Cholinergic Drugs

views updated May 18 2018

Cholinergic Drugs

Definition

Cholinergic drugs are medications that produce the same effects as the parasympathetic nervous system.

Purpose

Cholinergic drugs produce the same effects as acetylcholine. Acetylcholine is the most common neurohormone of the parasympathetic nervous system, the part of the peripheral nervous system responsible for the every day work of the body. While the sympathetic nervous system acts during times of excitation, the parasympathetic system deals with everyday activities such as salivation, digestion, and muscle relaxation.

The cholinergic drugs may be used in several ways. The cholinergic muscle stimulants are used to diagnose and treat myasthenia gravis, a disease that causes severe muscle weakness. This class of drugs includes ambenonium chloride (Mytelase), edrophonium chloride (Tensilon), neostigmine (Prostigmine), and piridogstimina (Mestinœn). These drugs are also widely used in surgery, both to reduce the risk of urinary retention, and to reverse the effects of the muscle relaxant drugs that are used in surgery.

Cholinergic drugs are also used in control of glaucoma, a disease that is caused by increased pressure inside the eye. The most common drugs used for this purpose are demecarium (Humorsol) and echthiophate (Phospholine iodide).

Description

Cholinergic drugs usually act in one of two ways. Some directly mimic the effect of acetylcholine, while others block the effects of acetylcholinesterase. Acetylcholinesterase is an enzyme that destroys naturally occurring acetylcholine. By blocking the enzyme, the naturally occurring acetylcholine has a longer action.

Recommended dosage

Cholinergic drugs are available only by prescription. They may be available as eye drops, capsules, tablets, or injections.

Precautions

Cholinergic drugs should be avoided when the patient has any sort of obstruction in the urinary or digestive tracts, such a a tumor, or severe inflammation which is causing blockage.

They should be used with caution in patients with asthma, epilepsy, slow heart beat, hyperthyroidism, or gastric ulcers.

The effects of the cholinergic drugs are to produce the same effects as stimulation of the parasympathetic nervous system. These effects include slowing of the heartbeat, increases in normal secretions including the digestive acids of the stomach, saliva and tears. For this reason, patients who already have a problem in one of these areas, such as a slow heartbeat or stomach ulcers, should use these drugs with great caution, since the medication will make their conditions worse.

Side effects

When used properly, cholinergic drugs will increase muscle strength in patients with myasthenia gravis. In eye drop form, they can reduce the intraoccular pressure in glaucoma.

KEY TERMS

Cholinergic Nerves that are stimulated by acetylcholine.

Glaucoma A disease of the eye marked by increased pressure within the eyeball that can result in damage to the optic disk and gradual loss of vision.

Myasthenia gravis A disease characterized by progressive weakness and exhaustibility of voluntary muscles without atrophy or sensory disturbance and caused by an autoimmune attack on acetylcholine receptors at neuromuscular junctions.

Parasympathetic nervous system The part of the nervous system that contains chiefly cholinergic fibers, that tends to induce secretion, to increase the tone and contractility of smooth muscle, and to slow the heart rate.

The possible adverse effects of cholinergic drugs are:

  • slow heart beat, possibly leading to cardiac arrest.
  • muscle weakness, muscle cramps, and muscle pain
  • convulsions
  • weak breathing, inability to breath
  • increased stomach acid and saliva
  • nausea and vomiting
  • izziness, drowsiness, and headache

Resources

PERIODICALS

"Classic Papers in Glaucoma." Archives of Ophthalmology March 2001.

"Congenital myasthenic syndromes: recent advances." Archives of Neurology February 1999.

Cholinergic Stimulants

views updated May 21 2018

Cholinergic stimulants

Definition

Cholinergic stimulants are a class of drugs that produce the same effects as those of the body's parasympathetic nervous system. Cholinergic drugs are used for a variety of purposes, including the treatment of myasthenia gravis and during anesthesia.

Purpose

The parasymapthetic nervous system is responsible for conserving and restoring energy in the body by regulating day-to-day functions such as digestion, sphincter muscle relaxation, salivation, and reducing heart rate and blood pressure. Nerve impulses in the parasympathetic nervous system are transmitted from one nerve junction to another with the help of acetylcholine, the most common neurotransmitter in the parasympathetic nervous system. Cholinergic drugs are drugs that affect the levels of acetylcholine at the nerve junction.

Cholinergic stimulants result in increased acetylcholine accumulation at the neuromuscular junction and prolong its effect. Cholinergic stimulant drugs are used in the diagnosis and treatment of myasthenia gravis, a disorder of nerve impulse transmission at the neuromuscular junction, resulting in severe muscle weakness. Cholinergic stimulants are also used in surgery to reduce urinary retention and to counteract the effects of some muscle relaxant medications given during anesthesia.

Description

Cholinergic stimulant drugs include edrophonium chloride, (brand name, Tensilon), neostigmine (Prostigmine), piridogstimina (Mestinon), and ambenonium chloride (Mytelase). Cholinergic stimulants are available in tablet, syrup, time-release tablet, and injectable forms.

Recommended dosage

Cholinergic stimulants are given in varying dosages according to the reason for use. In the treatment of myasthenia gravis, cholinergic stimulant dosages are tailored to the individual person. Patients are encouraged to keep a diary and record their response to each dose during the initial treatment period, as well as during periods of increased muscle weakness, stress, and other illness, as these conditions frequently require adjustments in dosage.

Precautions

Cholinergic stimulant drugs may not be suitable for persons with asthma, heart block or slow heart rate, epilepsy , hyperactive thyroid gland, bladder obstruction, gastrointestinal tract obstruction, or stomach ulcer. Patients should notify their physicians if they have any of these conditions before taking these drugs.

Side effects

The adverse effects of cholinergic stimulants include mostly rash and digestive system complaints, including queasiness, loose stools, nausea, vomiting, abdominal cramps, muscle pain , increased salivation, increase in stomach acid production, and diarrhea. Rare and potentially more serious side effects include reduced heart rate, possibly leading to cardiac arrest, and weak, shallow breathing.

Interactions

Certain antibiotics, especially neomycin, streptomycin, and kanamycin, can exacerbate the effects of some cholinergic stimulants. These antibiotics should be used with caution by people with myasthenia gravis.

Resources

BOOKS

Henderson, Ronald E. Attacking Myasthenia Gravis. Seattle Court Street Press, 2002.

Staff. The Official Patient's Sourcebook on Myasthenia Gravis: A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publications Group Int., 2002.

OTHER

"Myasthenia Gravis Fact Sheet." National Institute of Neurological Disorders and Stroke. February 11, 2004 (May 22, 2004). <http://www.ninds.nih.gov/health_and_medical/pubs/myasthenia_gravis.htm>.

"Tensilon Test." Medline Plus. National Library of Medicine. May 14, 2004 (May 22, 2004). <http://www.nlm.nih.gov/medlineplus/ency/article/003930.htm>.

ORGANIZATIONS

Myasthenia Gravis Foundation of America, Inc. 5841 Cedar Lake Road Suite 204, Minneapolis, MN 55416. (952) 545-9438 or (800) 541-5454; Fax: (952) 646-2028. [email protected]. <http://www.myasthenia.org>.

Adrienne Wilmoth Lerner

cholinergic

views updated May 23 2018

cholinergic (koh-lin-er-jik) adj.
1. describing or relating to nerve fibres that release acetylcholine as a neurotransmitter. c. receptor a receptor at which acetylcholine acts to pass on messages from cholinergic nerve fibres. c. urticaria see urticaria.

2. describing drugs that mimic the actions of acetylcholine (see parasympathomimetic). Compare adrenergic.

cholinergic

views updated May 18 2018

cholinergic Applied to nerve endings that secrete the neurotransmitter acetyl-choline into the synapse on the arrival of a nerve impulse. Cholinergic nerve endings are characteristic of the parasympathetic nerve system, although preganglionic synapses of the sympathetic nerve system also use acetylcholine.

cholinergic

views updated May 21 2018

cholinergic Describing a nerve fibre that either releases acetylcholine when stimulated or is itself stimulated by acetylcholine. Compare adrenergic.

cholinergic system

views updated Jun 11 2018

cholinergic system See NEUROTRANSMITTER.