Pethidine Hydrochloride

Indications

Pethidine Hydrochloride is used for: Anaesthesia, Postoperative pain, Moderate to severe acute pain, Obstetric analgesia

Adult Dose

Parenteral Moderate to severe acute pain Adult: 25-100 mg IM/SC inj or 25-50 mg by slow IV inj repeated after 4 hr. Obstetric analgesia Adult: 50-100 mg by IM/SC inj as soon as contractions occur at regular intervals; repeat after 1-3 hr if needed. Max: 400 mg in 24 hr. As a preoperative medication Adult: 25-100 mg IM/SC given 1 hr before surgery. Postoperative pain Adult: 25-100 mg IM/SC inj every 2-3 hr if necessary. Intravenous Adjunct to anaesthesia Adult: 10-25 mg by slow IV inj. Hepatic impairment: Dose reductions may be necessary.

Child Dose

Parenteral Moderate to severe acute pain Child: SC/IM: 2 mth to 12 yr: 0.5-2 mg/kg; 12-18 yr: 20-100 mg. Repeat dose every 4-6 hr if needed. IV inj: Neonates and children >12 yr: 0.5-1 mg/kg IV inj every 10-12 hr if needed in those up to 2 mth and every 4-6 hr if needed in older children. 12-18 yr: 25-50 mg every 4-6 hr if needed. Alternatively, >1 mth: Loading dose: 1 mg/kg by IV inj followed by 100-400 mcg/kg/hr via continuous IV infusion adjusted according to response. As a preoperative medication Child: 1-2 mg/kg given IM 1 hr before surgery. Postoperative pain Child: 0.5-2 mg/kg IM every 2-3 hr if necessary.

Renal Dose

Renal impairment: Dose reductions may be necessary.

Administration

Reconstitution: Dilute with water for inj to a concentration of 5-10 mg/ml.

Contra Indications

Hypersensitivity.

Precautions

May impair ability to drive or operate machinery. Hypovolaemia, CV disease; adrenal insufficiency; biliary tract disorder; CNS depression or coma; history of drug abuse or acute alcoholism; head injury, intracranial lesions, elevated intracranial pressure; hepatic or renal impairment; morbidly obese; prostatic hyperplasia; toxic psychoses; pre-existing respiratory compromise (hypoxia and/or hypercapnia), COPD or other obstructive airway disease; sickle-cell disease; supraventricular tachycardia; thyroid dysfunction. Elderly and debilitated patients. Withdraw gradually. Pregnancy (avoid prolonged use or high doses at term) and lactation.

Pregnancy-Lactation

Pregnancy Category B, D if prolonged use/high doses at term.

Interactions

Increased pethidine metabolite levels with aciclovir, cimetidine, ritonavir. Reduced analgesic effects with phenytoin, barbiturates. Additive sedative and/or respiratory depressive effects with alcohol, barbiturates, benzodiazepines, phenothiazines, TCAs, other CNS depressants. Potentially Fatal: Increased risk of serotonin syndrome with MAOIs (not be given concurrently or within 14 days of their discontinuation), serotonin agonists, serotonin reuptake inhibitors, sibutramine, TCAs.

Adverse Effects

Side effects of Pethidine Hydrochloride : Hypotension; fatigue, drowsiness, dizziness, nervousness, headache, restlessness, malaise, confusion, depression, hallucinations, tremors, muscle twitches, increased intracranial pressure, seizure, serotonin syndrome; rash, urticaria; nausea, vomiting, constipation, anorexia, stomach cramps, xerostomia, biliary spasm, paralytic ileus, sphincter of Oddi spasm; ureteral spasms, decreased urination; pain at inj site; weakness; dyspnoea; histamine release, physical and psychological dependence.

Mechanism of Action

Pethidine is a phenylpiperidine derivative opioid analgesic. It acts mainly as mu-receptor agonist. Like most, opioid analgesics, it mimics endogenous opioids by activating opioid receptors in the central and peripheral nervous system. It reduces the release of neurotransmitter substances and also reduces the activity of postsynaptic neurons in the spinal cord thus preventing transmission of pain impulse.