Patient gets prescription from hospital with 1.5 tablet nepresol

The nepresol specialty®: tablets of 25 mg of dihydralazine sulfate is not available. As a raw material, we do have hydralazine HCl.

One asks 1.5 tablet nepresol, ttz 37.5 mg dihydralazine sulfate. How can this be converted to hydralazine HCL?