Methadone suppresses testosterone in men, McMaster research suggests

Opioid addiction treatments can cause testosterone levels in men to plummet, according to new research from Hamilton’s McMaster University.

In a paper published Tuesday by the journal Scientific Reports, researchers say addiction treatments might need to change to cope with this side effect. It’s a symptom doctors have been aware of for years, says Dr. Zena Samaan, the principal investigator of the study – but they didn’t know just how drastic it was.

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In fact, when they study’s researchers first started checking results, they actually had to go back and make sure they didn’t accidentally test women by mistake because the testosterone levels were just so low.

“The numbers were striking,” Samaan said. “They were shockingly low.”

The study tested people who use methadone, a synthetic analgesic that’s used to treat opioid addiction. Men who participated in the study had testosterone levels that were 75 per cent lower than men who weren’t using methadone.

A major barrier

A drastic drop of testosterone like that is associated with many side effects, like low energy and quality of life, erectile dysfunction and mood disorders. “That’s a major barrier for men continuing on treatment,” Samaan said. Many men could enter a methadone program with depleted levels of testosterone before even starting treatment, as most opioids deplete testosterone because of the way they work on the hypothalamus.

Testosterone levels can also change over time when a man is taking methadone. When a person is in a methadone program, they slowly wean themselves off other opioids by adjusting their dosage to stave off withdrawal symptoms. As methadone is a synthetic opioid itself, testosterone levels fluctuate alongside the methadone dose.

But these aren’t insurmountable problems, Samaan says. Hormone replacement therapy and supplements can help mitigate the effects of treatment. It’s something that patients should be open to discussing with their doctor, she says. “It’s a conversation that should be happening,” she said.

At Hamilton’s John Street Clinic, about 20 per cent of men who are prescribed methadone also need some sort of hormone replacement therapy, officials say.

Outcomes on methadone much better than without

Debbie Bang, the manager of St. Joseph’s Healthcare Womankind addictions service, says she worries that this kind of research might dissuade men from entering a methadone program if they really need it.

“But we know the outcomes are much better for people living and getting along with their lives with methadone,” Bang said. “It dramatically changes things and allows them to get on with their lives.”

Bang did, however, say this research provides doctors with useful information. “It means now that clinicians can have this discussion.”

This study used information from 231 patients with opioid dependence receiving methadone in Ontario, as well as 783 Ontarians who weren’t using opioids. Testosterone levels for women were not significantly impacted by opioids.

The study was conducted by the Population Genomics Program of McMaster’s Chanchlani Research Centre and Ontario Addiction Treatment Centres. It was funded by the Drug Safety and Effectiveness Network of the Canadian Institutes of Health Research and the McMaster Department of Psychiatry and Behavioural Neurosciences.