Q: 53 year old male has been started on furosemide drip for oliguric renal insufficiency with gradually escalating dose. On 3rd day of infusion patient c/o hearing disturbances. What is the mechanism of action of loop diuretics to cause ototoxicity?
Answer: In the loop of Henle part of nephrons, where transport is mediated by a Na-K-2Cl cotransporter, it gets inhibited by loop diuretics. Interestingly, a secretory isoform of this cotransporter is also present in the inner ear and plays a role in the composition of endolymph. Inactivation of this cotransporter leads to reduced endolymph secretion, and so to structural damage to the inner ear, deafness, and imbalance.
Due to similar action, furosemide has been used to diagnose Meniere disease.
#nephrology
#pharmacology
References:
1. Delpire E, Lu J, England R, et al. Deafness and imbalance associated with inactivation of the secretory Na-K-2Cl co-transporter. Nat Genet 1999; 22:192.
2. Seo T, Node M, Yukimasa A, Sakagami M. Furosemide loading vestibular evoked myogenic potential for unilateral Ménière's disease. Otol Neurotol 2003; 24:283.
No comments:
Post a Comment