Multi-drug interactions are a common occurrence in medicine and can potentially harm the health of patients in a number of ways. Combined hormonal contraception, such as birth control pills, patches, vaginal rings or injections, are often overlooked when it comes to medication lists, but they too can be affected by or, in turn, affect the blood levels of other drugs.
According to the Guttmacher Institute, almost 22 percent of women between ages 15-44 use contraception, primarily in the form of the pill. That is a total of 13 million women in the U.S. alone . Any medication that may interfere with the effectiveness of birth control can lead to an unwanted or unplanned pregnancy. Depending on the medication, it also may impact the development and health of the fetus.
Modafinil and its derivative armodafinil are medications that promote alertness and mental focus. They are approved by the Food and Drug Administration (FDA) for narcolepsy, obstructive sleep apnea and excessive sleepiness associated with shift work . Both are very similar to each other in their chemical structure and the way they work.
Like a lot of medications, modafinil is pregnancy category C, meaning animal studies have shown an adverse effect on the fetus and there are no adequate and well-controlled pregnancy outcome studies in humans. The potential benefits, though, may warrant use of the drug in pregnant women despite the potential harms . Therefore, it is important for both health care providers and women taking modafinil to avoid unplanned pregnancies while on the drug and to make an informed choice of continuing treatment only if the benefits outweigh the risks.
Neurologists, sleep specialists, psychiatrists and sometimes primary care physicians prescribe both of these drugs for the indications above as well as to combat fatigue in other conditions such as multiple sclerosis and depression , and to improve alertness at jobs requiring sustained and elevated levels of attention such as air traffic control . Their interaction, however, with contraceptives remains under-recognized by doctors and patients alike.
A specific enzyme in the liver breaks down modafinil to its composing molecules, which are then eliminated in the urine. The same enzyme that is responsible for clearing the body of modafinil also breaks down contraceptives. Studies have shown that, when taken together with modafinil, the overall blood levels of contraceptives decrease by 18 percent, resulting in potentially significantly lower effectiveness of the contraceptives . At least theoretically, this can lead to unplanned pregnancies on a medication that may cause harm to the fetus.
Despite the package insert clearly advising women to use alternate or concomitant forms of contraception while taking modafinil or armodafinil, including up to one month after discontinuing use , most prescribing physicians are unaware of these consequences from drug interaction and so do not advise their female patients about them.
In our women's neurology clinic, we see a fair number of women with sleep problems who are taking modafinil, often with contraceptives. Yet neither they nor their prescribing physicians are aware of the potential failure of the contraceptive when taken together with modafinil .
There is a clear knowledge gap when it comes to the interaction between contraceptives and neurological medications, specifically modafinil. This is despite the fact that, in the age of electronic medical records, software can often automatically warn prescribers about these issues.
Both physicians and consumers need to be better educated on the impact of other medications on contraceptives. Educational programs about women's health in general and contraceptive health in particular are sorely needed for physicians outside the field of obstetrics and gynecology.
Teaching about women's health should not be confined to a single specialty but should be included in all fields of health care. It's time we all recognize that sex differences exist in all areas of medicine.
By Hrayr Attarian, MD, FACCP, FAASM, Member of the SWHR Network on Sleep and Associate Professor of Neurology, Department of Neurology, Circadian Rhythms and Sleep Research Lab
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