L2 Cholinergic Agents (Exam #1) Flashcards by Kyle Campbell

What are the three muscarinic agonists and what is the MOA for all three?

MOA: non-specific (work on N and M receptors)

Acetylcholine
Bethanechol (Urecholine)
Pilocarpine (Isoptocarpine)

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What are three general contraindications for muscarinic agonists?

Asthma/COPD
Peptic ulcer
Bowel obstruction

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What symptoms are associated with muscarinic toxicity/poisoning?

Salivation
Lacrimation
Urination
Defecation
Gastric distress
Emesis/vomiting

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What two medications can be used to treat muscarinic toxicity/poisoning?

Atropine (antagonist)

- Albuterol (B-agonist)

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Which medication has no real clinical use because of its short half-life? What CAN it be used for occasionally?

Acetylcholine has a very short half-life but it can be used IV to decrease BP

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What are the two primary uses associated with Bethanechol (Urecholine)?

Increase GI motility

- Treat urinary retention

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What is one system that is not affected by Bethanechol (Urecholine), and why?

CNS is unaffected because Bethanechol cannot cross the BBB

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What are the two primary uses associated with Pilocarpine (Isoptocarpine)?

Oral: xerostoma/dry mouth

- Topical: treat closed angle glaucoma

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What are the three primary SEs associated with Pilocarpine (Isoptocarpine)?

Sweating (oral)
Blurred vision (topical)
HA/browache (both)

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What is the tissue order by which Atropine affects PNS tone from most to least?

MOST AFFECTED (highest PNS tone, lowest Atropine dose needed)
- Salivary, sweat glands, lungs
- Heart, eyes
- GI, GU
- CNS
LEAST AFFECTED (lowest PNA tone, highest Atropine dose needed)

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What are the two primary uses of Atropine?

Decrease bradycardia due to reverse heart block OR excessive vagal stimulation
Block muscarinic effects (i.e. pesticide/nerve gas poisoning, mushroom poisoning)

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What condition is treated with a combination drug involving Atropine and an opioid, and what is this combination drug called?

Lomotil treats diarrhea

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What two systems does Atropine have little effect on, and why?

Blood vessels: no PNS

- CNS: cannot cross BBB

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What is the primary use of Scopolamine (Transderm Scop), and what does this say about its pharmacokinetics/MOA?

Relieves motion sickness

- Good CNS penetration/can cross BBB

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What are two primary SEs associated with Scopolamine (Transderm Scop)?

Drowsiness

- Hallucinations (toxic dose)

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What are two primary uses of Tropicamide (Mydriacil)?

Mydriasis (for eye exams)

- Cycloplegia

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What is the primary use of Ipratropium (Atrovent)? What is another possible use?

Primary: COPD to reverse bronchoconstriction (cause bronchodilation)
- Can also be used for acute asthma attacks

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What is the primary use of Tolterodine/Fesoterodine, Darifenacin/Solifenacin? What is specific to this group of medications?

Treat overactive bladder

- GREAT M3 receptor specificity

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What is the primary use of Oxybutynin (Ditropan)?

Treat bladder spasms

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What is the primary use of Dicyclomine (Bentyl), and what specific condition is it used to treat?

Reduces abdominal cramping (reduce GI wall contraction)

- Treats diarrhea-predominant IBS

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What is the primary MOA of OnabotuliniumtoxinA (Botox)?

Blocks ACh release

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What are three potential uses of OnabotuliniumtoxinA (Botox)?

Not often used because $$$ but:

Urinary incontinence in patients refractory to antimuscarinics
Chronic migraine prophylaxis
Wrinkles

What is the primary AE associated with OnabotuliniumtoxinA (Botox)?

Asthenia (speech, swallowing, numbness, ptosis)

What are the two primary CIs associated with muscarinic antagonists?

Closed angle glaucoma (closes angle which increases IOP)

- BPH

What are the seven primary AEs associated with muscarinic antagonists?

- Dry mouth - Dry eyes - Mydriasis - Cycloplegia - Increase HR - Decrease GI motility - Urinary retention

What is the phrase associated with the symptoms of Atropine poisoning?

"Hot as a hare, dry as a bone, blind as a bat, red as a beet, mad as a hatter"

What are the six symptoms associated with Atropine poisoning?

- Hot/dry skin - Urinary retention, constipation - Pupils dilated, poor vision - Agitation, delirium, dementia - Tachycardia - CV/Resp. issues

What is the primary treatment for Atropine poisoning, and why?

Supportive care and Physostigmine (increase ACh levels in brain)

How do receptors differ between muscarinic and nicotinic?

- Muscarinic: primarily PNS (except glands) | - Nicotinic: SNS AND PNS, as well as brain and NMJ

What characteristic is specific to nicotinic receptors?

They are ligand-gated Na+ channels that rapidly desensitize

How does nicotinic activity effect the brain (hint: low (2) vs. high (4) vs. toxic doses(2))

- Low: increase alertness and attention - High: N, V, tremor, increase breathing - Toxic: convulsions, seizures

How does nicotinic activity effect SNS (2)?

- HTN | - Increase HR alternating with decrease HR (baroreflex)

How does nicotinic activity effect PNS (4)?

- N - V - D - Urination

How does nicotinic activity effect NMJ, and what can this potentially lead to?

Muscle twitch/contraction leads to depolarizing block (with possible paralysis if persistent)

What is the primary MOA of Varenicline (Chantix), and how does this occur?

Partial agonist of N receptors (stimulates reward system in brain by releasing DA)

What is the primary use of Varenicline (Chantix), and how does this occur?

Smoking cessation - When smoking is stopped, less DA is released so cravings increase BUT Chantix decreases cravings and provides some N stimulation (can block some N if smoking continues)

What are the five primary AEs associated with Varenicline (Chantix)?

- N - V - Nightmares - Psychosis - SI

What is the general MOA of all AChE inhibitors?

Inhibit ACh breakdown, resulting in high levels of ACh in synaptic cleft and increased ACh receptor activation

What are the three primary uses of Neostigmine/Pyridostigmine?

- Myasthenia Gravis - Reverse NM blockade - Post-op ileus

What is the primary use of Physostigmine, and why does this occur?

Treat muscarinic antagonist (Atropine) poisoning | - Enters CNS so able to help the brain

What are the two primary uses of Edrophonium?

- Diagnose and determine treatment dose for Myasthenia Gravis - Reverse NM blockade

How is Edrophonium used to diagnose Myasthenia Gravis?

- If patient strength improves, diagnose with MG and increase dose - If patient strength worsens, dose may need to be adjusted (too high)

What is the primary use of Donepezil (Aricept)?

Treat Alzheimer's disease

What is enzyme "aging", and what type of poisoning is it associated with?

Organophosphate poisoning | - Within 3-4 hours of poisoning, covalent bond formed between organophosphate and AChE becomes irreversible

What are the general toxicities associated with Organophosphates (5)?

Similar to M Agonist toxicity - SLUDGE - Bradycardia - Hypotension - CNS effects (confusion, ataxia, slurring, convulsions, coma) - NM stimulation → blockade → paralysis → respiratory arrest → death

What is the treatment for Organophosphate poisoning (hint: 3 parts)?

1. Atropine until pupils dilate 2. 2-PAM IF LESS THAN 3-4 HOURS 3. Diazepam (Valium) for convulsions

Why can 2-PAM only be administered within 3-4 hours of poisoning? What must be confirmed prior to administering 2-PAM?

2-PAM is able to attract the organophosphate from AChE before "aging" can occur (but must be prior to aging) - Must confirm that it is Organophosphate-specific poisoning because 2-PAM can also inhibit AChE itself

What is the primary use of nondepolarizing blockers, and in what order does this occur? Is there CNS penetration?

Paralyze muscles during surgical procedures - Starts with small muscles → larger muscles → IC muscles/diaphragm - NOTE: recovery occurs in reverse order NO CNS PENETRATION (does not cross BBB)

What is the MOA of Succinylcholine (hint: 2 parts)?

Initial stimulation and contraction → receptor desensitization and blocked = paralysis

What are three significant PK characteristics of Succinylcholine, and how does this relate to its use?

- IV only - Rapid onset of action - Rapid recovery Used for rapid, short-acting procedures like tracheotomy or intubation

What are the two primary AEs associated with Succinylcholine, and why does each occur?

- Hyperkalemia leading to cardiac arrest, arrhythmias (issue in burn patients, soft tissue damage because already hyperkalemic) - Malignant hyperthermia due to muscle rigidity and high temperature

What are the three primary CIs associated with Succinylcholine?

- History of malignant hyperthermia - Extensive soft tissue damage - Burns

What drug is associated with possible malignant hyperthermia, and how is this treated?

Succinylcholine can cause malignant hyperthermia with repeated doses - Treat with Dantrolene