Could high daily doses (1000 mg) of vitamin B6 (pyridoxine) be used to treat nausea during pregnanc

Fråga: Could high daily doses (1000 mg) of vitamin B6 (pyridoxine) be used to treat nausea during pregnancy?

Sammanfattning: There are studies reporting effects of pyridoxine (30-75 mg) daily on nausea during pregnancy. The evidence is not impressive and pyridoxine is not an established treatment of nausea during pregnancy.

Svar: The question concerning efficacy of pyridoxine to treat nausea during pregnancy has been documented in Drugline previously (1). In conclusion it, was stated that the documentation of the value of pyridoxine during pregnancy is limited, but no evidence of a teratogenic effect has been reported.

Two studies have shown that oral doses of pyridoxine are effective in alleviating nausea and vomiting of pregnancy. In one randomized, double-blind placebo-controlled study 31 pregnant women was treated with 25 mg pyridoxine orally every eight hours for 72 hours and 28 patients received placebo (2). A visual analogous scale was used (0 no nausea and 10 worst possible nausea) to grade the severity of nausea. Patients treated with pyridoxine with severe nausea had a significant decrease in mean difference nausea (4.3 +/- 2.1) compared with the placebo group (1.8 +/- 2.2). In patients with mild to moderate nausea no significant difference between treatment and placebo groups was observed. After three days of treatment eight of 31 patients in the group treated with pyridoxine vomited compared with 15 of 28 patients in the placebo group. In another study, 173 pregnant women were treated with 10 mg pyridoxine every eight hours and 169 women received placebo (3). The results showed a significant improvement in mean nausea scores in patients receiving pyridoxine compared with those who received placebo (2.9 +/- 2.2 and 2.0 +/- 2.7 respectively). The results of this study are difficult to evaluate since the variability in response between subjects is impressive.

The recommended treatment of dietary pyridoxine deficiency during pregnancy is a dose of 5-25 mg daily for three weeks, followed by 1.5-2.5 mg daily of maintenance therapy (4). No documentation of treatment with doses as high as 1000 mg pyridoxine daily has been found. In a small number of pregnancies high doses of pyridoxine early in the gestation period may alter fetal pyridoxine metabolism causing convulsions in the newborn (5). This can be controlled by pyridoxine treatment. One case suggests a link between pyridoxine dose and development of phocomelia (6). One woman was taking 50 mg pyridoxine daily for the first seven months of pregnancy but since her weight was only 47 kg, the dose per kg was high. The infant was born with a near-total amelia of her left leg at the knee.

Human data suggest that doses of pyridoxine greater than 500 mg/day for prolonged periods of time can cause sensory nerve damage (7). Pyridoxine in doses of 150 mg/ kg body weight given daily to beagles for 100 days caused degeneration of the central tracts arising from spinal and trigeminal ganglia (4).