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Biomedical subjects

A Darragh

Publications and source records attributed to A Darragh.

At least 91 records · Page 5Linked to original sources
PubMed1978

Plasma concentrations of isosorbide dinitrate after administration of increasing doses of a sustained-release formulation to human subjects.

Plasma concentrations of isosorbide dinitrate have been measured after administration of increasing doses in the range 20--100 mg as sustained-release tablets (Isoket retard) containing 20 mg to human subjects. Means of peak concentrations of 4.2 ng/ml, 13.1 ng/ml, 20.7 ng/ml, 36.8 ng/ml, and 34.9 ng/ml were measured after doses of 20 mg, 40 mg, 60 mg, 80 mg and 100 mg, respectively. In the plasma of individual subjects, peak concentrations of isosorbide dinitrate increased in proportion to the dose administered. Areas under the plasma isosorbide dinitrate concentration-time curves also increased in proportion to the dose administered. Bioavailability parameters were better correlated to the dose over the range 20--60 mg than over the range 20--100 mg.

Adult↗
PubMedDate not supplied

Plasma concentrations and pharmacokinetics of dihydralazine after single oral doses to human subjects.

After single oral doses of 20 mg of a suspension of dihydralazine sulphate to human subjects, the peak of mean plasma concentrations of dihydralazine of 47.0 ng ml-1 +/- 11.0 standard deviation (S.D.) (n = 7) was reached at 1 h. Mean concentrations declined biphasically with apparent half-lives of 0.57 and 4.96 h respectively. Dihydralazine was partly converted to hydralazine. The peak of mean plasma concentrations of the latter drug of 3.9 ng ml-1 +/- 1.7 S.D. (n = 7) occurred at 1-2 h after dosing with dihydralazine sulphate and declined to 1.5 ng ml-1 +/- 1.5 S.D. at 6 h. Of the seven subjects studied, three were classified as fast and four as slow acetylators. Mean clearances appeared to be slightly more rapid in fast acetylators (1.63 l min-1 +/- 0.32 S.D.) when compared to slow acetylators (1.31 l min-1 +/- 0.31 S.D.) but this difference and differences in plasma concentrations and in areas under the plasma drug concentration-time curves were not significant (p > 0.1).

Acetylation↗
PubMedDate not supplied

Pharmacokinetics of isosorbide dinitrate after intravenous infusion in human subjects.

Plasma concentrations of isosorbide dinitrate have been measured after intravenous infusion of drug at a rate of 5.0 mg h-1 for 150 min and after single equal oral doses of 12.5 mg of drug in solution to two normal human subjects. During the infusion, uneven plateau concentrations were approached after 30 min. The calculated average steady-state plasma levels were 258 ng ml-1 and 514 ng ml-1 in the two subjects respectively. The half-life of elimination of isosorbide dinitrate after termination of the infusion was 9--10 min. After oral doses, peak plasma levels of 26.6 ng ml-1 and 12.7 ng ml-1 occurred at 10 min and 20 min in the two subjects respectively. The terminal half-life of drug after the oral doses was much longer than the elimination half-life (about 10 min), and was associated with the absorption phase. Fairly good agreement was obtained between the observed concentrations and those predicted by a one-compartment open model. The systemic availability of isosorbide dinitrate after the oral doses was up to only 3 per cent of the equal doses infused, indicating that presystemic elimination processes accounted for very large proportions of the oral doses. The systemic clearances of drug after infusion of 0.32 l min-1 and 0.16 l min-1 were unexpectedly low for a drug of reported high liver extraction ratio.

Adult↗