Physostigmine is a medication used primarily to treat glaucoma and to reverse the effects of certain types of anesthesia. It works by inhibiting the enzyme acetylcholinesterase, which breaks down the neurotransmitter acetylcholine. This leads to increased levels of acetylcholine in the body, enhancing nerve signal transmission. Additionally, physostigmine is sometimes used in cases of anticholinergic toxicity, where it can help counteract the effects of drugs that block acetylcholine receptors. While effective, it must be used with caution due to potential side effects, including muscle twitching and increased salivation.