Cholinergic drugs
Actions and uses

Cholinergic drugs are medications that produce the same effects as the parasympathetic nervous system, especially imitating acetylcholine. Acetylcholine is the most common neurohormone of the parasympathetic nervous system, it is responsible for the everyday 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. 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. 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. This inhibition permits the buildup of acetylcholine and results in more intensive and prolonged activation of the receptor site. The effects of cholinergic stimulation include: vasodilatation of blood vessels; slower heart rate; constriction of bronchioles and increased secretion of mucus in the respiratory tract; intestinal cramps; secretion of salvia; sweat and tears; and constriction of eye pupils.

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

Nursing Implications

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



Anticholinergic Drugs
Actions and uses

Anticholinergics are a class of medications that restrain parasympathetic nerve impulses by selectively blocking the binding sites of acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movements of smooth muscles present in the body.
Anticholinergics are divided into three categories in accordance with their specific targets in the central and/or peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.

Side effects and Adverse effects
Antimuscarinic agent side effects are
delirium, hallucinations, coma, circulatory and respiratory collapse, rapid heart rate, dilation of pupils and blurred vision, restlessness, burning pain in the throat, marked mouth dryness, and urinary retention.
Side effects of ganglionic blockers include paralysis of gastrointestinal movements, nausea, gastritis, urinary retention, and blurred vision.
Neuromuscular blockers effects may include failure in breathing due to paralysis of the diaphragm, low blood pressure, tachycardia, post-surgery muscle pain, high fever.

Nursing Implications
Monitor patients vital signs and urine output carefully. Tell patients to only take drug as prescribed, and advise them not to drive until they know the sides effects the drug can give them. Patient should drink plenty of fluids to prevent constipation, and to report rash or skin irritation.

Sources
Ophardt, C (2003). Cholinergic Drugs I. Retrieved July 1, 2009, from Virtual Chembook Web site: http://www.elmhurst.edu/~chm/vchembook/662cholinergic.html

Cholinergic Drugs. (n.d.) Gale Encyclopedia of Medicine. (2008). Retrieved July 1 2009 from http://medical-dictionary.thefreedictionary.com/Cholinergic+Drugs