DRUG CLASS AND MECHANISM: Benztropine is an oral and injectable synthetic medication. It is structurally similar to atropine (AtroPen) and diphenhydramine (Benadryl). Benztropine has anticholinergic effects. Anticholinergic drugs block the action of acetylcholine, a neurotransmitter (chemical) that nerves use to communicate with other nerves. In Parkinson's there is an imbalance between levels of dopamine and acetylcholine neurotransmitters.