Xonvea is a combination of doxylamine (an antihistamine) and pyridoxine (vitamin B6). Commonly prescribed as Diclegis/Diclectin to treat morning sickness in the US and Canada, it is now available in the UK.
Xonvea is indicated to treat nausea and vomiting of pregnancy in women who do not respond to conservative management.
The recommended starting dose is 2 tablets at bedtime, increased according to response to a maximum of 4 tablets daily.
In a randomised, double-blind, placebo controlled trial (n=256), 14 days' treatment with doxylamine/pyridoxine resulted in a significantly larger improvement in symptoms of nausea and vomiting of pregnancy compared with placebo based on the Pregnancy Unique Quantification of Emesis (PUQE) score (-4.8 ± 2.7 vs -3.9 ± 2.6; p=0.006). The PUQE score incorporates the number of daily vomiting episodes, number of daily heaves, and the length of daily nausea in hours, for an overall score of symptoms rated from 3 (no symptoms) to 15 (most severe).
After the trial, 48.9% women receiving the combination asked to continue compassionate use of their medication, compared with 32.8% of placebo-treated women (p=0.009).
The most commonly reported adverse reactions of doxylamine/pyridoxine were somnolence, dizziness, dry mouth and fatigue.
Consultant obstetric physician Professor Catherine Nelson-Piercy said, 'I am delighted that at last the UK has a licensed medication for the treatment of nausea and vomiting of pregnancy where conservative treatment has failed. This delayed release formulation of doxylamine and pyridoxine has been used in millions of pregnant women worldwide'.
She added, 'In women who do not respond completely to Xonvea, doctors can prescribe other anti-sickness drugs recommended by National Clinical Guidelines'.