PHARMACOLOGY

Pharmacotherapeutic Group: Opioid analgesics

Pharmacodynamic properties: Tramadol inhibits reuptake of norepinephrine, serotonin and enhances serotonin release. It alters perception and response to pain by binding to mu-opiate receptors in the CNS.

Pharmacokinetic properties:

Absorption: Readily absorbed from the GI tract. Bioavailability: Approximately 70-75% (oral), Onset: Approx1 hour; Duration: 9 hours

Distribution: Widely distributed. Crosses the placenta and enters breast milk. Protein binding: 20%

Metabolism: Extensive hepatic first-pass metabolism. Converted to O-desmethyltramadol (active) via N- and O-demethylation by CYP3A4 and CYP2D6 isoenzymes and also via glucorinadation or sulfation.

Excretion: Via urine (as metabolites). Elimination half-life: Approximately 6 hours

INDICATIONS

Post operative pain, Cancer pain, Arthralgia, Neuralgia, Severe acute and chronic pain

 DOSE

 Adults, Moderate to severe pain: 50-100 mg 4-6 hourly. Max: 400 mg/day.

CONTRAINDICATIONS

Hypersensitivity, suicidal patients, acute alcoholism, head injuries, raised intracranial pressure, severe renal impairment, lactation.

 SPECIAL PRECAUTIONS

Hypothyroidism, adrenocortical insufficiency, renal or hepatic impairment, history of epilepsy or increased risk of seizures, inflammatory or obstructive bowel disease, myasthaenia gravis, respiratory depression, prostatic hyperplasia. Pregnancy

 ADVERSE DRUG REACTIONS

Serious AEs: Respiratory depression

Common AEs: Nausea, dizziness, headache, somnolence, constipation, vomiting, dry mouth, sweating, fatigue, vertigo, euphoria.

 DRUG INTERACTIONS

Possible increase in anticoagulation with warfarin. Increased risk of seizures with SSRI, TCA. Increased risk of serotonin syndrome with mirtazapine, venlafaxine, SSRI and MAOI. Reduced analgesic efficacy of tramadol with carbamazepine, 5-HT₃ receptor antagonist e.g. ondansetron. Increased respiratory and CNS depression with CNS depressants e.g. alcohol, opioids, anaesthetic agents, narcotics, phenothiazines, tranquilizers or sedative hypnotics.

 PRESENTATION

Each box is supplied with 10 strips of 10 caps packed in blisters.