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Procyclidine (marketed as Kemadrin) is a synthetic antimuscarinic agent used to treat parkinsonism and antipsychotic-induced extrapyramidal symptoms such as acute dystonia and tardive movement disorders. Its principal action is competitive blockade of central muscarinic acetylcholine receptors, restoring the striatal dopamine-acetylcholine balance disrupted in these conditions. Beyond its anticholinergic profile, procyclidine also antagonizes NMDA glutamate receptors, a property that has drawn interest in combination pretreatment regimens against organophosphate nerve-agent poisoning, where it contributes anticonvulsant and neuroprotective effects. Although a legitimate prescription medicine, procyclidine is, like other brain-penetrant anticholinergics, capable of producing a dangerous deliriant and anticholinergic-toxidrome state in overdose.
- Treats Parkinsonism, particularly rigidity and tremor
- Relieves antipsychotic-induced dystonia and extrapyramidal symptoms
- Injectable form treats acute drug-induced dystonic reactions
- Muscarinic antagonist with NMDA-blocking anticonvulsant activity
- Dry mouth, blurred vision and constipation
- Urinary retention
- Confusion and memory problems, especially in the elderly
- Delirium and hallucinations at high doses
Mechanism
Procyclidine is a competitive receptor . In Parkinsonism and antipsychotic-induced movement disorders, blocking central cholinergic activity helps restore the -acetylcholine balance in the basal ganglia (a motor-control region), which reduces tremor, rigidity and dystonia. Because it crosses into the brain and antagonizes central muscarinic receptors, high doses cause anticholinergic delirium; peripheral muscarinic blockade at the same time produces the classic toxidrome of dry, hot, flushed skin, blurred vision, urinary retention and a racing heart.
receptor fingerprint
receptors (M1-M5)Antagonist
Safetyrisks and cautions, not medical advice
Procyclidine is a serious prescription drug; at high doses it causes anticholinergic delirium with realistic hallucinations mistaken for reality, confusion and memory loss, plus the toxidrome: blurred vision, dangerous overheating, flushed dry skin, dry mouth, racing heart, urinary retention, seizures and potentially death. Stacking it with other anticholinergics, sedating antihistamines or other deliriants adds up the anticholinergic burden and the danger. High anticholinergic burden is associated with greater dementia risk in older people and with long-term use. Not medical advice.
Subjective profileweighing the evidence above
A legitimate prescription for parkinsonian rigidity and antipsychotic-induced dystonia, and a bad drug to experiment with. The anticholinergic load brings dry mouth, urinary retention and confusion that lands hardest on older adults, and high doses tip into outright delirium.
Resources
This entry is here for reference.
Research
- 1994first citedAcute dystonic reactions complicated by psychotic phenomena.
- 2023most recentCombination of acetylcholinesterase inhibitors and NMDA receptor antagonists increases survival…
- 1.Acute dystonic reactions complicated by psychotic phenomena.
- 2.Effects of discontinuing anticholinergic treatment on movement disorders, cognition and psychopathology in patients with schizophrenia.
- 3.Physostigmine as treatment for severe CNS anticholinergic toxicity.
- 4.Anticholinergic medication for antipsychotic-induced tardive dyskinesia.
- 5.Atraumatic trismus induced by duloxetine: an uncommon presentation of acute dystonia.
- 6.Rivastigmine for the treatment of anticholinergic delirium following severe procyclidine intoxication.
- 7.Combination of acetylcholinesterase inhibitors and NMDA receptor antagonists increases survival rate in soman-poisoned mice.
- 8.Pretreatment of rhesus monkeys with transdermal patches containing physostigmine and procyclidine: implications of the delivery system for the potential application against VX nerve agent intoxication in humans.
- 9.Pretreatment and prophylaxis against nerve agent poisoning: Are undesirable behavioral side effects unavoidable?
9 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
What is procyclidine used for?
Mainly Parkinsonism and the drug-induced movement problems, especially dystonia, that antipsychotics can cause. It works by blocking muscarinic acetylcholine receptors.
Is procyclidine safe to take recreationally?
No. High doses cause a frightening anticholinergic delirium and a dangerous toxidrome, not a pleasant high, and overdose can be life-threatening.
Why does blocking acetylcholine help dystonia?
Antipsychotics block dopamine, tipping the dopamine-acetylcholine balance in motor circuits. Procyclidine blocks acetylcholine to help restore that balance and relieve the abnormal movements.
Adverse effects
- Dry mouth, blurred vision and constipation
- Urinary retention
- Confusion and memory problems, especially in the elderly
- Delirium and hallucinations at high doses