Autonomic Pharmacology | Muscarinic Antagonists

Introduction to Anti-Muscarinic Agents

In this section, the speaker introduces anti-muscarinic agents and invites viewers to like, comment, and subscribe. The speaker also encourages viewers to check out their website for notes and illustrations.

Physiology of the Parasympathetic Nervous System

• To understand anti-cholinergic drugs, it is important to understand the basic physiology of the parasympathetic nervous system.

• Acetylcholine releasing neurons and muscarinic receptors are present within the central nervous system.

• The basal ganglia is involved in regulating movement through a balance between dopamine and acetylcholine.

• Alterations in this pathway can lead to movement disorders.

• Muscarinic receptors are present in the vomiting center located near the medulla.

Muscarinic Receptors on the Eye

• Muscarinic receptors are present on different tissues of the eye.

• The natural function of this pathway is pupil constriction and increased aqueous humor drainage.

Conclusion

The speaker provides an introduction to anti-muscarinic agents and discusses their effects on various parts of the body. They also provide a brief overview of the physiology of the parasympathetic nervous system.

Medulla and Scopolamine

This section discusses the role of the medulla in the body and how scopolamine can be used to inhibit vomiting.

Medulla

• The medulla works in the eye and can act on the heart.

• It can decrease salivation and is used pre-intubation or perioperatively to clear up upper airway secretions.

• Atropine is a medication that can be given to treat symptomatic bradycardia caused by severe low heart rate due to cholinergic agonists.

Scopolamine

• Scopolamine inhibits vomiting by blocking muscarinic receptors on the ammetic center in the medulla.

• It is commonly used for motion sickness and post-operative nausea and vomiting from anesthesia and opioids.

Atropine

This section discusses atropine, its effects on M2 receptors, and when it should be used.

• Atropine acts on M2 receptors present on the AV node and SA node, which naturally decreases heart rate and cardiac output.

• It is used to increase heart rate in patients with severe bradycardia.

• Atropine can also be considered as an antidote for a cholinergic crisis caused by increased cholinergic agonist use.

Biperiden, Trihexyphenidyl, Basal Ganglia

This section discusses biperiden, trihexyphenidyl, basal ganglia, neurotransmitters involved in movement modulation.

• Biperiden and trihexyphenidyl are drugs that modulate movement through a balance between two neurotransmitters in the CNS.

• Movement is modulated by a balance between two particular neurotransmitters in the CNS.

• The basal ganglia is involved in movement modulation.

Cholinergic Physiology and Muscarinic Antagonist

This section covers the cholinergic physiology and muscarinic antagonist. It explains the difference between short-acting and long-acting muscarinic antagonists.

Short-Acting vs Long-Acting Muscarinic Antagonist

• Short-acting muscarinic antagonist is more short acting, while long-acting muscarinic antagonist is more long acting.

• Tyotroprium is a long-acting muscarinic antagonist, while other drugs are short acting.

• Taking too much of these drugs can cause anticholinergic toxicity.

Anticholinergic Toxicity

This section covers anticholinergic toxicity, its causes, and symptoms.

Causes of Anticholinergic Toxicity

• Taking too much of an antimuscarinic agent or tricyclic antidepressants can cause anticholinergic toxicity.

• Antipsychotics and first-generation antihistamines can also cause anticholinergic toxicity.

• Belladonna plant berries and leaves may have antimuscarinic properties that could cause anticholinergic toxicity.

Symptoms of Anticholinergic Toxicity

• Patients with anticholinergic toxicity experience intense changes in cognition that can lead to delirium or seizures.

• Massive pupil dilation, blurry vision, dry eyes, dry mouth, tachycardia, hypertension, bronchodilation are common symptoms of anticholinergic toxicity.

• Patients may develop hyperthermia due to the inhibition of sweating, and they may experience constipation.

Atropine

In this section, the speaker discusses the use of atropine as a medication.

Uses of Atropine

• Decreases salivation in patients with excessive drooling or pre-intubation.

• Increases heart rate and cardiac output in patients with severe bradycardia.

• Can be used as an antidote for cholinergic crisis caused by cholinergic agonists.

Scopolamine

In this section, the speaker discusses scopolamine and its uses.

Uses of Scopolamine

• Blocks muscarinic receptors on the ammetic center to inhibit vomiting reflex. Used to treat motion sickness and post-operative nausea and vomiting.

Biperiden and Trihexyphenidyl

In this section, the speaker discusses biperiden and trihexyphenidyl.

Dopamine and Acetylcholine Balance

• Movement is modulated by dopamine and acetylcholine balance in CNS.

• Diseases with massive reduction in dopamine can cause acetylcholine to overpower, throwing off movement equilibrium.

Benztropine

In this section, the speaker discusses benztropine.

Uses of Benztropine

• Treat Parkinson's disease by blocking excess acetylcholine activity caused by dopamine deficiency.

• Can be used to treat extrapyramidal symptoms caused by antipsychotic medications.

Glycopyrrolate

In this section, the speaker discusses glycopyrrolate.

Uses of Glycopyrrolate

• Decreases salivation and respiratory secretions during surgery or anesthesia.

• Can be used to treat bradycardia and as an antidote for cholinergic crisis.

Inadequate Release and Cause

The speaker discusses the release and cause of inadequate bronchodilation.

Inadequate Bronchodilation

• The speaker talks about the release and cause of inadequate bronchodilation.

COPD Treatment Options

The speaker discusses treatment options for a 50-year-old male recently diagnosed with COPD.

Muscarinic Receptors and Bronchodilation

• Muscarinic receptors play a role in bronchodilation.

• Tiotropium is appropriate for long-term management, while epitropin is more suitable for acute exacerbations.

Vestibular Function and Motion Sickness

• Vestibular function is connected to motion sickness.

• Acetylcholine on the M2 prevents AV node inhibition, allowing heart rate to increase.

Overall, the speaker provides information on inadequate bronchodilation and treatment options for COPD patients. They discuss muscarinic receptors' role in bronchodilation, appropriate drugs for long-term management versus acute exacerbations, vestibular function's connection to motion sickness, and how acetylcholine affects heart rate.