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Prescription Medications Common in Pregnancy

Drugs that could harm fetus given to 42% of Medicaid recipients

More than four out of five pregnant Medicaid recipients (82.5%) were prescribed at least one medication — and 42.0% were prescribed a drug that is potentially harmful to the developing fetus, researchers found in a large, population-based study.

According to a Medscape report, the study presents a disturbing pattern. Kristin Palmsten, ScD, of the University of California at San Diego, and colleagues published the results of their cohort study in the September issue of Obstetrics & Gynecology.

The most commonly dispensed medications are those used to treat infections, the study found, and dispensing is more common for younger pregnant women and white women. The research is based on data for women enrolled in Medicaid before pregnancy (N = 1,106,757), using 2000 to 2007 Medicaid Analytic eXtract data for prospectively collected medication information. The analysis included over-the-counter (OTC) medications dispensed by a pharmacist, but excluded OTC medications purchased directly or prescribed during hospitalizations.

The most commonly dispensed medications were nitrofurantoin (21.6%), metronidazole (19.4%), amoxicillin (18.0%), azithromycin (19.9%), and promethazine (13.5%). Other frequently dispensed medications include promethazine, cephalexin and codeine with acetaminophen. Compared with women older than 35 years, younger women (less than 20 years of age) were more likely to receive nitrofurantoin (23.9% versus 15.4%), metronidazole (20.7% versus 12.0%), and azithromycin (21.1% versus 11%).

The investigators note that nine of the 20 most commonly dispensed medications are rated as having limited to fair data quality and quantity to inform human teratogenic risk assessments by the Teratogen Information System.

Palmsten and colleagues also found that 42.0% of pregnant women filled a prescription for a former Food and Drug Administration (FDA) category D or X drug during pregnancy. Category D medications are associated with evidence of human fetal risk based on adverse reaction data. The top five most commonly prescribed category D medications were codeine (11.9%), hydrocodone (10.2%), ibuprofen (4.9%), sulfamethoxazole (4.0%), and hydrocortisone (4.0%). The authors note that some of those agents are considered category B or C drugs, depending on the circumstances of use.

Class X medications have been tested in animals or humans and found to cause fetal abnormalities. The five most commonly prescribed category X drugs were hormonal contraceptives (4.9%), temazepam (0.11%), atorvastatin (0.07%), simvastatin (0.04%), and warfarin (0.04%).

The researchers note that many of the most commonly dispensed medications have limited or low-quality data available regarding safety during pregnancy. “Lack of unambiguous safety information may lead to the use of medications with potential to cause adverse pregnancy outcomes, whereas beneficial medications may be avoided,” they write.

Many opioids are category N, meaning the FDA has not classified the drug. An accompanying commentary by Mallory E. Kremer, MD, and Kavita Shah Arora, MD, MBE, from Case Western Reserve University in Cleveland, Ohio, described the clinical, legal, and ethical considerations associated with treating pregnant women who are addicted to opioids. They conclude that "obstetricians must be clear: addiction is a chronic disease and not a moral failing. Criminally targeting women for chronic health conditions in pregnancy is medically and ethically inappropriate and reinforces societal stigmas. Surreptitious legal encroachments on women's autonomy highlight their continued vulnerable role in society."

As of June 30, 2015, the FDA has changed the way it labels human prescription medications and biologic preparations for use in pregnancy and lactation. The new labels will include a summary of the risks of the drug during pregnancy.

Source: Medscape; August 7, 2015.

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