Matrifen (Fentanyl)

Fentanyl, an opioid analgesic, is indicated for conditions requiring sustained opioid therapy.

• Chronic severe pain: provides continuous analgesia for patients with severe, non‑cancer pain unresponsive to other treatments.
• Cancer pain: manages moderate to severe pain associated with malignant disease, improving quality of life.
• End‑of‑life care: offers reliable pain control for hospice patients during terminal phases.

• Fentanyl is a highly lipophilic synthetic opioid that binds selectively to mu‑opioid receptors in the central nervous system. Activation of these receptors inhibits adenylate cyclase activity, reduces calcium influx, and increases potassium efflux, leading to decreased neuronal excitability and suppression of nociceptive transmission, thereby producing potent analgesia.

Transdermal fentanyl may cause a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Nausea: feeling of queasiness that may lead to vomiting.
• Constipation: reduced bowel movements often requiring laxatives.
• Dizziness: light‑headed sensation, especially when standing quickly.
• Somnolence: increased sleepiness or drowsiness during daily activities.

Serious or Rare Side Effects

• Respiratory depression: slowed or shallow breathing that can be life‑threatening.
• Severe hypotension: marked drop in blood pressure causing faintness or shock.
• Anaphylaxis: rare allergic reaction with hives, swelling, and difficulty breathing.

When using transdermal fentanyl, careful assessment and monitoring are essential to minimize risks.

• Assess opioid tolerance: confirm patient has adequate prior opioid exposure before initiating therapy.
• Monitor respiratory function: observe for signs of depression, especially during dose changes.
• Evaluate CNS depression: avoid concurrent central nervous system depressants without supervision.
• Adjust for hepatic impairment: consider lower strength patches in patients with liver dysfunction.
• Educate on patch handling: advise patients to avoid heat sources and to rotate application sites.
• Store at room temperature: keep patches in original packaging, protect from moisture and direct sunlight.

Fentanyl can interact with other medicines, altering its effects or increasing adverse risks.

Major Interactions (Avoid)

• Concomitant opioids: additive respiratory depression risk.
• Benzodiazepines or other CNS depressants: heightened sedation and respiratory suppression.
• MAO inhibitors: potential for severe hypotension and serotonin syndrome.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): increase fentanyl plasma levels.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce analgesic effect.
• Alcohol: can enhance sedation and respiratory depression.
• Antihistamines or certain antidepressants: may increase CNS depression.