 −22.5 min (90% CI −35.5 to −9.5); week 12 −0.9 min (−14.0 to 12.1)

NIRVANA randomised 110 postmenopausal women aged 40 to 65 with moderate-to-severe hot flushes and objectively disturbed sleep to elinzanetant 120 mg, a dual neurokinin-1 and -3 receptor antagonist, or placebo for 12 weeks.

At week 4, wakefulness after sleep onset on polysomnography fell by about 22.5 minutes more with elinzanetant (90% CI −35.5 to −9.5). At week 12 the difference on that measure had all but gone (−0.9 minutes, 90% CI −14.0 to 12.1). A post hoc model across all time points, home monitoring and sleep diaries favoured elinzanetant on several sleep-continuity measures.

This is a small phase 2 study whose primary-measure benefit was not sustained at 12 weeks, and the more favourable picture rests on post hoc modelling. It adds to the case that neurokinin antagonists help night-time symptoms, but it is not yet evidence to choose one specifically for insomnia.

• Ask women with hot flushes specifically about night waking; it is a common reason they seek treatment
• Treat this as phase 2, sleep-focused evidence rather than a sleep indication
• Note that the objective benefit at week 12 was not different from placebo
• Screen for other causes of poor sleep, such as sleep apnoea and low mood, before attributing it all to vasomotor symptoms

Why it matters

It tempers the expectation that a non-hormonal hot-flush drug will also fix menopausal insomnia.

Don't overread it

The sustained benefit rests on post hoc modelling; the week-12 primary measure showed no difference.

The statistics, in plain English

The trial reported 90% rather than the usual 95% confidence intervals, which makes the ranges narrower and results look firmer than a conventional analysis would. The week-12 interval runs from 14 minutes better to 12 minutes worse, so it is consistent with no effect.

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