Trihexyphenidyl
These drugs have a higher central peripheral anticholinergic action than atropine but pharmacological profile is similar to it. They acts by reducing imbalanced cholinergic activity in striatum of parkinsonian patients. Tremor is benefited more than rigidity; hypokinesia is affected the least. Sialorrhoea is controlled by their peripheral action. The overall efficacy is much lower than levodopa. However, they are cheap and produce less side effects than levodopa. They can be combined with levadopa in an attempt to lower its dose.Parkinsonism, drug induced extra-pyramidal symptoms, spasticity, closed cranio-cerebral trauma with concussion syndrome. Trigeminal neuralgia. Nicotine poisoning. Adjunct in Parkinsonism therapy.
2-10 mg/day in divided doses. Initially 2.5 mg thrice daily after meals increasing at intervals of 2-3 days by 2.5-5 mg daily. Usual max. : 30 mg daily. Not recommended for children.
Acute narrow angle glaucoma, urinary retention, tachycardia, paralytic ileus, prostatic hypertrophy.
Tendency to convulsion. recent M.I. concurrent admin. of C.N.S. depressants. Paediatrics: Not recommended. Pregnancy: Safety not clearly established. Lactation: Safety not clearly established. Elderly: Strict supervision and dosage monitoring.
Dryness of mouth, blurring of vision, headache, nausea, nervousness. Impairment of memory and organic confusional states, dizziness, constipation, delusions and hallucinations.
Tricyclic antidepressants, antiparkinsonism drugs, anti-histaminics, phenothiazines and quinidines have anticholinergic. Other oral drugs delays absorption.
