In Parkinson’s disease, there is a deficiency of a neurotransmitter called dopamine in the brain. Normally there is a balance between the activity of dopamine and the activity of acetylcholine in the brain. However, in Parkinson’s disease, the deficiency of dopamine causes overactivity of acetylcholine. This causes some of the symptoms of the disease. Procyclidine works by blocking the receptors that acetylcholine acts on. This reduces the activity of the acetylcholine, and helps restore the balance of acetylcholine and dopamine in the brain. In this way, procyclidine helps control some of the symptoms of Parkinson’s disease. It is most effective at reducing the tremor and rigidity associated with the disease, but it has little effect on the slow movements (bradykinesia).