CORRELATION OF AMINOGLYCOSIDE AND VANCOMYCIN PHARMACOKINETIC PARAMETERS

OBJECTIVE: To investigate a correlation between the elimination rate c onstants (K(e)) of aminoglycosides (AG) and vancomycin; to investigate the correlation between actual K(e) and creatinine clearance (Cl(cr)) for AG versus vancomycin; to investigate the calculated versus actual K(e) for AG and vancomycin; and to investigate a correlation between volumes of distribution (V(d)) between AG and vancomycin. DESIGN: Retr ospective data collection. METHODs: Patients in our institution who re ceived AGs or vancomycin concomitantly or within six weeks of each oth er were identified retrospectively. Patient subpopulations were identi fied and analyzed collectively as well as individually. Steady-state s erum concentrations of AG and vancomycin (more than four half-lives) w ere obtained and kinetic parameters (K(e), V(d)) were calculated using first-order pharmacokinetic equations. Linear regression was used to determine correlation coefficients. RESULTS: In the total population a nd all subpopulations, the correlation between K(e) of AG and vancomyc in was superior to the correlation between K(e) and Cl(cr)). The corre lations (r2) between K(e) for AG and vancomycin in the total, general medicine, oncology, and intensive care units (ICU) populations were 0. 572, 0.878, 0.349, and 0.561, respectively. The correlations (r2) betw een K(e) and Cl(cr) for AG in the total, general medicine, oncology, a nd ICU populations were 0.235, 0.430, 0.005, and 0.238, respectively. The correlations (r2) between K(e) and Cl(cr), for vancomycin in the t otal, general medicine, oncology, and ICU populations were 0.300, 0.40 7, 0.055, and 0.309, respectively. CONCLUSIONS: The correlation betwee n K(e) of AG and vancomycin may be beneficial for predicting K(e) of v ancomycin when AG concentrations have already been obtained or vice ve rsa, and may give more accurate estimations of dosing intervals and re quire less time adjusting, ordering, and interpreting concentrations a nd dosages.