Erythromycin

ERYTHROCIN

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Pronunciation: er-ith-roe-MYE-sin

Erythromycin ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Erythromycin ballicule

Erythromycin E-MYCIN mascot mnemonic cartoon — Visual mnemonic: Erythromycin mascot
**“(Eryth) throw your mice in here”**
macrolide ring
erythro = red

What it isMacrolide inhibiting the 50S ribosomal subunit; atypical infection, and used off-label as a prokinetic.

Why this oneIts motilin agonism makes it useful for gastroparesis, which no other antibiotic offers.

What limits itA strong CYP3A4 inhibitor and QT prolonger, so interactions are constant. GI upset limits the dose; tachyphylaxis develops in prokinetic use.

Erythromycin molecular structure (skeletal formula) — Molecular structure: Erythromycin

FDA-approved for

bacterial infections (1952)
pertussis (1952)

FDA label

Read the full label on DailyMed ↗

FDA dosing	Population	Start	Target	Max
Susceptible infections (usual)	Adults	400 mg QID (q6h)	400 mg QID (q6h)	4 g/day
Susceptible infections (usual)	Children	30-50 mg/kg/day divided q6h	30-50 mg/kg/day	100 mg/kg/day (severe)
Streptococcal prophylaxis (rheumatic heart disease)	Adults	400 mg BID	400 mg BID	400 mg BID

Renal Undefined

Hepatic Undefined

Instructions

May be administered without regard to meals
Treat streptococcal infections for at least 10 days

Available strengths

tab 250, 500 mg (base/stearate)
tab 400 mg (EES)

Contraindications

Concomitant terfenadine, astemizole, pimozide, or cisapride
Concomitant CYP3A4-metabolized statins (lovastatin, simvastatin) — rhabdomyolysis risk

Cautions

Hepatotoxicity/hepatic dysfunction
QT prolongation and ventricular arrhythmias incl. torsades de pointes
C. difficile/pseudomembranous colitis
Reversible hearing loss (renal insufficiency, high doses)

Adverse reactions

Nausea
Vomiting
Abdominal pain
Diarrhea
Anorexia
Allergic reactions (urticaria to anaphylaxis)

Pregnancy No evidence of teratogenicity or reproductive harm in animal studies

Lactation Undefined

Cost

Erythromycin (ERYTHROCIN)

Strength		#/mo	CostPlus
250 mg	tab	120 QID	not offered
500 mg	tab	120 QID	not offered
400 mg	tab	120 QID	not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Erythromycin is dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Generic entry1990

NO BOXED WARNINGS

Principal riskA strong CYP3A4 inhibitor; QT prolongation

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades3 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryC

Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.

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Memory aids: interaction avatars

CYP3A4 inhibitor

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