Benzatropine is an anticholinergic drug used in patients to reduce the side effects of antipsychotic treatment, such as parkinsonism and dystonia. Benzatropine is also a second-line drug for the treatment of Parkinson's disease. It improves tremor, but not rigidity and bradykinesia. Benzatropine is also sometimes used for the treatment of dystonia, a rare disorder that causes abnormal muscle contraction, resulting in twisting postures of limbs, trunk, or face.
While some studies suggest that use of anticholinergics increases the risk of tardive dyskinesia (a long-term side effect of antipsychotics), other studies have found no association between anticholinergic exposure and risk of developing tardive dyskinesia, although symptoms may be worsened.
Benzatropine is a centrally acting anticholinergic/antihistamine agent resulting from the combination of the tropine portion of the atropine molecule and the benzohydryl portion of diphenhydramine. Animal studies have indicated that anticholinergic activity of benzatropine is approximately one-half that of atropine, while its antihistamine activity approaches that of mepyramine. Its anticholinergic effects have been established as therapeutically significant in the management of Parkinsonism. Benzatropine antagonizes the effect of acetylcholine, decreasing the imbalance between the neurotransmitters acetylcholine and dopamine, which may improve the symptoms of early Parkinson's disease.
Benzatropine is also a dopamine reuptake inhibitor, which makes it useful for people with extrapyramidal symptoms who take antipsychotics.
Benzatropine has been also identified, by a high throughput screening approach, as a potent differentiating agent for oligodendrocytes, possibly working through M1 and M3muscarinic receptors. In preclinical models for multiple sclerosis, benzatropine decreased clinical symptoms and enhanced re-myelination (Deshmukh et al., Nature 2013).
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