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Action/Kinetics:
One-tenth as potent an analgesic as morphine. Its analgesic effect is only one-half when given PO rather than parenterally. Has no antitussive effects and does not produce miosis. Less smooth muscle spasm, constipation, and antitussive effect than equianalgesic doses of morphine.
Duration: Less than that of most opiates; keep in mind when establishing a dosing schedule. Produces both psychologic and physical dependence; overdosage causes severe respiratory depression (see
Narcotic Overdose).
Onset: 10-45 min.
Peak effect: 30-60 min.
Duration: 2-4 hr.
t
1/2: 3-4 hr.
Uses:
PO, Parenteral: Analgesic for moderate to severe pain. Particularly useful for minor surgery, as in orthopedics, ophthalmology, rhinology, laryngology, and dentistry; also for diagnostic procedures such as cystoscopy, retrograde pyelography, and gastroscopy. Spasms of GI tract, uterus, urinary bladder. Anginal syndrome and distress of CHF.
Parenteral: Preoperative medication, adjunct to anesthesia, obsetrical analgesia.
Additional Contraindications:
Hypersensitivity to drug, convulsive states as in epilepsy, tetanus and strychnine poisoning, children under 6 months, diabetic acidosis, head injuries, shock, liver disease, respiratory depression, increased cranial pressure, and before labor during pregnancy.
Special Concerns:
Use with caution during lactation, in older, or debilitated clients. Use with extreme caution in clients with asthma. Atropine-like effects may aggravate glaucoma, especially when given with other drugs used with caution in glaucoma.
Additional Side Effects:
Transient hallucinations, transient hypotension (high doses), visual disturbances. Active metabolite may accumulate in renal dysfunction, leading to an increased risk of CNS toxicity.
Overdose Management:
Symptoms: Severe respiratory depression. See
Narcotic Analgesics.
Treatment: Naloxone 0.4 mg IV is effective in the treatment of acute overdosage. In PO overdose, gastric lavage and induced emesis are indicated. Treatment, however, is aimed at combating the progressive respiratory depression usually through artificial ventilation.
Additional Drug Interactions:
-
Antidepressants, tricyclic / Additive anticholinergic side effects
-
Cimetidine /
Respiratory and CNS depression
-
Hydantoins /
Effect of meperidine due to
breakdown by liver
-
MAO inhibitors /
Risk of severe symptoms including hyperpyrexia, restlessness, hyper- or hypotension, convulsions, or coma
-
Protease inhibitors / Avoid combination
How Supplied:
Injection: 10 mg/mL, 25 mg/mL, 50 mg/mL, 75 mg/mL, 100 mg/mL;
Syrup: 50 mg/5 mL;
Tablet: 50 mg, 100 mg
Dosage
?Tablets, Syrup, IM, SC
Analgesic.
Adults: 50-100 mg q 3-4 hr as needed;
pediatric: 1.1-1.8 mg/kg, up to adult dosage, q 3-4 hr as needed.
Adults, PCA dosage, initial: 10 mg with a range of 1-5 mg per incremental dose. Recommended lock-out interval is 6-10 min (minimum of 5 min).
Preoperatively.
Adults, IM, SC: 50-100 mg 30-90 min before anesthesia;
pediatric, IM, SC: 1-2 mg/kg (up to adult dose) 30-90 min before anesthesia.
Obstetrical analgesia.
Adults, IM, SC: 50-100 mg q 1-3 hr when pains become regular.
?IV
Analgesic.
Adults: 15-35 mg/hr by continuous IV.
Support of anesthesia.
IV infusion: 1 mg/mL or
slow IV injection: 10 mg/mL until client needs met.
