Brands, Medical Use, Clinical Data
- Antiparkinson Agents
- Skeletal Muscle Relaxants
- 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
Indicated for the treatment of Parkinson's disease.
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.
Orphenadrine is almost completely absorbed in the gastrointestinal tract.
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.
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.
No information provided.