Alanine aminopeptidase and beta 2-microglobulin excretion in patients receiving vancomycin and gentamicin

The effects of vancomycin, gentamicin, and combination vancomycin-gentamicin treatments on alanine aminopeptidase (AAP) and beta 2-microglobulin (beta 2M) elimination in 30 hospitalized patients were assessed and compared with elimination in a control group. Twenty-four-hour urine excretion values for AAP and beta 2M were determined on treatment day 1 and day 5 for patients receiving the three treatment regimens and for the control group. AAP excretion values for the vancomycin-treated group were not found to be statistically different from those of the control group. Both the gentamicin and the vancomycin-gentamicin groups had statistically higher AAP excretion values on treatment day 1 as well as on treatment day 5 when compared with the vancomycin and control groups. AAP excretion on day 5 of treatment was highest for the vancomycin-gentamicin group. Overall, beta 2M elimination was variable in all treatment groups. Although the beta 2M values were elevated as early as day 1 in all treatment groups, they were significantly elevated only in the vancomycin-gentamicin group on day 1 and only in the gentamicin group on day 5 compared with the vancomycin and the control groups. AAP appears to be a sensitive indicator of renal tubular damage. The combination of vancomycin and gentamicin results in greater AAP excretion than does either agent alone.