RESUMEN
An isocratic reversed-phase high-performance liquid chromatographic method was developed to determine free didanosine concentrations in human serum. An ultrafiltration technique was used to recover didanosine from the samples. didanosine was analyzed using a 150 mm x 3.9 mm I.D. Nova-Pak phenyl column and a mobile phase of 0.02 M sodium citrate (pH 5)-isopropanol (97.5:2.5, v/v) with detection set at 250 nm. Linearity was verified from 25 to 3000 ng/ml. The limit of detection at a signal-to-noise ratio of 3 was 25 ng/ml. The mean recovery of didanosine added to serum at 50, 100, 250 and 750 ng/ml was 97.4%, 97.3%, 92.9% and 95.4%, respectively. A within-day variation of 3.6% at 50 ng/ml and 1.7% at 250 ng/ml, and a day-to-day variation of 9.3% at 50 ng/ml and 3.6% at 230 ng/ml were found. Stability studies indicated that didanosine is stable in serum for at least 8.5 months at 20 degrees C, 4 degrees C and -20 degrees C.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Didanosina/sangre , Inhibidores de la Transcriptasa Inversa/sangre , Ultrafiltración/métodos , Humanos , Espectrofotometría UltravioletaRESUMEN
The pharmacokinetics of gentamicin in adult patients with endocarditis were studied. The records were reviewed for 64 patients treated for bacterial endocarditis and for whom serum gentamicin concentrations had been requested between May 1990 and May 1993. The patients were divided into those with serum creatinine concentration (SCr) <1.2 mg/dL and those with SCr > or = 1.2 mg/dL. The measured serum gentamicin concentrations, patient demographic information, dosage interval, and SCr were entered into a pharmacokinetics program for analysis. The pharmacokinetic values evaluated were steady-state distribution volume (V), clearance (CL), elimination rate constant (k), and half-life (t1/2). The mean +/- S.D. t1/2 and V of gentamicin were 4.7 +/- 2.4 hr and 0.29 +/- 0.11 L/kg. Half-life was correlated with SCr and V. These two variables may explain 66% of the variation in t1/2. No difference in V was observed between patients with normal versus abnormal SCr. Men had a lower k than women. V and CL were lower in patients under age 60 than in older patients. Adult patients with endocarditis may have expanded gentamicin V. V and CL accounted for most of the variation in gentamicin t1/2.