Pharmacokinetics of Amikacin in the Bedridden Elderly Patients

Abstract

Pharmacokinetics of amikacin (200 mg/body, im) was studied in the bedridden elderly patients, in comparison with those in normal healthy volunteers and elderly volunteers.
Elimination of amikacin from plasma was seen to follow the course of delete one compartment model system. Interindividual variations in serum concentration were observed in the bedridden elderly patients. Values for the following pharmacokinetic parameters were obtained: Elimination rate constant (Kel) =0.461±0.069 hr^-1, biological half life (T1/2) =1.53±0.24 hr, volume of distribution (Vd) =0.236±0.025 1/kg for normal healthy volunteers (n=4), Kel =0.208±0.05 hr^-1, T1/2 =3 .55±1.02 hr, Vd=0.376±0. 091 1/kg for bedridden elderly patients (n=5), Kel=0.303±0.026hr^-1, T1/2=2.30±0.19hr, Vd=0.263±0.032 1/kg for elderly volunteers (n=3).
Cumulative renal excretion of amikacin was 36.3% of total dose by 6 hrs for bedridden elderly patients, 62.5% for elderly volunteers and 79.3% for normal healthy volunteers. Decreased renal excretion of amikacin was related to decreased renal function due to aging and increased Vd.