A delayed-release combination of
doxylamine-
pyridoxine (D-P) (
Diclectin) is the only approved
antiemetic medication for use in pregnancy in Canada. The standard recommended dose is up to 4
tablets a day, regardless of
body weight or severity of symptoms. The objective of this study was to determine the incidence of adverse maternal and fetal effects and pregnancy outcome in 225 women taking
Diclectin at the recommended (n = 123) or higher than recommended (n = 102) doses. In this observational, prospective study, one-third (33.6%) of women reported having adverse effects (
sleepiness, tiredness, and/or drowsiness) temporally related to the medication. There was no association between the dose per kg and rates of reported maternal adverse effects with doses ranging from 0.1 mg/kg to 2.0 mg/kg (1-12 tablets).
Nausea and
vomiting of pregnancy (NVP) was reported as severe by the majority (75.8%) of women. Mean
birth weight (BW) was 3,400 g and gestational age (GA) 39 weeks. Multivariate analysis revealed that only prepregnancy weight and GA predicted lower BW, not the dose of D-P or the severity of NVP. There were two pregnancies with major malformation, a finding that is consistent with the rates of
birth defects in the general population. It was concluded that the higher than standard dose of
Diclectin, when calculated per kg of
body weight, does not affect either the incidence of maternal adverse effects or pregnancy outcome. If needed,
Diclectin can be given at doses higher than 4
tablets/day to normalize for
body weight or optimize efficacy.