Procyclidine Hydrochloride Tablets

KEMADRIN (procyclidine hydrochloride) is indicated in the treatment of parkinsonism including the postencephalitic, arteriosclerotic, and idiopathic types. Partial control of the parkinsonism symptoms is the usual therapeutic accomplishment. Procyclidine hydrochloride is usually more efficacious in the relief of rigidity than tremor; but tremor, fatigue, weakness, and sluggishness are frequently beneficially influenced. It can be substituted for all the previous medications in mild and moderate cases. For the control of more severe cases, other drugs may be added to procyclidine therapy as indications warrant.

Clinical reports indicate that procyclidine often successfully relieves the symptoms of extrapyramidal dysfunction (dystonia, dyskinesia, akathisia, and parkinsonism) which accompany the therapy of mental disorders with phenothiazine and rauwolfia compounds. In addition to minimizing the symptoms induced by tranquilizing drugs, the drug effectively controls sialorrhea resulting from neuroleptic medication. At the same time, freedom from the side effects induced by tranquilizer drugs, as provided by the administration of procyclidine, permits a more sustained treatment of the patient's mental disorder.

Clinical results in the treatment of parkinsonism indicate that most patients experience subjective improvement characterized by a feeling of well-being and increased alertness, together with diminished salivation and a marked improvement in muscular coordination as demonstrated by objective tests of manual dexterity and by increased ability to carry out ordinary self-care activities. While the drug exerts a mild atropine-like action and therefore causes mydriasis, this may be kept minimal by careful adjustment of the daily dosage.

Anticholinergic effects can be produced by therapeutic doses although these can frequently be minimized or eliminated by careful dosage. They include: dryness of the mouth, mydriasis, blurring of vision, giddiness, lightheadedness, and gastrointestinal disturbances such as nausea, vomiting, epigastric distress, and constipation. Occasionally an allergic reaction such as a skin rash may be encountered. Feelings of muscular weakness may occur. Acute suppurative parotitis as a complication of dry mouth has been reported.

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Pharmacologic tests have shown that procyclidine hydrochloride has an atropine-like action and exerts an antispasmodic effect on smooth muscle. It is a potent mydriatic and inhibits salivation. It has no sympathetic ganglion- blocking activity in doses as high as 4 mg/kg, as measured by the lack of inhibition of the response of the nictitating membrane to preganglionic electrical stimulation.

The intravenous LD50 in mice was about 60 mg/kg. Subcutaneously, doses of 300 mg/kg were not toxic. In dogs, the intraperitoneal administration of procyclidine hydrochloride in doses of 5 mg/kg caused maximal dilation of the pupil and inhibition of salivation, but had no toxic action. When the dose was increased to 20 mg/kg, the same symptoms occurred, and in addition there were tremors and ataxia lasting 4 to 5 hours. In one animal, convulsions occurred which were controlled by pentobarbital. In all animals behavior returned to normal within 24 hours.

Chronic toxicity tests in rats showed that the compound caused only a very slight retardation in growth, and no change in the erythrocyte count or the histological appearance of the lungs, liver, spleen, and kidney when as much as 10 mg/kg body weight was given subcutaneously daily for 9 weeks.

• Parkinson's Disease