Pharmacokinetics of betamethasone in healthy adults after intravenous administration

Eur J Clin Pharmacol. 1983;25(5):643-50. doi: 10.1007/BF00542353.


The pharmacokinetics of betamethasone and its phosphate ester are described in 8 healthy adults after i.v. bolus injection of 10.6 mg betamethasone phosphate. Both compounds were measured by high-performance liquid chromatography with ultraviolet detection using sample handling methods which prevented hydrolysis of the ester in vitro. Betamethasone phosphate disappeared rapidly from plasma (mean half-life = 4.7 min) as betamethasone levels rose. Betamethasone plasma levels reached a peak 10-36 min after administration of the phosphate before declining in a biexponential manner. The terminal slow disposition phase had a mean half-life of 6.5 h. Only about 5% of the dose was recovered from urine as betamethasone, indicating extensive extrarenal clearance of betamethasone. Protein binding and blood/plasma concentration ratio were also determined. In comparison with its stereoisomer, dexamethasone, betamethasone is also cleared mainly by metabolism but has a lower plasma clearance, is less plasma bound, has a higher blood/plasma concentration ratio, and a higher volume of distribution. Endogenous cortisol levels were measured in the subjects who received betamethasone phosphate and in a matched control group of 4 subjects who did not. Betamethasone abolished the normal episodic secretion of cortisol and rapidly reduced its plasma concentration to a basal level. Cortisol plasma levels were not restored at 24 h but had returned to normal by 48 h after dosing.

MeSH terms

  • Adult
  • Betamethasone / administration & dosage
  • Betamethasone / metabolism*
  • Drug Interactions
  • Female
  • Half-Life
  • Humans
  • Hydrocortisone / metabolism
  • Injections, Intravenous
  • Kinetics
  • Male
  • Prednisolone / metabolism
  • Sex Factors


  • Betamethasone
  • Prednisolone
  • Hydrocortisone