Systemic Bioavailability and Pharmacokinetics of the Doxylamine–Pyridoxine Delayed-Release Combination (Diclectin)

Abstract

There was a 2.1-fold variability in the DOX-AUC0→∞ and 6.5-fold variability in the PLP-AUC0→∞ after oral administration of 20 mg Diclectin. Using literature values and data from the current study, we estimated the oral bioavailability of pyridoxine to be 100%. Therefore, interindividual differences in metabolism, and not in bioavailability, may be important sources of variability that need to be addressed in dosing guidelines.

The Delayed-Release Combination of Doxylamine and Pyridoxine (Diclegis®/Diclectin®) for the Treatment of Nausea and Vomiting of Pregnancy

“…Another single-center, open-label study including 18 non-pregnant, non-lactating, premenopausal women was conducted to determine the pharmacokinetics of doxylamine succinate and pyridoxine HCl after administration of a single dose of Diclectin ® (2 × 10 mg/10 mg) under fasting conditions [63]. The mean plasma–concentration profiles of doxylamine succinate and PLP demonstrated large variability among participants; furthermore, twofold variability was observed in the systemic exposure to doxylamine and 6.5-fold for PLP based on the mean area under the curve (AUC 0→∞ ).…”

“…For PLP, mean T ½ was 56 h, and mean C max was 42.9 ng/mL. This study also calculated the bioavailability of pyridoxine to be 100 % [63]. …”

Management of nausea and vomiting in pregnancy

“…Individual responses vary greatly, however, probably because of large differences in the onset and action of pyridoxine. 18 Ginger has also been used as an antiemetic in several small randomised controlled trials (RCTs), both alone and combined with pyridoxine, but with no significant difference in nausea scores between the two groups. The conflicting data on the efficacy of ginger may result from different preparations and potencies of ginger used in various studies.…”

Doxylamine succinate–pyridoxine hydrochloride (Diclegis) for the management of nausea and vomiting in pregnancy: an overview

“…However, there is some variability in its onset and duration of action among women. It is estimated that the oral bioavailability of pyridoxine is 100%, so interindividual differences in metabolism, rather than bioavailability, are thought to account for variation in therapeutic response 31. Both doxylamine and pyridoxine are hepatically cleared.…”