Welcome to this video tutorial on cholinergic and anticholinergic drugs, and their effects
on the parasympathetic nervous system.
First we'll take a look at the divisions of the nervous system.
The nervous system is made up of the central nervous system, which is the brain and spinal cord,
and the peripheral nervous system, which are the neurons outside the brain and spinal cord.
The peripheral nervous system is then divided into the autonomic and somatic nervous system.
The autonomic system is further broken down into the sympathetic and parasympathetic nervous system.
The sympathetic, or SNS, and parasympathetic, or PSNS, are opposing systems.
The SNS is the fight or flight response, also known as arousing or adrenergic.
The PSNS is the rest and digest response, also known as calming or cholinergic.
When the sympathetic system excites an organ, the parasympathetic system inhibits it.
When the parasympathetic system excites an organ, the sympathetic system inhibits the action.
Our focus in this lesson is on how cholinergic and anticholinergic agents
affect the parasympathetic nervous system.
Cholinergic agents are drugs that stimulate the parasympathetic system.
They are also called parasympathomimetics.
They mimic the effects of the PSNS neurotransmitter.
Cholinergic agents copy the action of acetylcholine, a nerouttransmitter released from the nerve
endings that bind on the receptors of cell membranes of organs, tissues, and glands.
There are two types of cholinergic drugs, direct acting and indirect acting.
Direct acting cholinergic drugs bind to cholinergic receptors on specific efector organs,
stimulating the organ in a similar way as acetylcholine.
Their synthetic derivatives of choline, and they have a widespread systemic effect including
cardiac muscle, smooth muscle, execrate glands, and the eye.
Indirect acting cholinergic drugs inhibit the enzyme acetylcholinesterase,
resulting in more acetylcholine available at the receptors.
These drugs have the added cholinergic effect of improved skeletal muscle tone and strength.
Indirect acting cholinergic drugs for Alzheimer's disease are widely distributed.
Including to the central nervous system, thus improving cholinergic neurotransmission in the brain.
Now we'll look at the effects of cholinergic drugs on different systems of the body.
On the central nervous system, it causes and enhanced cognitive functions such as arousal,
attention, and memory encoding.
It's used for treatment of Alzheimer's disease and dementia.
On the eye, cholinergic drugs cause pupil constriction,
and are used for surgery and treatment of glaucoma.
On the G.I. system, it is a smooth muscle stimulant, used for post op abdominal distention or paralytic ileus.
On the GU system, it is a urinary bladder stimulant,
used for post op or postpartum urinary retention.
On the musculoskeletal system, the indirect acting cholinergic drugs improve muscle tone
and strength and are used for myasthenia gravis.
Too much cholinergic medication can lead to an overstimulation of the parasympathetic
nervous system, and lead to unwanted side effects.
The acronym SLUDGEM will help us remember the adverse effects of cholinergic drugs.
Salivation and sweating, lacrimation or crying, urination, defecation, GI cramps, emesis,
miosis, which is people constriction and muscle spasm.
Some adverse effects of cholinergic drugs also include decreased heart rate and blood pressure,
conduction abnormalities, leading to AV block and cardiac arrest,
headache, dizziness, convulsions,
increased bronchial secretions and bronchus spasms.
Overdosing can cause life threatening problems.
The antidote for cholinergic's is the anticholinergic drug, atropine.
Some specific examples of cholinergic drugs include direct acting, bethanechol or urecholine.
This drug increases the tone and motility of the bladder and GI tract.
It should cause urination within 60 minutes in a patient with urinary retention.
Pilocarping or pilocar is used to constrict pupils,
which decreases intraocular pressure, and is used for glaucoma.
Indirect acting cholinergic drugs include neostigmine, or prostigman,
which is given for the diagnosis and treatment and myasthenia gravis.
It causes skeletal muscle contractions.
Also, donepezil, or aricept, is used to treat mild to moderate Alzheimer's disease.
It increases acetylcholine in the brain, and helps increase or maintain memory or learning capabilities.
It manages the symptoms, but is not a cure.
Contraindications to using cholinergic drugs include asthma, peptic ulcer disease,
coronary artery disease, and hyperthyroidism.
Cholinergic drugs can exacerbate these conditions and should be avoided.
Anticholinergic agents are drugs that block the action of acetycholine on the parasympathetic nervous system.
These cholinergic blocking agents compete with acetylcholine, and block it at the receptors in the PSNS.
Acetylcholine is unable to bind to the receptor site and cause a cholinergic effect.
Most anticholinergic drugs interact with muscarinic cholinergic receptors in the brain,
secretory glands, heart, smooth muscle, and eye.
Now, we will look at the effects of anticholinergic drugs on various systems.
On the central nervous system, they decrease muscle rigidity and muscle tremors,
and are given for Parkinson's disease.
On the eye, anticholinergic drugs cause people dilation, and are used for exams or surgery.
On the salivary and lacrimal glands, they decrease secretion.
On the heart, they increase the heart rate.
On the respiratory tract, anticholinergic drugs decreased bronchial secretions,
dilate bronchial airways, and decrease airway resistance,
and are given for COPD and asthma.
On the GI system, they relax the smooth muscle tone of the GI tract,
decrease intestinal and gastric secretions, decrease motility and peristalsis.
They're used for peptic ulcer disease and irritable bowel.
On the GU system, they have an antispasmodic effect on smooth muscle,
and are used for overactive bladder and incarnates.
The effect of the drug may be therapeutic, but becomes an adverse reaction if it is severe,
or if the drug is given for another purpose, or if there is an overdose.
On the central nervous system, it can cause excessive stimulation such as tremor, restlessness, or confusion,
followed by excessive CNS depression, respiratory depression, and coma.
Anticholinergic can also cause tachycardia, constipation, dry mouth, urinary retention,
hot dry skin,
blurred vision from dilation of the pupil, so the patient may need to wear sunglasses.
The specific antidote for anticholinergic overdose is physostigmine salicylate or antilirium
an acetylcholinesterase inhibitor.
Some specific examples of anticholinergic drugs include belladonna alkaloids and derivatives.
Such as atropine, which is a naturally occurring balladonna alkaloid given for bradyarrhythmias.
It produces a stimulant effect and is also given as an antidote for cholinergic poisoning.
Another example is ipratropuim, or atrovent which causes broncodilation and is used in asthma and COPD.
Also, scopolamine is given for motion sickness and nausea and vomiting.
Centrally acting anticholinergic drugs used in Parkinson's disease
include benztropine or cogentin
and is also used to treat dystonic reactions caused by antipsychotic drugs.
Urinary antispasmodics are given for overactive bladder and include oxybutynin or ditropan,
solifenacin succinate or VESIcare,
and tolterodine or detrol and detrol L.A.
Contraindications to using anticholinergic drugs
include any condition characterized by symptoms that would be aggravated by the drugs.
Such as myasthenia gravis, glaucoma, or MI.
Let's go over a quick review of what we've been talking about.
The autonomic nervous system is broken down into the sympathetic and parasympathetic nervous system.
The sympathetic nervous system being our fight or flight response, or adrenergic,
and the parasympathetic nervous system is our rest and digest response, or cholinergic
which has been our focus for this lesson.
Cholinergic drugs stimulate the parasympathetic nervous system by copying the action of acetycholine.
Cholinergic drugs are given for Alzheimer's disease, glaucoma,
paralytic Illius, urinary retention, and myastenia gravis.
Anticholinergic drugs block the action of acetycholine on the parasympathetic nervous system.
They are given for Parkinson's disease, asthma, COPD, and overactive bladder.
Thank you for watching this video tutorial on cholinergic and anticholinergic drugs and
their effects on the parasympathetic nervous system.
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