Drug reference

Erythromycin

Macrolide · Antibiotic

MacrolideAntibioticATC J01AA04

CDSCO approvedSchedule HATC J01AA04

EXCRETION

—

not curated

INTERACTIONS

12 major

incl. contraindicated

PREGNANCY

Not known to be harmful

FDA category + note

Top interactionssee all 12 →

AstemizoleContraindicatedTextbook-citedKDT 7e · p948
CisaprideContraindicatedTextbook-citedKDT 7e · p948
TerfenadineContraindicatedTextbook-citedKDT 7e · p948
CilostazoleContraindicatedTextbookKDT 7e · p555

Mechanism

Erythromycin binds reversibly to the 23S rRNA of the 50S ribosomal subunit, blocking the transpeptidation and translocation steps of bacterial protein synthesis to produce primarily bacteriostatic activity. Uniquely among antibiotics, erythromycin is also a motilin receptor agonist, stimulating gastrointestinal migrating motor complexes — a property exploited therapeutically for gastroparesis but responsible for its common GI side effects. It is a potent inhibitor of CYP3A4, producing clinically significant interactions with numerous drugs including warfarin, cyclosporine, and statins.

Indications

Oral bacterial infectionsDiabetic gastroparesis (short-term improvement of gastric emptying)Clear stomach of undigestible residue (e.g., bezoars, blood after GI bleed) prior to endoscopysuperficial ocular infections involving the conjunctiva or corneaprophylaxis of ophthalmia neonatorumreducing severe eyelid inflammationWhooping cough (prophylaxis for non-immunized child contact)streptococcal pharyngitistonsillitismastoiditiscommunity acquired respiratory infections (pneumococci and H. influenzae)prophylaxis of rheumatic feverprophylaxis of SABEdiphtheria (acute stage and carriers)tetanus (as an adjuvant)syphilis (as alternative when other drugs cannot be used)gonorrhoea (as alternative when other drugs cannot be used)leptospirosis (in penicillin allergic patients)atypical pneumonia (Mycoplasma pneumoniae)whooping coughchancroidcampylobacter enteritis (second choice)legionnaires’ pneumonia (second choice)chlamydia trachomatis infection of urogenital tract (alternative)Inflamed acne papulesRespiratory diphtheriaCutaneous diphtheriaAdjunctive antibiotic for patients with moderate or severe dehydration due to cholera

Dosing

Adult: Oral: 250-500 mg QDS or 500 mg-1 g BD for 7-14 days. Gastroparesis: 250-500 mg TDS before food for up to 4 weeks. IV: 6.25 mg/kg every 6h (mild); 12.5 mg/kg every 6h (severe).
Pediatric: 1-23 months: 125 mg QDS or 250 mg BD. 2-7 years: 250 mg QDS or 500 mg BD. 8-17 years: 250-500 mg QDS or 500 mg-1 g BD.
Renal adjustment: Max 1.5 g daily in severe renal impairment (ototoxicity risk)
Hepatic adjustment: Caution; hepatotoxicity risk
Max dose: 4 g/day oral; max IV dose based on weight

Pharmacokinetics

Peak effect

0.5 to 2.5 h (ethylsuccinate formulation)

Half-life

2 h

Bioavailability

35 ± 25%

Protein binding

84 ± 3%

Metabolism

Demethylation in the liver by CYP3A4

Excretion

Primarily in the feces

Contraindications

Acute porphyrias
Concurrent terfenadine, astemizole, or cisapride
pregnancy (especially estolate ester due to higher incidence of hepatitis with cholestatic jaundice)

Side effects

Common

NauseaVomitingAbdominal painDiarrhoeaCrampsImpairment of transitVomiting (at doses higher than 3 mg/kg, producing spastic contraction)Local irritancySuperinfection riskmild-to-severe epigastric painrashesfeverCan cause sensitizationDiarrhea

Serious

Hearing loss (large doses)
QT prolongation
Hepatotoxicity
Stevens-Johnson syndrome
Pancreatitis
GI toxicity
Ototoxicity
Pseudomembranous colitis
Induction of resistant strains of bacteria
Sudden death (particularly with CYP3A4 inhibitors)
reversible hearing impairment (with very high doses)
hepatitis with cholestatic jaundice (with estolate ester)
QTc interval prolongation
Exacerbation of myasthenia gravis
Tinnitus and reversible deafness (especially in elderly)

Pregnancy & lactation

Pregnancy

Not known to be harmful

Drug interactions

Astemizole

Contraindicated

Textbook-cited

Dangerous ventricular arrhythmia (QT prolongation, torsades de pointes)

Concurrent use is contraindicated

Source: KDT 7e · p948

Cisapride

Contraindicated

Textbook-cited

QT prolongation and ventricular arrhythmia.

Concurrent use is contraindicated

Source: KDT 7e · p948

Terfenadine

Contraindicated

Textbook-cited

Dangerous ventricular arrhythmia (QT prolongation, torsades de pointes)

Concurrent use is contraindicated

Source: KDT 7e · p948

Cilostazole

Contraindicated

Textbook

Increased plasma levels and toxicity of cilostazole.

Should not be administered along with inhibitors of CYP3A4.

Source: KDT 7e · p555

Pasteurella Multocida

Contraindicated

Textbook

ineffective treatment

Pasteurella multocida is resistant to erythromycin; other β-lactam antimicrobial agents, quinolones, tetracycline, and erythromycin are sensitive. Amoxicillin-clavulanate, ampicillin-sulbactam, and cefoxitin are good choices.

Source: Harrison 22e · p1054

Amisulpride

Contraindicated

Database

Increased risk of Torsades de Pointes (TdP) and other ventricular arrhythmias

Concomitant use is contraindicated. Avoid combination.

Source: DDInter

Domperidone

Contraindicated

Database

CYP3A4 inhibition and QT prolongation; significantly increased cardiac risk

Avoid combination