Products
Pyridoxine has been approved in many countries as a monopreparation in tablet form since the 1950s for pregnancy nausea (Benadon, vitamin B6 Streuli). In combination with the antihistamine and antiemetic meclozine, it is registered for nausea and vomiting of any origin and motion sickness (Itinerol B6). It is also combined with doxylamine.
Structure and properties
Pyridoxine or vitamin B6 is present in drugs as pyridoxine hydrochloride (C8H12ClNO3, Mr = 205.6 g/mol), a white crystalline powder that is readily soluble in water.
Effects
Pyridoxine (ATC A11HA02) plays an important role in lipid, amino acid, and carbohydrate metabolism in the body as the coenzyme pyridoxal phosphate. Is pyridoxine effective against nausea? Through what mechanism of action are its properties mediated? The manufacturer writes in the package insert, “By activating protein breakdown, pyridoxine prevents accumulation of certain nitrogen-containing metabolic intermediates responsible for the occurrence of nausea and vomiting.” There has also been speculation about vitamin B6 deficiency during pregnancy causing the pregnancy vomiting. The use of pyridoxine for nausea probably dates back to small, uncontrolled studies in the 1940s (e.g., Willis et al., 1942). Modern pivotal studies are not available. We have identified only two small randomized and placebo-controlled clinical trials from the 1990s in the recent scientific literature, exclusively in the indication of vomiting during pregnancy (Sahakian, 1991; Vutyavanich, 1995). From our point of view, there are indications for a possible efficacy, but it has not been scientifically proven so far. A therapeutic trial is possible because of its good tolerability.
Indications
Pregnancy vomiting, in combination with meclozine for nausea and vomiting of any origin and motion sickness.
Dosage
According to the SmPC. For pregnancy vomiting, the literature recommends a dose of 10-25 mg 3 times daily.
Contraindications
Pyridoxine is contraindicated in hypersensitivity. Full precautions can be found in the drug label.
Interactions
Pyridoxine in high doses may reverse the effects of levodopa. Other interactions have been described with phenytoin and phenobarbital.
Adverse effects
Possible adverse effects include digestive symptoms such as heartburn and nausea. Reversible peripheral sensory neuropathies may occur with prolonged overdose.
