Iv%2525252525252525252525252525252525252525252525252525252525252520gentamicin

## Overview Gentamicin is an aminoglycoside antibiotic used for the treatment of serious infections caused by aerobic gram-negative bacteria. It is bactericidal and works by inhibiting protein synthesis. ## Primary Indications * Treatment of serious infections caused by susceptible aerobic gram-negative bacteria, including *Pseudomonas aeruginosa*, *Klebsiella*, *Enterobacter*, *Serratia*, *Proteus*, *Escherichia coli*, *Providentia*, and *Citrobacter*. * Often used in combination with a beta-lactam antibiotic for synergistic effect, particularly in serious infections like endocarditis or sepsis. * Treatment of plague (*Yersinia pestis*). * Treatment of tularemia (*Francisella tularensis*). ## Adult Dosing Dosing is highly individualized based on indication, severity of infection, patient weight, renal function, and target trough concentrations. Standard dosing typically involves: * **Serious infections:** 3-5 mg/kg/dose every 8 hours. * **Complicated urinary tract infections (UTIs):** 3 mg/kg/dose every 8 hours. * **Synergy against gram-positive organisms (e.g., enterococcal endocarditis):** 1 mg/kg/dose every 8 hours. **Maximum dose:** Total daily dose should not exceed 5 mg/kg/day unless for life-threatening infections with close monitoring. **"Once-daily" dosing (extended interval dosing):** This strategy is often preferred as it can be more nephrotoxic and ototoxic but may lead to higher efficacy and lower toxicity in certain patient populations. Dosing is typically 5-7 mg/kg every 24, 36, or 48 hours depending on indication and renal function. Specific protocols vary widely. Dosing for obese patients >30% ideal body weight should be calculated using ideal body weight plus 40% of the ideal body weight. ## Pediatric Dosing Dosing is weight-based and age-dependent due to differences in renal maturity. * **Neonates ( < 7 days):** 4 mg/kg/dose every 12-24 hours. * **Infants and Children ( > 7 days, < 5 years):** 2-2.5 mg/kg/dose every 8 hours OR 5-7.5 mg/kg/dose every 24 hours (extended interval). * **Children ( > 5 years):** 1.5-2 mg/kg/dose every 8 hours OR 5-7.5 mg/kg/dose every 24 hours (extended interval). **Maximum dose (pediatric):** Generally 5-7.5 mg/kg/day. ## Dose Adjustments Dose must be adjusted based on renal function (creatinine clearance or serum creatinine). Refer to institutional guidelines or pharmacokinetic dosing services for specific adjustments. Dosing frequency is typically increased (doses given more often) with impaired renal function, or the dose itself may be reduced. ## Contraindications * Known hypersensitivity to gentamicin or other aminoglycosides. * Concurrent use with potentially nephrotoxic or ototoxic drugs. ## Adverse Effects * **Nephrotoxicity:** Most common; characterized by rising serum creatinine and BUN. Usually reversible upon discontinuation. * **Ototoxicity:** Irreversible; can manifest as hearing loss (cochlear toxicity) or vestibular dysfunction (vertigo, dizziness, ataxia). * **Neuromuscular blockade:** Can cause respiratory depression or paralysis, especially with rapid IV administration or in patients with hypocalcemia or myasthenia gravis. * Hypersensitivity reactions, rash, urticaria, eosinophilia. ## Key Drug Interactions * **Loop diuretics (e.g., furosemide):** Increased risk of ototoxicity. * **Other nephrotoxic agents (e.g., vancomycin, amphotericin B, cisplatin, NSAIDs):** Increased risk of nephrotoxicity. * **Neuromuscular blocking agents (e.g., succinylcholine, rocuronium):** Increased risk of neuromuscular blockade and respiratory depression. * **Penicillins/Cephalosporins:** Can inactivate gentamicin *in vitro* when mixed in the same IV solution. Administer separately. Combination therapy can be synergistic *in vivo*. * **Indomethacin:** May increase gentamicin levels in premature infants. ## Monitoring * **Serum gentamicin concentrations:** Peak and trough levels are crucial for optimizing efficacy and minimizing toxicity. * **Conventional dosing (e.g., TID):** Trough levels should ideally be < 1-2 mcg/mL. Peak levels achieved 30-60 minutes after the end of a 30-60 minute infusion should be between 4-10 mcg/mL (depending on infection and organism). * **Extended-interval dosing:** Usually a single post-dose level is obtained (e.g., 4-12 hours after the start of infusion, depending on specific dosing interval and renal function). * **Renal function:** Monitor serum creatinine and BUN regularly (daily or more frequently in critically ill patients). * **Electrolytes:** Monitor magnesium, potassium, and calcium, as aminoglycosides can cause wasting of these electrolytes. * **Auditory and Vestibular function:** Monitor for signs and symptoms of ototoxicity, especially with prolonged therapy or in patients with risk factors. ## Clinical Pearls * Gentamicin is primarily active against aerobic gram-negative bacteria. It has limited activity against gram-positive organisms and anaerobes. * For serious infections, combination therapy with a beta-lactam is often recommended. * Extended-interval dosing (once-daily or less frequent) is often preferred due to potentially lower nephrotoxicity and enhanced effectiveness in some settings, but requires careful monitoring of post-dose serum concentrations. * Hydration is important to minimize the risk of nephrotoxicity. * Avoid concurrent use with other nephrotoxic or ototoxic agents whenever possible. * Do not mix gentamicin in the same IV infusion with penicillins or cephalosporins. *** **Disclaimer:** This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information, institutional guidelines, and drug interaction databases before administering any medication. Dosing and monitoring parameters can change and may vary based on individual patient factors and local protocols.