Editors:Elham Rehid and Hailemariam Shimelis.
Gentamicin is the usual drug of choice under the class of aminoglycosides, commonly given for serious gram-negative infections with some action against some gram-positive bacteria.
Nephrotoxicity (appears in 10–25% of therapeutic courses) and ototoxicity are the most important side effects and therapeutic limitations of aminoglycoside antibiotics with gentamicin encountering the largest proportion.
On the other hand, furosemide is a type of loop diuretics which is used whenever a rapid diuresis and long-term therapy is required. Despite the interaction, furosemide is known to be given with gentamicin in different clinical conditions. Although the two drugs are known to interact, the onset of interaction is not specified in many literature, except the fact that the severity of interaction falls under major category.
The mechanism of interaction proposed in many literature is that Furosemide results in in-creased Gentamicin plasma and tissue concentrations and hence, additive ototoxicity and/or nephrotoxicity.
In one study, intravenous gentamicin 20 mg and inulin were administered during one phase of a trial, and gentamicin 20 mg and furosemide 20 mg were administered during the second phase to healthy young volunteers. The phases of the trial were separated by at least 7 days.
The administration of furosemide caused the total plasma clearance of gentamicin to decrease, with the overall clearance being 142 mL/min in the control period and 110 mL/min when furosemide was given.
In other similar studies, ototoxicity has also been evaluated,. As measured by audiograms, toxicity developed when combination of these drugs were given together compared to aminoglycosides alone.
Management of interaction includes avoidance of concomitant administration of these two drugs by using other alternatives. Alternatives should constitute drugs with the same coverage like gentamicin.
If both medications are to be given together, patients need a dose adjustment or special test to monitor nephrotoxicity and ototoxicity.
Great emphasis should be given when it comes to older adults or those with high dosages of either drug, preexisting kidney problems, and dehydration.
References:www.ncbi.nlm.nih.gov/pmc/articles/PMC184630/ www.medscape.com/view arti-cle/738549 Oxford handbook of drug therapy. Stockley’s drug interaction book. Eighth edition. Drug Interactions from Online databases. Micromedex Drug Interaction Checker. Medscape Drug interacton Checker. Drugs.com Drug Interaction Checker.