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Active ingredient: Orphenadrine - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Antiparkinson Agents
  • Antidyskinetics
  • Skeletal Muscle Relaxants

Dosage Forms

  • Tablet (extended-release)

Brands / Synonyms

Antiflex; Banflex; Biorphen; Brocadisipal; Brocasipal; Disipal; Flexoject; Mephenamine; Mio-Rel; Myolin; Myotrol; Norflex; O-Methyldiphenhydramine; Orfro; Orphenadine; Orphenadrin; Orphenadrine; Orphenadrine Citrate; Orphenate; Orphenedrine

Indications

Indicated for the treatment of Parkinson's disease.

Pharmacology

Orphenadrine is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions. Orphenadrine is an anticholinergic with a predominantly central effect and only a weak peripheral effect. In addition, it has mild antihistaminic and local anaesthetic properties. Parkinson's syndrome is the consequence of a disturbed balance between cholinergic and dopaminergic neurotransmission in the basal ganglia caused by a decrease in dopamine. Orphenadrine restores the physiological equilibrium and has a favourable effect on the rigidity and tremor of Parkinson's disease and Parkinsonian syndromes. The effect is somewhat less on bradykinesia.

Mechanism of Action

Orphenadrine binds to both histamine H1 receptors and NMDA receptors. It restores the motor disturbances induced by neuroleptics, in particular the hyperkinesia. The dopamine deficiency in the striatum increases the stimulating effects of the cholinergic system. This stimulation is counteracted by the anticholinergic effect of orphenadrine. It may have a relaxing effect on skeletal muscle spasms and it has a mood elevating effect.

Absorption

Orphenadrine is almost completely absorbed in the gastrointestinal tract.

Toxicity

Oral, mouse LD50 = 100 mg/kg; oral, rat LD50 = 255 mg/kg

Biotrnasformation / Drug Metabolism

Biotransformation occurs mainly in the liver. Pharmacologically active metabolites are N-demethyl orphenadrine and N,N-didemethyl orphenadrine.

Contraindications

Contraindicated in patients with glaucoma, pyloric or duodenal obstruction, stenosing peptic ulcers, prostatic hypertrophy or obstruction of the bladder neck, cardiospasm (megaesophagus) and myasthenia gravis.

Contraindicated in patients who have demonstrated a previous hypersensitivity to the drug.

Drug Interactions

No information provided.

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