Paper II — 2025 August (Supplementary) (2010 Scheme) — Q5
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Paper II
2025 August (Supplementary) (2010 Scheme)
Question
Aminoglycosides
Q53 marksShort Notes
Answer
Aminoglycosides are bactericidal antibiotics active mainly against aerobic Gram-negative organisms.
MOA: aminoglycoside → binds the bacterial 30S ribosomal subunit → causes misreading of mRNA codons and blocks translocation → production of abnormal/nonfunctional proteins and inhibition of protein synthesis → bactericidal. Uptake requires an oxygen-dependent transport process, explaining their lack of activity against anaerobes.
Examples and uses: Gentamicin, Amikacin — severe Gram-negative infections, often combined with a beta-lactam for synergy (the beta-lactam’s cell-wall damage improves aminoglycoside penetration); Streptomycin — second-line tuberculosis.
Adverse effects: nephrotoxicity (reversible, from proximal tubular accumulation), ototoxicity (often irreversible — vestibular and/or cochlear), neuromuscular blockade at high doses. Once-daily dosing regimens exploit their concentration-dependent killing while reducing nephrotoxicity.
