European Journal of Clinical Pharmacology

, Volume 9, Issue 2, pp 161-168

First online:

Quantitation of phenobarbital and its main metabolites in human urine

  • N. KållbergAffiliated withThe Karolinska Pharmacy
  • , S. AgurellAffiliated withThe Karolinska Pharmacy
  • , Ö. EricssonAffiliated withDept. of Organic Chemistry, Faculty of Pharmacy, University of Uppsala
  • , E. BuchtAffiliated withDept. of Clinical Pharmacology, Karolinska Hospital
  • , B. JallingAffiliated withDept. of Clinical Pharmacology, Karolinska Hospital
  • , L. O. BoréusAffiliated withDept. of Clinical Pharmacology, Karolinska Hospital

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A method for the quantitative determination of phenobarbital and free and conjugatedp-hydroxyphenobarbital in urine samples is described. The method includes initial extraction, purification on a small chromatographic column and finally determination by gas chromatography. The barbituric acids are methylated by trimethylanilinium hydroxide which serves as a “flash heater” methylating agent. The conjugate ofp-hydroxyphenobarbital, which appears to be a glucuronide, is hydrolysed with hydrochloric acid.

Key words

Conjugate-cleavage drug metabolism gas chromatography phenobarbital urinary excretion