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Cholinergic Agonists and Acetylcholinesterase Inhibitors

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72 Questions

What are cholinergic agonists also known as?

Parasympathomimetics or muscarinic agonists

How can the effects of cholinergic agonists be achieved?

By either direct agonist effect or by preventing the breakdown of ACh by AChE

What is the main difference between the desired drug action and the adverse drug reactions (ADRs) of cholinergic agonists?

The desired drug action targets a specific organ, while the ADRs affect other organs

Which category of cholinergic agonists includes nicotine as the prototypical drug?

Ganglionic stimulants

Where are muscarinic receptors located?

In the eye, heart, blood vessels, lung, GI tract, urinary bladder, and sweat glands

How do muscarinic agonists modify organ function?

By both activating muscarinic receptors on target organs and inhibiting the release of neurotransmitters from nerve terminals

Which of the following is a characteristic of bethanechol?

It increases the tone of the detrusor urinae muscle.

Which of the following is a reason bethanechol is contraindicated in patients with peptic ulcer disease?

It can cause excessive secretion of gastric acid.

Which of the following is a characteristic of ACh (Miochol)?

It is highly susceptible to cholinesterase.

Which of the following is a use of pilocarpine?

Treating glaucoma.

Which of the following is a characteristic of the pharmacokinetics of bethanechol?

Its effects peak in 60 minutes for the oral dose.

Which of the following is a reason bethanechol is contraindicated in patients with urinary tract obstruction?

It can increase pressure within the urinary tract.

Which of the following is a characteristic of carbachol?

It acts at both muscarinic and nicotinic receptors.

Which of the following is a characteristic of the pharmacokinetics of bethanechol?

Its effects are more prolonged than those of ACh.

Which of the following is a reason bethanechol is contraindicated in patients with bronchospastic disorders?

It can stimulate muscarinic receptors in the lungs, resulting in bronchoconstriction.

Which of the following is a characteristic of methacholine (Provocholine)?

It is active at muscarinic receptors only.

What is the primary contraindication for bethanechol?

Cardiovascular disease

How does bethanechol affect heart rate and blood pressure in patients with hyperthyroidism?

It causes increased heart rate due to increased NE release.

What is the recommended route of administration for atropine as an antidote for bethanechol toxicity?

Subcutaneous

Which of the following drugs should not be taken concurrently with bethanechol?

All of the above

What is the recommended initial oral dose of bethanechol for urinary retention?

10-50 mg

What is the recommended initial subcutaneous dose of bethanechol for urinary retention?

2.5 mg

How should the patient take bethanechol to avoid nausea and vomiting?

Take 1 hour before or 2 hours after meals

What is the maximum single dose of atropine recommended for children under 12 years old for bethanechol toxicity?

0.4 mg

What adverse reactions may occur with bethanechol administration?

All of the above

What is the primary use of bethanechol in primary care?

Treatment of urinary retention due to neurogenic atony of the bladder

What percentage of the population has a genetic variation that leads to reduced levels of activity of CYP 2D6?

7%

What percentage of the dose of galantamine is excreted unchanged in the urine?

20%

What is the total renal elimination percentage for galantamine?

95%

What is the recommended maximum daily dose of galantamine for patients with moderate hepatic impairment or moderate renal impairment?

16 mg/day

What is the mechanism of metabolism for rivastigmine?

Primarily by cholinesterase-mediated hydrolysis

How does moderate renal impairment affect the clearance of rivastigmine?

Decreases clearance by 64%

What is the primary route of elimination for memantine?

Renal excretion

What is the Pregnancy Category for donepezil?

Category C

What is the Pregnancy Category for rivastigmine and galantamine?

Category B

What is the Pregnancy Category for memantine?

Category B

In patients with hepatic impairment, how should donepezil be dosed?

Donepezil should be titrated to response and tolerability

What is the recommended dosage of memantine for patients with CrCl between 5 and 29 mL/min?

The dosage should not exceed 14 mg

Which of the following adverse reactions is commonly associated with the use of cholinergic agonists and cholinesterase inhibitors?

All of the above

Which of the following is true regarding the adverse reactions associated with donepezil, galantamine, and rivastigmine?

They are well tolerated, with few adverse reactions

What is the recommended treatment for cholinergic-associated adverse reactions?

Temporarily reducing the dose or taking the drug with meals

What is the main reason why cholinergic agonists and cholinesterase inhibitors should be used with caution in patients with a history of bronchospastic disorders?

They can exacerbate bronchospastic symptoms

Which of the following drug interactions is considered unacceptable for cholinergic agonists and cholinesterase inhibitors?

Suppression of warning symptoms of overdose with atropine and belladonna derivatives

Why are cholinergic agonists thought to have some potential to cause generalized seizures?

They can increase cholinergic activity in the brain

Which of the following is true regarding the metabolism of donepezil and galantamine?

They undergo significant metabolism by the CYP enzyme systems of the liver

In patients with renal impairment, what is the recommended dosing for donepezil?

No dosage adjustments are recommended

What effect does erythromycin have on the bioavailability of galantamine?

Increases it due to inhibition of CYP 3A4

Which enzyme inhibition causes an increase in the AUC of galantamine when taken with paroxetine?

CYP 2D6

What effect do drugs that make urine alkaline have on the renal clearance of memantine?

Decrease renal clearance

Which drugs interact with memantine due to shared renal cation exchange system for clearance?

Loop diuretics

What is the mainstay treatment for myasthenia gravis?

Neostigmine and pyridostigmine

How is the optimal dose for neostigmine and pyridostigmine in myasthenia gravis typically established?

By administering small initial doses followed by titration to an optimal dose

What is the primary mechanism of action for cholinesterase inhibitors?

They prevent the degradation of ACh by acetylcholinesterase (AChE)

Which of the following is NOT a reversible cholinesterase inhibitor?

Organophosphate cholinesterase inhibitors

Which of the following statements about memantine (Namenda) is correct?

It is a cholinesterase inhibitor used to treat Alzheimer's disease

What is the primary mechanism by which reversible cholinesterase inhibitors increase acetylcholine levels?

They bind to the active center of AChE, preventing the breakdown of ACh

Which of the following statements about donepezil (Aricept) is correct?

It is a piperidine-type AChE inhibitor with increased affinity for the CNS

What is the primary mechanism by which cholinesterase inhibitors can increase the risk of adverse effects?

They can intensify ACh activity at all cholinergic junctions (muscarinic, ganglionic, and nicotinic)

Which of the following statements about rivastigmine (Exelon) is correct?

It is a potent selective inhibitor of AChE in the cortex and hippocampus

Which of the following is NOT a potential adverse effect of cholinesterase inhibitors?

Increased production of AChE

Which of the following statements about irreversible cholinesterase inhibitors is correct?

They are found in pesticides and chemical weapons

What is the primary reason for using cholinesterase inhibitors in the treatment of Alzheimer's disease?

Alzheimer's disease is associated with profound cholinergic depletion

What accounts for the decreased number of peripheral cholinergic ADRs of the drug, like donepezil?

The drug's selectivity for the brain

How does the drug's carbamate structure affect its binding to AChE?

It results in slower dissociation from AChE compared to ACh

What type of inhibitor of AChE is this drug considered to be?

Pseudo-irreversible

How does the drug's plasma half-life compare to the duration of AChE inhibition?

The plasma half-life is shorter than the duration of AChE inhibition

What additional mechanism of action does galantamine have besides AChE inhibition?

Enhancing the effect of ACh on nicotinic receptors

How does the progression of Alzheimer's disease affect the efficacy of these cholinergic drugs?

The drugs become less effective as the disease progresses

What is the primary mechanism of action of memantine in the treatment of Alzheimer's disease?

Noncompetitive antagonism of NMDA receptors

How does the bioavailability of rivastigmine compare to donepezil and galantamine?

Rivastigmine has lower bioavailability due to a significant first-pass effect

How are neostigmine and pyridostigmine primarily eliminated from the body?

Primarily as unchanged drug in the urine

How is donepezil primarily metabolized?

Primarily by CYP 2D6 and 3A4 isoenzymes in the liver

Learn about the pharmacological agents that promote or mimic the action of acetylcholine (ACh) either through direct agonist effects or by inhibiting acetylcholinesterase (AChE). Understand how these drugs affect various organs and their therapeutic applications.

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