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
Erythromycin
Macrolide (PO, IV, topical)
Indication
Atypical infection when others unavailable β’ gastroparesis adjunct β’ ophthalmic topical
INDICATIONS (CORE USE)
Older macrolide β **prokinetic** side effect used sometimes; **QT + CYP3A** like clarithro; **neonatal pyloric stenosis** risk maternal/postnatal.
ADULT DOSE (STANDARD)
250β500 mg PO q6β12h base vs ethylsuccinate formulations differ
MAX DOSE
~4 g/day IV extreme β rarely used
Route
PO, IV, topical
PEDIATRIC DOSE
30β50 mg/kg/day divided q6β8h ethylsuccinate β max per label
Must-not-miss safety points
Major warning
- QT prolongation β worse than azithro in many drug interaction scenarios - CYP3A inhibition β statins, colchicine, calcineurin inhibitors - Infantile hypertrophic pyloric stenosis with neonatal/postnatal exposure - Phlebitis IV
USE IF: Penicillin-allergic strep pharyngitis (declining preference), GI motility in gastroparesis, chlamydia alt. AVOID IF: Better tolerated macrolide available; QT risk; on simvastatin.
Primary
Secondary
Other
STANDARD (ADULT PO)
250β500 mg PO q6β12h (salt-dependent) OR IV per severe infection protocol
ADULT DOSE
Base vs stearate vs ethylsuccinate β confirm salt form mg equivalence
PEDIATRIC DOSE
Ethylsuccinate suspension common.
MAX DOSE
IV high dose rare β GI side effects limit oral
Practical Note
Take with food if estolate formulation GI upset.
Clinical warnings
Adverse effects
Pediatrics
30β50 mg/kg/day divided q6β8h ethylsuccinate β max per label
Pregnancy
Generally low risk; pyloric stenosis association neonatal β discuss with OB/peds.
Lactation
See lactation references and product labeling.
Renal impairment
No major adjust oral; severe hepatic β reduce dose. **CrCl scaffold (FMBM β titrate to FDA/SFDA label + institutional pharmacy nomogram):** - **CrCl β₯50** β standard per agent (azithro PO often unchanged) - **CrCl 10β50** β clarithro/erythro β check label for interval/dose; azithro usually minimal change - **CrCl <10** β extend interval or reduce dose per label (Zmax / IV forms β **verify product**)
Hepatic impairment
Erythromycin hepatically cleared β toxicity if impaired.
Elderly
QT + drug interactions.
IV slowly to reduce phlebitis; PO forms as directed.
Clinical Picture
**Life-threatening (first):** **torsades / polymorphic VT** (QT). **Secondary:** GI upset; hearing at extreme exposure.
Immediate Actions
Stop macrolide β ECG; K+/Mg2+ repletion; telemetry if symptomatic
Antidote
No specific antidote; treat complications (e.g. anaphylaxis β epinephrine per ACLS)
Decontamination
Recent large PO β charcoal if appropriate
Escalation
Torsades / unstable VT β **ICU** ACLS; magnesium per protocol; **severe renal failure with accumulation β consider HD** (erythromycin more than azithro) β pharmacy
Common mistakes, resistance logic, and bedside traps
**Grandparent macrolide** β more **GI** and **QT/CYP3A** baggage than azithro. Still sees **gastroparesis** use. Think **pyloric stenosis** in neonates context.
Prefer azithro when macrolide needed for tolerance/interactions. Stewardship: pharyngitis often penicillin first. *Stewardship (all antimicrobials):* Empiric choice β syndrome severity + **local antibiogram**; shortest effective course.
Hepatic CYP3A metabolism; erythromycin base vs salt affects absorption.
50S inhibitor β motilin receptor agonism at lower doses (prokinetic).
Global data (no country-specific data available)
Saudi Arabia
(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.
Saudi Arabia
International