General Information

Diclegis is a fixed-dose combination drug product of doxylamine succinate, an antihistamine, and pyridoxine hydrochloride, a vitamin B6 analog.

Diclegis is specifically indicated for the treatment of nausea and vomiting of pregnancy in women who do not respond to conservative management.

Diclegis is supplied as a tablet for oral administration. The recommended dose is two tablets daily at bedtime. If symptoms are not adequately controlled, the dose can be increased to a maximum recommended dose of four tablets daily (one in the morning, one mid-afternoon and two at bedtime).

Mechanism of Action

Diclegis is a fixed-dose combination drug product of doxylamine succinate, an antihistamine, and pyridoxine hydrochloride, a vitamin B6 analog. The mechanism of action by which Diclegis exerts its’ effects is unknown.

Side Effects

The most common adverse reaction associated with the use of Diclegis is somnolence.

Clinical Trial Results

The FDA approval of Diclegis was based on a double-blind, randomized, multi-center, placebo-controlled study in adult women in 7 to 14 weeks gestation (median 9 weeks of gestation) with nausea and vomiting of pregnancy. The subjects were adminitered two tablets of Diclegis or placebo at bedtime on Day 1. If symptoms of nausea and vomiting persisted into the afternoon hours of Day 2, they were directed to take the usual dose of two tablets at bedtime that night and, beginning on Day 3, to take one tablet in the morning and two tablets at bedtime. Based upon assessment of remaining symptoms at the clinic visit on Day 4, the subject may have been directed to take an additional tablet mid-afternoon. A maximum of four tablets (one in the morning, one in the mid-afternoon and two at bedtime) were taken daily. Over the treatment period, 19% of Diclegis-treated subjects remained on 2 tablets daily, 21% received 3 tablets daily, and 60% received 4 tablets daily. The primary efficacy endpoint was the change from baseline at Day 15 in the Pregnancy Unique-Quantification of Emesis (PUQE) score. This score incorporates the number of daily vomiting episodes, number of daily heaves, and length of daily nausea in hours, for an overall score of symptoms rated from 3 (no symptoms) to 15 (most severe). At baseline, the mean PUQE score was 9.0 in the Diclegis arm and 8.8 in the placebo arm. There was a 0.7 (p-value 0.006) mean decrease (improvement in nausea and vomiting symptoms) from baseline in PUQE score at Day 15 with Diclegis compared to placebo.