Pharmacology of Ganglion Drugs

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Questions and Answers

What are the main physiological effects of ganglion-stimulating drugs like Nicotine?

They stimulate both sympathetic and parasympathetic ganglia, leading to tachycardia, increased blood pressure, and variable effects on gastrointestinal motility and secretions.

What is the primary clinical use of Nicotine among ganglion-stimulating drugs?

Nicotine is primarily used to assist individuals in giving up smoking.

What are the effects of ganglion-blocking drugs like Hexamethonium?

They induce hypotension, loss of cardiovascular reflexes, inhibition of secretions, gastrointestinal paralysis, and impaired micturition.

Why are ganglion-blocking drugs considered clinically obsolete?

They are largely deemed obsolete because of their extensive side effects, with occasional use of Trimetaphan for controlled hypotension in anesthesia. Signup and view all the answers

What are some potential side effects of using ganglion-stimulating drugs?

Potential side effects include increased bronchial and salivary secretions as well as variable effects on GI motility. Signup and view all the answers

What are the main side effects associated with scopolamine?

The main side effects include urinary retention, dry mouth, blurred vision, constipation, tachycardia, and CNS disturbances. Signup and view all the answers

Why is scopolamine contraindicated in patients with glaucoma?

Scopolamine can increase intraocular pressure, which is dangerous for patients with glaucoma, especially closed-angle glaucoma. Signup and view all the answers

Describe the mechanism of action of non-selective antimuscarinic drugs like scopolamine in relation to gastric ulcers.

They slow gastric emptying, which may worsen the symptoms of gastric ulcers and cause food delay. Signup and view all the answers

What is the primary use of scopolamine in clinical practice?

Scopolamine is primarily used as the drug of choice for treating motion sickness. Signup and view all the answers

How does Hyoscine-N-butyl bromide differ from scopolamine in terms of effects on the CNS?

Hyoscine-N-butyl bromide has CNS stimulant action, whereas scopolamine causes CNS depression. Signup and view all the answers

What glands are inhibited by very low doses of atropine?

Salivary, lacrimal, bronchial, and sweat glands are inhibited. Signup and view all the answers

How does atropine affect mucociliary clearance in the lungs?

Atropine inhibits mucociliary clearance, leading to accumulation of secretions in the lungs. Signup and view all the answers

What is the primary cardiovascular effect of atropine and how does it achieve this?

Atropine causes moderate tachycardia by blocking cardiac mAChRs (M2) and reducing parasympathetic tone. Signup and view all the answers

What unique effect can very low doses of atropine produce regarding heart rate?

Very low doses of atropine can cause paradoxical bradycardia. Signup and view all the answers

What distinguishes scopolamine, the primary component of Datura Stramonium, in terms of its pharmacological properties?

Scopolamine is a tertiary amine that is lipid-soluble and can cross the blood-brain barrier. Signup and view all the answers

What is the effect of atropine on pupil size and responsiveness?

Atropine causes pupil dilation (mydriasis), making the pupils unresponsive to light. Signup and view all the answers

How does atropine influence the ability to focus on near objects?

Atropine leads to paralysis of accommodation (cycloplegia), causing difficulty focusing on near objects and blurred vision. Signup and view all the answers

What mechanism contributes to increased intraocular pressure when using atropine?

Atropine can increase intraocular pressure by blocking the action of acetylcholine on the ciliary muscle. Signup and view all the answers

In what circumstances is atropine used in relation to gastrointestinal motility?

Atropine is used to inhibit gastrointestinal motility in cases of excessive motility. Signup and view all the answers

What effect does atropine have on bronchial smooth muscles during anesthesia?

Atropine relaxes bronchial smooth muscles, preventing reflex bronchoconstriction during anesthesia. Signup and view all the answers

What are the CNS effects associated with low and high doses of atropine?

Low doses may cause mild restlessness, while high doses can lead to agitation and disorientation. Signup and view all the answers

What symptoms might indicate atropine poisoning, especially in children?

Atropine poisoning can cause marked excitement, irritability, and may progress to atropine fever. Signup and view all the answers

Why is atropine not used to treat conditions involving relaxation of smooth muscles?

Atropine is primarily used for conditions characterized by increased activity in smooth muscles, not relaxation. Signup and view all the answers

What is the primary mechanism of action of atropine?

Atropine primarily acts as a non-selective muscarinic receptor antagonist, blocking these receptors. Signup and view all the answers

How is atropine absorbed and metabolized in the body?

Atropine is readily absorbed from the gastrointestinal tract and is partially metabolized, with 60% excreted unchanged in urine. Signup and view all the answers

List two medical uses of atropine.

Atropine is used as an adjunct in anesthesia and as an antidote for anticholinesterase poisoning. Signup and view all the answers

What effects does atropine have on the central nervous system?

Atropine can cause sedation at low doses and excitation at high doses within the CNS. Signup and view all the answers

How does atropine affect patients with Parkinson's disease?

Atropine can reduce involuntary movements and rigidity in patients with Parkinson's by acting on the extrapyramidal system. Signup and view all the answers

What are the classic symptoms of atropine poisoning, specifically in children?

The classic symptoms include dry mouth, dilated pupils (mydriasis), and agitation. Signup and view all the answers

What is atropine flush and how can it aid in diagnosis?

Atropine flush is a cutaneous vasodilation that appears as a red rash on the body, particularly on the head and neck. Signup and view all the answers

Why is physostigmine considered a controversial antidote for atropine poisoning?

Physostigmine may cause convulsions and should only be used with caution in indicated patients. Signup and view all the answers

What is hyperthermia in the context of atropine poisoning and why is it particularly dangerous in infants?

Hyperthermia refers to an increase in body temperature due to blocked sweating, which can lead to heatstroke. Signup and view all the answers

Name two common side effects associated with muscarinic antagonists like atropine.

Common side effects include dry mouth and constipation. Signup and view all the answers

Study Notes

Ganglion-stimulating drugs

Include nicotine, DMPP and others.
Stimulate both sympathetic and parasympathetic ganglia, effects include tachycardia, increased blood pressure and variable effects on GI motility and secretions.
Therapeutic use limited to nicotine to assist in quitting smoking.

Ganglion-blocking drugs

Include Hexamethonium and Trimetaphan.
Block all autonomic ganglia and enteric ganglia.
Main effects include hypotension, loss of cardiovascular reflexes, inhibition of secretions, gastrointestinal paralysis, and impaired micturition.
Clinically obsolete, except for the occasional use of Trimetaphan for controlled hypotension during anesthesia.

Scopolamine (Hyoscine)

Causes urinary retention, dry mouth, blurred vision, constipation, tachycardia, and CNS disturbances such as restlessness, agitation and hallucinations.
Slows gastric emptying, may worsen gastric ulcer symptoms and lead to food delay.
Contraindicated in glaucoma, BPH, and caution is advised for infants with fever.
Crosses the blood-brain barrier and causes CNS depression.
Well absorbed from the GIT and skin, used in transdermal patches to treat motion sickness.
Drug of choice for motion sickness.

Hyoscine-N-butyl bromide

Synthetic derivative of scopolamine.
Has CNS stimulant action.
Effective in relaxing smooth muscles, used as an antispasmodic for the GIT, biliary system and urinary tract.

Dicycloverine

Similar to atropine.
Primarily used as an antispasmodic agent.

Cyclopentolate and Tropicamide

Tertiary amines developed for ophthalmic use, acting as mydriatics.
Shorter duration of action than atropine and scopolamine, lasting approximately 6 hours.

Effects of Atropine on the Eye

Causes pupil dilation (mydriasis) making pupils unresponsive to light.
Paralysis of accommodation (cycloplegia), inhibiting ciliary muscle, resulting in blurred vision.
Can increase intraocular pressure (IOP) in susceptible patients.

Effects of Atropine on the Gastrointestinal Tract

Inhibits gastrointestinal motility, requiring higher doses than other transmitters such as ACh.
Used in cases where there is excessive gastrointestinal motility.

Effects of Atropine on Other Smooth Muscles

Relaxes bronchial smooth muscles, preventing reflex bronchoconstriction.
Relaxes biliary and urinary tract smooth muscles.
Can lead to urinary retention, especially in elderly men with BPH.

Effects of Atropine on the Central Nervous System (CNS)

Primarily produces excitatory effects on the CNS.
Causes mild restlessness at low doses.
Leads to agitation and disorientation at high doses.
In poisoning cases in young children, marked excitement and irritability can develop, sometimes leading to atropine fever.

Pharmacological Effects of Muscarinic Antagonists

Atropine is the prototype drug.
Atropine inhibits secretions from salivary, lacrimal, bronchial and sweat glands at low doses.
Slightly reduces gastric secretions.
Inhibits mucociliary clearance in the bronchi, causing residual secretions to accumulate in the lungs, which is blocked by Ipratropium.
Causes tachycardia through the blockade of cardiac mAChRs (M2) up to 80-90 beats per minute.
At very low doses, atropine can cause paradoxical bradycardia possibly due to central action and inhibition of presynaptic M₂ receptors (that normally have an autoinhibitory effect on acetylcholine release).
The heart's response to exercise is unaffected.
Arterial blood pressure is unaffected.

Atropine

Belladonna alkaloid, non-selective muscarinic receptor antagonist.
Readily absorbed from GIT.
Partially metabolized and 60% excreted unchanged in urine.
Crosses the BBB, causing CNS stimulation.
Half-life is approximately 2 hours, but its effect on the eye can last 3 days to 1 week.
Blocks muscarinic receptors, reducing secretions and causing bronchodilation.
Used as an adjunct in anesthesia, antidote for anticholinesterase poisoning, treatment for bradycardia and gastrointestinal hypermotility.
Low doses cause sedation, high doses cause excitation.
Can affect the extrapyramidal system, reducing involuntary movement and rigidity in Parkinson’s patients.

Atropine Poisoning

Symptoms include dry mouth, mydriasis (dilated pupils), blurred vision, tachycardia, hot and flushed skin, agitation, delirium, dry skin, and hyperthermia.
Atropine flush may be a diagnostic sign.
Physostigmine is the antidote, use with caution and only for indicated patients as it may cause convulsions.
Side effects are generally less severe than the effects of atropine poisoning, including dry mouth, constipation and blurred vision.
Centrally acting muscarinic antagonists (Benztropine, Benzhexol, Procyclidine, and Biperiden) effect the extrapyramidal system and are used to reduce tremors, involuntary movements and rigidity in Parkinson's disease patients, they can also counteract extrapyramidal side effects of some antipsychotic medication.

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Description

This quiz covers the pharmacological effects and therapeutic uses of ganglion-stimulating and ganglion-blocking drugs. It includes detailed discussions on drugs like nicotine, Hexamethonium, and Scopolamine, highlighting their impact on the autonomic system. Ideal for students in pharmacology and medicine.