Adult: In patients not responsive to conservative management: Doxylamine 10 mg and pyridoxine 10 mg delayed-release tab
Initially, 2 tabs at bedtime on Day 1. If symptoms improve the next day, continue with 2 tabs at bedtime. If symptoms persist into the afternoon of Day 2, continue the usual dose of 2 tabs at bedtime that night, then increase to 3 tabs (1 tab in the morning and 2 tabs at bedtime) on Day 3. If this dose adequately controls symptoms, continue with 3 tabs daily on Day 4. If symptoms are not adequately controlled on Day 3, may increase to 4 tabs (1 tab in the morning, 1 tab in the mid-afternoon, and 2 tabs at bedtime) starting on Day 4. Max dose: 4 tabs daily.
Doxylamine 20 mg and pyridoxine 20 mg extended-release tab
Initially, 1 tab at bedtime on Day 1, continue with the same dose if symptoms are adequately controlled. If symptoms are not adequately controlled on Day 2, dose may be increased to 2 tabs daily (1 tab in the morning and 1 tab at bedtime). Max dose: 2 tabs daily. Reassess the need for continued treatment as the pregnancy progresses.
What are the brands available for Doxylamine + Pyridoxine in Philippines?
Prolonged and intensified anticholinergic effects with MAOIs. May enhance the CNS depressant effect with other CNS depressants (e.g. sedative hypnotics, tranquillisers), which may result in severe drowsiness.
Food Interaction
Decreased absorption and delayed onset of action with food. May enhance the CNS depressant effect of alcohol, which may result in severe drowsiness.
Lab Interference
May result in false-positive urine screening test for methadone, opiates and phencyclidine phosphate.
Action
Description: Mechanism of Action: The exact mechanism of doxylamine and pyridoxine in pregnancy-associated nausea and vomiting has not been established.
Doxylamine, an ethanolamine derivative 1st generation antihistamine, selectively binds to H1 receptors in the brain. It inhibits the chemoreceptor trigger zone, reduces vestibular stimulation, and decreases labyrinthine function by exerting its central anticholinergic effects.
Pyridoxine, a water-soluble vitamin and precursor of pyridoxal, is involved in protein, carbohydrate, and fat metabolism. Pyridoxal also helps release glycogen stored in the liver and muscles, and in the synthesis of GABA in the CNS and haeme. Synonym(s): Pyridoxine: Vitamin B6. Pharmacokinetics: Absorption: Food decreases the rate of absorption.
Doxylamine: Absorbed from the gastrointestinal tract, mainly in the jejunum. Time to peak plasma concentration: 2-4 hours.
Pyridoxine: Readily absorbed in the gastrointestinal tract. Distribution: Enters breast milk.
Pyridoxine: Mainly stored in the liver; lesser amounts in muscle and brain. Crosses the placenta. Metabolism: Doxylamine: Metabolised in the liver via N-dealkylation to N-desmethyldoxylamine and N,N-didesmethyldoxylamine.
Pyridoxine: Metabolised in the liver into pyridoxal phosphate and pyridoxamine phosphate (active forms). Excretion: Doxylamine: Via urine (mainly as metabolites). Elimination half-life: 10-12 hours.
Pyridoxine: Via urine (as metabolites).
Chemical Structure
Doxylamine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 3162, Doxylamine. https://pubchem.ncbi.nlm.nih.gov/compound/Doxylamine. Accessed Apr. 29, 2025.
Pyridoxine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 1054, Pyridoxine. https://pubchem.ncbi.nlm.nih.gov/compound/Pyridoxine. Accessed Apr. 29, 2025.
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