Pharmacokinetics of the H1-receptor antagonist ebastine and its active metabolite carebastine in healthy subjects

Arzneimittelforschung. 1994 Jan;44(1):59-64.


Pharmacokinetics of ebastine (CAS 90729-43-4), a histamine H1-receptor antagonist, was evaluated in healthy male volunteers. The subjects were given single oral doses of 5, 10, 20 and 40 mg of ebastine (5 or 6 subjects) and repeated oral doses of 20 mg once daily for 7 days (6 subjects). Administration of ebastine resulted in a negligible level of the unchanged drug in plasma and urine. Mean plasma concentration of carebastine (CAS 90729-42-3), an active carboxylated metabolite, reached maximum levels of 40, 112, 195 and 388 ng/ml at 4-6 h after single oral administration of ebastine at doses of 5, 10, 20 and 40 mg, respectively. Plasma levels of carebastine showed a first-order decrease with apparent half-lives of 13.8 to 15.3 h. The Cmax and AUC of carebastine increased in proportion to the dose. Urinary excretion of carebastine during 72 h after single administration accounted for 1.3-1.8% of the dose. Food intake did not affect the pharmacokinetics and gastrointestinal absorption of ebastine. Repeated administrations of ebastine once daily for 7 days did not cause any change in the pharmacokinetics of ebastine and carebastine. Plasma concentration of carebastine reached the steady state on day 4. The Cmax (360-396 ng/ml) was 1.6- to 1.7-fold greater than that after the first administration (229 ng/ml). These results strongly suggest that carebastine is responsible for the antihistamine activity after administration of ebastine.

MeSH terms

  • Adult
  • Butyrophenones / administration & dosage
  • Butyrophenones / pharmacokinetics*
  • Butyrophenones / urine
  • Food
  • Half-Life
  • Histamine H1 Antagonists / administration & dosage
  • Histamine H1 Antagonists / pharmacokinetics*
  • Histamine H1 Antagonists / urine
  • Humans
  • Male
  • Middle Aged
  • Piperidines / administration & dosage
  • Piperidines / pharmacokinetics*
  • Piperidines / urine
  • Protein Binding


  • Butyrophenones
  • Histamine H1 Antagonists
  • Piperidines
  • carebastine
  • ebastine