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June 13, 1980

Gentamicin and Ticarcillin Levels

Author Affiliations

The University of Texas Health Science Center at Houston

JAMA. 1980;243(22):2285-2286. doi:10.1001/jama.1980.03300480011005

To the Editor.—  The article by Murillo et al (241:2401, 1979) entitled "Gentamicin and Ticarcillin Serum Levels" reported that mean concentrations of gentamicin sulfate and ticarcillin disodium in adult patients with neutropenia who received gentamicin plus ticarcillin were substantially lower than concentrations of gentamicin in patients receiving gentamicin plus cephalothin sodium or ticarcillin in patients receiving ticarcillin and cephalothin. Postulated mechanisms for these observations were differences in renal excretion between the groups and chemical interaction between ticarcillin and gentamicin with subsequent inactivation.The three groups described by Murillo et al differed with regard to age. The patients with low concentrations of ticarcillin and gentamicin in serum were younger (mean, 37.6 years) than patients in the groups receiving ticarcillin plus cephalothin (mean, 50.9 years) or cephalothin plus gentamicin (mean, 50.3 years). The glomerular filtration rate (GFR) as measured by inulin clearance is age related.1 Representative values are listed in the