Valpromide increases the plasma concentrations of amitriptyline and its metabolite nortriptyline in depressive patients.

The effects of valpromide on amitriptyline (AMT) and nortriptyline (NT) plasma levels were examined in 20 depressed inpatients. They all were treated with AMT, 125 mg once daily, and 10 patients also received 600 mg of valpromide daily after 10 days on AMT. In the 10 patients receiving valpromide in addition to AMT, the mean AMT level increased from 70.5 +/- 35 to 105.5 +/- 49 ng/ml (p less than 0.0003) and the mean NT level from 61.0 +/- 34 to 100.5 +/- 65 ng/ml (p less than 0.01). This increase was not related to valpromide metabolite plasma levels, nor to the age of the patients. The addition of valpromide to a stable AMT regimen may result in an increase of antidepressant plasma level with clinical implications.