Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Gentamicin

Gentamicin

Aminoglycoside (IV, IM, topical)

SynergyGram-negativeLevelsNephrotoxic

Indication

Endocarditis synergy (GNR/strep) β€’ bacteremia combo β€’ pyelonephritis adjunct β€’ febrile neutropenia combo

At a glance

INDICATIONS (CORE USE)

Gram-negative serious infection (often synergy); **levels + renal monitoring**; once-daily vs traditional per pharmacy.

ADULT DOSE (STANDARD)

5–7 mg/kg IV q24h extended interval OR traditional divided β€” **pharmacy-driven**

MAX DOSE

Serum levels define safety more than mg ceiling β€” avoid arbitrary high daily totals

Route

IV, IM, topical (ophthalmic/otic distinct products)

PEDIATRIC DOSE

2.5–7.5 mg/kg/dose q8–24h per age/indication β€” pharmacy

Do not miss

Must-not-miss safety points

Major warning

- **Nephrotoxicity + ototoxicity** β€” cumulative with vancomycin, diuretics, contrast - Levels mandatory for extended-interval and many traditional regimens - Neuromuscular blockade potentiation with NMB / myasthenia - Pregnancy β€” fetal ototoxicity risk

Indications

USE IF: Serious gram-negative infection as combination; endocarditis synergy; pyelonephritis per guideline. AVOID IF: Can be replaced by less toxic beta-lactam monotherapy; baseline severe CKD without dialysis plan; single-agent uncomplicated UTI (usually avoid).

Primary

  • Serious gram-negative infection in combination with beta-lactam when guideline supports synergy
  • Enterococcal / streptococcal endocarditis synergy component (dosing distinct β€” consult ID/pharmacy)

Secondary

  • Febrile neutropenia combination regimens
  • Pyelonephritis short-course adjunct in selected protocols

Other

  • Topical ophthalmic/otic products β€” separate systemic toxicity profile

Dosing

STANDARD (ADULT PO)

~5–7 mg/kg IV q24h extended-interval OR 1–1.7 mg/kg q8h traditional β€” pharmacy

ADULT DOSE

Extended interval: ~5–7 mg/kg IV q24h (adjust for renal function) Traditional: 1–1.7 mg/kg q8h β€” pharmacy nomogram

PEDIATRIC DOSE

Neonatal/pediatric dosing highly specialized β€” consult.

MAX DOSE

Trough targets cap therapy β€” not a fixed mg/day max.

Practical Note

Synergy low-dose for endocarditis β‰  sepsis extended interval β€” never confuse.

Warnings

Clinical warnings

  • Vestibulotoxicity may be irreversible
  • AKI can be oliguric late β€” monitor creatinine trend

Adverse effects

  • AKI
  • ototoxicity
  • neuromuscular blockade

Contraindications

  • Myasthenia gravis relative β€” avoid if possible

Drug interactions

  • Vancomycin β€” additive nephrotoxicity
  • Loop diuretics β€” ototoxicity
  • NMB agents

Special populations

Pediatrics

2.5–7.5 mg/kg/dose q8–24h per age/indication β€” pharmacy

Pregnancy

Pregnancy: avoid unless no alternative β€” fetal ototoxicity.

Lactation

low oral absorption by infant but caution.

Renal impairment

**Mandatory** interval extension / dose reduction; dialysis redosing; vancomycin co-therapy extra caution. **CrCl scaffold (FMBM β€” titrate to FDA/SFDA label + institutional pharmacy nomogram):** - **CrCl β‰₯50** β†’ extended-interval or traditional q8h per **pharmacy nomogram** - **CrCl 10–50** β†’ prolong interval; **trough before 2nd extended dose** mandatory - **CrCl <10** β†’ **dialysis-dependent** redosing; avoid accumulation (**nephro/oto**); consult pharmacy

Hepatic impairment

No major adjustment.

Elderly

Assume reduced CrCl; higher toxicity risk.

Administration

IV over 30–60 min; IM if needed; adequate hydration.

Monitoring

  • Monitor: - Before next extended dose β†’ **trough** (Β± peak per protocol) β†’ rising trough β†’ extend interval / hold - Inpatient β†’ creatinine + urine output **β‰₯2–3Γ—/week**; **daily** if unstable, elderly, or vancomycin co-therapy - Vertigo or acute hearing change β†’ **stop drug** β†’ evaluate **ototoxicity** - Audiology baseline if course >5–7d or vestibular symptoms
  • Recheck: - No clinical improvement at 48–72h β†’ reassess diagnosis, resistance, source control, and drug interactions - If targets not met after reassessment of dose, organ function, and interactions β†’ escalate per protocol (DO NOT continue blindly)

Overdose / toxicity

Clinical Picture

**Life-threatening (first):** **AKI / dialysis-requiring nephrotoxicity**; acute **vestibular failure / deafness** (ototoxicity). **Secondary:** electrolyte derangement from renal injury.

Immediate Actions

Stop aminoglycoside β†’ IV fluids if hypovolemic β†’ BMP; **obtain drug level**; hearing/vestibular symptom review

Antidote

No specific antidote; treat complications (e.g. anaphylaxis β†’ epinephrine per ACLS)

Decontamination

Parenteral β€” hold further doses; extended-interval error β†’ level-guided next dose

Escalation

Dialysis-requiring AKI, acute deafness/vestibular failure, severe electrolyte derangement β†’ **ICU** + nephrology/ENT; **hemodialysis removes aminoglycosides** β€” redose per pharmacy after HD

Clinical pearls

Common mistakes, resistance logic, and bedside traps

High-Yield Summary

**Synergy / gram-negative rocket fuel** β€” also **kidney + ear poison**. Trough is your safety brake. Never mix endocarditis synergy dose with sepsis extended dose mentally.

Clinical pearls

Stewardship: shortest course; one aminoglycoside at a time. De-escalation off aminoglycoside when cultures narrow. Once-daily vs divided β€” follow pharmacy, not memory. *Stewardship (all antimicrobials):* Empiric choice β†’ syndrome severity + **local antibiogram**; shortest effective course.

Stewardship & safety

  • Trough monitoring
  • Creatinine trend
  • Vanco combo

Pharmacokinetics

Renal elimination; post-antibiotic effect; minimal oral absorption.

Mechanism of action

Binds 30S ribosome β†’ misreading β†’ concentration-dependent killing.

Common brand names

Saudi Arabia

Garamycin, Gentamicin

Global

(placeholder β€” verify local formulary)

Common trade names are curated examples only β€” formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • Empiric choice β†’ tie to syndrome, severity, and local antibiogram β€” not habit.
  • IV β†’ PO step-down when oral bioavailability and susceptibility allow.
  • Do not use antibiotics for uncomplicated viral illness β€” stewardship.

References

Saudi Arabia

  • SFDA (Saudi Food & Drug Authority)
  • Saudi National Formulary / MOH (where available)

International

  • WHO Model List of Essential Medicines (verify current edition)
  • US FDA or EU EMA product information (when national SmPC is unavailable)
  • Sanford Guide
  • IDSA / ESCMID (indication-specific)
  • Local antimicrobial stewardship / hospital formulary
  • FDA / SFDA / regional product labeling
  • Sanford Guide
  • IDSA / ESCMID (indication-specific)
  • Local antimicrobial stewardship / hospital formulary
  • FDA / SFDA / regional product labeling

Do not miss

  • Uncomplicated viral URI/bronchitis β†’ antibiotics rarely indicated
  • Narrow or stop when susceptibilities + clinical stability allow
  • Rising trough β†’ stop / extend interval before permanent injury.
  • Vancomycin double hit.
  • Trough monitoring
  • Creatinine trend
  • Vanco combo