gentamicin sulfate

Drug Name

Generic Name :  gentamicin sulfate

Brand Name:

  • Parenteral, intrathecal: Alcomicin (CAN), Garamycin, Pediatric Gentamicin Sulfate
  • Topical dermatologic cream, ointment: Garamycin
  • Ophthalmic: Garamycin, Gentacidin, Gentak, Genoptic, Genoptic S.O.P.
  • Gentamicin impregnated PMMA beads: Septopal
  • Gentamicin Liposome injection: Maitec

Classification:

  • Aminoglycoside

Pregnancy Category D

Dosage & Route
  • Available forms :Injection—10, 40 mg/mL; ophthalmic solution—3 mg/mL; ophthalmic ointment—3 mg/g; topical ointment—0.1%; topical cream—0.1%; ointment—1 mg; cream—1 mg
Parenteral

ADULTS

  • 3 mg/kg/day in three equal doses q 8 hr IM or IV. Up to 5 mg/kg/day in three to four equal doses in severe infections. For IV use, a loading dose of 1–2 mg/kg may be infused over 30–60 min, followed by a maintenance dose, usually for 7–10 days.
    • PID: 2 mg/kg IV followed by 1.5 mg/kg tid plus clindamycin 600 mg IV qid. Continue for at least 4 days and at least 48 hr after patient improves, then continue clindamycin 450 mg orally qid for 10–14 days total therapy.
    • Surgical prophylaxis regimens: Several complex, multidrug prophylaxis regimens are available for preoperative use; consult manufacturer’s instructions.

PEDIATRIC PATIENTS

  • 2–2.5 mg/kg q 8 hr IM or IV.
    • Infants and neonates: 2.5 mg/kg q 8 hr.
    • Premature or full-term neonates: 2.5 mg/kg q 12 hr.

GERIATRIC PATIENTS OR PATIENTS WITH RENAL FAILURE

  • Reduce dosage or extend time dosage intervals, and carefully monitor serum drug levels and renal function tests.
Ophthalmic solution

ADULTS AND PEDIATRIC PATIENTS

  • 1–2 drops into affected eye or eyes q 4 hr; use up to 2 drops hourly in severe infections.
Ophthalmic ointment

ADULTS AND PEDIATRIC PATIENTS

  • Apply small amount to affected eye bid–tid.
Dermatologic preparations

ADULTS AND PEDIATRIC PATIENTS

  • Apply tid to qid. Cover with sterile bandage if needed.
Therapeutic actions
  • Gentamicin is an aminoglycoside that binds to 30s and 50s ribosomal subunits of susceptible bacteria disrupting protein synthesis, thus rendering the bacterial cell membrane defective.
Indications
Parenteral
  • Serious infections caused by susceptible strains of Pseudomonas aeruginosa, Proteus species, Escherichia coli, Klebsiella-Enterobacter-Serratia species, Citrobacter, Staphylococcus species
  • 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
Intrathecal
  • Gram-negative infections
  • Serious CNS infections, such as meningitis, ventriculitis, 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 posttraumatic, postoperative, or hematogenous origin
Gentamicin liposome injection
  • Orphan drug use: Treatment of disseminated Myobacterium avium-intracellulare infection
Adverse effects
  • Dizziness or vertigo; acute renal failure, interstitial nephritis, acute tubular necrosis; electrolyte imbalances; transient elevation of serum bilirubin and aminotransferases; purpura; nausea, vomiting; convulsions, mental depression, hallucinations. Atrophy or rat necrosis at inj sites.
  • Potentially Fatal: Nephrotoxicity, ototoxicity and neuromuscular blockade (may unmask or aggravate myasthaenia gravis).
Contraindications
  • History of hypersensitivity to aminoglycoside; pregnancy; hepatic impairment, perforated ear drum.
Nursing considerations
Assessment
  • History: 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, pregnancy
  • Physical: Site of infection; skin color, lesions; orientation, reflexes, eighth cranial nerve function; P, BP; R, adventitious sounds; bowel sounds, liver evaluation; urinalysis, BUN, serum creatinine, serum electrolytes, LFTs, CBC
Interventions
  • 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.
  • Avoid long-term therapies because of increased risk of toxicities. Reduction in dose may be clinically indicated.
  • Patients with edema or ascites may have lower peak concentrations due to expanded extracellular fluid volume.
  • Cleanse area before application of dermatologic preparations.
  • Ensure adequate hydration of patient before and during therapy.
  • BLACK BOX WARNING: Monitor hearing with long-term therapy; ototoxicity can occur.
  • BLACK BOX WARNING: Monitor renal function tests, CBCs, serum drug levels during long-term therapy. Consult with prescriber to adjust dosage.
Teaching points
  • Apply ophthalmic preparations by tilting head back; place medications into conjunctival sac and close eye; apply light pressure on lacrimal sac for 1 minute. Cleanse area before applying dermatologic preparations; area may be covered if necessary.
  • You may experience these side effects: Ringing in the ears, headache, dizziness (reversible; use safety measures if severe); nausea, vomiting, loss of appetite (eat frequent small meals, perform frequent mouth care); burning, blurring of vision with ophthalmic preparations (avoid driving or performing dangerous activities if visual effects occur); photosensitization with dermatologic preparations (wear sunscreen and protective clothing).
  • Report pain at injection site, severe headache, dizziness, loss of hearing, changes in urine pattern, difficulty breathing, rash or skin lesions; itching or irritation (ophthalmic preparations); worsening of the condition, rash, irritation (dermatologic preparation).