Question

Complete a concept map for cholinergic and anti-cholinergic drugs.

Classification-

Indications-

Nursing Considerations-

Contraindications-

Adverse Effects-

Protypes-

Answer 1

Cholinergic drugs are a wide variety of drugs used to work on the parasympathetic nervous system. These drugs work by enhancing the actions of acetylcholine, a neurotransmitter or chemical messenger in the brain. Effects of increased acetylcholine are considered the everyday work of the body, such as salivation, digestion, and skeletal muscle relaxation. An alternative way in which cholinergic drugs work is by blocking the enzyme that breaks down acetylcholine, which results in naturally occurring acetylcholine being able to work longer.

If cholinergic drugs work to enhance the parasympathetic nervous system, then anticholinergic drugs work to enhance the sympathetic nervous system. By blocking acetylcholine from sending chemical messages, anticholinergic drugs cause a decrease in parasympathetic effects. The results of blocking parasympathetic effects are referred to as anticholinergic effects, and they include: reduced smooth muscle spasm, reduced digestive tract movement, pupil dilation, decreased production of secretions, increased heart rate, airway relaxation, and reduced urine output.

An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. These agents inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, and many other parts of the body. Anticholinergics are divided into three categories in accordance with their specific targets in the central and peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.

Classification of cholinergic and anti-cholinergic drugs

Cholinergic drugs are classified as, direct acting (stimulate nicotinic and muscarinic receptor), indirect acting (work by inhibiting the enzyme cholinesterase).

Direct Acting Cholinergic Drug

Choline Ester - choline ester gave to secrete salivary, gastric and intestinal mucosa, to dilate pupils of the eye, to maintain normal heart rate and contraction of muscles. Choline esters are carbachol, bethanechol, acetylcholine, methacholine.

Cholinomimetic Drug – Cholinomimetic alkaloid is obtained through plants, act by stimulating the cholinergic receptor, similar to acetylcholine (reason choline-mimetic) Cholinomimetic alkaloid drug are pilocarpine, arecoline, muscarine, nicotine.

Indirect Acting Cholinergic Drug

Antic-Cholinesterase contains two sites, namely anionic and esteratic site. Reversible anticholinesterase bind and act on both sites while irreversible bind to the only esteratic site.

Reversible anticholinesterase –physostigmine, neostigmine, donepezil, rivastigmine, caffeine, pyridostigmine

Irreversible anticholinesterase – echothiophate, isoflurophate, malathion.

Anticholinergics are classified according to the receptors that are affected:

• Antimuscarinic agents operate on the muscarinic acetylcholine receptors. The majority of anticholinergic drugs are antimuscarinics.
• Antinicotinic agents operate on the nicotinic acetylcholine receptors. The majority of these are non-depolarising skeletal muscle relaxants for surgical use that are structurally related to curare. Several are depolarizing agents.

Indications for cholinergic and anti-cholinergic drugs.
The effects of activating cholinergic receptors include muscle contraction, heart rate deceleration, constriction of the iris (miosis) and of the lens, mucus secretion and broncho-constriction. Conversely, the effects of inactivating cholinergic receptors include muscle relaxation, heart rate acceleration, pupil dilation (mydriasis) and lens flattening (cyclopegia), dryness of the upper airway (of the respiratory system), inhibition of tear production, urine retention, mouth dryness, slowing down of mucociliary activity in the respiratory tract, constipation and muscle relaxation (skeletal muscle and smooth muscle).

Anticholinergic drugs are used to treat a variety of conditions:

• Dizziness (including vertigo and motion sickness-related symptoms)
• Extrapyramidal symptoms, a potential side-effect of antipsychotic medications.
• Gastrointestinal disorders (e.g., peptic ulcers, diarrhea, pylorospasm, diverticulitis, ulcerative colitis, nausea, and vomiting)
• Genitourinary disorders (e.g., cystitis, urethritis, and prostatitis)
• Insomnia, although usually only on a short-term basis
• Respiratory disorders (e.g., asthma, chronic bronchitis, and chronic obstructive pulmonary disease [COPD])
• Sinus bradycardia due to a hypersensitive vagus nerve

Anticholinergics generally have antisialagogue effects (decreasing saliva production), and most produce some level of sedation, both being advantageous in surgical procedures.

When a significant amount of an anticholinergic is taken into the body, a toxic reaction known as acute anticholinergic syndrome may result. This may happen accidentally or intentionally as a consequence of recreational drug use. Anticholinergic drugs are usually considered the least enjoyable by many recreational drug users, possibly because the side effects are so unpleasant and that they do not induce euphoria. There have, however, been a few reported cases of users experiencing what they described as "euphoria" from the use of an anticholinergic drug. In terms of recreational use, these drugs are commonly referred to as deliriants. The risk of addiction is low in the anticholinergic class, and recreational use is uncommon.

Nursing considerations for cholinergic
Medication should be taken as ordered, not abruptly stopped and dosage should be spread evenly apart. Overdosing can cause life-threatening problems. Patients should not adjust dosages unless directed by their physician. Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing. When cholinergic drugs are prescribed for Alzheimer's disease, be honest with patients that the drugs are for management of symptoms and not cure. Patients should notify their physician if they experience muscle weakness, abdominal cramps, diarrhea, difficulty breathing.

Monitor for therapeutic effects:

1. In postoperative patients for decreased GI peristalsis
2. Alleviated signs and symptoms of myasthenia gravis
3. In patients with urinary retention/ hypotonic bladder, urination should occur within 60 minutes of bethanechol adminitration

Assess for:

1. Allergies
2. Asthma
3. Presence of GI and GU obstructions
4. Peptic ulcer disease
5. Coronary artery disease

Nursing considerations for anti-cholinergic drugs
Here are important nursing considerations when administering anticholinergics:

Nursing Assessment
These are the important things the nurse should include in conducting assessment, history taking, and examination:

• Assess for contraindications or cautions (e.g., history of allergy to drug, GI obstruction, hepatorenal dysfunction, etc.) to avoid adverse effects.
• Establish baseline physical assessment to monitor for any potential adverse effects.
• Assess neurological status (e.g., orientation, affect, reflexes) to evaluate any CNS effects.
• Assess abdomen (e.g., bowel sounds, bowel and bladder patterns, urinary output) to evaluate for GI and GU adverse effects.
• Monitor laboratory test results to determine need for possible dose adjustments and to identify potential toxicity.

Nursing Diagnoses and Care Planning
Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

• Acute pain related to GI, CNS, GU, and CV effects
• Decreased cardiac output related to CV effects
• Impaired urinary elimination related to effects on the bladder
• Constipation related to GI effects

Adverse Effects of cholinergic and anti-cholinergic drugs.
Cholinergic drugs can help treat some disorders and ameliorate symptoms but they also have negative side effects. Most cholinergic drugs are anticholinergics, i.e. they reduce or block the effects of acetylcholine. For instance, the acetylcholine antagonists hexamethonium and trimethaphan, used to treat high blood pressure, can produce paralysis of the autonomic nervous system, producing effects such as blurred vision and inability to urinate. Anticholinergics in general can cause a raise in body temperature because they reduce the amount of sweating; they can also induce drowsiness, hallucinations, confusion, dry mouth, constipation, difficulty urinating and memory deficits. In older people, they can cause confusion, memory loss and cognitive decay. Mixing anticholinergics with alcohol have similar side effects as overdosing with anticholinergics, which include dizziness, fever, confusion, accelerated heart rate, trouble breathing, hallucinations, unconsciousness and even death. Caution is therefore warranted when taking cholinergic drugs.

The possible side effects of anticholinergics depend on the specific drug and dosage you take. Side effects can include: dry mouth, blurry vision, constipation, drowsiness, sedation, hallucinations, memory problems, trouble urinating, confusion, delirium, decreased sweating, decreased saliva.

Long-term use of anticholinergics, as well as use of these drugs in older people, has been linked with an increased risk of dementia. If you’ve been prescribed one of these drugs and have concerns about this risk, be sure to talk to your doctor.