Thirty Years, a Proven Mechanism, and Still No Product

The mechanism has not been in doubt for three decades. Exogenous androgens suppress the hypothalamic-pituitary-gonadal axis, and that suppression reduces spermatogenesis.[1] The trials of the 1990s showed it produced contraceptive effect. The Cochrane review assessed the class systematically.[2] And there is still nothing to prescribe.

The reason is that the requirements multiply rather than add.

Five conditions, all of which must hold

1. Near-total suppression. Not reduction — suppression to azoospermia or close to it. Millions of sperm remaining is not contraception.

2. In nearly everyone. Incomplete responders stay fertile. A contraceptive with a definable non-responding minority needs semen monitoring to find them, which turns a consumer product into a clinical programme.

3. Reversibly. Cessation may result in spontaneous recovery in a reasonable number of men given sufficient time — and some men do not recover normal spermatogenesis.[1] For a treatment given to healthy young men who intend to have children later, that is a serious constraint.

4. Tolerably, for a healthy person. The side-effect bar is far lower than for treating disease. This is where candidates have historically failed.

5. Through an acceptable route. Weekly intramuscular injection is not it. Solving that produced DMAU orally and NES/T as a daily gel.

Each condition is individually surmountable. The product needs all five simultaneously.

What has genuinely changed

NES/T reached the design of an international efficacy trial — a study built to measure whether pregnancies are prevented, using a self-administered daily transdermal gel.[3] That is further than the field had previously reached, and it addresses conditions four and five directly.

The transdermal route works for the same reasons it works in testosterone replacement: it bypasses the liver, where oral testosterone is inactivated,[4] and gels are tolerated and accepted.[5]

What has not changed

The biological asymmetry. Interrupting one monthly event remains an easier target than suppressing continuous production — see why male contraception is hard.

The safety bar for healthy users. Unchanged and unchangeable.

The absence of a marketed product. Thirty years on.

The one thing to take from this season

If you are on testosterone therapy: it is not contraception. Suppression of spermatogenesis is real but not reliable or complete enough to prevent pregnancy.[1]

And in the other direction, if you want children: fertility plans are first on the Endocrine Society's list of conditions under which testosterone therapy should not be started.[6] The full clinical treatment of that is in TRT and fertility.

Frequently asked questions

Will there be a male pill? Candidates are in development. No product has been marketed, and the requirements are demanding.[2][3]

Why has it taken so long? Not for lack of a mechanism. Five conditions must hold simultaneously in a healthy population.

Is it a funding problem? Funding is part of it. The biological and safety requirements would remain even with unlimited funding.

Can I do anything now? Discuss existing contraceptive options with a clinician. Testosterone therapy is not among them.[1]

Where the story goes next

The delivery problem that has shaped every one of these attempts is the same one running through the whole of testosterone's history. The remaining T Files seasons cover the platform question and the state of modern practice.

In the meantime: the pharmacokinetic Goldilocks problem and the published clinical evidence.

References

6 sources

1. McBride JA, Coward RM. Recovery of spermatogenesis following testosterone replacement therapy or anabolic-androgenic steroid use. Asian J Androl. 2016;18(3):373–380. doi:10.4103/1008-682X.173938 · PMID 26908067
2. Grimes DA, Lopez LM, Gallo MF, et al. Steroid hormones for contraception in men. Cochrane Database Syst Rev. 2012;2012(3):CD004316. doi:10.1002/14651858.CD004316.pub4 · PMID 22419294
3. Amory JK, Blithe DL, Sitruk-Ware R, et al. Design of an international male contraceptive efficacy trial using a self-administered daily transdermal gel containing testosterone and segesterone acetate (Nestorone). Contraception. 2023;124:110064. doi:10.1016/j.contraception.2023.110064 · PMID 37210024
4. Nieschlag E, Nieschlag S. ENDOCRINE HISTORY: The history of discovery, synthesis and development of testosterone for clinical use. Eur J Endocrinol. 2019;180(6):R201–R212. doi:10.1530/EJE-19-0071 · PMID 30959485
5. Hadgraft J, Lane ME. Transdermal delivery of testosterone. Eur J Pharm Biopharm. 2015;92:42–48. doi:10.1016/j.ejpb.2015.02.015 · PMID 25709060
6. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715–1744. doi:10.1210/jc.2018-00229 · PMID 29562364