Demerol, Pethadol , Pethidine Hydrochloride 
Classifications: narcotic (opiate) agonist analgesic;
Therapeutic: narcotic analgesic

Prototype: Morphine
Pregnancy Category: B (D at term)
Controlled Substance: Schedule II


50 mg, 100 mg tablets; 50 mg/5 mL syrup; 10 mg/mL, 25 mg/mL, 50 mg/mL, 75 mg/mL, 100 mg/mL injection


Synthetic morphine-like compound. Opiates do not alter the pain threshold of afferent nerve endings, nor do they affect the conductance of impulses along peripheral nerves. Analgesia is mediated through changes in the perception of pain at the spinal cord (mu2, delta, kappa receptors) and higher levels in the CNS (mu1 and kappa3 receptors).

Therapeutic Effect

Control of moderate to severe pain.


Relief of moderate to severe pain, for preoperative medication, for support of anesthesia, and for obstetric analgesia.


Hypersensitivity to meperidine; convulsive disorders; acute abdominal conditions prior to diagnosis; MAOI therapy; pregnancy prior to labor [(category C), at term (category D)].

Cautious Use

Head injuries, increased intracranial pressure; asthma and other respiratory conditions; supraventricular tachycardias; prostatic hypertrophy; urethral stricture; glaucoma; older adult or debilitated patients; impaired kidney or liver function, hypothyroidism, Addison's disease.

Route & Dosage

Moderate to Severe Pain
Adult: PO/SC/IM/IV 50–150 mg q3–4h prn
Child: PO/SC/IM/IV 1–1.5 mg/kg q3–4h (max: ≤100 mg q4h) prn

Adult: IM/SC 50–150 mg 30–90 min before surgery
Child: IM/SC 1.1–2.2 mg/kg 30–90 min before surgery

Obstetric Analgesia
Adult: IM/SC 50–100 mg when pains become regular, may be repeated q1–3h


  • Give syrup formulation in half a glass of water. Undiluted syrup may cause topical anesthesia of mucous membranes.
Subcutaneous and Intramuscular Injections
  • Be aware that SC route is painful and can cause local irritation. IM route is generally preferred when repeated doses are required.
  • Aspirate carefully before giving IM injection to avoid inadvertent IV administration. IV injection of undiluted drug can cause a marked increase in heart rate and syncope.
  • Note: Verify correct IV concentration and rate of infusion/injection for administration to infants or children with physician.

PREPARE: Direct: Dilute 50 mg in at least 5 mL of NS or sterile water to yield 10 mg/mL.  IV Infusion: Dilute to a concentration of 1–10 mg/mL in NS, D5W, or other compatible solution.  

ADMINISTER: Direct: Give slowly over 3–5 min at a rate not to exceed 25 mg/min. Slower injection preferred.  IV Infusion: Usually given through a controlled infusion device at a rate not to exceed 25 mg/min.  

INCOMPATIBILITIES Solution/additive: Aminophylline, barbiturates, furosemide, heparin, methicillin, morphine, phenytoin, sodium bicarbonate. Y-site: Allopurinol, amphotericin B cholesteryl complex, cefepime, cefoperazone, doxorubicin liposome, furosemide, idarubicin, imipenem/cilastatin, mezlocillin, minocycline, tetracycline.

  • Store at 15°–30° C (59°–86° F) in tightly closed, light-resistant containers unless otherwise directed by manufacturer.

Adverse Effects (≥1%)

Body as a Whole: Allergic (Pruritus, urticaria, skin rashes, wheal and flare over IV site), profuse perspiration. CNS: Dizziness, weakness, euphoria, dysphoria, sedation, headache, uncoordinated muscle movements, disorientation, decreased cough reflex, miosis, corneal anesthesia, respiratory depression. Toxic doses: muscle twitching, tremors, hyperactive reflexes, excitement, hypersensitivity to external stimuli, agitation, confusion, hallucinations, dilated pupils, convulsions. CV: Facial flushing, light-headedness, hypotension, syncope, palpitation, bradycardia, tachycardia, cardiovascular collapse, cardiac arrest (toxic doses). GI: Dry mouth, nausea, vomiting, constipation, biliary tract spasm. Urogenital: Oliguria, urinary retention. Respiratory: Respiratory depression in newborn, bronchoconstriction (large doses). Skin: Phlebitis (following IV use), pain, tissue irritation and induration, particularly following subcutaneous injection. Metabolic: Increased levels of serum amylase, BSP retention, bilirubin, AST, ALT.

Diagnostic Test Interference

High doses of meperidine may interfere with gastric emptying studies by causing delay in gastric emptying.


Drug: Alcohol and other cns depressants, cimetidine cause additive sedation and CNS depression; amphetamines may potentiate CNS stimulation; mao inhibitors, selegiline, furazolidone may cause excessive and prolonged CNS depression, convulsions, cardiovascular collapse; phenytoin may increase toxic meperidine metabolites. Herbal: St. John's wort may increase sedation.


Absorption: 50–60% from GI tract. Onset: 15 min PO; 10 min IM, SC; 5 min IV. Peak: 1 h PO, IM, SC. Duration: 2–4 h PO, IM, SC; 2 h IV. Distribution: Crosses placenta; distributed into breast milk. Metabolism: In liver. Elimination: In urine. Half-Life: 3–5 h.

Nursing Implications

Assessment & Drug Effects

  • Give narcotic analgesics in the smallest effective dose and for the least period of time compatible with patient's needs.
  • Assess patient's need for prn medication. Record time of onset, duration, and quality of pain.
  • Note respiratory rate, depth, and rhythm and size of pupils in patients receiving repeated doses. If respirations are 12/min or below and pupils are constricted or dilated (see ACTIONS AND USES) or breathing is shallow, or if signs of CNS hyperactivity are present, consult physician before administering drug.
  • Monitor vital signs closely. Heart rate may increase markedly, and hypotension may occur. Meperidine may cause severe hypotension in postoperative patients and those with depleted blood volume.
  • Schedule deep breathing, coughing (unless contraindicated), and changes in position at intervals to help to overcome respiratory depressant effects.
  • Chart patient's response to drug and evaluate continued need.
  • Repeated use can lead to tolerance as well as psychic and physical dependence of the morphine type.
  • Be aware that abrupt discontinuation following repeated use results in morphine-like withdrawal symptoms. Symptoms develop more rapidly (within 3 h, peaking in 8–12 h) and are of shorter duration than with morphine. Nausea, vomiting, diarrhea, and pupillary dilatation are less prominent, but muscle twitching, restlessness, and nervousness are greater than produced by morphine.

Patient & Family Education

  • Do not smoke and walk without assistance after receiving the drug. Bed side rails may be advisable.
  • Be aware nausea, vomiting, dizziness, and faintness associated with fall in BP are more pronounced when walking than when lying down (these symptoms may also occur in patients without pain who are given meperidine). Symptoms are aggravated by the head-up position.
  • Do not drive or engage in potentially hazardous activities until any drowsiness and dizziness have passed.
  • Do not take other CNS depressants or drink alcohol because of their additive effects.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 10/01/2022 (0)
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