Norflex (Orphenadrine Citrate)

Orphenadrine citrate is a centrally acting muscle relaxant indicated for conditions involving skeletal muscle spasm.

• Muscle spasm: reduces involuntary muscle contraction and associated discomfort.
• Acute musculoskeletal pain: alleviates pain from strains, sprains or minor injuries.
• Post‑operative musculoskeletal discomfort: helps control pain and spasm after surgical procedures.

• Orphenadrine citrate exerts anticholinergic (muscarinic antagonist) and antihistamine activity, which dampens central neuronal excitability. By blocking muscarinic receptors and histamine H1 receptors in the central nervous system, it decreases reflex muscle tone, leading to relaxation of skeletal muscles and reduction of spasm-related pain.

Adverse reactions may occur with any centrally acting muscle relaxant.

Common Side Effects

• Dry mouth: reduced salivary secretion causing a feeling of thirst.
• Drowsiness: mild to moderate sedation, especially after initial doses.
• Dizziness: sensation of light‑headedness or imbalance.
• Blurred vision: temporary visual disturbances.
• Constipation: slowed gastrointestinal motility.
• Nausea: mild stomach upset.

Serious or Rare Side Effects

• Tachycardia: rapid heart rate requiring medical evaluation.
• Urinary retention: difficulty emptying the bladder.
• Severe allergic reaction: rash, swelling, or breathing difficulty.
• Hepatotoxicity: signs of liver injury such as jaundice.
• Psychotic symptoms: hallucinations or confusion in susceptible individuals.
• Cardiac arrhythmias: irregular heart rhythms observed in rare cases.

Before prescribing Norflex, clinicians should consider patient‑specific factors and safety measures.

• Pregnancy: use only if the potential benefit justifies the potential risk to the fetus.
• Breastfeeding: caution advised as the drug may be excreted in milk.
• Elderly patients: start with lower doses and monitor for increased sedation.
• Hepatic impairment: dose adjustment may be required due to reduced metabolism.
• Concomitant CNS depressants: avoid additive sedation or respiratory depression.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Orphenadrine citrate can interact with several medication classes, influencing efficacy or safety.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): risk of hypertensive crisis.
• Anticholinergic drugs: additive anticholinergic burden leading to severe dry mouth, constipation, or urinary retention.
• CNS depressants (e.g., benzodiazepines, opioids): heightened sedation and respiratory depression.

Moderate Interactions (Monitor Closely):\n- Antihistamines: increased drowsiness.

• Beta‑blockers: may mask tachycardia.
• Alcohol: potentiates central nervous system effects.
• Antihypertensive agents: possible additive blood pressure lowering.