DEMEROL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DEMEROL (DEMEROL).
Meperidine is an opioid agonist that binds to mu-opioid receptors in the central nervous system, mimicking endogenous endorphins to produce analgesia, sedation, and euphoria. It also has additional weak actions at kappa and delta receptors.
| Metabolism | Primarily hepatic via hydrolysis to meperidinic acid and N-demethylation to normeperidine (active metabolite) by CYP3A4 and CYP2B6. |
| Excretion | Renal (90% as metabolites and unchanged drug; ~5% unchanged) and biliary/fecal (minor). |
| Half-life | 2.5-4 hours; prolonged in hepatic impairment (7-11 hours) and elderly. |
| Protein binding | 65-75% bound (primarily to alpha1-acid glycoprotein and albumin) |
| Volume of Distribution | 2.4-3.7 L/kg; large due to extensive tissue distribution |
| Bioavailability | Oral: 50-60% (first-pass metabolism); IM: ~75% |
| Onset of Action | IV: 1-2 min; IM: 10-15 min; Oral: 15-30 min |
| Duration of Action | 2-4 hours (parenteral); oral: 2-4 hours (slightly longer) |
50-150 mg IM, IV, or SC every 3-4 hours as needed for pain; oral 50-150 mg every 3-4 hours.
| Dosage form | INJECTABLE |
| Renal impairment | GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: administer 75% of dose; GFR <10 mL/min: administer 50% of dose. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use or reduce dose by 75%. |
| Pediatric use | 1-2 mg/kg IM, IV, or SC every 3-4 hours (max 100 mg/dose); oral 1-2 mg/kg every 3-4 hours. |
| Geriatric use | Lower initial doses (25-50 mg) with extended intervals (every 4-6 hours); monitor for respiratory depression and CNS effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DEMEROL (DEMEROL).
| Breastfeeding | Meperidine excreted into breast milk with M/P ratio approximately 1.0. Breastfeeding not recommended due to risk of neonatal CNS depression and accumulation of active metabolite normeperidine. Avoid use if breastfeeding; if necessary, monitor infant for sedation and poor feeding. |
| Teratogenic Risk | Pregnancy Category C. First trimester: No well-controlled studies; potential risk based on animal studies showing increased skeletal malformations at high doses. Second trimester: Risk of fetal dependence and withdrawal if used chronically. Third trimester: Use near term may cause neonatal respiratory depression, withdrawal syndrome (irritability, tremors, poor feeding), and reduced uterine tone leading to prolonged labor. |
■ FDA Black Box Warning
Risk of respiratory depression; risk of addiction, abuse, and misuse; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risk of medication errors leading to accidental overdose; risk of serotonin syndrome if used with serotonergic drugs; risk of adrenal insufficiency.
| Serious Effects |
["Hypersensitivity to meperidine","Concurrent use of MAOIs or within 14 days","Severe respiratory depression","Acute or severe bronchial asthma","Gastrointestinal obstruction","Suspected surgical abdomen"]
| Precautions | ["Respiratory depression, especially in elderly or debilitated patients","Serotonin syndrome risk with MAOIs, SSRIs, SNRIs, and other serotonergic drugs","Contraindicated in patients taking MAOIs or within 14 days of stopping","Risk of seizures with normeperidine accumulation in renal impairment","Hypotension, especially with rapid dose escalation","Prolonged use may lead to physical dependence; abrupt cessation may cause withdrawal"] |
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| Fetal Monitoring | Monitor maternal respiratory rate, blood pressure, oxygen saturation, and level of sedation. Fetal monitoring: continuous electronic fetal monitoring during labor due to risk of non-reassuring fetal status. Assess neonatal Apgar scores and respiratory effort at delivery. |
| Fertility Effects | Limited data. Animal studies suggest no significant impairment of fertility at therapeutic doses. Chronic use may cause amenorrhea or anovulation due to hyperprolactinemia. Effects are reversible upon discontinuation. |