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What is the primary action of cholinergic drugs?
What is the primary action of cholinergic drugs?
Which of the following is NOT classified as a cholinergic agonist?
Which of the following is NOT classified as a cholinergic agonist?
What is the mechanism by which anticholinesterase drugs function?
What is the mechanism by which anticholinesterase drugs function?
Which drug is primarily used for treating glaucoma?
Which drug is primarily used for treating glaucoma?
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What are the pharmacotherapeutic uses of cholinergic agonists?
What are the pharmacotherapeutic uses of cholinergic agonists?
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Which of the following statements about anticholinesterase drugs is true?
Which of the following statements about anticholinesterase drugs is true?
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What is a common side effect when using cholinergic drugs?
What is a common side effect when using cholinergic drugs?
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What can cholinergic blocking drugs be used to treat?
What can cholinergic blocking drugs be used to treat?
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Which of the following cholinergic blocking drugs is used preoperatively to reduce secretions?
Which of the following cholinergic blocking drugs is used preoperatively to reduce secretions?
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Which anticholinesterase drug is primarily used for diagnosing myasthenia gravis?
Which anticholinesterase drug is primarily used for diagnosing myasthenia gravis?
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Which effect is NOT associated with cholinergic agonists?
Which effect is NOT associated with cholinergic agonists?
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Which of the following describes the absorption of belladonna alkaloids?
Which of the following describes the absorption of belladonna alkaloids?
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What are common side effects associated with long-term use of anticholinergics?
What are common side effects associated with long-term use of anticholinergics?
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Which of the following actions do cholinergic blocking drugs have depending on the dosage?
Which of the following actions do cholinergic blocking drugs have depending on the dosage?
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Which of the following is a nursing responsibility for patients taking anticholinesterase drugs?
Which of the following is a nursing responsibility for patients taking anticholinesterase drugs?
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Which type of adrenergic drugs directly act on the organ or tissue innervated by the sympathetic nervous system?
Which type of adrenergic drugs directly act on the organ or tissue innervated by the sympathetic nervous system?
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Which of the following drugs primarily exhibits dopaminergic activity?
Which of the following drugs primarily exhibits dopaminergic activity?
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Which action is primarily caused by the activation of alpha receptors?
Which action is primarily caused by the activation of alpha receptors?
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What is a common use for beta 2 adrenergic receptor stimulants?
What is a common use for beta 2 adrenergic receptor stimulants?
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Which pharmacokinetic characteristic is true about catecholamines?
Which pharmacokinetic characteristic is true about catecholamines?
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How do alpha-adrenergic blockers primarily affect blood vessels?
How do alpha-adrenergic blockers primarily affect blood vessels?
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Which drug class is primarily used to disrupt the sympathetic nervous system's function?
Which drug class is primarily used to disrupt the sympathetic nervous system's function?
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Which of the following non-catecholamines is used for nasal decongestion?
Which of the following non-catecholamines is used for nasal decongestion?
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What is the primary action of beta-blockers?
What is the primary action of beta-blockers?
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How do indirect-acting adrenergic drugs function?
How do indirect-acting adrenergic drugs function?
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What effect do non-catecholamines primarily have on smooth muscle?
What effect do non-catecholamines primarily have on smooth muscle?
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In which situation are alpha-adrenergic blockers indicated?
In which situation are alpha-adrenergic blockers indicated?
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Which route of administration generally provides faster absorption for alpha-adrenergic blockers?
Which route of administration generally provides faster absorption for alpha-adrenergic blockers?
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What is one potential therapeutic use of dopamine?
What is one potential therapeutic use of dopamine?
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Study Notes
Cholinergic Drugs
- Cholinergic drugs are agonists or stimulants that promote the action of acetylcholine, the neurotransmitter.
- They're also called parasympathomimetic drugs because they mimic the parasympathetic nervous system's effects.
- Two major classes of cholinergic drugs are:
- Cholinergic agonists: Directly stimulate cholinergic receptors, mimicking acetylcholine's action. Examples include acetylcholine, bethanecol, carbachol, and pilocarpine.
- Anticholinesterase: Inhibit acetylcholine's breakdown at cholinergic receptor sites. Examples include ambenonium, donepezil, edrophonium, neostigmine, physostigmine salicylate, pyridostigmine, and tacrine for reversible effects, and echothiophate for irreversible effects.
Cholinergic Agonists: Pharmacokinetics
- Actions and metabolism vary widely.
- Poorly penetrate the central nervous system (CNS), primarily working peripherally.
- Rapidly destroyed in the body making intravenous (IV) or intramuscular (IM) administration risky.
- Commonly administered topically (eye drops), orally, or via subcutaneous (SQ) injections.
- Metabolized by cholinesterases at muscarinic and nicotinic receptor sites, in plasma, and in the liver.
- Excreted by the kidneys.
Cholinergic Agonists: Pharmacodynamics
- Mimic acetylcholine's action on neurons in target organs.
- Stimulate muscle and produce:
- Salivation
- Bradycardia
- Vasodilation
- Bronchoconstriction
- Increased activity of the gastrointestinal (GI) tract
- Increased tone and contraction of the bladder muscles
- Constriction of the pupils
Cholinergic Agonists: Pharmacotherapeutics
- Treat atonic bladder conditions and postoperative/postpartum urine retention.
- Treat GI disorders like postoperative abdominal distention and GI atony.
- Reduce eye pressure in patients with glaucoma and during eye surgery.
- Treat salivary gland hypofunction caused by radiation therapy and Sjogren’s syndrome.
### Anticholinesterase Drugs: Pharmacokinetics
- Most are easily absorbed via the gastrointestinal tract (GIT), SQ, and mucous membranes.
- Neostigmine requires a higher dose compared to others.
- Only physostigmine can cross the blood-brain barrier (BBB).
- Donepezil is highly protein-bound, while tacrine is about 55% bound to plasma proteins.
- Most are metabolized by plasma enzymes and excreted in the urine.
- Donepezil and tacrine are metabolized in the liver.
Anticholinesterase Drugs: Pharmacodynamics
- Promote acetylcholine's action at receptor sites.
- Reversible anticholinesterases block acetylcholine breakdown for minutes to hours, while irreversible effects last for days or weeks.
Anticholinesterase Drugs: Pharmacotherapeutics
- Reduce eye pressure in glaucoma and during eye surgery.
- Increase bladder tone.
- Improve GI tone and peristalsis in patients with reduced motility and paralytic ileus.
- Promote muscular contraction in myasthenia gravis patients.
- Diagnose myasthenia gravis using neostigmine and edrophonium.
- Act as an antidote to cholinergic blocking drugs (anticholinergics), tricyclic antidepressants (TCAs), belladonna alkaloids, and narcotics.
- Treat mild to moderate Alzheimer's type dementia.
Anticholinesterase Drugs: Nursing Responsibilities
- Emphasize compliance with prescribed doses.
- Report side effects like dizziness or decreased heart rate.
- Rise slowly from a lying position to prevent dizziness.
- Maintain effective oral hygiene.
- Report signs and symptoms of respiratory distress.
Cholinergic Blocking Drugs
- Include major drugs like atropine, belladonna, homatropine, hyoscyamine sulfate, and scopolamine hydrobromide.
- Synthetic derivatives or quaternary ammonium drugs include:
- Clidinium, glycopyrrolate, and propantheline
- Tertiary amines include:
- Benztropine, dicyclomine, ethopropazine, oxybutynin, and trihexyphenidyl.
Cholinergic Blocking Drugs: Pharmacokinetics
- Belladonna alkaloids are absorbed from the eyes, GIT, mucous membranes, and skin.
- Quaternary and tertiary amines are primarily absorbed through the GIT.
- Belladonna alkaloids have broader distribution compared to quaternary amines.
- Belladonna alkaloids have low to moderate protein binding, are metabolized in the liver, and excreted by the kidneys as unchanged drugs and metabolites.
Cholinergic Blocking Drugs: Pharmacodynamics
- Can have paradoxical effects, stimulating or depressing, depending on the dosage and condition.
- Effects vary depending on the targeted organ.
Cholinergic Blocking Drugs: Pharmacotherapeutics
- Treat spastic or hyperactive conditions of the GI and urinary tracts.
- Belladonna alkaloids are used with morphine for biliary colic.
- Injectables are used pre-endoscopy and pre-sigmoidoscopy to relax GI smooth muscle.
- Atropine is used pre-surgery to reduce oral and gastric secretions, and in the respiratory system, to prevent vagal nerve stimulation-induced heart rate drops during anesthesia.
Cholinergic Blocking Drugs: Pharmacotherapeutics (Continued)
- Belladonna alkaloids impact the brain:
- Scopolamine combined with pain medications like morphine or meperidine causes drowsiness and amnesia during surgery and is also used to treat motion sickness.
- Cholinergic blockers treat extrapyramidal (Parkinson-like) symptoms caused by drugs and in Parkinson's disease.
- Atropine is the drug of choice (DOC) to treat symptomatic sinus bradycardia and arrhythmias caused by anesthetics.
- Atropine is a cycloplegic, acting as a mydriatic.
Cholinergic Blocking Drugs: Nursing Responsibilities
- Inform patients about common side effects like dry mouth, decreased urination, and constipation due to long-term use.
- Increase fluid intake to counter constipation.
- Offer hard candies, ice chips, or chewing gum to relieve dry mouth.
- Encourage patients to urinate before taking anticholinergics.
Adrenergic Drugs
- Also known as sympathomimetic drugs.
- Classified based on chemical structure:
- Catecholamines (both naturally occurring and synthetic)
- Non-catecholamines
- Classified based on action:
- Direct-acting: Act directly on organs or tissues innervated by the sympathetic nervous system (SNS).
- Indirect-acting: Trigger the release of a neurotransmitter, usually norepinephrine.
- Dual-acting: Have both direct and indirect actions.
Adrenergic Drugs (Continued)
- Affect alpha-beta adrenergic receptors, beta-adrenergic receptors, and dopamine receptors.
- Most stimulate alpha and beta receptors, mimicking the action of norepinephrine or epinephrine.
- Dopamine drugs primarily act on dopamine-stimulated sympathetic nervous system receptors.
Catecholamines
- Stimulate the nervous system, constrict peripheral blood vessels, increase heart rate, and dilate bronchi.
- Common examples include dobutamine, dopamine, epinephrine (bitartrate and hydrochloride), norepinephrine, isoproterenol hydrochloride, and sulfate.
Catecholamines: Pharmacokinetics
- Cannot be taken orally.
- SQ absorption is slowed due to vasoconstriction.
- IM absorption is faster due to less constriction.
- Widely distributed, metabolized primarily in the liver, but also inactivated in the GIT, lungs, kidneys, plasma, and other tissues.
- Primarily excreted in the urine.
Catecholamines: Pharmacodynamics
- Primarily direct-acting.
- When combined with alpha or beta receptors, they can cause excitatory or inhibitory effects.
- Alpha receptor activation is excitatory except for intestinal relaxation.
- Beta receptor activation is mostly inhibitory, except for heart cells.
- They are potent inotropes.
Catecholamines: Pharmacotherapeutics
- Effects depend on the activated receptor activity.
- Norepinephrine has mostly pure alpha activity.
- Dobutamine and isoproterenol have only beta-related therapeutic uses.
- Epinephrine stimulates alpha and beta receptors.
- Dopamine primarily exhibits dopaminergic activity.
- Drugs stimulating alpha receptors treat low blood pressure caused by relaxed blood vessel muscle tone and blood loss.
Catecholamines: Pharmacotherapeutics (Continued)
- Drugs stimulating beta 1 receptors treat:
- Bradycardia, heart block, low cardiac output.
- Drugs with beta 2 activity treat:
- Acute and chronic bronchial asthma, pulmonary emphysema, bronchitis, acute hypersensitivity reactions to drugs.
- Dopamine in low doses improves renal blood flow by dilating renal blood vessels.
Non-catecholamines: Effects
- Locally or systemically constrict blood vessels (mephentermine, metaraminol, methoxamine, and phenylephrine).
- Cause nasal and eye decongestion and bronchiole dilation (albuterol, ephedrine, isoetharine hydrochloride, isoetharine mesylate, metaproterenol, and terbutaline).
- Relax smooth muscle (ritodrine hydrochloride and terbutaline).
Non-catecholamines: Pharmacokinetics
- Absorption depends on administration route.
- Inhaled drugs (albuterol) are absorbed from the bronchi.
- Oral drugs are well absorbed from the GIT and distributed widely in body fluids and tissues.
- Some (ephedrine) cross the BBB and are found in high concentrations in the brain and cerebrospinal fluid (CSF).
- Primarily metabolized in the liver but also in the lungs, GIT, and other tissues.
- Excreted mainly in the urine.
Non-catecholamines: Pharmacodynamics
- Direct-acting non-catecholamines:
- Stimulate alpha activity: methoxamine and phenylephrine
- Stimulate Beta 2 activity: albuterol, isoetharine, metaproterenol, ritodrine, and terbutaline.
- Indirect-acting non-catecholamines:
- Phenylpropanolamine
- Dual-acting non-catecholamines:
- Ephedrine, mephentermine, and metaraminol.
Non-catecholamines: Pharmacotherapeutics
- Stimulate the SNS, producing various effects.
- Metaraminol causes vasoconstriction and is used to treat hypotension in severe shock.
- Ritodrine prevents preterm labor.
Adrenergic Blocking Drugs
- Also known as sympatholytic drugs.
- Disrupt the SNS function by blocking impulse transmission at adrenergic neurons or receptor sites.
- Interrupt sympathomimetic drug actions or reduce available norepinephrine.
- Classified as alpha-adrenergic blockers or beta-adrenergic blockers.
Alpha-Adrenergic Blockers
- Interrupt catecholamines epinephrine and norepinephrine actions at alpha receptors, causing:
- Relaxation of blood vessel smooth muscle
- Increased vasodilation
- Decreased blood pressure
- Examples include ergoloid mesylates, ergotamine, phenoxybenzamine, phentolamine, and prazosin.
Alpha-Adrenergic Blockers: Pharmacokinetics
- Action is not well understood.
- Erratic oral absorption, more rapid and complete sublingual absorption.
- Varying onset, peak, and duration.
Alpha-Adrenergic Blockers: Pharmacodynamics
- Interfere or block norepinephrine synthesis, storage, release, and reuptake by neurons.
- Antagonize epinephrine, norepinephrine, or adrenergic drugs at alpha receptor sites.
- Occupy alpha receptor sites on blood vessel smooth muscle, preventing catecholamines from stimulating them.
Alpha-Adrenergic Blockers: Pharmacotherapeutics
- Increase local blood flow to the skin and other organs, reducing blood pressure.
- Indications include:
- Hypertension
- Peripheral vascular disorders like Raynaud’s disease, acrocyanosis, and frostbite
- Pheochromocytoma
Beta-Adrenergic Blockers
- Most widely used adrenergic blockers.
- Prevent SNS stimulation by inhibiting catecholamine action at beta-adrenergic receptor sites.
- Commonly called beta-blockers.
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Description
This quiz covers the essential aspects of cholinergic drugs, including their classifications, mechanisms of action, and pharmacokinetics. Understand the role of cholinergic agonists and anticholinesterase medications in the body. Test your knowledge on how these drugs affect the neurotransmitter acetylcholine and their applications.
