How it works
TDI-11861 is an investigational non-hormonal male contraceptive pill that works on demand. It inhibits soluble adenylyl cyclase (sAC), an enzyme that sperm need to swim and to undergo capacitation, the process that lets them fertilize an egg. When sAC is blocked, sperm become immobile within hours. The drug does not affect testosterone, other hormones, or sperm production. It is taken before sex, similar to how some female contraceptives are used on demand.
Research and approval status
TDI-11861 is in preclinical development. Sacyl Pharmaceuticals, a company founded by Weill Cornell Medicine researchers Dr. Jochen Buck and Dr. Lonny Levin, is developing it. A study published in Nature Communications in 2023 showed that in mice, a single dose of TDI-11861 immobilized sperm for up to 2.5 hours and produced 100% contraceptive efficacy: zero pregnancies in 52 treated mice versus 30% in controls (PMID 36794605). Fertility recovered completely by 24 hours after the dose. Sacyl Pharmaceuticals has stated a goal of starting human clinical trials in 2025. No ClinicalTrials.gov registry has been posted yet, and the drug is not available outside of research.
Why it matters
Most male contraceptive candidates in development are hormonal, meaning they suppress testosterone to stop sperm production. TDI-11861 is genuinely non-hormonal: it targets a sperm-specific enzyme without affecting hormone levels. Its on-demand design is also different from daily pills or long-acting implants. If human trials confirm the preclinical results, it would be the first on-demand male contraceptive. Commercial availability is still several years away.