Pharmacokinetics and absolute bioavailability of diltiazem in humans

Klin Wochenschr. 1984 Apr 2;62(7):303-6. doi: 10.1007/BF01716446.


Six healthy male volunteers received single doses of diltiazem hydrochloride on three occasions separated by at least 10 days. Modes of administration were: 10-minute intravenous infusion of a 20-mg dose; oral administration of 120 mg in solution form; and oral administration of 120 mg as two 60-mg sustained-release tablets. Diltiazem concentrations were measured by electron-capture gas chromatography in multiple plasma samples drawn during the 36 hours after dosage. Following intravenous administration, mean (+/- S.E.) pharmacokinetic variables were: elimination half-life, 11.2 (+/- 2.1) hours; volume of distribution, 11.1 (+/- 3.0) liters/kg; and total clearance, 11.5 (+/- 0.7) ml/min/kg. Oral diltiazem in solution form was rapidly absorbed, with peak plasma levels attained at 38 (+/- 6) minutes after the dose. Absolute systemic availability averaged 44% (+/- 4%). Oral administration of sustained-release tablets yielded, as predicted, slower absorption, with peak plasma concentrations attained at an average of 165 (+/- 22) minutes after dosage. Thus, oral diltiazem is incompletely bioavailable after oral administration, mainly because of first-pass hepatic extraction.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Benzazepines / metabolism*
  • Biological Availability
  • Chromatography, Gas
  • Delayed-Action Preparations
  • Diltiazem / administration & dosage
  • Diltiazem / metabolism*
  • Half-Life
  • Humans
  • Infusions, Parenteral
  • Kinetics
  • Male


  • Benzazepines
  • Delayed-Action Preparations
  • Diltiazem