McMaster University

McMaster University

Faculty of
Health Sciences

Drug coating investigated as source of low sperm counts, infertility

By Suzanne Morrison
Published: August 9, 2010
Warren Foster
Dr. Warren Foster, professor of obstetrics and gynecology

Health risks of phthalates have focused on their use in plastic toys, hair spray, food packaging and medical equipment, such as intravenous tubing.

Could  slow-release prescription drugs also be a source of phthalate exposure — causing low sperm counts, reduced libido and infertility — in men suffering from Crohn’s and Colitis, also known as inflammatory bowel disease (IBD).

A phthalate and semen quality study led by Dr. Warren Foster, professor of obstetrics and gynecology in the Michael G. DeGroote School of Medicine at McMaster University, is investigating this possibility and study participants are being sought.

Foster recently learned phthalate-containing polymer, designed to slow the release of medication, thinly coats some timed-release drugs. He has had trouble finding out specific medications where they are used but knows they are contained in one drug used to treat Crohn’s and Colitis.

Phthalates are used to soften plastics and everyone has some low-level exposure to them. However, it’s known that they interfere with the ability of testosterone, the male sex hormone, to bind to its receptor, by displacing testosterone and acting like an anti-testosterone.

"The concern is that phthalates may be one of the factors contributing to lower sperm counts," Foster said. "If the exposure is in utero, they could have an effect on developmental abnormalities of the male reproductive tract."

The issue, he said, is that one manufacturer of slow-release capsules for treating Crohn’s and Colitis uses phthalates in their product but a second manufacturer with a similar capsule does not.

A retrospective study by the Centre for Disease Control (CDC) reported patients using slow-release medications had approximately 50 times higher phthalate metabolite levels in their urine. Concentrations that are much higher than in the general population may be great enough to affect the reproductive health of men who use these medications.

In his study of 40 men suffering from some form of IBD, Foster is investigating two of the many slow-release drugs routinely used to treat IBD. Anyone volunteering to participate in the study will be assessed by a gastroenterologist to determine if they are suitable for this medication. Study participants will be randomly assigned to receive one of the drugs. Before taking the drug, and again between three and six months, they will be asked to provide semen, urine and blood samples at which times semen quality and libido will be assessed. At the same time phthalate metabolites concentrations will be measured.

Foster’s hypothesis is that exposure to phthalates will be related to lower sperm counts and semen quality. "However, until we do the study, we won’t know, and we will not be able to provide appropriate advise to either Health Canada or patients concerning these medications," he said.

His is the only lab that he is aware of that is looking at the relationship between phthalates in slow-release capsules and male reproductive function. Results are expected early next year and Foster anticipates they could garner a lot of attention.

Anyone wishing to participate in the study should contact Dr. Sandra Gregorovich, research co-ordinator, at 905-25-9140, ext. 28654.

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