Neostigmine Health Dictionary

Any compound that inhibits the activity of CHOLINESTERASE, thus permitting ACETYLCHOLINE to continue its function of transmitting nerve impulses. Drugs with anticholinesterase properties include distigmine, NEOSTIGMINE and PHYSOSTIGMINE.... anticholinesterase

These drugs produce partial or complete paralysis of skeletal muscle (see under MUSCLE – Structure of muscle). Drugs in clinical use are all reversible and are used to help insert a breathing tube into the TRACHEA (endotracheal tube) during general ANAESTHESIA and ARTIFICIAL VENTILATION OF THE LUNGS. They may be broadly divided into depolarising and nondepolarising muscle relaxants. Depolarising muscle relaxants act by binding to acetylcholine receptors at the motor end-plate where nerves are attached to muscle cells, and producing a more prolonged depolarisation than acetylcholine, which results in initial muscle fasciculation (overactivity) and then ?accid paralysis of the muscle. The only commonly used depolarising drug is succinylcholine which has a rapid onset of action and lasts approximately three minutes. Non-depolarising muscle relaxants bind to the acetylcholine receptors, preventing acetylcholine from gaining access to them. They have a slower onset time and longer duration than depolarisers, although this varies widely between di?erent drugs. They are competitive antagonists and they may be reversed by increasing the concentration of acetylcholine at the motor end-plate using an anticholinesterase agent such as neostigmine. These drugs are broken down in the liver and excreted through the kidney, and their action will be prolonged in liver and renal failure. Other uses include the relief of skeletal muscle spasms in TETANUS, PARKINSONISM and spastic disorders. The drugs dantrolene and diazepam are used in these circumstances.... muscle relaxants

A serious disorder in which the chief symptoms are muscular weakness and a special tendency for fatigue to come on rapidly when e?orts are made. The prevalence is around 1 in 30,000. Two-thirds of the patients are women, in whom it develops in early adult life. In men it tends to develop later in life.

It is a classical example of an autoimmune disease (see AUTOIMMUNITY). The body develops ANTIBODIES which interfere with the working of the nerve endings in muscle that are acted on by ACETYLCHOLINE. It is acetylcholine that transmits the nerve impulses to muscles: if this transmission cannot be e?ected, as in myasthenia gravis, then the muscles are unable to contract. Not only the voluntary muscles, but those connected with the acts of swallowing, breathing, and the like, become progressively weaker. Rest and avoidance of undue exertion are necessary, and regular doses of neostigmine bromide, or pyridostigmine, at intervals enable the muscles to be used and in some cases have a curative e?ect. These drugs act by inhibiting the action of cholinesterase – an ENZYME produced in the body which destroys any excess of acetylcholine. In this way they increase the amount of available acetylcholine which compensates for the deleterious e?ect of antibodies on the nerve endings.

The THYMUS GLAND plays the major part in the cause of myasthenia gravis, possibly by being the source of the original acetylcholine receptors to which the antibodies are being formed. Thymectomy (removal of the thymus) is often used in the management of patients with myasthenia gravis. The incidence of remission following thymectomy increases with the number of years after the operation. Complete remission or substantial improvement can be expected in 80 per cent of patients.

The other important aspect in the management of patients with myasthenia gravis is IMMUNOSUPPRESSION. Drugs are now available that suppress antibody production and so reduce the concentration of antibodies to the acetylcholine receptor. The problem is that they not only suppress abnormal antibody production, but also suppress normal antibody production. The main groups of immunosuppressive drugs used in myasthenia gravis are the CORTICOSTEROIDS and AZATHIOPRINE. Improvement following steroids may take several weeks and an initial deterioration is often found during the ?rst week or ten days of treatment. Azathioprine is also e?ective in producing clinical improvement and reducing the antibodies to acetylcholine receptors. These effects occur more slowly than with steroids, and the mean time for an azathioprine remission is nine months.

The Myasthenia Gravis Association, which provides advice and help to sufferers, was created and is supported by myasthenics, their families and friends.... myasthenia gravis

n. an *antimuscarinic drug that occurs in deadly nightshade (see belladonna). Because it dilates the pupil and paralyses the ciliary muscle (see cycloplegia; mydriatic), atropine is used in eye examinations and the treatment of anterior *uveitis. It is also administered by injection to treat a slow heart rate (*bradycardia) associated with arrhythmias or, with *neostigmine, to reverse the action of muscle relaxants used during surgery. It is sometimes used to treat gut spasms and – rarely – for *premedication. Common side-effects include dryness of the throat, thirst, impaired vision, and increased heart rate.... atropine

(Ogilvie’s syndrome) n. functional impairment of intestinal peristalsis without evidence of an obstructing lesion (acute colonic pseudo-obstruction). It presents with vomiting, marked abdominal distension, and constipation. It commonly occurs in hospitalized patients with serious illness, probably caused by abnormalities in colonic autonomic regulation and often associated with trauma, sepsis, the postoperative state following abdominal, pelvic, or orthopaedic surgery, or cardiac dysfunction (heart failure, myocardial infarction). Management is usually conservative and involves treatment of the underlying condition, the ‘drip and suck’ approach (see ileus), decompression of the colon, and prokinetic agents (such as neostigmine). Surgery is required when the conservative approach fails or in cases of perforation.... pseudo-obstruction