5-Alpha Reductase Inhibitors
Although only low ejaculate volume was found in single-year premarketing clinical trials of finasteride, there appears to be a more profound effect when they are taken for longer periods of time. Profound decreases in sperm concentration and motility as well as infertility have been noted in numerous case reports since the market approval of the drug. This has led the Food and Drug Administration (FDA) to recently amend the product insert to now state that male fertility and sexual function can be impaired by this class of drugs.[66,67,68] Finasteride has also been shown to cause increased sperm DNA damage in patients. It is expected that patients will regain baseline sperm parameters when the medication is discontinued, but this could take 6 months or more.[6,68,69]
Medications such as tadalafil and sildenafil are frequently used to help with situational erectile dysfunction that is commonly associated with scheduled sexual intercourse needed to conceive. Interestingly, several studies have shown that phosphodiesterase-5 inhibitors may also improve sperm motility.[70,71,72] One study even suggested that daily use of sildenafil could improve sperm concentration. Most of this research, however, is observational and uncontrolled in nature.
Alpha blockade has been used to treat symptomatic lower urinary tract symptoms such as urinary frequency, slow stream, and incomplete emptying, but this has also been associated with retrograde ejaculation. In controlled trials, the incidence of ejaculatory dysfunction associated with tamsulosin was reported in 4 to 26% of patients and appeared to be dose related. A prospective, double-blinded study also showed decreased ejaculate volume with tamsulosin but not alfuzosin. Anejaculation occurred in 35% of patients on tamulosin. There may also be drug-related effects on sperm morphology (lower normal forms) and motility (lower), but this needs further confirmation.
Semin Reprod Med. 2013;31(4):286-292. © 2013 Thieme Medical Publishers