Are men and women affected the same by the same dose of a drug?

It turns out that the answer to that question for some drugs is no, and the Food and Drug Administration understood that for the sleeping aid Ambien as far back as 1992.

CBS’s 60 Minutes tackled the issue last week by focusing on the sleep aid Ambien. The FDA has moved to cut the recommended dose for women in half. It appears men and women metabolize the drug differently and women were found to have much more drug remaining in their system the next day making driving dangerous.

Courtesy of K3i8c84media

Various zolpidem (Ambien) tablets made by different manufacturers.

Back in 1992, when Ambien was approved, FDA reviewers noted the effect the drug had on the two genders. Women had 45% higher residues remaining in her blood than in his.

What did they do with that information? Back in 1992 it was noted as interesting and never explored further because there was no information that showed the differences mattered. Men and women were thought of as essentially similar except for their reproductive systems. Most of the drug studies on rats were done on male rats because there were no female hormones to get in the way of the data.

That is typical across the board for all drug trials, said a scientist interviewed for the story. In the meantime Ambien was prescribed 40 million times to both sexes last year.

How many other drugs may be metabolized differently by the genders – the answer is potentially all of them. Aspirin for example, is known to cut the heart attack risk in men, not so in women for whom it cuts the risk of stroke.

Heart disease is the number one killer of both men and women but symptoms of a heart attack are often vague in a woman. She may not even have a tightening of the chest or chest pains but instead may experience nausea and back pain. That’s because the blood clot causing the attack may occur in microvessels inside the heart. It is not uncommon for women to never be fully diagnosed with a heart attack. Another difference is found in female stem cells. Men’s stem cells are less powerful and die off while the female stem cells remain stable.

The report concludes that this lack of understanding represents a disadvantage for researchers, showing that drugs’ effects on the sexes should be studied differently.

The General Accounting Office looking at recalled drugs found eight of ten recalled between 1997 and 2001 posed a greater risk for women than men.

In the meantime, Ambien remains the only sleep aide on the market that has a different dosage for men than women.