Last updated: October 17, 2014

Trade Names: Demerol

Synonyms: Meperidine hydrochloride, pethidine

Drug Class: Narcotic analgesic, opioid

Tablets: 50- and 100 mg
Syrup: 50 mg/5 mL (500 mL)
Injection: 10-, 25-, 50-, 100 mg/mL

Dose: Oral, intramuscular, or subcutaneous: 50–100 mg/dose every 3–4 hours (50–75 mg of meperidine is roughly equivalent to 10 mg morphine). The oral dose is less potent than the intramuscular dose.

Indications: Pain not controlled by nonopioid drugs. Morphine is generally preferred. Do not use to treat chronic pain.

Mechanism of Action: Binds to opioid receptors in the CNS

Contraindications: Hypersensitivity to meperidine, substance abuse, patients receiving MAOIs in the previous 14 days, renal failure

Precautions: Use caution in patients with hypersensitivity to other opioids, seizure disorder, respiratory disease, renal or hepatic impairment. Decrease the dose if there is hepatic or renal impairment. The metabolite normeperidine accumulates in patients with impaired renal function and causes CNS stimulation, anxiety, tremors  and seizures. Meperidine is not suitable for long-term use. Use the lowest dose necessary to control pain. Escalate dose only with uncontrolled pain. Avoid in the elderly.

Monitoring: Monitor blood pressure and respiration if used parenterally.

Pregnancy Risk: C; D in high doses (neonatal abstinence syndrome)

Adverse Effects
Common: Drowsiness, constipation, dysphoria, nausea, hypotension, confusion, pruritus
Less common: Rash, CNS stimulation, insomnia, twitchiness, seizures, respiratory depression, dependence, histamine release

Drug Interactions
CNS depressants: Increased toxicity
MAOIs: Avoid because risk of serious potentially fatal reactions including hypertension, seizures, coma
SSRIs: Avoid fluoxetine and other drugs in this class because of increased toxicity of meperidine
Cimetidine: Increased meperidine levels

Patient Instructions: Drug is a narcotic and addictive. Use only to control pain. Do not use with alcohol or other CNS depressants. Impairs driving and ability to operate machinery.

Comments: Meperidine offers little advantage over morphine and has a worse adverse effect profile, particularly the increased risk of seizures due to normeperidine. Most pain authorities recommend against its use.

Clinical Pharmacology: Onset of action within 10 minutes, duration of effect is 2–4 hours, hepatic metabolism, urinary elimination as metabolites. Half-life of meperidine is 3–4 hours, but that of the toxic metabolite normeperidine is 15–30 hours and depends on renal function.

Cost: $

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