Bactericidal aminoglycoside (aerobic gram-negative)
Gentamicin is an aminoglycoside antibiotic given by injection, used to treat serious infections caused by Gram-negative bacteria (Pseudomonas, E. coli, Klebsiella, Proteus, Serratia), including sepsis, meningitis, urinary and respiratory infections. Like other aminoglycosides, it can damage the kidneys and the inner ear; monitoring of levels and renal function is required.
Also known as: Garamicina, Gentalin
Combining Gentamicin with Vancomycin significantly increases the risk of nephrotoxicity and ototoxicity, with an additive effect on the kidney and the eighth cranial nerve.
Vancomycin and aminoglycosides are nephro- and ototoxic through overlapping mechanisms (renal tubular accumulation and cochlear/vestibular damage). The vancomycin label states that "systemic vancomycin exposure may result in acute kidney injury (AKI)", and the gentamicin label that aminoglycosides "have an inherent potential for causing ototoxicity and nephrotoxicity", with "greater risk when administered for longer periods or in higher doses than recommended". The combination is frequent in endocarditis, sepsis and critically ill patients, and the risk adds up especially in the elderly, pre-existing renal impairment, hypovolaemia or prolonged therapy. Monitor creatinine and urine output daily, vancomycin and gentamicin levels (troughs/peaks), and ototoxicity signs (tinnitus, vertigo, hearing loss); adjust doses to creatinine clearance and consider extended intervals.
Vancomycin + gentamicin: additive nephro- and ototoxicity (tubular + cochlear/vestibular damage). Monitor renal function, levels and hearing.
Vancomycin and aminoglycosides are nephrotoxic and ototoxic; co-administration potentiates renal tubular and auditory injury, a well-documented risk particularly in critically ill patients or those with renal impairment.
Closely monitor renal function, vancomycin and gentamicin serum levels, urine output and signs of ototoxicity.
Rising creatinine, oliguria, tinnitus, vertigo or hearing loss require immediate reassessment of therapy.
Avoid when possible; if clinically necessary, minimize duration, ensure hydration and adjust doses to renal function.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f ; approved Vancomycin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b01aaa02-8f1d-4b57-96a5-337503428af1 — with additional reference: Prontuário Terapêutico do INFARMED, INFARMED (11th ed., 2012)
Aminoglycoside + magnesium: risk of neuromuscular blockade and additive nephrotoxicity.
Aminoglycosides (gentamicin) can cause neuromuscular blockade, especially in patients with myasthenia gravis, botulism or hypocalcaemia; magnesium at high concentrations also depresses neuromuscular transmission. Together, the risk of muscle weakness and respiratory depression increases. In addition, both can damage the kidney: nephrotoxicity is additive, and impaired renal function reduces clearance of both, raising levels even further. In patients receiving gentamicin and IV magnesium sulfate (e.g., pre-eclampsia with infection), monitor renal function, serum magnesium and aminoglycoside levels, and watch muscle strength and ventilation.
Aminoglycoside + magnesium: risk of neuromuscular blockade and additive nephrotoxicity.
Magnesium sulfate may potentiate aminoglycoside neuromuscular blockade; both may affect renal function.
Renal function, magnesium, neurological signs.
Weakness, respiratory depression, rising creatinine.
Monitor renal function and signs of muscle weakness during co-administration.
DailyMed (FDA) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=977180b3-a222-4282-d485-4a3217674305 ; approved Magnesium sulfate label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a5a9f565-639c-4b22-b9e5-718bac7cfcf3 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Combining Gentamicin with Furosemide increases the risk of ototoxicity and, to a lesser degree, nephrotoxicity, through an additive effect on the inner ear and the kidneys.
Gentamicin (aminoglycoside) is ototoxic and nephrotoxic, and furosemide increases the ototoxic potential of aminoglycosides, especially in the presence of renal impairment; the furosemide label recommends avoiding the combination except in life-threatening situations. Furosemide-induced hypovolaemia can also reduce gentamicin renal clearance and increase the risk of nephrotoxicity. If the combination is unavoidable, use the lowest effective doses, monitor renal function, aminoglycoside serum levels (when available), audiometry and vestibular signs, and maintain adequate hydration.
Furosemide + gentamicin: additive ototoxicity and nephrotoxicity. Avoid the combination, except in life-threatening situations.
Both Furosemide (loop diuretic) and Gentamicin (aminoglycoside) are ototoxic and nephrotoxic; together they exert additive toxicity on the cochlea/vestibule and the renal tubule, particularly in patients with renal impairment or volume depletion.
Monitor renal function (creatinine/clearance), urine output, electrolytes and signs of ototoxicity (tinnitus, vertigo, hearing loss). Check aminoglycoside serum levels during prolonged therapy.
Tinnitus, vertigo, hearing loss, oliguria or a rapid rise in creatinine require prompt discontinuation and evaluation.
Avoid the combination whenever possible; if unavoidable, use the shortest course and adjust doses to renal function. Consider an alternative to either drug.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f ; approved Furosemide label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7cdcd001-ab4b-4210-a455-2e17a7bc4972 — with additional reference: Prontuário Terapêutico do INFARMED, INFARMED (11th ed., 2012)
Gentamicin is given intravenously, intramuscularly or topically; food does not affect its pharmacokinetics.
May be administered regardless of meals.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f
No relevant pharmacokinetic interaction, but alcohol can worsen vestibular symptoms and dehydration.
Moderate alcohol intake during treatment.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f
Gentamicin is eliminated renally; renal impairment increases the risk of nephrotoxicity and ototoxicity.
Adjust the dose and monitor serum levels and renal function.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f
Aminoglycosides are ototoxic; patients with pre-existing hearing loss or vestibular disease are at increased risk.
Monitor for ototoxic symptoms and consider audiometry in prolonged treatment.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f
Aminoglycosides can cause fetal ototoxicity; use only if the benefit outweighs the risk.
Use only in severe infections when there is no alternative.
Present in breast milk in small amounts; the ototoxicity risk to the infant is considered low.
No specific contraception required.
DailyMed/FDA (NIH/NLM) — approved Gentamicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=441b6232-bb60-40ad-85ec-7c41ba43fd5f
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Broad-spectrum bactericidal aminoglycoside (mainly Gram-negatives, including Pseudomonas; also staphylococci), used in serious infections (septicaemia, respiratory, complicated urinary, intra-abdominal, CNS, skin and soft tissue, bone). Potential for ototoxicity, nephrotoxicity and neuromuscular blockade — monitor renal function and levels. Peak serum levels up to 4x the single IM dose (mg/kg); ≥70% excreted in urine within 24 h.
Bactericidal aminoglycoside antibiotic: binds to the bacterial ribosomal subunit (30S) and inhibits protein synthesis, with bactericidal effect against susceptible bacteria. Like all aminoglycosides, it has the potential for auditory, vestibular and renal toxicity and neuromuscular blockade.
After intramuscular administration, peak serum concentrations usually occur within 30-60 minutes, with measurable levels for 6-8 hours; IV infusion over 2 hours gives similar concentrations. Distributed in extracellular fluid (lower peaks with large extracellular fluid volume, fever and burns). Low protein binding (0-30%).
Little, if any, metabolic transformation; excreted principally by glomerular filtration. Generally 70% or more of the dose is recoverable in urine within 24 hours (urinary concentrations above 100 mcg/mL); small amounts are retained in tissues, especially the kidneys (detectable in urine weeks after discontinuation). In renal impairment elimination is slower — adjust the dose.
Half-life of 2-3 hours in patients with normal renal function (24-48 h in significant renal impairment); 1 mg/kg IM produces a peak of up to 4 mcg/mL. With doses of 4 mg/kg/day or more for 7-10 days there may be a progressive rise in levels; in severely burned patients the half-life may decrease significantly.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
