This document discusses two types of cholinergic drugs - direct acting cholinergic agonists and indirect acting cholinesterase inhibitors. It provides examples of natural and synthetic alkaloids that act as direct agonists, such as bethanechol and pilocarpine. It also lists several classes of cholinesterase inhibitors, including carbamates, organophosphates, and carbonates like physostigmine and donepezil, along with examples of drugs within each class.