Plasma concentrations and bioavailability of isosorbide dinitrate and pindolol from a combination formulation

The plasma concentrations and bioavailability of sustained-release isosorbide dinitrate and standard-release pindolol have been compared after administration of these drugs in combination and alone. Bioavailability parameters of isosorbide dinitrate and pindolol obtained after administration of the drugs in combination were not significantly different (P greater than 0.05) to those obtained after administration of either drug alone. Two peaks of mean concentrations of isosorbide dinitrate occurred in plasma after administration of 30 mg of this drug in combination with 7.5 mg pindolol (4.4 ng ml-1 at 1 h and 4.5 ng ml-1 at 5 h), or alone (5.9 ng ml-1 at 2 h and 5.7 ng ml-1 at 5 h). In each case, plasma concentrations of isosorbide dinitrate were maintained during at least 8 h, whereas the drug was not detected in plasma at 2.5 h after administration of a standard-release formulation. The peaks of mean concentrations of pindolol were 39.7 ng ml-1 at 1.5 h after administration of 7.5 mg drug in combination with isosorbide dinitrate and 38.0 ng ml-1 at 1 h administration of the drug alone. Concentrations of pindolol in plasma declined with a half-life of 3 h.