Journal of Pharmaceutical and Biomedical Analysis 28 (2002) 169–172 Short communication Rapid determination of acetazolamide in human plasma A. Zarghi *, A. Shafaati Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Shaheed Beheshti Uniersity of Medical Sciences, Tehran, Iran Received 28 February 2001; received in revised form 27 August 2001; accepted 3 September 2001 Keywords: Acetazolamide; Plasma; HPLC www.elsevier.com/locate/jpba 1. Introduction Acetazolamide (5-acetamido-1,3,4-thiazole-2- sulfonamide) is a carbonic anhydrase inhibitor which reduces the rate of aqueous humor forma- tion and correspondingly decreases the intra ocu- lar pressure in patients with glaucoma. It is also used, either alone or in association with other antiepileptics, for the treatment of various forms of epilepsy [1]. Absorption is fast, reaching peak plasma concentrations approximately 1 – 3 h after oral administration. About 80% of the drug is excreted by tubular secretion of the anionic spe- cies, and 70–90% of the administered dose is recovered unchanged within 24 h [2]. Therefore, the determination of acetazolamide concentra- tions in biological fluids is of particular interest in pharmacokinetic studies. In order to study the pharmacokinetics of acetazolamide in humans a selective and sensitive assay for acetazolamide in biological fluids is necessary. Methods for the quantitation of this drug in biological fluids in- clude measurement of carbonic anhydrase inhibi- tion [3], polarography [4], electron-capture GLC [5] and high-performance liquid chromatography [6–10]. However, the GLC method is time-con- suming and the polarographic method is only partially successful and the modified enzymatic assay lacks sufficient precision. HPLC methods differ with respect to the mode of HPLC (normal- phase or reversed-phase) and sample preparation (solvent extraction and solid-phase extraction). The problem of sample preparation, in particular, has attracted much attention in recent years, as this procedure has often been a rate limiting step in HPLC analyses of biological fluids. Most of these methods required liquid – liquid extraction with evaporation of the extract or on-line solid- phase extraction and therefore sample preparation is time-consuming, complex or both. The present paper reports a simple, rapid and sensitive HPLC method with UV detection using a single-step extraction procedure for separating and quantify- ing acetazolamide in plasma. The sample prepara- tion only involves protein precipitation and no evaporation step is required. * Corresponding author. Tel.: +98-21-877-3523; fax: +98- 21-879-5008. E-mail address: azarghi@safineh.net (A. Zarghi). 0731-7085/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0731-7085(01)00615-X