Therapeutic drug monitoring

Determinants of adherence to delayed-release doxylamine and pyridoxine in patients with nausea and vomiting of pregnancy.

PMID 22972538


Women often hesitate to take medications in pregnancy due to fears of perceived potential fetal damage. The authors' objective is to identify the determinants of adherence to delayed-release doxylamine-pyridoxine (Diclectin) in patients with nausea and vomiting of pregnancy (NVP). The authors performed a prespecified secondary analysis of a multicenter double-blind randomized controlled trial of Diclectin versus placebo for the treatment of NVP. Data on adherence to study medication were collected in all patients. The primary outcome of this analysis was adherence to study medication, which was determined by pill counting and patient diaries. The treatment regimen in the original trial was not fixed and depended on patient's symptoms. There was no difference in the adherence rates between subjects in the Diclectin or placebo arms of the study, so the 2 arms were analyzed as one cohort. The degree of adherence was analyzed in the various subgroups. Subsequently, a multiple linear regression model was constructed to identify predictors to adherence. Two hundred fifty-eight women were included in this analysis. There were no differences in adherence rates according to ethnicity, race, or the presence of adverse events. Gravidity, average number of prescribed tablets per day, site of enrollment, and change in NVP severity measured by the pregnancy unique-quantification of emesis score were associated with adherence. In multivariable analysis, average number of tablets per day, change in pregnancy unique-quantification of emesis, number of treatment days, site of enrollment were significantly predictive of adherence, with the former being negatively correlated. Adherence to antinauseants for NVP is affected by number of tablets prescribed per day, and treatment duration and effectiveness.