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Gentamicin in the Renal Failure Patient

- dosage must be adjusted in pts with impaired renal failure to assure adequate, but not excessive, blood levels;
- one method of dosage adjustment is to increase the interval between administration of the usual dosages;
- the interval between doses (in hrs) may be approximated by multiplying the serum creatinine level (mg/100 ml) by 8;
    - ex: a pt weighing 60 kg w/ a serum creatinine level of 2.0 mg/100 ml could be given 60 mg (1mg/kg) every 16 hrs (2 x 8);
- in pts with serious systemic infections and renal impairment, it may be desirable to administer the antibiotic more frequently but in reduced dosage;
    - after the usual initial dose, a rough guide for determining reduced dosage at 8 hr intervals is to divide the normally recommended dose by by the serum creatinine level;
        - ex: a pt wting 60 kg w/ a cr of 2.0 could be given 30 mg q 8hr 60 mg/kg divided by 2.0 = 30 mg q 8hr;
* in patients with RF undergoing dialysis, the amount of gentamicin removed from the blood may vary depending upon several factors including the method of dialysis;
- a 8 hr dialysis may reduce the serum concentrations of gentamicin by approx 50%;
- the recommended dose at the end of each dialysis period is 1 to 1.7 mg/kg depending on the severity of the the infection (children up to 2 mg/kg)
- Alternative:
- Supplement dose after Dialysis:
   Hemo: 1-2 mg/kg
   CAPD: 3-4 mg/Lit of dialysis