07/04/2009 16:13

Gentamicin sulfate

Brand Name: Garamycin, G-myticin

Pregnancy Category C

Drug class: Aminoglycoside



Therapeutic actions

Bactericidal: inhibits protein synthesis in susceptible strains of gram-negative bacteria; appears to disrupt functional integrity of bacterial cell membrane, causing cell death.






· Serious infections caused by susceptible strains of Pseudomonas aeruginosa, Proteus sp., Escherichia coli, Klebsiella-Enterobacter-Serratia species, Citrobacter, Staphylococcus sp.

· In serious infections when causative organisms are not known (often in conjunction with a penicillin or cephalosporin)

· Unlabeled use: with clindamycin as alternative regimen in PID


· For serious CNS infections caused by susceptible Pseudomonas species

Ophthalmic preparations

· Treatment of superficial ocular infections due to strains of microorganisms susceptible to gentamicin

Topical dermatologic preparation

· Infection prophylaxis in minor skin abrasions and treatment of superficial infections of the skin due to susceptible organisms amenable to local treatment

Gentamicin-impregnated PMAA beads on surgical wire

· Orphan drug use: treatment of chronic osteomyelitis of post-traumatic, postoperative, or hematogenous origin

Gentamicin liposome injection

· Orphan drug use: treatment of disseminated Myobacterium avium-intracellulare infection




· Contraindicated with allergy to any aminoglycosides; renal or hepatic disease; preexisting hearing loss; active infection with herpes, vaccinia, varicella, fungal infections, myobacterial infections (ophthalmic preparations); myasthenia gravis; parkinsonism; infant botulism; lactation.



Adverse effects

Ototoxicity--tinnitus, dizziness, vertigo, deafness (partially reversible to irreversible), vestibular paralysis, confusion, disorientation, depression, lethargy, nystagmus, visual disturbances, headache, numbness, tingling, tremor, paresthesias, muscle twitching, convulsions, muscular weakness, neuromuscular blockade

Palpitations, hypotension, hypertension

Hepatic toxicity, nausea, vomiting, anorexia, weight loss, stomatitis, increased salivation


Leukemoid reaction, agranulocytosis, granulocytosis, leukopenia, leukocytosis, thrombocytopenia, eosinophilia, pancytopenia, anemia, hemolytic anemia, increased or decreased reticulocyte count, electrolyte disturbances

Purpura, rash, urticaria, exfoliative dermatitis, itching

Pain, irritation, arachnoiditis at IM injection sites

Fever, apnea, splenomegaly, joint pain, superinfections


· Increased ototoxic, nephrotoxic, neurotoxic effects with other aminoglycosides, cephalothin, potent diuretics

· Increased neuromuscular blockade and muscular paralysis with anesthetics, nondepolarizing neuromuscular blocking drugs, succinylcholine, citrate-anticoagulated blood

· Potential inactivation of both drugs if mixed with beta-lactam–type antibiotics (space doses with concomitant therapy)

· Increased bactericidal effect with penicillins, cephalosporins (to treat some gram-negative organisms and enterococci), carbenicillin, ticarcillin (to treat Pseudomonas infections)



Nursing considerations

· Give by IM route if at all possible; give by deep IM injection.

· Culture infected area before therapy.

· Use 2 mg/mL intrathecal preparation without preservatives, for intrathecal use.

· Cleanse area before application of dermatologic preparations.

· Ensure adequate hydration of patient before and during therapy.

· Monitor renal function tests, complete blood counts, serum drug levels during long-term therapy. Consult with prescriber to adjust dosage.