Rapid assay for determination of trimethoprim and sulfamethoxazole levels in serum by spectrofluorometry.

Antimicrobial Agents and Chemotherapy
D M LichtenwalnerA M Sugar

Abstract

A rapid spectrofluorometric method for determining the levels of both trimethoprim and sulfamethoxazole from the same specimen of serum is described. The method involves stepwise extraction of the specimen first with chloroform at an alkaline pH (pH 9.0) for trimethoprim followed by n-butyl chloride at an acidic pH (pH 2.0) for sulfamethoxazole. To quantitate trimethoprim, the chloroform layer was subjected to fluorometry by exciting the specimen at 295 nm and measuring the relative intensity at 330 nm. To determine sulfamethoxazole levels, the n-butyl chloride layer was subjected to fluorometry by exciting the specimen at 285 nm and measuring the relative intensity at 330 nm. Relative intensities were linear (r greater than 0.99) over the concentration ranges of 0.5 to 40 microgram/ml for trimethoprim and 1 to 400 microgram/ml for sulfamethoxazole. Values obtained by this spectrofluorometric procedure were in excellent agreement with those obtained by a conventional fluorometric assay for trimethoprim and a colorimetric assay for sulfamethoxazole. Elevated levels of endogenous metabolic products and numerous other drugs, including a number of antimicrobial agents, did not interfere with the method. Although salicylates interfe...Continue Reading

References

Dec 29, 1977·The New England Journal of Medicine·W T HughesS L George
Mar 1, 1979·Antimicrobial Agents and Chemotherapy·W E GroseT L Loo
Aug 1, 1979·Antimicrobial Agents and Chemotherapy·D M LichtenwalnerA M Sugar

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Citations

Jan 1, 1985·European Journal of Clinical Pharmacology·A NowakM Kadyków
Nov 1, 1982·Biochemical Pharmacology·D M LichtenwalnerW A Craig
Feb 1, 1985·Journal of Clinical Microbiology·R YogevL Tan-Pong

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