Meperidine

DEMEROL

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Pronunciation: me-PER-i-deen

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

Meperidine DEMEROL mascot mnemonic cartoon — Visual mnemonic: Meperidine mascot
**“Meeper Demoralized”**

What it isMu-opioid agonist; acute pain and postoperative shivering.

Why this oneIts unusually strong anti-shivering effect is the main niche that survives its abandonment as a routine analgesic.

What limits it⚑ Normeperidine accumulates in renal disease and can provoke seizures; avoid repeated dosing. MAO inhibitors can trigger serotonin syndrome.

Pearls

Limit to 24–48 hours of acute pain.
Avoid IM or SC: tissue irritation and muscle fibrosis.
Normeperidine toxicity also rises with PCA and in the elderly.
Weak: one-tenth the potency of morphine (MME factor 0.1).

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

Meperidine prescription history

Animated chart of estimated U.S. prescriptions per year, Opioid analgesics (1900–2026). Meperidine enters in 1942 (estimated).

FDA-approved for

pain (~1942)

Off-label

postoperative shivering

Classes and tags

Clinical profile

Therapeutic safety burden3 / 4

Overdose danger4 / 4

Weight-gain liability0 / 4

Sedation liability2 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk2 / 4

Legacy pregnancy categoryC

Defining liabilityRespiratory depression, dependence and overdose; risk rises sharply with sedatives or impaired clearance.

FDA label

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BOXED WARNING Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks with benzodiazepines/CNS depressants; CYP3A4 interactions; MAOI use within 14 days contraindicated; oral-solution dosing errors (mg vs mL); REMS.

FDA dosing	Population	Start	Target	Max
Acute pain	Adults	50–150 mg PO q3–4h PRN	Lowest effective dose	≤600 mg/day (discontinue if inadequate)
Acute pain	Pediatric	1.1–1.8 mg/kg PO q3–4h PRN (up to adult dose)	Lowest effective dose	Up to adult dose

Renal Use with caution; titrate slowly (meperidine/normeperidine accumulation)

Hepatic Use with caution; titrate slowly (meperidine/normeperidine accumulation)

Dose q3–4h as needed

Instructions

Reduce dose 25–50% when given with phenothiazines or other tranquilizers
Oral solution: prescribe/measure in both mg and mL to avoid dosing errors; use a graduated device
Do not abruptly discontinue in physically dependent patients; taper by ≤10–25% of daily dose every 2–4 weeks

Available strengths

tab 50, 100 mg
sol 50 mg/5 mL
inj 10, 25, 50, 75, 100 mg/mL

Contraindications

Significant respiratory depression
Acute or severe bronchial asthma in an unmonitored setting or absent resuscitative equipment
Known or suspected GI obstruction, including paralytic ileus
MAOIs (concurrently or within 14 days) due to risk of coma, severe respiratory depression, cyanosis, and hypotension

Cautions

Serotonin syndrome with concomitant serotonergic drugs
Opioid-induced hyperalgesia and allodynia
Life-threatening respiratory depression, especially at initiation/titration and in elderly/debilitated/pulmonary disease
Adrenal insufficiency
Severe hypotension; avoid in circulatory shock
Increased intracranial pressure/head injury; avoid in impaired consciousness or coma
Normeperidine accumulation may cause CNS excitation/seizures

Adverse reactions

Lightheadedness
Dizziness
Sedation
Nausea
Vomiting
Sweating

Pregnancy Insufficient data; prolonged use may cause neonatal opioid withdrawal; not recommended during/immediately before labor

Lactation Meperidine appears in human milk; monitor breastfed infant for excess sedation and respiratory depression

Cost

Meperidine (DEMEROL)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/unit	CostPlus
50 mg	tab	per unit		not offered
100 mg	tab	per unit		not offered
50 mg/5 mL	sol	per unit	$0.16/mL	not offered
10 mg/mL	inj	per unit		not offered
25 mg/mL	inj	per unit		not offered
50 mg/mL	inj	per unit		not offered
75 mg/mL	inj	per unit		not offered
100 mg/mL	inj	per unit		not offered

Generic entry1984

Serotonin and MAOI

Provisional washout figures

SRI significance3 / 4

MAO-A inhibition0 / 4

Serotonin release0 / 4

Elevating mechanismSRI

Non-elevating actionNone recorded

Exposure dependenceTherapeutic exposure; severe toxicity requires meaningful MAO-A inhibition

Washout BEFORE an MAOI14 days

Evidence confidenceHigh

InterpretationOpioid with clinically significant SRI activity; dangerous with meaningful MAO-A inhibition. A second SRI generally represents therapeutic duplication/additive adverse effects, not the classic life-threatening interaction.

Active metabolites

Normeperidine

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Memory aids: interaction avatars

CYP3A4 substrate

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Self-check

What meperidine metabolite can accumulate and provoke seizures?
Normeperidine.
What non-analgesic use is listed for meperidine?
Postoperative shivering.