To reduce the development of drug-resistant bacteria and maintain the effectiveness of Gentamicin Injection, USP and other antibacterial drugs, Gentamicin Injection, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Gentamicin Injection is indicated in the treatment of serious infections caused by susceptible strains of the following microorganisms: Pseudomonas aeruginosa, Proteus species (indole-positive and indole-negative), Escherichia coli, Klebsiella-Enterobacter-Serratia species, Citrobacter species, and Staphylococcus species (coagulase-positive and coagulase-negative).

Clinical studies have shown Gentamicin Injection to be effective in bacterial neonatal sepsis; bacterial septicemia; and serious bacterial infections of the central nervous system (meningitis), urinary tract, respiratory tract, gastrointestinal tract (including peritonitis), skin, bone and soft tissue (including burns). Aminoglycosides, including gentamicin, are not indicated in uncomplicated initial episodes of urinary tract infections unless the causative organisms are susceptible to these antibiotics and are not susceptible to antibiotics having less potential for toxicity.

Specimens for bacterial culture should be obtained to isolate and identify causative organisms and to determine their susceptibility to gentamicin.

Gentamicin may be considered as initial therapy in suspected or confirmed gram-negative infections, and therapy may be instituted before obtaining results of susceptibility testing. Thedecision to continue therapy with this drug should be based on the results of susceptibility tests, the severity of the infection, and the important additional concepts contained in the WARNINGS box above. If the causative organisms are resistant to gentamicin, other appropriate therapy should be instituted.

In serious infections when the causative organisms are unknown, gentamicin may be administered as initial therapy in conjunction with a penicillin-type or cephalosporin type drug before obtaining results of susceptibility testing.If anaerobic organisms are suspected asetiologic agents, consideration should be given to using other suitable antimicrobial therapy in conjunction with gentamicin. Following identification of the organism and its susceptibility, appropriate antibiotic therapy should then be continued.

Gentamicin has been used effectively in combination with carbenicillin for the treatment of life-threatening infections caused by Pseudomonas aeruginosa. It has also been found effective when used in conjunction with a penicillin-type drug for the treatment of endocarditis caused by group D streptococci.

Gentamicin Injection has also been shown to be effective in the treatment of serious staphylococcal infections. While not the antibiotic of first choice, gentamicin may be considered when penicillins or other less potentially toxic drugs are contraindicated and bacterial susceptibility tests and clinical judgment indicate its use. It may also be considered in mixed infections caused by susceptible strains of staphylococci and gram-negative organisms.

In the neonate with suspected bacterial sepsis or staphylococcal pneumonia, a penicillin-type drug is also usually indicated as concomitant therapy with gentamicin.

Gentamicin Injection may be given intramuscularly or intravenously. 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.

Dosage For Patients With Normal Renal Function

Children: 6 to 7.5 mg/kg/day. (2 to 2.5 mg/kg administered every 8 hours.) Infants and Neonates: 7.5 mg/kg/day. (2.5 mg/kg administered every 8 hours.)

Premature or Full-term Neonates One Week of AgeorLess: 5mg/kg/day.(2.5 mg/kg administered every 12 hours.)

It is desirable to measure periodically both peak and trough serum concentrations of gentamicin when feasible during therapy to assure adequate but not excessive drug levels. For example, the peak concentration (at 30 to 60 minutes after intramuscular injection) is expected to be in the range of 3 to 5 mcg/mL. When monitoring peak concentrations after intra muscular or intravenous administration, dosage should be adjusted so that prolonged levels above12 mcg/mL are avoided. When monitoring trough concentrations (just prior to the next dose), dosage should be adjusted so that levels above 2 mcg/mL are avoided. Determination of the adequacy of a serum level for a particular patient must take into consideration the susceptibility of the causative organism, the severity of the infection, and the status of the patient's host-defense mechanisms.

In patients with extensive burns, altered pharmacokinetics may result in reduced serum concentrations of aminoglycosides. In such patients treated with gentamicin, measurement of serum concentrations is recommended as a basis for dosage adjustment.

The usual duration of treatment is 7 to10 days. In difficult and complicated infections, a longer course of therapy may be necessary. In such cases monitoring of renal, auditory, and vestibular functions is recommended, since toxicity is more apt to occur with treatment extended for more than 10 days. Dosage should be reduced if clinically indicated.

For Intravenous Administration

The intravenous administration of gentamicin may be particularly useful for treating patients with bacterial septicemia or those in shock. It may also be the preferred route of administration for some patients with congestive heart failure, hematologic disorders, severe burns, or those with reduced muscle mass.

For intermittent intravenous administration, a single dose of Gentamicin Injection may be diluted in 0.9% Sodium Chloride Injection or in 5% Dextrose Injection. The solution may be infused over a period of one-half to two hours.

The recommended dosage for intravenous and intramuscular administration is identical.

Gentamicin Injection should not be physically premixed with other drugs, but should be administered separately in accordance with the recommended route of administration and dosage schedule.

Dosage For Patients With Impaired Renal Function

Dosage must be adjusted in patients with impaired renal function to assure therapeutically adequate but not excessive, blood levels. Whenever possible, serum concentrations of gentamicin should be monitored. One method of dosage adjustment is to increase the interval between administration of the usual doses. Since the serum creatinine concentration has a high correlation with the serum half-life of gentamicin, this laboratory test may provide guidance for adjustment of the interval between doses. In adults, 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 mg/100 mL could be given 60 mg (1 mg/kg) every 16 hours (2 x 8). These guidelines may be considered when treating infants and children with serious renal impairment.

In patients with serious systemic infections and renal impairment, it may be desirable to administer the antibiotic more frequently but in reduced dosage. In such patients, serum concentrations of gentamicin should be measured so that adequate but not excessive levels result.

A peak and trough concentration measured intermittently during therapy will provide optimal guidance for adjusting dosage. After the usual initial dose, a rough guide for determining reduced dosage at eight-hour intervals is to divide the normally recommended dose by the serum creatinine level (Table I). For example, after an initial dose of 20 mg (2 mg/kg), a child weighing10 kg with a serum creatinine level of 2 mg/100 mL could be given 10 mg every eight hours (20 x 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.

TABLE I: DOSAGE ADJUSTMENT GUIDE FOR PATIENTS WITH RENAL IMPAIRMENT (Dosage at Eight-Hour Intervals After the Usual Initial Dose)

In patients 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%. In children, the recommended dose at the end of each dialysis period is 2 to 2.5 mg/kg depending upon the severity of the infection.

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.

A variety of methods are available to measure gentamicin concentrations in body fluids; these include microbiologic, enzymatic and radio-immunoassay techniques.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Gentamicin Injection (Pediatric), available preserved or preservative-free, is supplied in 2 mL (20 mg) flip-top vials, in trays of 25.

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Abraxis Pharmaceutical Products, Schaumburg, IL 60173. Revised: June 2006. FDA Rev date: 9/7/2000

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