Male contraceptive successfully stops sperm without affecting hormones in monkeys.
Men have two practical choices for contraception; the condom which has a high typical use failure rate of approximately 18% or vasectomy which is expensive and not readily reversible. Now, a study from researchers led by the University of North Carolina shows how a compound called EP055 binds to sperm proteins to significantly slow the overall mobility of the sperm without affecting hormones, making EP055 a potential ‘male pill’ without side effects. The team state their compound turns-off the sperm’s ability to swim, significantly limiting fertilization capabilities which makes it an ideal candidate for non-hormonal male contraception. The opensource study is published in the journal PLOS ONE.
Previous studies show that there are hormonal drugs in clinical trials which target the production of sperm, however, these affect the natural hormones in men much like female contraceptives affect hormones in women. Non-hormonal contraceptives are also under development that target either the production of sperm or the delivery of sperm. One particular target is the sperm protein EPPIN, which is present on the surface of human spermatozoa. Eppin’s functions include modulating PSA (prostate-specific antigen) enzyme activity, providing antimicrobial protection and inhibiting sperm motility before PSA hydrolyses SEMG in the ejaculate coagulum, to improve spermatozoa motility. The current study demonstrates in macaque monkeys that the sperm surface protein EPPIN is a reasonable non-hormonal contraceptive target using the EP055 compound.
The current study utilises rhesus male monkeys to assess the availability of EP055 in semen and its effect on sperm motility as a measure of the drug’s efficacy in targeting the EPPIN protein. Results show that thirty hours after a high-dose intravenous infusion of EP055 male rhesus macaques exhibit no indication of normal sperm motility; further, no physical side effects were observed. Data findings show that 18 days post-infusion, all macaques showed signs of complete recovery, suggesting that the EP055 compound is reversible.
The lab state that EPP05 works by preventing a-EAb, an SEMG substitute, from binding to EPPIN to inhibit human sperm motility, has a plasma half-life of 10–12 minutes, and was found to remain in the testis and epididymis of male monkeys for at least six hours. They go on to add that the plasma levels of EP055 were barely detectable at 30 hours post-infusion, with data demonstrating that infusion of EP055 results in the drug being retained in semen for up to 78 hours; effectively giving a potential contraceptive window of 24–48 hours following administration of the drug.
The team surmise their data shows that the EP055 compound has the potential to be a male contraceptive that could provide a reversible, short-lived pharmacological alternative. For the future, the researchers state that more work is needed before EP055 becomes available for human use; they have begun to test a pill form of the compound and will eventually conduct a mating trial of EP055’s effectiveness against pregnancy.
Source: UNC-Chapel Hill