An On-Demand Male Pill Taken 30 Minutes Before Sex? Weill Cornell's NIH-Funded Candidate
Published October 27, 2026 · Investigational · Not approved
Most male contraceptives in development are taken every day or last for months. On October 23, 2026, Weill Cornell Medicine announced a four-year, $8.2 million grant from the National Institute of Child Health and Human Development (NICHD) to develop an experimental pill with a very different idea: take it shortly before sex, and its effect wears off within hours. It is preclinical, investigational and not approved, and it has not yet been tested in people.
How it's designed to work
The researchers, pharmacology professors Dr. Jochen Buck and Dr. Lonny Levin, target an enzyme called soluble adenylyl cyclase (sAC). According to Weill Cornell, their 2023 proof-of-concept work, published in Nature Communications, showed that blocking sAC left sperm immobile and prevented pregnancies in preclinical models. In Dr. Buck's words: "We've developed an on-demand contraceptive pill that men would take 30 minutes before having sex. The pill provides a six-to-eight-hour window of protection from pregnancy, and afterwards, fertility returns to normal." Those are the developers' design goals, based on preclinical work; they haven't been shown in human trials.
What the grant pays for
This is the third NICHD grant to the lab. It funds the toxicology and safety studies needed before human testing, plus an oral formulation and manufacturing protocols. The next step is a Phase 1 placebo-controlled trial in healthy men, which would track side effects and test sperm motility, and check that the effect is temporary. The researchers co-founded Sacyl Pharmaceuticals, which has licensed the technology; they hold equity and patents, as Weill Cornell discloses.
Why "on demand" matters
Weill Cornell points out that longer-acting methods take weeks to become effective and their effects can linger for weeks after stopping. An on-demand pill would, in theory, let men use contraception only when needed. The release cites surveys suggesting a short-term, on-demand option was the most appealing to men. In WHO's new framework, this approach falls under "inhibiting sperm function" rather than suppressing sperm production (see our guide to WHO's standards).
It isn't the only on-demand idea: PausePill
NEXT Life Sciences is developing PausePill (NLS-133), a hormone-free pill taken before sex with effects intended to last about 24 hours, according to Vice. The idea is different from sAC inhibition: it aims to temporarily stop sperm from being released during ejaculation. Vice reports it's in a small Phase 2 trial of 10 men and that its ability to prevent pregnancy remains unproven. PausePill is investigational and not approved. NEXT also develops Plan A, a hydrogel covered in our injectable-race explainer.
How it fits the bigger picture
| sAC inhibitor (Weill Cornell) | PausePill / NLS-133 | YCT-529 | |
|---|---|---|---|
| When taken | ~30 min before sex (design goal) | Before sex, ~24 h (design goal) | Daily |
| Hormonal? | No | No | No |
| Stage | Preclinical; Phase 1 planned | Small Phase 2 (per Vice) | Phase 1b/2a (see our update) |
| Approved? | No | No | No |
Questions a Phase 1 trial would need to answer
Based on Weill Cornell's description, the first human study would look at three things: whether the drug causes side effects compared with placebo, whether sperm motility drops after a dose, and whether that effect fully wears off. Dr. Peter Meinke, who worked on optimizing the compounds, notes that the bar is high because contraceptives are given to healthy people: the molecule must be fast-acting and potent, and it must keep sperm from swimming even after they leave the man's body. A motility signal in Phase 1 would be encouraging, but it wouldn't show pregnancy prevention. That takes larger, longer trials with couples.
An on-demand pill is years from any pharmacy even if everything goes well: it still needs Phase 1, then larger trials, then regulatory review. For where every candidate stands, see the status tracker.
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