Pharmacology Anticholinergics

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Anthicholinergics: mechanism of actions

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-Will look like adrenergic effects.
-Block Ach, by binding to cholinergic receptors (muscarinic only).
-Blocks cholinergic mediated effects through competitive inhibition.
-All antidepressants, antihistamines, antipsychotics, and antiparkinson's drugs have some anti-chol effects

*For 70 y.o.+, anti-cholinergics quadruples risk of long term cognitive impairment b/c Ach is involved in memory and cognition.

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Anticholinergics: antimuscarinic mechanism of action

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-occupy cholinergic muscarinic receptor sites of the parasympathetic system

-Fewer sites are free to respond to Ach; CNS stimulation followed by depression.

-Vagus nerve stimulation by Ach--increasing heart rate, BP, bronchodilation, and decreased respiratory secretions.

-Anti spasmodic effects in GI tract, decreased motility and secretions.

-Mydriasis (pupillary dilation) in eye--increasing pressure on the outflow tract, increasing eye pressure.

-Decreased saliva and sweat

-Increased urinary retention: relaxed bladder, tightened sphincter

-Relaxation of GB and bile ducts; decreased production of bile.

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Anticholinergics: indications

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GI-colitis, IBS (antispasmodic)
GU-cystitis, urethritis, prostatitis, dysuria, overactive bladder.
Ophth--pupillary dilation for eye exam, surgery
Resp--bronchoconstricion, also decreases resp secretion
CV--bradycardia, heart block
Parkinson's--spasticity, tremors, salivation
CNS--when crossing BBB, can be used for sedation, insomnia. Motion sickness (anti-emetic).
Other--Pre-op to reduce salivation and respiratory secretion, antidote to pesticide poisoning, mushroom poisoning.

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Anticholinergics: common drugs :5

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Atropine
Scopolamine
Benzotropine/cogentin
Tolterodine/Detrol
Ipratropium/Atrovent

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Anticholinergics: adverse effects

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*Most of these drugs have a narrow therapeutic index
-most SE result from excessive inhibition of parasymp system.
-Beladonna alkaloids in OTC, plants, poisonous berries.
*Elderly most likely to develop SE

CV--hypotension, palps, tachycardia, bradycardia
CNS--excessive stimulation (tremor, agitation, confusion, hallucinations, excess depression (coma, respiratory depression), short term memory problems, drowsiness, restlessness, h/a,
GI--constipation, paralytic ileus, dry mouth, dysphagia
GU--urinary retention, hesitancy, dysuria
Other--rash, hives, blurred vision, dilated pupils, photophobia, fever, flushing of the skin (d/t vasodilation and inhibited sweating).

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Anticholinergics: Drug interactions:

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-increased effects of anticholinergics
-decreased effects of anticholinergics
-decreased absorption: antidiarrehals, antacids

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Anticholinergics: Contraindications:

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Glaucoma
tachycardia, MI, congestive HT failure,
BPH
Reflux esophagitis (delay in gastric emptying, and relaxation of the esophageal sphincter, allowing reflux).

-Ganglion blockers
-Neuromuscular blockers

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Anticholinergics: TCM description

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Acrid, windy
Qi rectifier
--they may disperse too much qi, and plunder yin fluids.

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Atropine

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*prototype for anticholinergics.
--A belladonna alkaloid--rapidly absorbed, enter CNS, many SE, so synthetics were developed with fewer SE.

-For emergencies: inc heart rate, pre-op sedation,
-reduce secretions
-enuresis, colic
-antidote to pesticide poisoning

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Scopolamine

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-Belladonna alkaloid
-Patch for motion sickness,
-ophth for mydriasis

*Think peri-scope--motion sickness in a submarine, and open pupils because it's dark in the deep sea.

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Benzotropine/Cogentin

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-mildly sedating
-frequent use for akasthisia (uncontrollable restlessness) and parkinson-like reactions to anti-psychotics

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Tolterodine/Detrol

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-overactive bladder
-only slightly more effective than placebo

* Da troll needs to be "toilet-trained"

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Ipratropium/Atrovent

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-bronchospasm