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Any woman who has spent time drinking alcohol around men is familiar with the term “light-weight.” Drink for drink, women often can’t keep up.
This makes sense for women who weigh less than men. But women also metabolize alcohol differently. For instance, women generally have less of an enzyme made in the liver, called alcohol dehydrogenase, that’s responsible for the breakdown of alcohol. Because they have less of this enzyme, women metabolize alcohol slower, and get intoxicated more rapidly.
If women react differently than men do to alcohol, why wouldn’t they to drugs? Well, they do. And research has begun to show how just how much gender can play a role in things like potency, efficacy, and side effects of a wide range of medications.
Female Biology Affects Drug Action
Aside from weight being a factor, a myriad of other parts of female biology can affect how a woman reacts to a particular medication. One factor is extra body fat compared with men.
Because women have a larger storage of fat than men, any medication that is “fat soluble” (dissolves in fat before going to the brain) will be distributed differently in a woman. This impacts several medications used in psychiatry – including antidepressants, anti-anxiety medications and antipsychotics – because most of them fall into this category, says Philip Muskin, MD, professor of psychiatry at Columbia University Medical Center in New York City, and chair of the American Psychiatry Association’s scientific program committee.
It is not known why, but women tend to respond better to certain antidepressants and antipsychotics than men. For example, women do better than men with the selective serotonin reuptake inhibitors (SSRIs) like Zoloft, with verapamil for bipolar disorder, and also tricyclic antidepressants like Tofranil, according to Heather Whitley, PharmD at the University of Alabama School of Medicine in Tuscaloosa.
Antidepressants, however, can cause both sexes to experience problems with sexual function, notes the Mayo Clinic. While men can look to Viagra and similar drugs to control their issues; women have no such solution to their challenge.
Another difference between women and men is digestion. Women tend to produce less gastric acid than men do, resulting in slower digestion of foods. Because of this, medications that need an acidic environment to be absorbed, like the antifungal ketoconazole for example, may not be as effective in women. Also, drugs that require an empty stomach for absorption, like the antibiotic tetracycline, may not work as well if women don’t wait long enough before taking it after a meal.
The Estrogen Effect on Drug Action
Hormones can also play a role in how drugs are metabolized and used in the body. Women’s hormones fluctuate during their menstrual cycles and also surrounding menopause. Estrogen, for instance, can have an inhibitory effect on the way a woman’s liver breaks down medication, Dr. Muskin says.
Muskin correlates the liver to a giant oil filter. “Everything we eat goes through there and liver’s job is to filter out toxins,” he says. “The body thinks medications are toxins.”
When the liver doesn’t filter well, the concentration of a drug in the blood may be higher than expected, even when taking a “normal” dose, he says. Some medications are also filtered in the kidneys, like the cancer drug methotrexate, for example. According to an article in American Family Physician, methotrexate clears the body 13 to 17 percent slower in women than in men.
Heart Medications in Women
Heart-related drugs can also affect women differently than men. While low-dose aspirin has long been given to help reduce the risk of heart attack, this recommendation has been removed for women. This is due to the greater potential for bleeding in women.
In addition, beta-blockers have been shown to come with greater risk of re-hospitalization in women than in men.
The drug warfarin, a blood thinner used to prevent strokes and blood clots, is one example where smaller doses are recommended for women than men. A recent article in the American Family Physician noted that a woman needs 2.5 to 4.5 mg less warfarin a week than a man.
Digoxin, used to treat patients with heart failure, was initially shown in the early 2000s to increase mortality rates in women by up to 20 percent. But a 2012 study in the British Medical Journal of more than 20,000 patients found no difference in mortality between the two sexes.
Pain Medication and Sleep Aides
Painkillers are a class of medications that have different side effects in women and men. A large study from 2002 found that women taking acetaminophen (Tylenol) and non-steroidal anti-inflammatory medications, like ibuprofen, were more likely to have high blood pressure than those who didn’t take the drugs. Specifically, women taking NSAIDs for more than 22 days a month had an 86 percent increased risk of having hypertension and those taking acetaminophen were two times as likely to have hypertension.
Another group of medications where sex-related differences are seen is sleep aides. In general, sleep aides are excreted more slowly from a woman’s system than a man’s. Women reported having more problems than men did driving the day after taking medications like Ambien the previous evening. In fact, in 2013, the Food and Drug Administration (FDA) recommended women should take only half as much Ambien as men.
Drug Safety for Women
It is important to know that many of these biological differences are very minor. Women should not be afraid to take medication, says Muskin. Most of the time, men and women are safe taking the same doses, but women may be more likely to experience more obvious or annoying side effects.
Muskin says remember to talk with your doctor about how you have responded to other medications (i.e. did you gain weight, experience sexual dysfunction, have a bad reaction?) before you take anything new.
By Tammy Worth for Everyday Health; Medically Reviewed by Michael Culter DO, PhD
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This article originally appeared on EverydayHealth.com: Drugs That Work Differently in Women and Men