Plasma concentrations of isosorbide dinitrate after cutaneous and sublingual doses to human subjects.

After application of 100 mg (nominal dose) isosorbide dinitrate as an ointment to the skin of human subjects, mean drug concentrations were 1 to 2 ng/ml for 1.5 hour and reached a peak of 6.2 ng/ml at 6 hours. Thereafter, mean concentrations declined slowly to 2.9 ng/ml at 12 hours and 1.2 ng/ml at 24 hours. After a sublingual dose of 5 mg isosorbide dinitrate, mean drug concentrations reached a peak of 15.9 ng/ml at 0.5 hour and declined with a half-life of about 50 minutes. The mean bioavailability of isosorbide dinitrate from the ointment was estimated as 30 per cent of that from the sublingual tablet when corrected for differences in dose/body weight ratio. The results demonstrate that concentrations of isosorbide dinitrate in plasma can be maintained for relatively long periods when the drug is applied to the skin.