Neostigmine is a medication primarily used to treat myasthenia gravis, a condition that causes muscle weakness. It works by inhibiting the enzyme acetylcholinesterase, which breaks down the neurotransmitter acetylcholine. By preventing this breakdown, neostigmine increases the levels of acetylcholine at the neuromuscular junction, enhancing communication between nerves and muscles. Additionally, neostigmine is sometimes used to reverse the effects of certain muscle relaxants used during surgery. It can help restore normal muscle function after anesthesia. The medication is typically administered through injection or orally, depending on the patient's needs and the specific condition being treated.