Neostigmine, sold under the brand name Bloxiverz, among others, is a medication used to treat myasthenia gravis, Ogilvie syndrome, and urinary retention without the presence of a blockage. It is also used in anaesthesia to end the effects of non-depolarising neuromuscular blocking medication. It is given by injection either into a vein, muscle, or under the skin. After injection effects are generally greatest within 30 minutes and last up to 4 hours. Common side effects include nausea, increased saliva, crampy abdominal pain, and slow heart rate. More severe side effects include low blood pressure, weakness, and allergic reactions. It is unclear if use in pregnancy is safe for the baby. Neostigmine is in the cholinergic family of medications. It works by blocking the action of acetylcholinesterase and therefore increases the levels of acetylcholine. Neostigmine was patented in 1931. It is on the World Health Organization's List of Essential Medicines. The term is from Greek neos, meaning "new", and "-stigmine", in reference to its parent molecule, physostigmine, on which it is based. Medical uses It is used to improve muscle tone in people with myasthenia gravis, and also to reverse the effects of non-depolarizing muscle relaxants such as rocuronium and vecuronium at the end of an operation. Another indication for use is the conservative management of acute colonic pseudo-obstruction, or Ogilvie's syndrome, in which patients get massive colonic dilatation in the absence of a true mechanical obstruction. Neostigmine is often prescribed for underactive urinary bladder. Hospitals sometimes administer a solution containing neostigmine intravenously to delay the effects of envenomation through snakebite. Some promising research results have also been reported for administering the drug nasally as a snakebite treatment. Side effects Neostigmine has a wide variety of side-effects due to its action that increases acetylcholine (ACh) binding muscarinic receptors on exocrine glandular cells throughout the body, cardiac muscle cells, and smooth muscle cells. These effects include: salivation, lacrimation, diarrhea, bradycardia, and bronchoconstriction. Gastrointestinal symptoms occur earliest. For this reason, it is usually given along with an anti-cholinergic drug such as atropine or glycopyrrolate which act only on muscarinic receptors while permitting neostigmine action at nicotinic receptors. Neostigmine can also induce generic ocular side effects including: headache, brow pain, blurred vision, phacodonesis, pericorneal injection, congestive iritis, various allergic reactions, and rarely, retinal detachment. Pharmacology Acetylcholine is metabolized by the enzyme acetylcholinesterase that cleaves acetylcholine in the neuromuscular junction into acetate and choline. Neostigmine