Plasma levels of isosorbide dinitrate and its main metabolites following oral administration of two sustained release formulations in normal man

The plasma levels of isosorbide dinitrate (ISDN) and the two pharmacologically active metabolites were measured following administration of two oral sustained release formulations containing 40 mg ISDN in nine healthy male volunteers. The new galenic formulation (pellets in a hard gelatin capsule) resulted in generally higher plasma levels for all three assayed substances over the time period of 24 h. The pharmacokinetic interpretation of the plasma levels following administration of the sustained release capsule assuming a one-compartment body model with zero-order invasion and first-order elimination showed a constant liberation over approximately 5 h. The elimination of all three substances was not altered by the new formulation. The plasma levels after administration of the tablet formulation showed great variations within and between individuals. These data could therefore not be interpreted by the same model.