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ANS Rx - Ms
ANS rx - muscarinic agonists and blockers
35
Pharmacology
Undergraduate 2
11/20/2011

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Cards

Term
Adverse Reactions of Cholinergic Agonists
Definition

Miosis

Diaphoresis & Flushing

Salivation

Nausea and Abdominal pain

↓BP & HR

Bronchospasm

Diarrhea

Urinary urgency

Term

Direct Acting Cholinergic Agonists

(3 mechanisms and examples)

Definition
  1. Choline Esters
    • ACh
    • Methacholine
    • Bethanechol
    • Carbachol
  2. Plant alkaloids
    • Pilocarpine
  3. Other
    • Cevimeline
Term
ACh
Definition

Direct acting cholinergic agonist

↓ HR + CO (by dec. SA firing)

M3 ->NO -> vasodilation

Salivation + Int secretions + GIm + urination

Ciliary ms contraction + pupillae sphincter ms contraction -> miosis

Tx: No use (AChE is fast)

Term

Methacholine

Definition

R: Muscarinic

 

M: dec. HR + CO via dec. SA firing

Bronchoconstriction

 

Tx: Dx of Asthma

 

SE: Lightheadedness, Headaches, Pruritus

 

 

Term

Bethanechol

Definition

R: Strong muscarinic

 

M: Inc. GIm + tone

GU -> +detrussor ms, -trigone, -sphincter -> inc. urination

 

Tx: inc. GI/GU (post-op, post-partum, Rx related)

 

SE: General cholinergic adverse effects (seperate card)

- Atropine --> reverse CVS and Resp effects

Term

Carbachol

Definition

R: Muscarinic and Nicotinic

 

M: +ganglin --> 1st stimulate then represses CVS/GIS

Release Epi from A. Medulla (N receptor)

Eye - miosis + accommodation

 

Tx: Glaucoma (pupillary contraction -> intraocular P dec.)

Miosis during Sx

 

SE: Diffused Nicotinic action (so no systemic)

Topical -> dec. or no SE

Term
Pilocarpine
Definition

A plant alkaloid (direct acting)

R: Muscarinic agonist

M: Eye - miosis - contraction of ciliary ms (dec. Pio)

- inc. Aq Humor draining

Secretogogue - inc. secretion (sweat, saliva, tears)

Tx: Glaucoma

inc. Pio (Rx of choice)

myodriasis from atropine

xerostomia from radiation

Sjorgen's syndrome

SE: CNS disturbances, inc. pSNS effects (atropine to dec.)

Term

Indirect acting cholinergic agonists

- Reversible AChE inhibitors

 

Definition
  1. Edrophonium
  2. Physostigmine
  3. Neostigmine
  4. Pyridostigmine
  5. Ambenoium
  6. Tacrine
  7. Donepezil
  8. Rivastigmine
  9. Galantamine
Term

Indirect acting cholinergic agonists

- Irreversible AChE inhibitors

 

Definition
  1. Echothiophate
  2. Isoflurophate
Term
Edrophonium
Definition

Short acting AChE I

Reversibly inhibits AChE - acts on the periphary

 

Dx of MG

Antidote to Tubocurarine

 

Cholinergic Crisis

Term
Physostigmine
Definition

Intmed acting AChE I

 

M:Stimulate N&M  in ANS, NMJ and the CNS

 

Tx:Bowel/Bladder atony, Glaucoma, Treatment of MG

Rx of Choice: antidote to anticholinergic Rx overdose with CNS effects (Atropine)

 

SE: CNS effects, dec. HR, Skeletal Ms Paralysis

Term
Neostigmine
Definition

Intmed acting AChE I

 

M: Rev inhibits AChE --> gr8er effect on Sk ms; contracts before paralyzing

 

Tx: for Post-op abd distension & urinary retention

MG, Antidote for Tubocurarine

 

SE: generalized cholinergic effects, skeletal ms paralysis

Term
Pyrodistigmine & Ambenonium
Definition

Intmed actinG AChE

M: Rev inhibits AChE

 

Tx: chronic managing MG

 

SE: Generalized chol effects

Term

Galatamine

Tacrine

Donepezil

Rivastigmine

Definition

Intmed AChEI

 

M: Rev inhibits AChE in the CNS

 

Tx: 1st line for Alzheimer Dz

 

SE: GI distress; Hepatotoxicity (tacrine)

Term
Organophosphates
Definition

Irreversible AChE I

 

Covalent bind to AChE - phosphorylation - perma inactive

 

Tx: NONE!

 

SE: Generalized cholinergic effect

ms weakness and cramps

CNS problems (depression, agitation, convulsoins, confusions, delirium, coma)

Resp paralysis

Term
Echothiphosphate
Definition

Irreversible but safe AChEI

M: Generalized cholinergic effect, intense Miosis

 

Tx: Glaucoma - topical solution on eye

- no longer used cuz of cataracts!

 

SE: Paralysis of motor function --> resp paralysis

General cholinergic stimulation

Cataracts

Term
Adverse Reactoins of Cholinergic Antagonists
Definition

Blind as a bat - mad as a hatter - red as a beet - hot as hell - Dry as a bone - bowel and bladder lose their tone

 

Mydriasis

Confusion

Tachycardia

Blurred vision

Dry mouth/eyes

Constipation

Urinary retention

Term
Anti-muscarinic agents and Their uses
Definition

Atropine

Scopolomine

Pirenzepine

 

COPD: Ipatropium & Piatropium

 

Refractive error: Tropicamide & Cyclopentalate

 

Parkinson's: Trihexypheniyl, Benztropine & Amantadine

 

Overactive bladder: Darifenacin, Fesoterodine, Oxybutinin, Trospium

Term
Atropine
Definition

binds to M receptors

Action:

Greatest inhibitory effects on bronchial tissue & secretion of sweat and saliva

Eye: mydriasis, unresponsiveness to light, cycloplegia, inc. IOP

GI: antispasmodic (withtout much effect on acid)

Bladder: urinary retention

CV: inc. HR at high dose

dec. secretion from salivary, lacrimal and sweat glands

 

Tx: Mydraisis for ophthalmologic sx, antidote for cholinergic agonists, preop resp tract secretoin blockade, Acute symptomatic bradycardia

 

SE: attach of eye pain in glaucoma pts, general effec of a muscarinic block, CNS (restless, confusion, hallucination), problesm with body temp regulation (inhibits sweat glands)

Term
Scopolomine
Definition

Binds M receptors

Action: Strong CNS action - sedation at therapeutic doses, excitation and euphoria at high doses

Blocks short term memory

 

Tx: Drug of choice - motion sickness

Block short term memory with anesthesia

 

SE: General effects of a muscarinic block

CNS effects: restlessness, confusion, hallucination

Term
Pirenzepine
Definition

M1 receptor antagonist

 

Action: decrease stomach acid secretion

 

Tx: PUD

 

SE: general effect of a M-block

Term

Anti-muscarinics used in COPD?

and their action, tx, and SE?

Definition

Iprotropium & Tiotropium

 

Action: Bronchodilation

 

Tx: COPD (and asthma) maintenance treatment (inhalers)

 

SE: Gen effects of a M-block

Term
The two drugs used as eye solutions in eye exams?
Definition

Tropicamide & Cyclopentolate

 

Action: Mydriasis & Cycloplegia

 

Tx: Ophthalmic solution

 

SE: Eye pain in glaucoma pts

Term
3 M-blockers used in parkinson treatment?
Definition

(Too Bloody Active)

Trihexyphenydyl

Benztropine

Amantadine

 

Tx: Parkinson's Dz - tremors and rigidity

parkinsonian syndromes

 

SE: general effects of muscarinic block

Term
4 M-block Rx used in overactive bladder?
Definition

(Far Too Overactive Diuretics)

Action: Lower intravasc pressure, inc. bladder capacity, dec. frequency of bladder contractions

 

Tx: Overactive urinary bladder

 

SE: general effects of a M-block

Term
How do ganglionic blocks work?
Definition

- Act on the N receptors at the ganglion

- both pS and SNS

(NOT USED TX) eg: Nicotine

block the entire output of the ANS:

  • preferentially block the predominant input
  • eg:
    • blood vessels: sym is blocked --> vasodil
    • GI: pS is blocked --> atony
    • Heart: pS is blocked --> inc. HR
    • Eyes: pS is blocked --> cycloplegia, xerostomia
Term
Therapeutic use of NMJ blockers?
Definition
  1. Surgical anethesia - reduce the need for deeper anesthesia
  2. Orthopedic procedures
  3. reduce the risk in electroshock therapy
  4. facilitate tracheal intubation (+ anesthetics)
  5. adjunct in control of ventilation (reduce chest wall resistance)
Term
Different categories of NMJ blockers?
Definition

1. Competitive (non-depolarizing)

- Structure different from ACh

- competitive ACh antagonist at N receptors - low dose blocks reversed by inc. [ACh] --> AChEI - (neostigmine, edrophonium)

- use IV, not metabolized, dose <=> duration of relaxant needed

eg: D-tubocurarine

2. Depolarizing

- structure resembles ACh

- binds and activate the N receptors for a prolonged period

-

eg: Succinylcholine

Term
Competitive NMJ blockers? Activity wise?
Definition

Short acting:

Mivacurium

 

Intmed acting:

Vecuronium,    Atracuronium,    Rocuronium

 

Long acting: (Dont Move Please Dont Contract)

D-tubocurarine

Metocurine

Pancuronium

Doxacurium

Cisatracurium

Term

Adverse effects of competitive NMJ blockers

(and which Rx causes it)

Definition

 

Ganglionic block (dec. BP inc. HR)

- Tubocurarine

- Metocurine

 

Vagal block (vagonium block)

- Pancuronium

- Rocuronium

 

Histamine release (bronchospasm, hypotension, inc. bronchial salivary secretions, flusing)

- Atracurium

- Mivacurium

- Tubocurarine

 

Seizures

- Atracurium only

 

Term
Which drug interactions inc. NMJ blockade?
Definition

Cholinesterase inh. (physostigmine, pyridostigmine)

- Tx dose: reverse action

- high dose: ACh increase too high and cause depol block

 

Halogenated Hydrocarbon Anesthetics (Halothane)

- senstitize NMJ to blockers

 

Aminoglycoside Abx (gentamicyn, tobramycin)

- inhibits ACh release of nerves (dec. competition)

 

Ca channel blockers (amlodipine, diltiazem)

- block ca channels --> dec. ACh release

Term

Succinylcholine

 

Definition

Only depolarizing NMJ blocker used Txly

- Injected IV

- similar stucture to ACh

- not metabolized by AChE

- prolonged action on receptors

- Metabolized by Butyrylcholinesterase (pseudocholinesterase)

--> variation of BuChE in pt can lead to dangerous prolongation of the NMJ block

Term
Adverse effects of the depolarizing NMJ blockers?
Definition
  1. Hyperkalemia - rapid K release from intracells
    • consequences: rhbdomyolysis, cardiac arrest
    • contraindications: soft tissue trauma, burns, ocular lacerations, spinal cord injuries, ms dystrophies
  2. Apnea - def in BuChE
    • diaphragm paralysis and slow metab
  3. inc. IOP, inc. intragrastric P
  4. postop myalgias (muscle pain)
  5. Malignant hyperthermia
    • Inc. Ca release from SR in SkMs - contracture, heat production, inc. ms metab, metab acidosis, tachyK, hyperthermia
    • tx: IV dantrolene (blocks Ca release)

 

Term
Treatment for Glaucoma?
Definition

1. beta-receptor antagonists

- dec. aq humour production

- timolol,levobunolol

 

2. alpha-2 receptor agonist

- dec. aq humour production

- Alpraclonidine, brimonidine

 

3. Muscarinic agonists

- inc. aq flow

- Pilocarpine, carbachol, AChEI(physostigmine, echothiphosphate, isoflurophate)

 

4. Prostaglandin PGF2α analogues - 1st line

- inc. aq humour outflow

- Latanoprost, Travopost

 

5. Carbonic anhydrase inhibitors

- dec. aq prodcution

- dorzolamide, brinzolamide

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