Viagra may Affect Sperm Motility

Published June 18th, 2000 - 02:00 GMT

Drugs used to treat erectile dysfunction may have improved the sex lives of men around the world, but a new study conducted in the lab suggests that these drugs may have a negative effect on sperm motility--sperm's ability to move, said Reuters Health, sourcing American Journal of Obstetrics and Gynecology.  

Because sperm must be able to swim to reach and fertilize the egg in the female reproductive tract, the finding raises questions about the possible effect of these drugs on male fertility, said June 16th report. 

The new study findings show that sildenafil (commonly known as Viagra) or drugs injected directly into the penis, such as phentolamine, may reduce sperm motility.  

Lead author Dr. J. Roberto Andrade, an obstetrician and gynecologist at Union Memorial Hospital in Baltimore, Maryland, was quick to point out that the study was done on small samples of sperm in the laboratory, a situation that does not completely replicate conditions in the body. The study used semen samples from 10 men aged 18 to 44, he noted. 

While both drugs at high concentrations affected sperm motility, the research was not done under ideal conditions, Andrade told Reuters Health. "We tried to isolate the Viagra molecule but couldn't do it at the normal pH (you would find) in the real world." Instead, the researchers mixed Viagra with sperm kept at a low pH. 

A 200-microgram dose of Viagra had no effect on sperm motility, but the highest dose used--2,000 micrograms--decreased motility by 50%, the report indicates. These are much lower doses than a man would normally take, but the drug was also diluted in a very small amount of sperm, Andrade noted. 

Still, it was not the result Andrade expected since he had anticipated the sperm would move faster once given Viagra. "I thought we would find the opposite," Andrade told Reuters Health. 

The effect of phentolamine was more expected because the drug is known to inhibit androgenic receptors, he said. A dose of 20 micrograms had no effect, but 200 micrograms mixed with sperm "resulted in a significant reduction in sperm motility," the researchers report. At 2,000 micrograms, almost all sperm were stopped in their tracks. 

"People are really curious about this study. No one ever thought about the sperm quality with erectile dysfunction drugs" since the focus has been on obtaining sexual satisfaction, Andrade noted. While the majority of men who take these drugs are older and perhaps less concerned with fertility, "many younger men are using these drugs, too." 

In their report, the study authors note that the concentrations of these drugs in the semen of men using them is not known. "Clinical studies are needed to evaluate concentrations in semen of drugs intended for erectile dysfunction and also to determine how these drugs affect the quality and quantity of sperm--and ultimately fertility," Andrade and colleagues conclude. 

The researchers plan to study the effect of these drugs on sperm motility in human subjects, Andrade commented. 

While these results are very preliminary, if a couple is experiencing fertility problems, and the man is using erectile dysfunction drugs, their doctor should be told, Andrade advised. "There could be a problem." – Albawaba.com 

 

© 2000 Al Bawaba (www.albawaba.com)

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