Tramadol IR

Weak Opioid + SNRI·Analgesia - Opioids

Moderate to severe acute and chronic pain

Authority requiredPBSOPIOIDTramal, Zydol50 mg tablet+2

Max Dose

400 mg/day

Half-life

6 h

Seizure Risk

DOSE-DEP

Serotonin Synd.

RISK

Rapid Summary

Overview

Atypical centrally-acting analgesic. Combines weak mu-opioid agonism with Serotonin and Noradrenaline Reuptake Inhibition (SNRI). Highly effective but riddled with neurological drug interactions.

Maximum Dose

Max 400 mg/day (Max 300 mg/day in the elderly).

Clinical Focus

Massively lowers the seizure threshold and carries a severe risk of Serotonin Syndrome if mixed with antidepressants.

Bottom Line

Tramadol IR is a dual-mechanism analgesic (weak opioid + SNRI) for moderate pain, but lowers the seizure threshold significantly and causes serotonin syndrome when combined with other serotonergic drugs.

Formulation & Access

Brand Names

Tramal, Zydol

Oral Routes

Capsules/Tablets (50 mg). Sustained Release (100, 150, 200 mg).

Parenteral

Ampoules (100 mg/2 mL) for IV / IM use.

Prescribing & PBS

Authority Required (PBS). S4 (but tightly monitored due to abuse).

Indications & Use

Primary

PBSTGA

Moderate to severe acute and chronic pain.

Clinical Place

Step 2 on the analgesic ladder. Used when patients cannot tolerate the constipation of codeine or the strength of oxycodone.

Quick reference

Class & Role

Weak Opioid + SNRI — Atypical centrally-acting analgesic.

Route / Formulation

Capsules/Tablets (50 mg). Sustained Release (100, 150, 200 mg). (Tramal, Zydol)

Usual Dose & Max

PO / IV / IM 50-100 mg q4-6h PRN. Max 400 mg/day.

Key Indication Doses

Moderate-Severe Pain: PO / IV / IM 50-100 mg q4-6h PRN. Max 400 mg/day. Elderly (> 75 years): Max 300 mg/day. Start low (25-50 mg). Renal Impairment: Max 200 mg/day if eGFR < 30. Increase dosing interval to q12h.

Best Uses

Avoid / Cautions

Uncontrolled epilepsy, concurrent MAOI use. Pregnancy Category C.

Key Risks

Neurological: Seizures (highly dose-dependent, occurs even in patients without epilepsy). CRITICAL — Serotonin Syndrome. HIGH — Dizziness, confusion, delirium (especially in elderly). Gastrointestinal: Severe nausea/vomiting (much higher than other opioids). MODERATE — Constipation (less than codeine/morphine). Respiratory: Respiratory depression is significantly less common than with classical opioids.

Key Interactions

SSRIs, SNRIs, TCAs, St John's Wort. Massive risk of lethal Serotonin Syndrome (hyperthermia, rigidity, clonus). CYP2D6 inhibitors (Fluoxetine, Paroxetine) block conversion to the active M1 opioid metabolite, robbing the patient of opioid pain relief while increasing the SNRI seizure/serotonin risks.

Monitoring

Monitor for signs of serotonin toxicity (agitation, sweating, shivering, brisk reflexes). Co-prescribe an antiemetic (Ondansetron) for the first few days. Check eGFR to guide maximum daily dose limits.

Clinical Pearl

Ondansetron is a 5-HT3 antagonist. Tramadol relies on serotonin pathways for pain relief. Giving them together not only increases serotonin syndrome risk, but actually *reduces* the pain relief of Tramadol. Consider Metoclopramide instead if not contraindicated.

Access

Authority requiredTramal, Zydol50 mg tablet

Brand: Tramal, Zydol
PBS status: Authority required
Formulation: Capsules/Tablets (50 mg)