Male contraceptive successfully stops sperm without affecting hormones in monkeys.

Men have two practical choices for contraception, namely, the condom accompanied by a high failure rate of approximately 18 percent or a vasectomy known to be expensive and hard to reverse.  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 their overall motility without affecting hormones, making EP055 a potential ‘male pill’ without side effects.  The team states their compound works by switching off the sperm’s ability to swim, significantly limiting fertilization capabilities.   The opensource study is published in the journal PLOS ONE.

Previous studies report the existence of hormonal drugs in clinical trials capable of targeting 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 targetting either the production of sperm or the delivery of sperm. One particular target is the sperm protein EPPIN, present on the surface of human spermatozoa.  Eppin’s functions include modulating prostate-specific antigen enzyme activity, providing antimicrobial protection, and inhibiting sperm motility.  The current study demonstrates in macaque monkeys the sperm surface protein EPPIN is a reasonable non-hormonal contraceptive target using the EP055 compound.

The current study utilizes 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 thirty hours after a high-dose intravenous infusion of EP055 male rhesus macaques exhibit no indication of normal sperm motility, with no physical side effects observed.  Data findings show eighteen days post-infusion, all macaques showed signs of complete recovery, suggesting the EP055 compound is reversible.

The lab states EPP05 works by preventing a-EAb from binding to EPPIN to inhibit human sperm motility and has a plasma half-life of 10–12 minutes, remaining in the testis and epididymis of male monkeys for at least six hours.  They go on to add the plasma levels of EP055 were barely detectable at thirty hours post-infusion, with data demonstrating infusion of EP055 results in the drug being retained in semen for up to seventy-eight hours, effectively giving a potential contraceptive window of 24–48 hours following administration of the drug.

The team surmises their data shows the EP055 compound has the potential to be a male contraceptive abe to provide a reversible, short-lived pharmacological alternative.  For the future, the researchers state more work is needed before EP055 becomes available for human use.

Source: UNC-Chapel Hill

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