Currently doxylamine succinate-pyridoxine HCl is the only drug indicated for the treatment of nausea and vomiting of pregnancy (NVP) symptoms in women who do not respond to conservative management, but is it superior to pyridoxine alone? A newly published prospective, controlled cohort study is the first to compare the effectiveness of pyridoxine vs. doxylamine succinate-pyridoxine HCl in improving NVP symptoms.

Cases from 80 women who called a NVP helpline from 2000-2014 and treated with pyridoxine were compared to matched doxylamine succinate-pyridoxine HCl users; co-interventions such as alternative treatments like acupressure and ginger were permitted. The primary endpoint was change in Pregnancy Unique Quantification of Emesis (PUQE) score over one week of therapy compared to baseline. Women in the pyridoxine arm received an average of 2.5 times more pyridoxine daily compared to those who received it as part of doxylamine succinate-pyridoxine HCl, corresponding to the labeled dose of four daily tablets.

Compared to the women receiving pyridoxine only, those taking doxylamine succinate-pyridoxine HCl had significantly greater improvement in PUQE scores (-0.2 vs.+0.5, respectively) (p=0.002). The mean PUQE improvement in women with high-moderate and severe NVP was 0.4 with pyridoxine and 2.6 with doxylamine succinate-pyridoxine HCl. Fewer doxylamine succinate-pyridoxine HCl patients remained in these categories during follow-up vs. pyridoxine users (seven vs. 17), despite receiving a significantly lower dose of pyridoxine.

The results from this study support the use of doxylamine succinate-pyridoxine HCl for NVP symptoms as first-line antiemetic treatment, particularly for women with high-moderate and severe NVP. However, long-term studies are needed, as are comparisons to other antiemetic therapies.