Prescription Meds Common in Pregnancy; Maybe Too Common

Lara C. Pullen, PhD

August 07, 2015

Although most physicians acknowledge the complexity of prescribing drugs to pregnant women, they nonetheless prescribe them frequently. More than four of five (82.5%) pregnant women 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.

The study, which details the type and timing of medications prescribed to pregnant Medicaid patients, presents a disturbing pattern, according to Kristin Palmsten, ScD, from the University of California, San Diego, in La Jolla, and colleagues. The authors published the results of their cohort study online July 31 and in the September issue of Obstetrics & Gynecology.

Landscape Now

Dr Palmsten and colleagues found that the most commonly dispensed medications are those used to treat infections. They also report that dispensing is more common for younger pregnant women and white women.

The researchers examined 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 medications dispensed by a pharmacist, but excluded medications purchased over the counter 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 (<20 years) were more likely to receive nitrofurantoin (23.9% vs 15.4%), metronidazole (20.7% vs 12.0%), and azithromycin (21.1% vs 11%).

The investigators also 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.

Drugs That May Cause Harm

Dr Palmsten and colleagues also found that 42.0% of pregnant women filled a prescription for a former US 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%).

Moreover, 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."

New Labeling From the FDA

Although the solution to the complex problem of drug use by pregnant women is not clear, the FDA has made a change that is designed to better inform healthcare providers and patients about the risks of drugs. 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.

"The articles in this issue, coupled with awareness of recent federal changes that affect our prescribing habits in pregnancy, will improve the quality of care our patients receive when medications are needed or are misused," write Nancy C. Chescheir, MD, editor-in-chief of Obstetrics & Gynecology, in an accompanying editorial.

The Pharmacoepidemiology Program at the Harvard School of Public Health (with which several of Dr Palmsten's colleagues are affiliated) is partially supported by training grants from Pfizer, Takeda, Bayer, and Phrma. The other authors have disclosed no relevant financial relationships.

Obstet Gynecol. 2015;126:463-478. Article abstract, Editorial extract

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