[PCOL] 2.6 Parasympathetic Nervous System (Parasympathomimetics)

The general class of drugs known as direct acting cholinergic agonists stimulates which two types of cholinergic receptors?

A. Alpha and Beta receptors

B. Muscarinic (M) and Nicotinic (N) receptors

C. Dopamine and Serotonin receptors

D. Gq and Gi receptors

B. Muscarinic (M) and Nicotinic (N) receptors

Explanation: Cholinergic agonists stimulate receptors that respond to Acetylcholine, which are classified as Muscarinic (M) and Nicotinic (N) receptors.

Which direct acting cholinergic agonist is used for the management of glaucoma?

A. Bethanechol

B. Methacholine

C. Varenicline

D. Carbachol

D. Carbachol

Explanation: Carbachol is listed as a cholinergic agonist used in the management of glaucoma, where it promotes miosis and aqueous humor outflow.

Which cholinergic agonist is used specifically for the management of atropine toxicity?

A. Neostigmine

B. Pilocarpine

C. Bethanechol

D. Carbachol

A. Neostigmine

Explanation: Neostigmine is listed as a cholinergic agonist used to manage atropine toxicity. Atropine is a muscarinic antagonist, and Neostigmine, an Acetylcholinesterase inhibitor, increases Acetylcholine to overcome the blockade.

Which cholinergic agonist is used for the management of non-obstructive ileus (reduced peristalsis)?

A. Methacholine

B. Pilocarpine

C. Nicotine

D. Varenicline

B. Pilocarpine

Explanation: Pilocarpine is listed as a cholinergic agonist used for the management of non-obstructive ileus, where its muscarinic agonism stimulates GI smooth muscle contraction.

Which cholinergic agonist is used for the management of urinary retention?

A. Methacholine

B. Bethanechol

C. Physostigmine

D. Echothiopate

B. Bethanechol

Explanation: Bethanechol is listed as a cholinergic agonist used for the management of urinary retention, as it stimulates M3 receptors on the detrusor muscle to promote urination.

Which cholinergic agonist is used as a diagnostic tool in the pulmonary challenge test?

A. Methacholine

B. Neostigmine

C. Carbachol

D. Demecarium

A. Methacholine

Explanation: Methacholine is listed as a cholinergic agonist used in the pulmonary challenge test, where its ability to cause bronchoconstriction is used to diagnose asthma.

Which cholinergic agonist is used for smoking cessation?

A. Pilocarpine

B. Methacholine

C. Varenicline

D. Physostigmine

C. Varenicline

Explanation: Varenicline is listed as a cholinergic agonist used for smoking cessation. It is a partial agonist at nicotinic receptors.

Which cholinergic agonist, listed as being used for GI atony, is also an Acetylcholinesterase inhibitor that can cross the blood-brain barrier (BBB)?

A. Bethanechol

B. Physostigmine

C. Nicotine

D. Carbachol

B. Physostigmine

Explanation: Physostigmine is listed as being used for GI atony. It is an indirect-acting agent (AChE inhibitor) that is uncharged and can therefore cross the BBB.

Which cholinergic agonist is used for the management of GI atony?

A. Neostigmine

B. Physostigmine

C. Bethanechol

D. Nicotine

B. Physostigmine

Explanation: Physostigmine is specifically listed as the cholinergic agonist used for the management of GI atony.

What is the primary mechanism of action (MOA) for Indirect Acting Cholinergic Agonists?

A. Direct stimulation of M and N receptors

B. Inhibition of AChE (Acetylcholinesterase)

C. Inhibition of Choline uptake

D. Stimulation of Acetylcholine (ACh) release (Exocytosis)

B. Inhibition of AChE (Acetylcholinesterase)

Explanation: Indirect Acting Cholinergic Agonists, or anticholinesterases, work by inhibiting the enzyme AChE, which increases the concentration and duration of action of ACh in the synaptic cleft.

Which structural class of AChE inhibitors is characterized as Short Acting and is a reversible inhibitor with a duration of action (DOA) of approximately 5-30 minutes?

A. Organocarbamates

B. Organophosphates

C. Aminoalcohols

D. Carbamyl Esters

C. Aminoalcohols

Explanation: Edrophonium is the key short-acting, reversible AChE inhibitor belonging to the Aminoalcohol class, with a very brief DOA (15-30 minutes).

What is the primary clinical use of Edrophonium (Tensilon) and the purpose of the Tensilon Test?

A. Reversal of severe atropine poisoning

B. Treatment of myasthenia gravis (MG)

C. Diagnosis of Myasthenia Gravis (MG) vs cholinergic crisis

D. Antidote for Tubocurarine poisoning

C. Diagnosis of Myasthenia Gravis (MG) vs cholinergic crisis

Explanation: The Tensilon Test uses Edrophonium to rapidly diagnose MG. If muscle strength increases and ptosis decreases, it confirms MG.

Which class of AChE inhibitors is characterized as Intermediate to Long Acting and includes reversible inhibitors with a DOA of 2-8 hours?

A. Aminoalcohols

B. Organophosphates

C. Organocarbamates / Carbamyl Esters

D. Alkaloids

C. Organocarbamates / Carbamyl Esters

Explanation: The Organocarbamates (stigmines) like Neostigmine and Physostigmine are intermediate-acting, reversible AChE inhibitors.

Which Organocarbamate is considered the Drug of Choice (DOC) for reversing Neuromuscular Blocker Toxicity (Tubocurarine poisoning)?

A. Physostigmine

B. Pyridostigmine

C. Edrophonium

D. Neostigmine

D. Neostigmine

Explanation: Neostigmine is the DOC for reversing the effects of non-depolarizing neuromuscular blockers like Tubocurarine due to its peripheral action and ability to increase ACh at the neuromuscular junction.

Which AChE inhibitor is the Drug of Choice (DOC) for the maintenance treatment of Myasthenia Gravis (MG)?

A. Neostigmine

B. Edrophonium

C. Pyridostigmine (Mestinon)

D. Physostigmine

C. Pyridostigmine (Mestinon)

Explanation: Pyridostigmine is the DOC for the long-term management and treatment of Myasthenia Gravis.

Which AChE inhibitor is a tertiary amine that is more lipophilic and used to reverse severe Atropine poisoning (IV route)?

A. Neostigmine

B. Pyridostigmine

C. Physostigmine (Eserine)

D. Demecarium

C. Physostigmine (Eserine)

Explanation: Physostigmine (Eserine) is a tertiary amine, allowing it to cross the BBB and reverse the central CNS effects of Atropine poisoning, which is a major clinical advantage.

The general side effects of AChE inhibitors are summarized by the mnemonic DUMBBELSS. What does the B in the mnemonic represent?

A. Blurred vision and Bowel movement

B. Bradycardia and Bronchial spasm

C. Blood pressure decrease and Bilirubinemia

D. BPH relief and Bowel atony

B. Bradycardia and Bronchial spasm

Explanation: DUMBBELSS stands for Diarrhea, Urination, Miosis, Bradycardia, Bronchial spasm, Emesis, Lacrimation, Salivation, Sweating.

What is the principal/first line treatment for the acute management of cholinergic toxicities?

A. Pralidoxime

B. Diacetyl monoxime

C. Atropine (Antimuscarinic)

D. Benzodiazepines (BZD)

C. Atropine (Antimuscarinic)

Explanation: Atropine is the first line treatment for cholinergic toxicity as it blocks the toxic excess of ACh at the muscarinic receptor sites.

Which drug is a ChE reactivator used in the management of Organophosphate (OP) poisoning if administered within 24-48 hours of exposure?

A. Atropine

B. Pralidoxime

C. Physostigmine

D. Edrophonium

B. Pralidoxime

Explanation: Pralidoxime (and Diacetyl monoxime) are ChE reactivators used for OP poisoning. They physically remove the OP group from the enzyme, restoring its function, but must be given before the ChE "ages" irreversibly.

What is the structural classification and duration of action (DOA) of the Very Long Acting Anticholinesterases?

A. Aminoalcohols; 5-30 minutes

B. Organocarbamates; 2-8 hours

C. Organophosphates; Irreversible (>24 hours)

D. Choline Esters; Irreversible (>24 hours)

C. Organophosphates; Irreversible (>24 hours)

Explanation: Organophosphates (OPs) are the structural class that causes Irreversible inhibition of AChE, leading to a very long duration of action (>24 hours).

What is the primary medically useful application of the Organophosphates Echothiopate and Isofluorophate?

A. Diagnosis of Myasthenia Gravis

B. Treatment of Atropine Toxicity

C. Management of Glaucoma

D. Reversal of Neuromuscular Block

C. Management of Glaucoma

Explanation: Echothiopate and Isofluorophate were used topically for Glaucoma due to their strong, long-lasting M3 agonism, which enhances aqueous humor outflow.

Which two Organophosphates are used as Insecticides and function as prodrugs that must be metabolized into their active forms (Malaoxon and Paraoxon)?

A. Tabun and Sarin

B. Echothiopate and Isofluorophate

C. Malathion and Parathion

D. Sarin and Soman

C. Malathion and Parathion

Explanation: The Insecticides Malathion and Parathion are inactive prodrugs that require metabolic conversion to the active malaoxon and paraoxon to inhibit AChE.

What is the process called when the Organophosphate (OP) inhibitor forms a covalent bond with the serine residue of AChE, resulting in the Irreversible Inhibition of the enzyme?

A. Hydrolysis

B. Acetylation

C. Aging

D. Reactivation

C. Aging

Explanation: Aging is the process where the bond between the OP and the AChE active site becomes chemically modified over time (>48 hours), making it permanently bound and the enzyme functionally irreversible.

What are Tabun, Sarin, and Soman primarily classified as, based on their extremely potent AChE inhibitory effects?

A. Insecticides

B. Nerve gases

C. Pharmaceuticals for Glaucoma

D. Anti-Alzheimer's agents

B. Nerve gases

Explanation: Tabun, Sarin, and Soman are highly toxic Organophosphates designated as Nerve gases, which cause rapid and overwhelming cholinergic toxicity.

Neurotoxins derived from 4o Amines, such as spider venom, interfere with ACh transmission by which mechanism?

A. Inhibiting AChE breakdown

B. Blocking ACh receptors

C. Promoting the release of ACh

D. Inhibiting Choline uptake

C. Promoting the release of ACh

Explanation: 4o Amine neurotoxins (like alpha-latrotoxin in black widow venom, which is a 4o Amine stimulant of ACh release) cause a massive release of ACh (Exocytosis).

The Centrally Acting Cholinergic Agonists are primarily used to treat which neurological condition?

A. Parkinson's disease

B. Huntington's chorea

C. Alzheimer's dementia

D. Myasthenia Gravis

C. Alzheimer's dementia

Explanation: Alzheimer's dementia is characterized by cholinergic deficiency in the CNS, which is treated symptomatically by these CNS-acting cholinesterase inhibitors.

What is the primary mechanism of action (MOA) of Tacrine, Donepezil, Galantamine, and Rivastigmine in treating Alzheimer's disease?

A. NMDA receptor antagonism

B. CNS-acting cholinesterase inhibition

C. Inhibition of beta-amyloid production

D. Stimulation of Nicotinic receptors

B. CNS-acting cholinesterase inhibition

Explanation: These drugs are lipophilic AChE inhibitors that cross the BBB to increase the concentration of Acetylcholine (ACh) in the brain's synapses, counteracting the cholinergic deficit.

Which drug used for Alzheimer's disease has a different mechanism of action, specifically NMDA antagonism?

A. Tacrine

B. Donepezil

C. Rivastigmine

D. Memantine

D. Memantine

Explanation: Memantine works by antagonizing NMDA receptors, which modulates glutamatergic neurotransmission, rather than inhibiting AChE.

Myasthenia Gravis (MG) is an autoimmune condition where antibodies target which specific receptor subtype?

A. M1 receptor

B. Nn receptor

C. Nm receptor

D. alpha1 receptor

C. Nm receptor

Explanation: MG is characterized by antibodies targeting the Nicotinic Muscular (Nm) receptors at the neuromuscular end plate, leading to muscle weakness.

What is the initial and the final characteristic sign/symptom of Myasthenia Gravis?

A. Initial:Diaphragmatic weakness; Final:Ptosis

B. Initial:Ptosis and late afternoon muscle weakness; Final:Diaphragmatic weakness

C. Initial:Tremors; Final:Seizures

D. Initial:Urinary retention; Final:Constipation

B. Initial:Ptosis and late afternoon muscle weakness; Final:Diaphragmatic weakness

Explanation: MG often presents initially with ptosis and muscle weakness that worsens over the day, and it culminates in life-threatening diaphragmatic muscle weakness.

Which class of drugs (e.g., Neostigmine, Pyridostigmine) is used to improve muscle strength in the treatment of Myasthenia Gravis?

A. NMDA antagonists

B. AChE Inhibitors

C. Non−DHP CCBs

D. Alpha blockers

B. AChE Inhibitors

Explanation: AChE Inhibitors increase the concentration of ACh at the Nm receptor, allowing the few remaining functional receptors to be stimulated more effectively, thereby improving muscle strength.

The side effects of cholinergic agonists are summarized by the DUMBBELS mnemonic. What does D, U, and M represent?

A. Dizziness, Ulceration, Mydriasis

B. Diarrhea, Urination, Miosis

C. Dyskinesia, Urticaria, Muscle contraction

D. Diaphoresis, Upset stomach, Mouth dryness

B. Diarrhea, Urination, Miosis

Explanation: DUMBBELS covers: Diarrhea, Urination, Miosis, Bronchoconstriction, Bradycardia, Emesis, Erection, Lacrimation, Lethargy, Sweating, Salivation, Secretions.

Severe Anticholinergic toxicity (e.g., Atropine poisoning) is often associated with the phrase "Alice in Wonderland Syndrome." Which symptom corresponds to the phrase "Blind as a bat"?

A. Cutaneous vasodilation (Red as a beet)

B. Decreased sweating (Dry as a bone)

C. Mydriasis and increased intraocular pressure

D. CNS effects (Mad as a hatter)

C. Mydriasis and increased intraocular pressure

Explanation: Anticholinergics block M3 on the circular muscle, leading to unopposed dilation (Mydriasis) and a risk of acute narrow-angle glaucoma (Blind as a bat).

What is the overall effect of anticholinergics on the bladder and exocrine glands that leads to the symptom "Full as a flask"?

A. Bronchodilation and secretion increase

B. Urinary retention and decreased secretions

C. Increased bowel motility and diarrhea

D. Increased heart rate and salivation

B. Urinary retention and decreased secretions

Explanation: Anticholinergics block M3 on the Detrusor muscle, causing urinary retention (Full as a flask), and decrease secretions (Dry as a bone).

What is the MOA of Pralidoxime (2−PAM), the antidote used for Organophosphate (OP) poisoning?

A. Muscarinic receptor blockade

B. Cholinesterase regenerator (AChE reactivator)

C. Seizure control via GABA agonism

D. Increased ACh release

B. Cholinesterase regenerator (AChE reactivator)

Explanation: Pralidoxime is an AChE reactivator that removes the Organophosphate group from the enzyme's active site, but it must be given before the enzyme "ages" (irreversible inhibition).

What common structural feature do all Choline Esters possess that makes them lipid insoluble and results in poor CNS distribution?

A. Ester group

B. Beta-methyl group

C. Quaternary ammonium group

D. Acetyl CoA group

C. Quaternary ammonium group

Explanation: All Choline Esters contain a quaternary ammonium group (four organic groups attached to the nitrogen atom). This positive charge makes the molecules highly polar and lipid insoluble, preventing them from crossing the blood-brain barrier (CNS distribution is poor).

Which structural feature, present in Methacholine and Bethanechol, makes a Choline Ester more selective for Muscarinic (M) receptors?

A. Quaternary ammonium group

B. Beta-methyl group

C. Ester group

D. Chloride group

B. Beta-methyl group

Explanation: The presence of a Beta-methyl group (as in Methacholine and Bethanechol) is a structural modification that confers selectivity for Muscarinic receptors and increases resistance to hydrolysis by AChE.

Which Choline Ester is the prototype for the class but has no clinical use due to its widespread effects and rapid hydrolysis?

A. Bethanechol

B. Carbachol

C. Methacholine

D. Acetylcholine

D. Acetylcholine

Explanation: Acetylcholine is the prototype and primary endogenous transmitter, but its widespread N and M effects and its rapid breakdown by AChE prevent its use as a therapeutic drug.

Which selective Muscarinic agonist is used for the management of urinary retention and bladder/bowel atony?

A. Carbachol

B. Acetylcholine

C. Bethanechol (Urecholine)

D. Nicotine

C. Bethanechol (Urecholine)

Explanation: Bethanechol is a selective Muscarinic agonist (M selective) used to stimulate the M3 receptor on the detrusor muscle of the bladder, causing contraction and relieving urinary retention. It is also used for bowel atony.

Which Choline Ester is primarily used in a pulmonary challenge test to diagnose bronchial asthma (BA)?

A. Acetylcholine

B. Carbachol

C. Methacholine

D. Bethanechol

C. Methacholine

Explanation: Methacholine is used in the pulmonary challenge test (provocative test) because its M3 receptor activation in the lungs readily causes bronchoconstriction in asthmatic patients.

Which non-selective Choline Ester, resistant to AChE hydrolysis, is used specifically for the management of glaucoma?

A. Methacholine

B. Bethanechol

C. Carbachol

D. Acetylcholine

C. Carbachol

Explanation: Carbachol is resistant to AChE breakdown and is used topically for glaucoma, where its M3 action causes miosis and increases aqueous humor outflow.

Which of the following statements about the non-selective Choline Esters is true?

A. They are all highly susceptible to hydrolysis by AChE.

B. They are M selective due to a Beta-methyl group.

C. They bind to both Nicotinic (N) and Muscarinic (M) receptors.

D. They are used for bladder atony after surgery.

C. They bind to both Nicotinic (N) and Muscarinic (M) receptors.

Explanation: The non-selective group (Acetylcholine and Carbachol) binds to both Nicotinic and Muscarinic receptors, unlike the selective group (Bethanechol and Methacholine).

The clinical use of Bethanechol for managing urinary retention is primarily mediated by which Muscarinic receptor subtype?

A. M1 receptor

B. M2 receptor

C. M3 receptor

D. N receptor

C. M3 receptor

Explanation: Bethanechol stimulates the M3 receptor on the detrusor muscle of the bladder, leading to its contraction and subsequent urination (micturition).

Which two Choline Esters are explicitly noted to be resistant to hydrolysis by Acetylcholinesterase (AChE)?

A. Acetylcholine and Methacholine

B. Bethanechol and Methacholine

C. Carbachol and Methacholine

D. Acetylcholine and Carbachol

C. Carbachol and Methacholine

Explanation: Carbachol and Methacholine are both listed as being resistant to AChE hydrolysis, leading to a longer duration of action than Acetylcholine.

The poor CNS distribution of Choline Esters makes them unsuitable for administration via which route?

A. Intravenous

B. Topical (eye drops)

C. Intramuscular

D. Gastrointestinal (GI)

D. Gastrointestinal (GI)

Explanation: Choline Esters are quaternary ammonium compounds, meaning they are poorly absorbed orally (GI administration), which is consistent with the note that they are not for GI administration.

The general class of drugs known as direct acting cholinergic agonists stimulates which two types of cholinergic receptors?

A. Alpha and Beta receptors

B. Muscarinic (M) and Nicotinic (N) receptors

C. Dopamine and Serotonin receptors

D. Gq and Gi receptors

B. Muscarinic (M) and Nicotinic (N) receptors

Explanation: Cholinergic agonists stimulate receptors that respond to Acetylcholine, which are classified as Muscarinic (M) and Nicotinic (N) receptors.

Which direct acting cholinergic agonist is used for the management of glaucoma?

A. Bethanechol

B. Methacholine

C. Varenicline

D. Carbachol

D. Carbachol

Explanation: Carbachol is listed as a cholinergic agonist used in the management of glaucoma, where it promotes miosis and aqueous humor outflow.

Which cholinergic agonist is used specifically for the management of atropine toxicity?

A. Neostigmine

B. Pilocarpine

C. Bethanechol

D. Carbachol

A. Neostigmine

Explanation: Neostigmine is listed as a cholinergic agonist used to manage atropine toxicity. Atropine is a muscarinic antagonist, and Neostigmine, an Acetylcholinesterase inhibitor, increases Acetylcholine to overcome the blockade.

Which cholinergic agonist is used for the management of non-obstructive ileus (reduced peristalsis)?

A. Methacholine

B. Pilocarpine

C. Nicotine

D. Varenicline

B. Pilocarpine

Explanation: Pilocarpine is listed as a cholinergic agonist used for the management of non-obstructive ileus, where its muscarinic agonism stimulates GI smooth muscle contraction.

Which cholinergic agonist is used for the management of urinary retention?

A. Methacholine

B. Bethanechol

C. Physostigmine

D. Echothiopate

B. Bethanechol

Explanation: Bethanechol is listed as a cholinergic agonist used for the management of urinary retention, as it stimulates M3 receptors on the detrusor muscle to promote urination.

Which cholinergic agonist is used as a diagnostic tool in the pulmonary challenge test?

A. Methacholine

B. Neostigmine

C. Carbachol

D. Demecarium

A. Methacholine

Explanation: Methacholine is listed as a cholinergic agonist used in the pulmonary challenge test, where its ability to cause bronchoconstriction is used to diagnose asthma.

Which cholinergic agonist is used for smoking cessation?

A. Pilocarpine

B. Methacholine

C. Varenicline

D. Physostigmine

C. Varenicline

Explanation: Varenicline is listed as a cholinergic agonist used for smoking cessation. It is a partial agonist at nicotinic receptors.

Which cholinergic agonist, listed as being used for GI atony, is also an Acetylcholinesterase inhibitor that can cross the blood-brain barrier (BBB)?

A. Bethanechol

B. Physostigmine

C. Nicotine

D. Carbachol

B. Physostigmine

Explanation: Physostigmine is listed as being used for GI atony. It is an indirect-acting agent (AChE inhibitor) that is uncharged and can therefore cross the BBB.

Which cholinergic agonist is used for the management of GI atony?

A. Neostigmine

B. Physostigmine

C. Bethanechol

D. Nicotine

B. Physostigmine

Explanation: Physostigmine is specifically listed as the cholinergic agonist used for the management of GI atony.

In contrast to Choline Esters, Choline Alkaloids are generally described as being more soluble in what medium, facilitating their absorption and CNS effects?

A. Water

B. Lipid

C. Protein

D. Carbohydrate

B. Lipid

Explanation: Choline Alkaloids are generally more lipid soluble and are well absorbed in most sites, enabling them to cross membranes, although Muscarine is an exception due to its quaternary amine structure.

Choline Alkaloids are chiefly excreted via the renal route. How can the rate of their excretion be enhanced?

A. Through urine alkalization

B. Through bile acid secretion

C. Through urine acidification

D. Through glucuronidation

C. Through urine acidification

Explanation: Since most alkaloids are basic compounds, their renal excretion is enhanced through urine acidification, which keeps the drugs in their ionized, water-soluble form, preventing reabsorption.

Which Choline Alkaloid, due to its quaternary amine group, is noted to be less completely absorbed from the gastrointestinal tract (GIT)?

A. Nicotine

B. Pilocarpine

C. Muscarine

D. Arecholine

C. Muscarine

Explanation: Muscarine is a quaternary amine, which makes it highly polar (lipid insoluble), similar to Choline Esters. This structure is specifically noted to cause less complete GIT absorption.

Which selective Muscarinic alkaloid is sourced from the mushroom Amanita muscaria?

A. Pilocarpine

B. Arecholine

C. Muscarine

D. Nicotine

C. Muscarine

Explanation: Muscarine is the M selective alkaloid derived from the poisonous mushroom Amanita muscaria.

Which selective Muscarinic alkaloid is used to treat glaucoma?

A. Muscarine

B. Nicotine

C. Pilocarpine

D. Lobeline

C. Pilocarpine

Explanation: Pilocarpine is the M selective alkaloid used in the management of glaucoma.

What is the mechanism by which Pilocarpine reduces ocular pressure in the management of glaucoma?

A. Relaxation of the ciliary muscle, reducing humor production

B. Contraction of the circular muscle, causing miosis

C. Contraction of the ciliary muscle fiber, opening the trabecular meshwork to enhance aqueous humor outflow

D. Blocking beta receptors, reducing humor secretion

C. Contraction of the ciliary muscle fiber, opening the trabecular meshwork to enhance aqueous humor outflow

Explanation: Pilocarpine is M selective and causes the contraction of the ciliary muscle, which in turn pulls on and opens the trabecular meshwork, allowing aqueous humor to drain more effectively.

Which Nicotinic selective alkaloid is derived from Nicotiana tabacum?

A. Lobeline

B. Varenicline

C. Cytisine

D. Nicotine

D. Nicotine

Explanation: Nicotine is the N selective alkaloid sourced from the tobacco plant, Nicotiana tabacum.

What is the source of the non-selective cholinergic alkaloid Arecholine?

A. Lobelia inflata

B. Areca catechu (betel nut)

C. Amanita muscaria

D. Pilocarpus jaborandi

B. Areca catechu (betel nut)

Explanation: Arecholine, which binds to both M and N receptors, is sourced from the betel nut (Areca catechu).

Which Nicotinic selective alkaloid is a Cytisine derivative used for smoking cessation?

A. Lobeline

B. Varenicline

C. Pilocarpine

D. Arecholine

B. Varenicline

Explanation: Varenicline is listed as a Cytisine derivative used for smoking cessation. Cytisine, Lobeline, and Varenicline are all N selective agonists used for this purpose.

Which cholinergic alkaloid is used for the management of non-obstructive ileus (along with Physostigmine)?

A. Nicotine

B. Muscarine

C. Lobeline

D. Pilocarpine

D. Pilocarpine

Explanation: Pilocarpine is listed for the management of non-obstructive ileus, where its muscarinic action stimulates GI motility.

What is the primary mechanism of action (MOA) for Indirect Acting Cholinergic Agonists?

A. Direct stimulation of M and N receptors

B. Inhibition of AChE (Acetylcholinesterase)

C. Inhibition of Choline uptake

D. Stimulation of Acetylcholine (ACh) release (Exocytosis)

B. Inhibition of AChE (Acetylcholinesterase)

Explanation: Indirect Acting Cholinergic Agonists, or anticholinesterases, work by inhibiting the enzyme AChE, which increases the concentration and duration of action of ACh in the synaptic cleft.

Which structural class of AChE inhibitors is characterized as Short Acting and is a reversible inhibitor with a duration of action (DOA) of approximately 5-30 minutes?

A. Organocarbamates

B. Organophosphates

C. Aminoalcohols

D. Carbamyl Esters

C. Aminoalcohols

Explanation: Edrophonium is the key short-acting, reversible AChE inhibitor belonging to the Aminoalcohol class, with a very brief DOA (15-30 minutes).

What is the primary clinical use of Edrophonium (Tensilon) and the purpose of the Tensilon Test?

A. Reversal of severe atropine poisoning

B. Treatment of myasthenia gravis (MG)

C. Diagnosis of Myasthenia Gravis (MG) vs cholinergic crisis

D. Antidote for Tubocurarine poisoning

C. Diagnosis of Myasthenia Gravis (MG) vs cholinergic crisis

Explanation: The Tensilon Test uses Edrophonium to rapidly diagnose MG. If muscle strength increases and ptosis decreases, it confirms MG.

Which class of AChE inhibitors is characterized as Intermediate to Long Acting and includes reversible inhibitors with a DOA of 2-8 hours?

A. Aminoalcohols

B. Organophosphates

C. Organocarbamates / Carbamyl Esters

D. Alkaloids

C. Organocarbamates / Carbamyl Esters

Explanation: The Organocarbamates (stigmines) like Neostigmine and Physostigmine are intermediate-acting, reversible AChE inhibitors.

Which Organocarbamate is considered the Drug of Choice (DOC) for reversing Neuromuscular Blocker Toxicity (Tubocurarine poisoning)?

A. Physostigmine

B. Pyridostigmine

C. Edrophonium

D. Neostigmine

D. Neostigmine

Explanation: Neostigmine is the DOC for reversing the effects of non-depolarizing neuromuscular blockers like Tubocurarine due to its peripheral action and ability to increase ACh at the neuromuscular junction.

Which AChE inhibitor is the Drug of Choice (DOC) for the maintenance treatment of Myasthenia Gravis (MG)?

A. Neostigmine

B. Edrophonium

C. Pyridostigmine (Mestinon)

D. Physostigmine

C. Pyridostigmine (Mestinon)

Explanation: Pyridostigmine is the DOC for the long-term management and treatment of Myasthenia Gravis.

Which AChE inhibitor is a tertiary amine that is more lipophilic and used to reverse severe Atropine poisoning (IV route)?

A. Neostigmine

B. Pyridostigmine

C. Physostigmine (Eserine)

D. Demecarium

C. Physostigmine (Eserine)

Explanation: Physostigmine (Eserine) is a tertiary amine, allowing it to cross the BBB and reverse the central CNS effects of Atropine poisoning, which is a major clinical advantage.

The general side effects of AChE inhibitors are summarized by the mnemonic DUMBBELSS. What does the B in the mnemonic represent?

A. Blurred vision and Bowel movement

B. Bradycardia and Bronchial spasm

C. Blood pressure decrease and Bilirubinemia

D. BPH relief and Bowel atony

B. Bradycardia and Bronchial spasm

Explanation: DUMBBELSS stands for Diarrhea, Urination, Miosis, Bradycardia, Bronchial spasm, Emesis, Lacrimation, Salivation, Sweating.

What is the principal/first line treatment for the acute management of cholinergic toxicities?

A. Pralidoxime

B. Diacetyl monoxime

C. Atropine (Antimuscarinic)

D. Benzodiazepines (BZD)

C. Atropine (Antimuscarinic)

Explanation: Atropine is the first line treatment for cholinergic toxicity as it blocks the toxic excess of ACh at the muscarinic receptor sites.

Which drug is a ChE reactivator used in the management of Organophosphate (OP) poisoning if administered within 24-48 hours of exposure?

A. Atropine

B. Pralidoxime

C. Physostigmine

D. Edrophonium

B. Pralidoxime

Explanation: Pralidoxime (and Diacetyl monoxime) are ChE reactivators used for OP poisoning. They physically remove the OP group from the enzyme, restoring its function, but must be given before the ChE "ages" irreversibly.

What is the structural classification and duration of action (DOA) of the Very Long Acting Anticholinesterases?

A. Aminoalcohols; 5-30 minutes

B. Organocarbamates; 2-8 hours

C. Organophosphates; Irreversible (>24 hours)

D. Choline Esters; Irreversible (>24 hours)

C. Organophosphates; Irreversible (>24 hours)

Explanation: Organophosphates (OPs) are the structural class that causes Irreversible inhibition of AChE, leading to a very long duration of action (>24 hours).

What is the primary medically useful application of the Organophosphates Echothiopate and Isofluorophate?

A. Diagnosis of Myasthenia Gravis

B. Treatment of Atropine Toxicity

C. Management of Glaucoma

D. Reversal of Neuromuscular Block

C. Management of Glaucoma

Explanation: Echothiopate and Isofluorophate were used topically for Glaucoma due to their strong, long-lasting M3 agonism, which enhances aqueous humor outflow.

Which two Organophosphates are used as Insecticides and function as prodrugs that must be metabolized into their active forms (Malaoxon and Paraoxon)?

A. Tabun and Sarin

B. Echothiopate and Isofluorophate

C. Malathion and Parathion

D. Sarin and Soman

C. Malathion and Parathion

Explanation: The Insecticides Malathion and Parathion are inactive prodrugs that require metabolic conversion to the active malaoxon and paraoxon to inhibit AChE.

What is the process called when the Organophosphate (OP) inhibitor forms a covalent bond with the serine residue of AChE, resulting in the Irreversible Inhibition of the enzyme?

A. Hydrolysis

B. Acetylation

C. Aging

D. Reactivation

C. Aging

Explanation: Aging is the process where the bond between the OP and the AChE active site becomes chemically modified over time (>48 hours), making it permanently bound and the enzyme functionally irreversible.

What are Tabun, Sarin, and Soman primarily classified as, based on their extremely potent AChE inhibitory effects?

A. Insecticides

B. Nerve gases

C. Pharmaceuticals for Glaucoma

D. Anti-Alzheimer's agents

B. Nerve gases

Explanation: Tabun, Sarin, and Soman are highly toxic Organophosphates designated as Nerve gases, which cause rapid and overwhelming cholinergic toxicity.

Neurotoxins derived from 4o Amines, such as spider venom, interfere with ACh transmission by which mechanism?

A. Inhibiting AChE breakdown

B. Blocking ACh receptors

C. Promoting the release of ACh

D. Inhibiting Choline uptake

C. Promoting the release of ACh

Explanation: 4o Amine neurotoxins (like alpha-latrotoxin in black widow venom, which is a 4o Amine stimulant of ACh release) cause a massive release of ACh (Exocytosis).

The Centrally Acting Cholinergic Agonists are primarily used to treat which neurological condition?

A. Parkinson's disease

B. Huntington's chorea

C. Alzheimer's dementia

D. Myasthenia Gravis

C. Alzheimer's dementia

Explanation: Alzheimer's dementia is characterized by cholinergic deficiency in the CNS, which is treated symptomatically by these CNS-acting cholinesterase inhibitors.

What is the primary mechanism of action (MOA) of Tacrine, Donepezil, Galantamine, and Rivastigmine in treating Alzheimer's disease?

A. NMDA receptor antagonism

B. CNS-acting cholinesterase inhibition

C. Inhibition of beta-amyloid production

D. Stimulation of Nicotinic receptors

B. CNS-acting cholinesterase inhibition

Explanation: These drugs are lipophilic AChE inhibitors that cross the BBB to increase the concentration of Acetylcholine (ACh) in the brain's synapses, counteracting the cholinergic deficit.

Which drug used for Alzheimer's disease has a different mechanism of action, specifically NMDA antagonism?

A. Tacrine

B. Donepezil

C. Rivastigmine

D. Memantine

D. Memantine

Explanation: Memantine works by antagonizing NMDA receptors, which modulates glutamatergic neurotransmission, rather than inhibiting AChE.

Myasthenia Gravis (MG) is an autoimmune condition where antibodies target which specific receptor subtype?

A. M1 receptor

B. Nn receptor

C. Nm receptor

D. alpha1 receptor

C. Nm receptor

Explanation: MG is characterized by antibodies targeting the Nicotinic Muscular (Nm) receptors at the neuromuscular end plate, leading to muscle weakness.

What is the initial and the final characteristic sign/symptom of Myasthenia Gravis?

A. Initial:Diaphragmatic weakness; Final:Ptosis

B. Initial:Ptosis and late afternoon muscle weakness; Final:Diaphragmatic weakness

C. Initial:Tremors; Final:Seizures

D. Initial:Urinary retention; Final:Constipation

B. Initial:Ptosis and late afternoon muscle weakness; Final:Diaphragmatic weakness

Explanation: MG often presents initially with ptosis and muscle weakness that worsens over the day, and it culminates in life-threatening diaphragmatic muscle weakness.

Which class of drugs (e.g., Neostigmine, Pyridostigmine) is used to improve muscle strength in the treatment of Myasthenia Gravis?

A. NMDA antagonists

B. AChE Inhibitors

C. Non−DHP CCBs

D. Alpha blockers

B. AChE Inhibitors

Explanation: AChE Inhibitors increase the concentration of ACh at the Nm receptor, allowing the few remaining functional receptors to be stimulated more effectively, thereby improving muscle strength.

The side effects of cholinergic agonists are summarized by the DUMBBELS mnemonic. What does D, U, and M represent?

A. Dizziness, Ulceration, Mydriasis

B. Diarrhea, Urination, Miosis

C. Dyskinesia, Urticaria, Muscle contraction

D. Diaphoresis, Upset stomach, Mouth dryness

B. Diarrhea, Urination, Miosis

Explanation: DUMBBELS covers: Diarrhea, Urination, Miosis, Bronchoconstriction, Bradycardia, Emesis, Erection, Lacrimation, Lethargy, Sweating, Salivation, Secretions.

Severe Anticholinergic toxicity (e.g., Atropine poisoning) is often associated with the phrase "Alice in Wonderland Syndrome." Which symptom corresponds to the phrase "Blind as a bat"?

A. Cutaneous vasodilation (Red as a beet)

B. Decreased sweating (Dry as a bone)

C. Mydriasis and increased intraocular pressure

D. CNS effects (Mad as a hatter)

C. Mydriasis and increased intraocular pressure

Explanation: Anticholinergics block M3 on the circular muscle, leading to unopposed dilation (Mydriasis) and a risk of acute narrow-angle glaucoma (Blind as a bat).

What is the overall effect of anticholinergics on the bladder and exocrine glands that leads to the symptom "Full as a flask"?

A. Bronchodilation and secretion increase

B. Urinary retention and decreased secretions

C. Increased bowel motility and diarrhea

D. Increased heart rate and salivation

B. Urinary retention and decreased secretions

Explanation: Anticholinergics block M3 on the Detrusor muscle, causing urinary retention (Full as a flask), and decrease secretions (Dry as a bone).

What is the MOA of Pralidoxime (2−PAM), the antidote used for Organophosphate (OP) poisoning?

A. Muscarinic receptor blockade

B. Cholinesterase regenerator (AChE reactivator)

C. Seizure control via GABA agonism

D. Increased ACh release

B. Cholinesterase regenerator (AChE reactivator)

Explanation: Pralidoxime is an AChE reactivator that removes the Organophosphate group from the enzyme's active site, but it must be given before the enzyme "ages" (irreversible inhibition).