Gentamicin is a potent, broad-spectrum aminoglycoside antibiotic that inhibits bacterial protein synthesis.
Always check the BNF or equivalent guidelines for up-to-date prescribing advice.

⚙️ Mode of Action

Binds to the 30S ribosomal subunit (some aminoglycosides also bind 50S).
Blocks translocation of peptidyl-tRNA from the A-site → P-site.
Causes misreading of mRNA, preventing synthesis of functional bacterial proteins.
Bactericidal against aerobic Gram-negative bacilli; requires oxygen for uptake (so ineffective against anaerobes).

🩺 Indications

Severe Gram-negative infections (e.g., sepsis, intra-abdominal sepsis, pyelonephritis).
Synergy with β-lactams in streptococcal/enterococcal endocarditis.
Staphylococcal infections (with other agents).
Occasionally used as a single-dose prophylaxis (e.g., around catheter changes) depending on local policy.

🚫 Contraindications & Cautions

Renal impairment: dose adjustment and frequent monitoring required (risk of accumulation).
Myasthenia gravis: risk of neuromuscular blockade.
Pregnancy: crosses placenta → risk of fetal ototoxicity.

Catheter change prophylaxis: 80–160 mg IV/IM pre-procedure.
Uncomplicated UTI: occasionally 3–5 mg/kg IV/IM single dose, if local resistance patterns support.
Monitor renal function in higher-risk patients (elderly, CKD).
Avoid if pre-existing vestibular/auditory impairment.

🧪 Monitoring

Serum levels:
- Once-daily: random level 6–14 hrs post-dose → nomogram.
- Multiple-daily: trough (before dose), peak (30 mins post-infusion).
Renal function: U&E, creatinine baseline and during therapy.
Ototoxicity: ask about tinnitus/balance; consider audiometry if prolonged therapy.

⚠️ Side Effects

Ototoxicity (auditory and vestibular damage; may be irreversible).
Nephrotoxicity (proximal tubular damage; often reversible if detected early).
Neuromuscular blockade (risk in Myasthenia Gravis or with rapid IV bolus).

👥 Other Aminoglycosides

Streptomycin: used in TB treatment regimens.
Tobramycin, Kanamycin: similar to gentamicin, with specific uses.
Neomycin: oral use pre-GI surgery (reduces colonic flora).

💊 Dosing – Gentamicin (always follow local policy & check BNF/datasheet)

Regimen	Details
📌 Once-daily / Extended-interval dosing	• 5–7 mg/kg IV or IM once daily (use actual or adjusted body weight) • Maximises bactericidal activity and may reduce nephrotoxicity • Levels: Take 6–14 h post-dose → plot on nomogram (e.g., Hartford, Birmingham) to adjust interval
📌 Conventional / Multiple-daily dosing	• 1–2 mg/kg every 8 h (q8h) • Peak levels: 5–10 mg/L (serious infection), 3–5 mg/L (synergy e.g., endocarditis) • Trough level: <1 mg/L (toxicity risk ↑ if >2 mg/L)
💉 Single-dose use	• May be used for catheter changes or uncomplicated UTIs • Always follow local antimicrobial guidance

The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms.

Aminoglycosides 💊

📖 About