Pharmacology of Muscarinic Receptor Antagonists
42 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is one major contraindication for the use of pilocarpine?

  • Patients with increased salivation
  • Patients experiencing bradycardia
  • Patients with retinal detachment (correct)
  • Patients with asthma

What type of receptors do ipratropium and tiotropium selectively block?

  • Nicotinic receptors
  • M1 muscarinic receptors
  • M2 muscarinic receptors
  • M3 muscarinic receptors (correct)

Which of the following is a systemic side effect of pilocarpine?

  • Blurred vision
  • Eye discomfort
  • Miosis
  • Increased salivation (correct)

What is the primary action of muscarinic receptor antagonists like ipratropium?

<p>Relax smooth muscle and block mucus secretion (A)</p> Signup and view all the answers

Which of the following side effects is NOT associated with pilocarpine?

<p>Bronchodilation (A)</p> Signup and view all the answers

What is the primary action of muscarinic receptor antagonists like Hyoscyamine?

<p>Blocks the action of acetylcholine at muscarinic receptors (B)</p> Signup and view all the answers

Which of the following conditions is a contraindication for using muscarinic receptor antagonists?

<p>Glaucoma (C)</p> Signup and view all the answers

What side effect is commonly associated with muscarinic receptor antagonists?

<p>Dry mouth (A)</p> Signup and view all the answers

What is the recommended oral dosage of Hyoscyamine for dogs with gastrointestinal disorders?

<p>0.1-0.2 mg/kg (B)</p> Signup and view all the answers

Which muscarinic receptor antagonist is used specifically for overactive bladder syndrome?

<p>Oxybutynin (A)</p> Signup and view all the answers

Which effect arises from the action of muscarinic receptor antagonists on the parasympathetic nervous system?

<p>Reduced smooth muscle contraction (A)</p> Signup and view all the answers

What is the origin of Hyoscyamine?

<p>Naturally occurring tropane alkaloid from specific plants (D)</p> Signup and view all the answers

Which side effect is NOT typically associated with muscarinic receptor antagonists?

<p>Decreased heart rate (B)</p> Signup and view all the answers

What is the primary action of Trihexyphenidyl?

<p>Inhibits M1 muscarinic receptors in the brain (A)</p> Signup and view all the answers

Which of the following is a common side effect of both Trihexyphenidyl and Bethanechol?

<p>Dry mouth (A)</p> Signup and view all the answers

Which muscarinic receptor subtype is primarily involved in heart rate regulation?

<p>M2 (D)</p> Signup and view all the answers

What is a contraindication for using Trihexyphenidyl?

<p>Bowel or urinary obstruction (D)</p> Signup and view all the answers

What effect does Bethanechol primarily produce?

<p>Promote urination (D)</p> Signup and view all the answers

Which of the following statements about Carbachol is true?

<p>It is resistant to enzymatic degradation (B)</p> Signup and view all the answers

What is an indication for using Bethanechol in small animals?

<p>Stimulating bladder contractions (D)</p> Signup and view all the answers

What is the primary function of Vesamicol?

<p>Inhibiting the vesicular acetylcholine transporter to reduce acetylcholine availability (C)</p> Signup and view all the answers

Which of the following side effects is specific to anticholinergic drugs like Trihexyphenidyl?

<p>Blurred vision (C), Tachycardia (D)</p> Signup and view all the answers

In which condition is Physostigmine primarily used to improve muscle function?

<p>Myasthenia Gravis (D)</p> Signup and view all the answers

What is a clinical application of Physostigmine outside of muscle function improvement?

<p>Topical treatment for Glaucoma (D)</p> Signup and view all the answers

Why is the clinical use of Vesamicol limited?

<p>Its specificity and potential side effects (A)</p> Signup and view all the answers

What mechanism does Physostigmine utilize to enhance acetylcholine activity?

<p>Inhibiting acetylcholinesterase activity (D)</p> Signup and view all the answers

What is the initial dose of Oxybutynin for humans?

<p>5 mg 1-2 times daily (C)</p> Signup and view all the answers

Which of the following is NOT a contraindication for using Muscarinic Receptor Antagonists?

<p>Food allergies (B)</p> Signup and view all the answers

What is one of the side effects commonly associated with Oxybutynin?

<p>Dry mouth (D)</p> Signup and view all the answers

What is the mechanism of action of Botulinum Toxin?

<p>Cleaves proteins to block acetylcholine (B)</p> Signup and view all the answers

What is a potential serious effect of untreated botulism?

<p>Muscle paralysis and respiratory failure (C)</p> Signup and view all the answers

Which of the following antibiotics is known to inhibit acetylcholine release?

<p>Aminoglycosides (C)</p> Signup and view all the answers

Which condition is magnesium sulfate used to treat?

<p>Preeclampsia (D)</p> Signup and view all the answers

Which side effect is associated with magnesium used for neuromuscular blockade?

<p>Respiratory paralysis (B)</p> Signup and view all the answers

What is the primary classification of xanomeline?

<p>Muscarinic Agonist (D)</p> Signup and view all the answers

What action does cevimeline primarily perform?

<p>Selective modulation of M1 and M3 receptors (B)</p> Signup and view all the answers

Which condition is xanomeline indicated for treating?

<p>Schizophrenia in adults (B)</p> Signup and view all the answers

What is a contraindication for the use of cevimeline?

<p>Severe kidney disease (D)</p> Signup and view all the answers

Which of the following is a known side effect of xanomeline?

<p>Urinary retention (D)</p> Signup and view all the answers

What is the origin of arecoline?

<p>Natural alkaloid from Areca catechu (B)</p> Signup and view all the answers

What was arecoline historically used for in veterinary medicine?

<p>Deworming agent (A)</p> Signup and view all the answers

What type of drug is xanomeline?

<p>Alkaloid muscarine (D)</p> Signup and view all the answers

Flashcards

Xanomeline

A muscarinic agonist that modulates neurotransmitter circuits like acetylcholine, dopamine, and glutamate.

What is a muscarinic agonist?

A drug that stimulates muscarinic receptors, which are involved in various bodily functions, including heart rate, digestion, and muscle contractions.

Xanomeline for Schizophrenia

Xanomeline is currently being explored as a potential treatment for schizophrenia in adults.

Cevimeline

A selective muscarinic agonist that focuses on M1 and M3 receptors.

Signup and view all the flashcards

Cevimeline for Dry Mouth

Cevimeline is used to treat dry mouth (xerostomia) associated with Sjogren's syndrome.

Signup and view all the flashcards

Arecoline

A natural alkaloid found in the betel nut (Areca catechu) that acts as a CNS stimulant.

Signup and view all the flashcards

Arecoline - Past Veterinary Use

Historically, arecoline was used as an anthelmintic (deworming agent) in livestock.

Signup and view all the flashcards

Arecoline Side Effects

Arecoline can cause side effects like vomiting, salivation, diarrhea, and toxicity at high doses.

Signup and view all the flashcards

Xerostomia Treatment

Using 0.1-0.2 g/kg of pilocarpine for 12 hours to address dry mouth.

Signup and view all the flashcards

Pilocarpine Contraindications (Ocular)

Pilocarpine is contraindicated for patients with retinal detachment, other conditions where mitosis is undesired, and hypersensitivity to pilocarpine.

Signup and view all the flashcards

Pilocarpine Contraindications (Systemic)

Pilocarpine is contraindicated in patients with asthma or respiratory conditions that may be worsened by bronchoconstriction.

Signup and view all the flashcards

Pilocarpine Side Effects (Ocular)

Pilocarpine can cause blurred vision, difficulty seeing in low light due to miosis, eye discomfort/irritation, and headache.

Signup and view all the flashcards

Pilocarpine Side Effects (Systemic)

Pilocarpine can cause sweating, flushing, increased salivation, nausea, vomiting, diarrhea, abdominal cramping, bradycardia, and hypotension.

Signup and view all the flashcards

M1 Receptor Blocker

A drug that selectively blocks M1 receptors in the stomach, reducing gastric acid secretion.

Signup and view all the flashcards

Trihexyphenidyl

A synthetic anticholinergic drug that inhibits M1 muscarinic receptors in the brain, helping manage Parkinson's disease symptoms.

Signup and view all the flashcards

Muscarinic Receptor Agonist

A drug that mimics the effects of acetylcholine by activating muscarinic receptors, particularly M2 receptors.

Signup and view all the flashcards

Bethanechol

A synthetic muscarinic receptor agonist primarily used to stimulate bladder contractions in small animals.

Signup and view all the flashcards

Carbachol

A long-acting synthetic muscarinic receptor agonist that mimics acetylcholine, used for various conditions including GI issues and bladder problems.

Signup and view all the flashcards

Bethanechol: Dose of Action

The effective dose of Bethanechol in canines and felines varies based on body weight and administration route. For dogs, it is given orally three times daily, while for cats, it is given orally two to three times daily.

Signup and view all the flashcards

M2 Receptor: Role

M2 muscarinic receptors play a role in regulating heart rate, smooth muscle contraction, and glandular secretions.

Signup and view all the flashcards

Side Effects of M1 Receptor Blockers

Common side effects of M1 receptor blockers include dry mouth, blurred vision, tachycardia, urinary retention, and constipation.

Signup and view all the flashcards

Trihexyphenidyl Contraindications

Contraindications for Trihexyphenidyl include glaucoma, bowel or urinary obstruction, and myasthenia gravis.

Signup and view all the flashcards

Bethanechol Side Effects

Common side effects of Bethanechol include bradycardia (slow heart rate) and urinary urgency.

Signup and view all the flashcards

Trihexyphenidyl: Effect

Trihexyphenidyl reduces symptoms of Parkinsonism by inhibiting M1 muscarinic receptors in the brain.

Signup and view all the flashcards

Carbachol: Effect

Carbachol increases peristalsis by mimicking acetylcholine.

Signup and view all the flashcards

Bethanechol: Action

Bethanechol mimics the action of acetylcholine.

Signup and view all the flashcards

Carbachol: Action

Carbachol mimics the effects of acetylcholine but is more stable.

Signup and view all the flashcards

Bethanechol: Indication

Bethanechol is primarily used to stimulate bladder contractions in small animals.

Signup and view all the flashcards

Carbachol: Indication

Carbachol is occasionally used for GI atony or bladder issues.

Signup and view all the flashcards

Trihexyphenidyl: Indication

Trihexyphenidyl is used to manage Parkinson's disease.

Signup and view all the flashcards

Trihexyphenidyl: Classification

Trihexyphenidyl is classified as an anticholinergic and a muscarinic receptor antagonist.

Signup and view all the flashcards

Hyoscyamine - Action

Hyoscyamine is a natural alkaloid that blocks acetylcholine at muscarinic receptors, especially M3 subtypes, leading to smooth muscle relaxation in glands and muscles.

Signup and view all the flashcards

Hyoscyamine - Indications

Hyoscyamine is used to treat irritable bowel syndrome (IBS), gastrointestinal disorders, bladder spasms, and other conditions.

Signup and view all the flashcards

Hyoscyamine - Side Effects

Common side effects of Hyoscyamine include dry mouth, blurred vision, constipation, and urinary retention.

Signup and view all the flashcards

Oxybutynin - Action

Oxybutynin selectively blocks acetylcholine at muscarinic receptors in the bladder smooth muscle, leading to relaxation of the detrusor muscle.

Signup and view all the flashcards

Oxybutynin - Indication

Oxybutynin is used to treat overactive bladder syndrome and neurogenic bladder by reducing bladder spasms and increasing bladder capacity.

Signup and view all the flashcards

Muscarinic Receptor Antagonist - Contraindication

Muscarinic receptor antagonists, like Hyoscyamine, are contraindicated in conditions like glaucoma, myasthenia gravis, tachycardia, prostatic hypertrophy, and obstructive gastrointestinal conditions.

Signup and view all the flashcards

Muscarinic Receptor Antagonist - Side Effects

Common side effects of muscarinic receptor antagonists include dry mouth, blurred vision, constipation, urinary retention, tachycardia, dizziness, nausea, photophobia, and an increased heart rate.

Signup and view all the flashcards

Vesamicol

A drug that inhibits the vesicular acetylcholine transporter (VAChT), preventing the uptake of acetylcholine into synaptic vesicles and reducing its availability for release.

Signup and view all the flashcards

How does Vesamicol affect acetylcholine?

Vesamicol inhibits the vesicular acetylcholine transporter (VAChT), preventing acetylcholine from being loaded into synaptic vesicles for release. This reduces acetylcholine's availability for neurotransmission.

Signup and view all the flashcards

Physostigmine

An acetylcholinesterase inhibitor (AChEI) that prolongs the action of acetylcholine by preventing its breakdown.

Signup and view all the flashcards

Physostigmine's effect on acetylcholine

Physostigmine, an acetylcholinesterase inhibitor, prevents the breakdown of acetylcholine. This increases the amount of acetylcholine available at the synapse, extending its duration of action.

Signup and view all the flashcards

Physostigmine's use in Myasthenia Gravis

Physostigmine is used to treat Myasthenia Gravis by increasing acetylcholine levels. This helps improve muscle function by countering the effects of antibodies that block acetylcholine receptors.

Signup and view all the flashcards

Oxybutynin

A muscarinic receptor antagonist used to treat overactive bladder. It blocks the action of acetylcholine at muscarinic receptors, reducing bladder muscle contractions.

Signup and view all the flashcards

Acetylcholine Release Inhibitor

A substance that prevents the release of acetylcholine from neurons, reducing its effects at synapses.

Signup and view all the flashcards

Botulinum Toxin (Botox)

A neurotoxin produced by bacteria that blocks acetylcholine release, causing temporary muscle paralysis. It is used for treating muscle spasms and cosmetic purposes.

Signup and view all the flashcards

Aminoglycosides: Impact on Acetylcholine Release

This class of antibiotics inhibits acetylcholine release by blocking calcium influx into nerve endings, thus reducing neurotransmission at the synapse.

Signup and view all the flashcards

Magnesium Ions: Role in Acetylcholine Release

Magnesium ions inhibit calcium entry at nerve terminals, which is crucial for acetylcholine release, effectively reducing neurotransmission.

Signup and view all the flashcards

Botulism: Symptoms and Cause

A severe illness caused by botulinum toxin, characterized by muscle paralysis, respiratory failure, and potentially life-threatening outcomes.

Signup and view all the flashcards

Aminoglycosides: Side Effects

These antibiotics can have adverse effects on the nervous system (neuromuscular blockade) and kidneys (nephrotoxicity) and inner ear (ototoxicity).

Signup and view all the flashcards

Magnesium Ions: Side Effects

High doses of magnesium ions can lead to neuromuscular blockade, causing muscle weakness and even respiratory problems.

Signup and view all the flashcards

Study Notes

Cholinergic Drugs

  • Cholinergic drugs mimic acetylcholine (ACh)
  • Also known as parasympathomimetic
  • Anticholinergic drugs block ACh
  • Also known as parasympatholytic

Cholinergic Receptors

  • Receptors to which acetylcholine binds
  • Perform major roles in neural transmission
  • Somatic and autonomic nervous systems
  • Drugs are not selective due to widespread presence of cholinergic receptors

Muscarinic Receptors

  • Present in the central nervous system (CNS) and the parasympathetic division of the autonomic nervous system (ANS)
  • Mediate innervation to visceral organs
  • G-protein coupled receptors
  • Named after muscarine

Muscarinic Receptor Subtypes

  • M1 receptors are associated with the CNS, parietal cells, and salivary glands
  • M2 receptors are associated with cardiac tissues, and the heart
  • M3 receptors are associated with glandular and smooth muscle, especially exocrine glands, GI smooth muscle, vascular endothelium, bladder, and genitalia

Nicotinic Receptors

  • Present in the CNS, neuromuscular junction, and autonomic ganglia
  • Involved in voluntary movement and mediating the autonomic nervous system
  • Ligand-gated ion channels
  • Named after nicotine

Location of Nicotinic Receptors

  • N1 or Nm receptors are in neuromuscular junctions
  • N2 or Nn receptors are in autonomic ganglia and the adrenal medulla
  • N1 receptors are excitory
  • N2 receptors are excitory

Nicotinic Receptors vs. Muscarinic Receptors

  • Nicotinic receptors are ion channels; muscarinic receptors are G-protein-coupled receptors
  • Nicotinic receptors mediate fast synaptic transmission; muscarinic receptors mediate slow, metabolic responses
  • Nicotinic receptors respond to nicotine; muscarinic receptors respond to muscarine

Cholinergic System

  • Nicotinic and muscarinic receptors are involved in the cholinergic system
  • The cholinergic system regulates peripheral and central receptors

Nicotine

  • Derived from the tobacco plant
  • Natural chemical compound, belonging to a class of alkaloids.
  • Common in tobacco products, and responsible for their addictive properties
  • Cholinergic nicotinic agonist

Anectine® (Succinylcholine Chloride)

  • Cholinergic nicotinic agonist
  • Mimics acetylcholine
  • Muscle relaxation, needed for surgical and diagnostic procedures, like endotracheal intubation
  • Skeletal muscle relaxant
  • Dosage varies by animal species

Pavulon® (Pancuronium Bromide)

  • Cholinergic nicotinic antagonist
  • Binds to receptors
  • Muscle relaxation during surgical procedures and mechanical ventilation
  • Skeletal muscle relaxant
  • Dosage varies by animal species

Zemuron® (Rocuronium Bromide)

  • Cholinergic nicotinic antagonist
  • Competes for cholinergic receptors at the motor end plate
  • Muscle relaxation during surgical procedures
  • Skeletal muscle relaxant
  • Dosage varies by animal species

Norcuron® (Vecuronium Bromide)

  • Cholinergic nicotinic antagonist
  • Competes for receptors at the motor end plate
  • Muscle relaxation during surgical procedures, or mechanical ventilation
  • Skeletal muscle relaxant
  • Dosage varies by animal species

Varenicline

  • Cholinergic nicotinic agonist
  • Stimulates the receptor, reduces nicotine cravings, and prevents nicotine's reinforcing effects
  • Used for smoking cessation therapy

Trimethaphan Camylate

  • Cholinergic nicotinic antagonist (ganglionic blocker)
  • Inhibits transmission in both sympathetic and parasympathetic ganglia
  • Used to manage hypertensive emergencies in animals

Mecamylamine

  • Cholinergic nicotinic antagonist (ganglionic blocker)
  • Inhibits transmission in both sympathetic and parasympathetic ganglia

Hexamethonium Bromide

  • Cholinergic nicotinic antagonist (ganglionic blocker)
  • Inhibits transmission in both sympathetic and parasympathetic ganglia
  • Used in hypertensive emergencies and for controlled hypotension during surgery

Inhibitor of Acetylcholine Release

  • Botulinum Toxin (Botox): Produced by Clostridium botulinum bacteria. Blocks acetylcholine (ACh) by cleaving proteins, causing temporary paralysis of muscles.
  • Aminoglycosides: Block the influx of calcium ions into nerve endings, reducing acetylcholine release. Used to treat bacterial infections, especially gram-negative infections.
  • Magnesium ions: Inhibits calcium entry at nerve terminals reducing acetylcholine release; used for preeclampsia, other conditions involving neuromuscular blockade.

Inhibitor of Acetylcholinesterase

  • Physostigmine: Acetylcholinesterase inhibitor, prolongs activity of ACh in body. Used in myasthenia gravis, glaucoma.

Summary of Agonist and Antagonist Effects

  • M1: Agonist (Xanomeline) enhances cognition, increases stomach acid; Antagonist (Pirenzepine) reduces gastric acid secretion.
  • M2: Agonist (rarely used clinically); Antagonist (Atropine) increases heart rate.
  • M3: Agonist (Pilocarpine) increases smooth muscle contraction & secretions; Antagonist (Ipratropium and Tiotropium) relaxes smooth muscle, reduces secretions

Muscarinic Drugs Outline

  • Includes M1 (neural), M2 (cardiac), and M3(glandular) agonists and antagonists.
  • Various specific drugs are mentioned for each receptor subtype.

Muscarinic Receptor Antagonists

  • Atropine: Derived from plants, blocks muscarinic receptors, increases heart rate, used in bradycardia, and other conditions; contraindicated in tachycardias and myocardial ischemia
  • Glycopyrrolate: Blocks M2 receptors, increases heart rate, treats bradycardia during anesthesia and in other conditions.
  • Scopolamine: Blocks muscarinic receptors, Treats motion sickness, motion sickness, nausea, and vomiting after surgery
  • Pirenzepine: Selectively blocks M1 receptors in the stomach, reduces gastric acid secretion.
  • Telenzepine: A selective M1 antagonist used primarily for its effects on the gastrointestinal system.
  • Hyoscyamine: Blocks muscarinic receptors, relieves spasms, IBS, GI tract disorders
  • Benztropine: Blocks M1 receptors, treats Parkinson's disease
  • Trihexyphenidyl: Blocks M1 receptors; for Parkinson's disease, and other disorders involving those receptors

Muscarinic Receptor Agonists

  • Bethanechol: Mimics ACh, designed for bladder issues, used in veterinary medicine, increases bladder contraction
  • Carbachol: Mimics ACh, more stable, used in veterinary and human medicine to promote peristalsis and bladder contraction, treating glaucoma
  • Pilocarpine: Derived from a plant, stimulates muscarinic receptors, increasing secretions, used to treat dry mouth, glaucoma.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Cholinergic Drugs PDF

Description

Test your knowledge on muscarinic receptor antagonists and their clinical applications with this quiz. You'll encounter questions about contraindications, side effects, and specific drugs like pilocarpine and Hyoscyamine. Perfect for pharmacology students and healthcare professionals.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser