Gentamicin

Patients with Normal Renal Function Adults: The recommended dosage of gentamicin sulfate for patients with serious infections and normal renal function is 3 mg/kg/day, administered in three equal doses every eight hours ( Table 1 ). For patients with life-threatening infections, dosages up to 5 mg/kg/day may be administered in three or four equal doses.

The recommended dosage for intravenous and intramuscular administration is identical. Gentamicin sulfate should not be physically premixed with other drugs, but should be administered separately in accordance with the recommended route of administration and dosage schedule. Patients with Impaired Renal Function Dosage must be adjusted in patients with impaired renal function to assure therapeutically adequate, but not excessive blood levels.

The interval between doses (in hours) may be approximated by multiplying the serum creatinine level (mg/100 mL) by 8. For example, a patient weighing 60 kg with a serum creatinine level of 2.0 mg/100 mL could be given 60 mg (1 mg/kg) every 16 hours (2 x 8). In patients with serious systemic infections and renal impairment, it may be desirable to administer the antibiotic more frequently but in reduced dosage.

For example, after an initial dose of 60 mg (1 mg/kg), a patient weighing 60 kg with a serum creatinine level of 2.0 mg/100 mL could be given 30 mg every eight hours (60 ÷ 2). It should be noted that the status of renal function may be changing over the course of the infectious process. It is important to recognize that deteriorating renal function may require a greater reduction in dosage than that specified in the above guidelines for patients with stable renal impairment. [See table below.] 0 100 1.1 — 1.3 70 — 100 80 1.4 — 1.6 55 — 70 65 1.7 — 1.9 45 — 55 55 2.0 — 2.2 40 — 45 50 2.3 — 2.5 35 — 40 40 2.6 — 3.0 30 — 35 35 3.1 — 3.5 25 — 30 30 3.6 — 4.0 20 — 25 25 4.1 — 5.1 15 — 20 20 5.2 — 6.6 10 — 15 15 6.7 — 8.0 <10 10 In adults with renal failure undergoing hemodialysis, the amount of gentamicin removed from the blood may vary depending upon several factors including the dialysis method used.

An eight-hour hemodialysis may reduce serum concentrations of gentamicin by approximately 50%. The recommended dose at the end of each dialysis period is 1 to 1.7 mg/kg depending upon the severity of infection. In children, a dose of 2 mg/kg may be administered. The above dosage schedules are not intended as rigid recommendations but are provided as guides to dosage when the measurement of gentamicin serum levels is not feasible.

DOSAGE AND ADMINISTRATION Gentamicin Sulfate Injection, USP may be given intramuscularly or by intravenous infusion. The patient's pretreatment body weight should be obtained for calculation of correct dosage. The dosage of aminoglycosides in obese patients should be based on an estimate of the lean body mass. It is desirable to limit the duration of treatment with aminoglycosides to short term.

For intermittent intravenous administration in adults, a single-dose of gentamicin sulfate may be diluted in 50 to 200 mL of sterile isotonic saline solution or in a sterile solution of 5% dextrose in water, in infants and children, the volume of diluent should be less. The solution may be infused over a period of one-half to two hours.

A variety of methods are available to measure gentamicin concentrations in body fluids; these include microbiologic, enzymatic and radioimmunoassay techniques. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.