Cholinoceptor Activating and Cholinesterase INhibiting drugs Flashcards by Nancy Urayani

Cholinomimetic (direct-acting, muscarinic) that Act on both M and N receptors. Activates M1-M3
receptors in all peripheral tissues.

Acetylcholine

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no Nicotinic action, resistant to

AChE, just like carbachol and bethanechol)

Methacholine

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Results to increased secretion, smooth muscle contraction (except in vascular smooth muscles where it causes relaxation) and changes in heart rate; very short-lived duration of action: 5-30sec, rapidly hydrolyzed by AChE

Acetylcholine

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Cholinomimetic (direct-acting, muscarinic that act on both muscarinic and nicotinic
action

Carbachol

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Activates muscarinic (M1-M3) receptors. Act on M
receptors only.
It is used for Bladder and bowel atony (post-surgery or spinalcord injury), Congenital megacolon

Betanechol

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are carbamic acid estersand are resistant to hydrolysis of AChE,

Betanechol and Carbachol

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used for glaucoma, used as miotic.

CArbachol

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an indirect acting cholinomimetic and is also

another drug useful for bladder and bowel atony.

Neostigmine

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Precaution using cholinimimetics

you must be certain that your patient doesn’t have mechanical obstruction to outflow. Because administration of cholinomimetics in a patient with bladder and bowel atony will worsen obstruction.

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Activates muscarinic (M3) receptors in ciliary muscle
(causing contraction of ciliary body to facilitate
aqueous humor outflow and diminish its rate of
secretion) and salivary glands (increasing salivation)

PILOCARPINE

CEVIMELINE [C] (M3 selective)

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Treatment Glaucoma, Sjögren syndrome, Sicca syndrome

PILOCARPINE

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SE of Pilocarpine

Miosis, Blurring of vision (due to cyclospasm),

Increased salivation, Hypertension

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Interesting exception to the rule for

pilocarpine

for Pilocarpine, hypertension maybe seen

after a brief period of hypotension due to the activation of sympathetic postganglionic M1 receptors

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What is Sjorgen Syndrome

autoimmune disorder characterized by triad of
• Xerostomia (Dry Mouth)
• Xerophthalmia (Dry Eyes)
• Rheumatoid Arthritis

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Selective partial agonist at nicotinic

receptors; DOA 12-24h

VArenicline

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NIcotine as drug

MOA: Activates nicotinic Ach receptors (Nn and Nm)
Uses: Smoking Cessation
SE: Generalized ganglionic stimulation (hypertension,
tachycardia, nausea, vomiting, diarrhea)

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Type of mushroom that can cause MUscarinic toxicity

mushrooms (genus: Inocybe)

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Sign and symptoms for Muscarinic toxicity

• CNS stimulation
• EYE: miosis, spasm of accommodation
• LUNGS: bronchoconstriction
• GIT/GUT: excessive gastrointestinal and genitourinary smooth muscle activity
• Increased secretory activity (sweat glands, airway,
gastrointestinal tract, lacrimal glands)
• Vasodilation

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Treatment for Muscarinic Activity

Atropine (Cholinergic antagonist)

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Sign and symptoms for Nicotinic toxicity

• blockade of neuromuscular end plate depolarization
o leading to fasciculations and paralysis
• CNS toxicity: stimulation (convulsions) followed by CNS depression

Remember sympathetic, parasympathetic and neuromuscular junctions
are ALL affected)

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Treatment for Nicotinic TOxicity

symptom directed:
•atropine for muscarinic excess,
•diazepam and anticonvulsants for CNS stimulation, •mechanical ventilation if with neuromuscular blockade

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Examples of INDIRECT-ACTING CHOLINOMIMETICS

Neostigmine
Pyridostigmine
Physostigmine
AMBENONIUM [C],
DEMECARIUM [CARBAMATES] [C], 
ECHOTHIOPHATE [ORGANOPHOSPHATE]
RIVASTIGMINE [B]
GALANTAMINE [B]
DONEPEZIL [C]
TACRINE [C]

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Cholinomimetic (indirect-acting) for diagnosis – Tensilon test. Differentiation of cholinergic crisis and myasthenic crisis (see note below for explanation) , Reversal of neuromuscular blockade

Edrophonium

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Myasthenia gravis (treatment) and Reversal of
nondepolarizing neuromuscular blockade

Study These Flashcards

Neostigmine

Among all indirect acting cholimimetics, which has a good lipid solubility

Physostigmine: good lipid solubility: able to enter the CNS because of its tertiary amine structure, DOA: 4-8h

When reversing the effects of non-depolarizing neuromuscular blockers with neostigmine or edrophonium, why do we need to coadminister ATROPINE?

To counteract the bradycardia associated with giving an indirect acting cholinomimetic

Nerve gases

Sarin, Tabun, Soman: Nerve Gases

What is myasthenia gravis?

``` An autoimmune destruction of nicotinic ACh receptors, characterized by: • fluctuating muscle • weakness • ocular symptoms • bulbar symptoms • proximal muscle weakness ```

Myasthenia gravis patients are sensitive to which drug class, that when given, may actually worsen their condition?

Nondepolarizing neuromuscular blockers (because the mechanism of the disease and its MOA are similar), Aminoglycoside antibiotics (because these drugs interfere with neuromuscular transmission)

Differentiate myasthenic crisis from cholinergic crisis

MYASTHENIC CRISIS • acute worsening of symptoms due to infection, stress or UNDERmedication CHOLINERGIC CRISIS • excessive activation of cholinoceptors (skeletal muscleweakness and parasympathetic signs) due to OVERmedication

How does EDROPHONIUM differentiate myasthenic crisis from cholinergic crisis?

* IMPROVES muscle strength in myasthenic crisis | * WEAKENS muscle strength in cholinergic crisis

Cholinomimetic (indirect-acting) used for Alzheimers

•Rivastigmine is available as transdermal patch •Donepezil is combined with Memantine (NMDA antagonist) for Alzheimer’s dementia

What are the signs and symptoms of organophosphate | poisoning?

``` Diarrhea Urination Miosis Bradycardia Bronchospasm Excitation (skeletal muscle and CNS) Lacrimation Sweating Salivation ```

NMDA receptor blocker; used for | moderate to severe Dementia

Memantine

Antidote for organophosphate poisoning (first choice) which completely blocks all muscarinic receptors

Atropine

Notorious for causing hyperthermia in susceptible | patients (because Atropine suppresses thermoregulatory sweating).

Atropine

Direct acting Muscarinic Agonist: cholinomimetics big responses are as follows:

1) a decrease in heart rate 2) increase in secretion and 3) increase in smooth muscle contraction (e.g. diarrhea and urinary incontinence)

Properties of INdirect Cholinomimetics

Acetylcholinesterase inhibitors: Indirect-acing cholinomimetics • they will not reach the blood vessels (they purely act on innervation) • they also stimulate nicotinic receptors

Muscarinic Antagonists for Parkinsonism

``` “Tri (try) to Park your BENZ, BIP (beep) here.” • TRIhexyphenidyl • BENZtropine • BIPeriden • PARK is for Parkinson’s disease ```

Difference between Cycloplegia and Mydriasis

C = Cycloplegia = Ciliary muscle paralysis = loss of Accommodation Mydriasis = Dilate (or you dilate your mouth when you say mydriasis)

Addresses BOTH Nicotinic and Muscarinic symptoms. Must be administered before 6-8 hours of organophosphate bond with cholinesterase occurs (before the bond has AGED or turned covalent, which is a stronger bond); has oxime group which has high affinity for phosphorus

Pralidoxime

T/F the role of your cholinergic antagonists in PArkinsons dse is to improve tremors

TRUE

It is Cholinergic antagonist (muscarinic) which Competitively blocks ALL muscarinic receptors and Antagonizes histamine and serotonin. It is used in Motion sickness, decrease acid secretion in GIT, Nausea and Vomiting

Scopalamine / Hyoscine (transdermal patch )

It is an M receptor antagonist which Blocks muscarinic receptors in bronchial smooth muscle and Prevents vagal stimulated bronchoconstriction Used Acute Asthma, COPD

Ipratropium

Advantage of Ipratropium compared to SABA

Less toxic than beta-agonists (LESS TACHYCARDIA | → LESS ARRHYTHMIA) in patients with COPD

It does not cross the BBB, and consequently has none to few central effects. It may be used as a monotherapy as maintenance for COPD. It may also be used as an anti-spasmodic and reduce salivation with some anesthetics

GLYCOYRRONIUM [B]

Competitively blocks M3 receptors. | Uses IBS, minor diarrhea, decrease acid secretion in GIT

DICYCLOMINE [B] HYOSCYAMINE [B], GLYCOPYRROLATE [B]

Slightly blocks M3 receptors. Reduces Detrusor muscle tone. Used in Urge incontinence, Post-operative spasms

Oxybutinin

Atropine Toxicity

* Atropine fever (hyperthermia) * Atropine flush (cutaneous vasodilation) * Decreased secretions * Tachycardia * Arrhythmias (intraventricular conduction block) * Constipation * Blurred vision * CNS toxicity

Treatment of Atropine TOxicity

Treatment: Symptomatic o Temperature control: use of cooling blankets o Seizure control: Diazepam o Physostigmine

Atropine Toxicity

* HOT as a hare (hyperthermia) * DRY as a bone (decreased secretion) * RED as a beet (cutaneous vasodilation) * BLIND as a bat (cycloplegia) * MAD as a hatter (CNS toxicity)

CONTRAINDICATIONS TO MUSCARINIC | BLOCKERS

• cautious use in infants (since they are sensitive to the hyperthermic effects of atropine) * acute angle-closure glaucoma (since mydriasis can block the normal drainage of aqueous humor) * benign prostatic hyperplasia (can precipitate further urinary retention already present in this subgroup because muscarinic antagonists will relax smooth muscle of the ureters and bladder wall)

``` Cholinergic antagonist (nicotinic) Competitively blocks Nn nicotinic ACh receptors Uses Hypertension (obsolete), Hypertensive emergencies ```

HEXAMETHONIUM [D] TRIMETHAPHAN, [D] MECAMYLAMINE [C]

Example of Depolarizing Neuromuscular blocker

Kapag nakapagDEPOsit ka sa toilet, SUCCess yun! | DEPOlarizing = SUCCinylcholine

Exampple of NONDEPOLARIZING Neuromuscular blocker

NONDEPOLARIZING (Tubocurarine, Pancuronium, | Atracurium, Vecuronium)

Synthesis of Acetylcholine is inhibited by

Hemicholinium

Storage of Acetylcholine is inhibited by

vesamicol

Release of Acetylcholine is inhibited by

botolinum toxin

Cholinoceptor Activating and Cholinesterase INhibiting drugs Flashcards

(58 cards)