Dose:     5 mg/kg/dose IV or IM
               Once daily Dosing Strategy
The FDA reported endotoxin-like reactions in patients receiving extended interval dosing, see adverse effects.
               Ophthalmic application
                Oral dosing: 2.5 mg/kg PO Q 6 hours

Frequency:     Q 24 hours (dose adjusted between 24 to 48 hours based on random serum level)

Comments: Gentamicin is an aminoglycoside antibiotic that is effective against Enterobacter species, E. coli, Klebsiella, and to a lesser extent, Serratia, Pseudomonas, Staph. epidermidis & aureus, and Proteus.  Recent work in adults has also shown the utility and safety of once daily gentamicin dosing. Two approaches for the once daily dosing have been reported in neonates. Current evidence suggests that both renal and otic toxicities are related to high trough concentrations.  Infants who are severely asphyxiated may have a prolonged serum half-life of gentamicin and an increased interval between doses should be used until serum levels are checked. There is no evidence of renal or ototoxicity occurring when gentamicin is used for 7 to 10 days. The potential for such damage increases with prolonged use or with the concurrent use of Lasix, another aminoglycoside, or other ototoxic medications. Unless there is evidence of gram negative sepsis, gram negative pneumonia, or evidence of renal failure, gentamicin levels are not necessary unless treatment continues beyond 72 or 96 hours if dosage guidelines are followed. Further comments on gentamicin.

Oral gentamicin was used in two trials in the 1980s to reduce the incidence of NEC. The oral dose suggested is based on these studies. However use of this treatment strategy was not adopted due to fear of increasing bacterial resistance to the aminoglycoside antibiotics. On occasion, oral gentamicin has been used to treat suspected bacterial overgrowth in infants with short gut syndrome. An alternative medication is metronidazole.

Toxicity:  Unlike adults, the risk of toxicity does not appear to be different for the different aminoglycosides.  The risk of toxicity increases when  therapeutic levels are exceeded, with prolonged use, or with the concurrent use of other ototoxic or nephrotoxic drugs.  See toxicity of aminoglycosides and adverse effects of gentamicin.

Preparation: Gentamicin (Garamycin) will be supplied by the pharmacy in a 10 mg/ml concentration for IV administration.  Infuse over 30 minutes using an infusion pump (infusion policy).  Do not mix any other drugs in the same IV line with gentamicin.  It should be compatible with dextrose solutions up to D25% or with normal saline.

The concentration for gentamicin administered intramuscularly is 40 mg/ml.

The concentration for gentamicin administered orally is 10 mg/ml.

Compatibility:  Compatible with TPN, lipids, and filter. It also appears to be compatible with TPN solutions containing heparin in a 1 unit/ml concentration. Gentamicin should be compatible with dextrose solutions up to D25% or with NS. Do not mix any other drugs in an IV bag with gentamicin.  Compatible with acyclovir, atracurium, aztreonam, clindamycin, enalaprilat, esmolol, famotidine, fentanyl, filgrastim, fluconazole, hydrocortisone, labetalol, lorazepam, lidocaine, magnesium sulfate, meropenem, methicillin, metronidazole, midazolam, morphine, pancuronium, penicillin G sodium, ranitidine, tolazoline, vecuronium, and zidovudine. Incompatible with allopurinol, amphotericin, ampicillin, carbenicillin, cefazolin, cephalothin, (presumably cefotaxime, ceftazidime, ceftriaxone), 10 % fat emulsion (we use 20% so not an issue), heparin (concentrations of heparin in the test solutions ranged from 50 to 200 units/ml), indomethacin, insulin, mezlocillin, nafcillin, propofol, and ticarcillin.   It is equivocally compatible with dopamine and furosemide.