Pharm: Cholinergic Drugs

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ACETYLCHOLINE physiological activity: direct acting cholinergic agonist

CARDIOVASCULAR SYSTEM
- vasodilation
- decrease heart rate
- decrease in force of contraction

SMOOTH MUSCLE: contraction
- increase GI motility
- constriction of Bronchioles
- contraction of ureter, bladder and uterine contraction
- miosis of eye, accomidation for near vision

GLANDS: secrections
- increase salivation, sweating, lacrimation, GI secretions, bronchiolar secretions

NEUROMUSCULAR (nicotinic)
- stimulation of motor end plate
ACETYLCHOLINE pharmocologic activity: therapeutic action is due to muscarinic activity

THERAPEUTIC USES:
- used to acheive miosis during eye surgery

ADVERSE EFX: "DUMBELS"
Diarrhea and Decreased BP
Urination
Miosis
Bronchoconstriction
Excitation of skeletal muscle
Lacrimation
Salivation
BETHANOCHOL CARBOCHOL Methacholine choline esters: RECEPTOR: muscarinic and nicotinic (Bethanichol- muscarinic)

PHYSIOLOGICAL AXN(s):
Activation of muscarinic receptors increases cGMP and potassium flux, accelerates phosphatidyl inositol turnover ---> increase in intracellular Ca or inhibition of adenyl cyclase activity

THERAPEUTIC USES:
- Bethanechol stimulates GI motility and is used to treat urinary retention (remember BBB)
- Carbachol is rarely used but may be used for glaucoma or to induce miosis

ADVERSE EFX:
"DUMBELS"

* Methacholine is used to test the severity of bronchial hyperreactivity
PILOCARPINE MUSCARINE "the natural alkaloids": RECEPTOR: primarily muscarinic

PHYSIOLOGICAL AXN(s):
- miosis and contraction of the ciliary muscle
- decreases heart rate
- causes bronchial SM contraction

THERAPEUTIC USES:
- xerostomia, to induce salivation
- glaucoma, onset of action 15-30 min, 4-8 duration

ADVERSE EFX:
- CNS disturbances such as hallucinations and convulsions along with DUMBELS
- contraindicated in pts w/ peptic ulcers, asthma, hyperthyroidism, parkinsons

* Muscarine is an alkaloid present in wild mushrooms, not used clinically; interest is due to accidental intoxication, treated w/ atropine
EDROPHONIUM: cholinesterase inhibitor

RECEPTOR: nicoinic receptors

PHYSIOLOGICAL AXN(s):
binds reversibly to AChE preventing access by ACh

THERAPEUTIC USES:
used in the diagnosis of Myasthemia Gravis b/c of its short duration of action (5-15 min). It is also used to differentiate btwn MG and cholinergic crisis - administration of Edrophonium helps MG but makes cholinergic crisis worse.

ADVERSE EFX:
excessive cholinergic stimulation
PHYSOSTIGMINE PYRIDOSTIGMINE NEOSTIGMINE: Carbamates Esters

RECEPTOR: nicotinic (not Physos.)

PHYSIOLOGICAL AXN(s):
binds active site of AChE making nzm resistant to hydrolysis

THERAPEUTIC USES:
Physostigmine (0.5-2h; inj,top)- glaucoma, atropine or trycylic depressant intoxication
Neostigmine (0.5-2h; PO,inj)- Myasthemia gravis, urinary retention, paralytic ileus
Pyridostigmine (3-6h; PO,inj)- Myasthemia Gravis

ADVERSE EFX: "DUMBELS"
tremors, convulsions
pyrido and neostig have CNS effects
ECHOTHIOPHATE MALATHION PARATHION SARIN soman: Organophosphates

PHYSIOLOGICAL AXN(s): "irreversible inhibitor"
bind to AChE yeilding phosphorylated nzm, nzm undergoes aging and new nzm must be sythesized

THERAPEUTIC USES:
Echothiophate- used topically for glaucoma, duration is greater than 100 hours
Malathion/ Parathion - agricultural pesticides, frequent accidental intoxication
Soman/ Sarin - nerve gases, used in chemical warfare

ADVERSE EFX: "DUMBELS"
tremors convulsions
death due to respiratory depression

* treat toxicities w/ O2, atropine, pralodoxime, and benzodiazapines (to reduce siezure activity
PRALODOXIME: RECEPTOR: cholinesterase reactivator

PHYSIOLOGICAL AXN(s):
has strong affinity for phosphorylated enzyme, oxime gets phosphorylated, thus regenerating free enzyme

THERAPEUTIC USES:
antidote to organophosphates; not effective once aging has taken place

ADVERSE EFX:
DONEPEZIL: Non competitive reversible cholinesterase inhibitors

PHYSIOLOGICAL AXN(s):
selective AChE of the brain

THERAPEUTIC USES:
treatment of cognitive deficits associated with Alzheimers Disease, selective for memory loss

ADVERSE EFX:
NICOTINE physiological actions: RECEPTOR: binds a subunit of nicotinic receptorscusing increase Na influx

CNS:
- small doses increase rate and depth of respiration
- tremors; convulsions at toxic doses
- irritability, nausea and vomiting, antidiuretic, increase in alertness and memory

CARDIOVASCULAR:
increased heart rate, CO, TPR, and blood pressure

GI TRACT:
increases secretions and motility; excaberates peptic ulceration
NICOTINE pharmacologic properties: Nicotine is highly soluble and well absorbed from all routes of administration

THERAPEUTIC USES:
nicotine gum, inhaler, nasal spray, and transdermal patch to aid in smoking cessation

ACUTE INTOXICATION:
respiratory failure, CV collapse, nausea, vomiting, headache, dizziness, palpitations and convulsions

CHRONIC TOXICITY:
- tolerance and physical dependence
- respiratory and CV disease
- cancer

* BUPORPION and antidepressant, used as an aid in smoking cessation
* CLONIDINE releives the symptoms of withdrawal
ATROPINE physiological characteristics: RECEPTOR: competative, reversible antagonists of ACh at muscarinic receptors; no intrinsic activity (natural alkaloid of the plant Atropa belladona)

CARDIOVASCULAR SYSTEM:
- low doses reduce heart (transient brachycardia) thru vagal stimulation
- high doses elevate heart rate

GI TRACT:
reduces salivary gland secretion

PULMONARY SYS:
reduces bronchial secretions and stimulates bronchodilation

EYE:
paralysis of muscles --> mydriasis and cyclopegia

URINARY BLADDER:
bladder wall relaxation

SECRETIONS:
reduces salivation and inhibits sweating
ATROPINE IPRATROPIUM pharmocologic characteristics: THERAPEUTIC USES:
- bradycardia/ MI in pts with excessive vagal activity
- mydriasis and cyclopegia
- treatment of organophosphate poisoning
- to dry salivary secretions
- diarrhea, gastrointestinal, bladder spasms
- COPD and bronchial asthma (IPRATROPIUM, used by B inhalaltion)

ADVERSE EFX:
dry as a bone
hot as a hare
red as a beet
blind as a bat
mad as a hatter

* contraindicated in patients with glaucoma, prostatic hyperplasia, and in elderly men
SCOPOLAMINE: belladonna alkaloid

RECEPTOR: muscarinic

PHSIOLOGICAL AXN(S):nonselective blockade of receptors; competes with ACh

THERAPEUTIC USES:
- prevention of motion sickness-"lotion for motion"
- long duration of action w/ potent CNS effects; given transdermally

ADVERSE EFX:
dry as a bone
hot as a hare
red as a beet
blind as a bat
mad as a hatter
HOMATROPINE CYCLOPENTOLATE TROPICAMIDE: RECEPTOR: muscarinic

PHSIOLOGICAL AXN(S):
semi/synthetic compounds nonselectively block muscarinic receptors

THERAPEUTIC USES:
given topically to induce mydriasis and cyclopegia; have much shorter duration of action than atropine and scopolamine

ADVERSE EFX:
similar to atropine but much milder
DICYCLOMINE GLYCOPYRROLATE: Synthetic anti-cholinergic agents

RECEPTOR: muscarinic

PHYSIOLOGICAL AXN(s): block muscarinic receptors

THERAPEUTIC USES:
- reduce gastrointestinal spasm gastrointestinal motility
- reduce acid secretion in peptic ulceration
- (glycopyrrolate) dries salivary secretions

ADVERSE EFX:
at high doses can lead to constipation in the elderly
BENZTROPINE TRIHEXYPHENIDYL: semi synthetic anti muscarinic agents

RECEPTOR: muscarinic

PHYSIOLOGICAL AXN(s): blockade of muscarinic receptors

THERAPEUTIC USES:
treatment of drug induced Parkinson's disease to lower relative excess in cholinergic activity

ADVERSE EFX:
delirium, mental confusion, and memory loss
OXYBUTANIN: RECEPTOR:muscarinic

PHYSIOLOGICAL AXN(s): blockade of muscarinic receptors

THERAPEUTIC USES:
relieve urgency of transient cystisitis and bladder spasms due to infection of after urologic surgery

ADVERSE EFX:
MECAMYLAMINE Trimethaphan: Anti-nicotinics, Ganglionic blockers; all synthetic amines

RECEPTOR: nicotinic

PHYSIOLOGICAL AXN(s):
non depolarizing, competitive blocker; binds to the ACh nicotinic receptor site but has no intrinsic activity

CNS: sedation, tremor, mental abberation

EYE: cyclopegia, loss of accom., moderate pupil dilation

CV SYS: decresed arteriolar and venomotor tone, leading to hypotension; moderate tachycardia

THERAPEUTIC USES:
limited; hypertensive emergency

ADVERSE EFX:

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