Pethidine

ADMINISTRATION ROUTES:

IV, IM, PO

ALTERNATIVE NAMES:

Meperidine

ICU INDICATIONS:

1. Analgesia
2. Shivering

PRESENTATION AND ADMINISTRATION:

IV:

Pethidine 100 mg in 2 mL 50 mg in 1 mL vial.

Dilute solution to 10 mg/mL with Water for Injection. Inject slowly over 3-5 minutes (do not exceed 50 mg per dose when administering via this route).

Compatible with the following IV fluids:

0.9% sodium chloride, Hartmanns, 5% or 10% dextrose, Glucose and sodium chloride

Store at room temperature

IM:

Preferred route for repeated or large doses (as it is less irritating than IV)

PO:

Tablets:

Pethidine 50 mg tablets (white), Pethidine 100 mg tablets (white)

DOSAGE:

IV:

25 - 50 mg IV 4 hourly

It is rare for more than a single dose to be used in ICU

IM:

25 - 100 mg IM 4 hourly

PO:

50 - 150 mg PO 4 hourly

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose in renal impairment

Dose in renal replacement therapy

DOSAGE IN PAEDIATRICS:

IM:

0.5 - 2 mg/kg 4 hourly

IV:

0.5 - 1 mg/kg 4 hourly

PO:

1.1 - 1.76 mg/kg (max 100 mg) 4 hourly

CLINICAL PHARMACOLOGY:

Pethidine is a narcotic analgesic with multiple actions qualitatively similar to those of morphine. The most prominent of these involve the central nervous system and organs composed of smooth muscle. The principal actions of therapeutic value are analgesia and sedation.

CONTRAINDICATIONS:

1. Hypersensitivity to pethidine
2. Respiratory depression
3. Cardiac arrhythmias
4. Concomitant monoamine oxidase inhibitor (MAOI) use or within 2 weeks prior
5. Severe liver disease

WARNINGS:

Impaired Respiration

Respiratory depression is the main adverse effect of all opioids. Respiratory depression occurs most frequently in the elderly and debilitated patients as well as in those suffering from conditions accompanied by hypoxia or hypercapnia when even moderate therapeutic doses may dangerously decrease pulmonary ventilation.

Pethidine should be used with extreme caution in patients with chronic obstructive pulmonary disease or cor pulmonale, and in patients having a substantially decreased respiratory reserve, hypoxia, hypercapnia, or pre-existing respiratory depression. In such patients, even usual therapeutic doses of pethidine may decrease respiratory drive while simultaneously increasing airway resistance to the point of apnoea.

Pethidine-associated neurotoxicity (PAN)

PAN may present as seizures and is associated with prolonged exposure to high doses of pethidine due to the metabolite norpethidine. The excretion of this metabolite is reduced in renal impairment and the elderly. Conversion of pethidine to norpethidine is increased when co-administered with drugs such as phenytoin or phenobarbitone. Pethidine should be avoided in these situations, and not used for periods greater than 24 hours. It is not suitable for use in Patient Controlled Analgesia (PCA) devices.

Pethidine may also worsen convulsions in pateints wih pre-existing seizure disorders or provoke seizures in patients with seizure disorders who were otherwise well controlled.

Cardiac arrhythmias

Pethidine has a vagolytic action so may produce a siginificant increase in the ventricular response rate. It should not be used in patients with atrial flutter or other supraventricular tachycardias.

Hypotensive Effect

Pethidine , like all opioid analgesics, may cause severe hypotension in an individual whose ability to maintain his blood pressure has already been compromised by a depleted blood volume, or a concurrent administration of drugs that lower blood pressure.

Anaphylaxis

Although extremely rare, cases of anaphylaxis have been reported.

PRECAUTIONS:

Laboratory Tests:

No tests in addition to routine ICU tests are indicated

Drug/Laboratory Test Interactions:

None noted

IMPORTANT DRUG INTERACTIONS IN ICU:

The concomitant use of other central nervous system depressants including sedatives or hypnotics, general anaesthetics, phenothiazines, tranquilisers, and alcohol may produce additive depressant effects. Respiratory depression, hypotension, and profound sedation or coma may occur.

ADVERSE REACTIONS:

Central Nervous System:

Euphoria, sedation, dysphoria, weakness, headache, agitation, tremor, uncoordinated muscle movements, severe convulsions, transient hallucinations and disorientation, visual disturbances

Respiratory:

Respiratory depression

Gastrointestinal:

Nausea and vomiting, dry mouth, biliary tract spasm, constipation, ileus, intestinal obstruction

Cardiovascular:

Flushing of the face, chills, tachycardia, bradycardia, palpitation, faintness, syncope, hypotension, hypertension

Genitourinary:

Urine retention or hesitance, reduced libido, impotency

Dermatologic:

Pruritus, urticaria, other skin rashes, oedema, diaphoresis