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Acetylcholinesterase
An Enzyme That Inactivates Acetylcholine
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Anticholinergic
Refers To Drugs or effects that reduce the activity of the parasympathetic nervous system
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Cholinergic
Refers to the nerves and receptors of the parasympathetic nervous system; Also refers to the drugs that stimulate this system
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Muscarinic Receptor
An Older But More Specific Term For the cholinergic receptor on smooth and cardiac muscle
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Nicotinic-Muscle (Nm) Receptor
Cholinergic receptor located at the neuromuscular junction of skeletal muscle
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Nicotinic-Neural (Nn) Receptor
Cholinergic receptor located on both sympathetic and parasympathetic ganglia
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Parasympatholytic
Refers to Drugs (Anticholinergic) that decrease activity of the parasympathetic nervous system
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Parasympathomimetic
Refers to drugs (Cholinergic) that mimic stimulation of the parasympathetic nervous system
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What is the neurotransmitter of the parasympathetic system
ACH
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What are the nerves that release ACH
Cholinergic Nerves
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What Are receptors that respond to cholinergic stimulation
cholinergic receptors
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What Are drugs that bind to cholinergic receptors and produce effects similar to ACH
Cholinergic Drugs
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What is antagonism
When drugs bind to receptor and do not produce an effect
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What Are cholinergic blocking drugs
Drugs that bind to cholinergic receptors and don't produce an effect
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What change occurs when ACH is released and travels to smooth or cardiac muscle membrane
Parasympathetic Stimulation
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What Enzyme is found in the cholinergic receptor
Acetylcholinesterase
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What Is acetylcholinesterase
A Enzyme that inactivates ACH only when it is outside a nerve ending and not on the receptor
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Why do the effects of ACH las only a few seconds
Inactivation of ACH occurs so quickly
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What does the cholinergic nerve ending look like
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How does the transfer of Acetylcholine work in a nutshell
Presynaptic nerve releases ACH, Postsynaptic membrane contains the cholinergic receptor, Acetylcholinesterase inactivates ACH
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What is the neurotransmitter for all 3 cholinergic receptors
ACH
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What Class of Cholinergic blocker is required to block all effects of ACH
All 3 of them
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What Are The Three cholinergic receptors
- Muscarinic receptor
- Nn Receptor
- Nm Receptor
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Muscarinic Receptor
Receptors at the parasympathetic postganglionic Nerve endings
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What Is he term Muscarinic from
The drug muscarine
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What is the drug Muscarinic
An alkaloid obtained from a particular mushroom, One of first drugs used to function on ANS, produces effects similar to ACH but only at muscarinic receptor sites
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What Are drugs that act like ACH or muscarine
Cholinergic, or muscarinic drugs
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What are drugs that block ACH
Anticholinergic or antimuscarinic drugs
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What is Nn
Nicotinic-Neurol
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What are the Nn Receptors
Cholinergic receptors at the ganglionic sites of both sympathetic and parasympathetic nerves
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What is the term Nicotinic derived from
The drug nicotine, the alkaloid obtained from the tobacco plant
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Why did early pharmacologists use nicotine to study the ANS
It Stimulates the Autonomic Ganglia in low doses and blocks the autonomic ganglia in high doses
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What are ganglionic stimulants
Drugs that act like ACH in low doses of nicotine
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What are ganglionic blockers
Drugs that block ACH or act like high doses of nicotine
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What is Nm
Nicotinic-muscle
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What is the Nicotinic-Muscle Receptor
The cholinergic receptor at the NMJ or skeletal muscle
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What is NMJ
Neuromuscular Junction
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What act like ACH at the Neuromuscular junction
Nicotine
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What are Neuromuscular Blockers
Drugs that Block the effects of ACH at the NMJ
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What are skeletal muscle relaxants
Drugs that Block the effects of ACH at the NMJ
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What Are Cholinergic Drugs
Drugs that mimic the actions of ACH at the Muscarinic receptors
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What Is another term Similar to cholinergic drugs
Parasympathomimetic drugs
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What are the two groups cholinergic drugs are divided into
- Direct-Acting
- Indirect-Acting
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What are the direct-drugs
Drugs that bind to the muscarinic receptors and produce effects similar to those of ACH
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What Are Indirect-Acting Drugs
Drugs that inhibit the enzyme Acetylcholinesterase
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What Happens when you inhibit the enzyme acetylcholinesterase
It Allows ACH to accumulate at each of the cholinergic receptor sites so a greater number of receptors become stimulated and the ACH effects are prolonged
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Where do direct-acting cholinergic drugs bind
Muscarinic receptors
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Why Is ACH not useful as a drug
Extremely short duration of action
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What Are the derivatives of ACH
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Why were the derivatives of ACH synthasized
To produce effects like ACH but more slowly inactivated by Acetylcholinesterase so the DOA is much longer
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What are the main pharmacological effects of ACH
- Increase in GI secretions
- Motility
- Increase in Genitourinary activity
- Bronchoconstriction
- Miosis
- Vasodilation
- Decrease in heart beat
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What does vasodilation cause
Decrease in BP
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What are the alkaloids of ACH
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What has no clinical importance except in cases of accidental poising
Muscarine
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What Is used in the form of eyedrops for treatment of Glaucoma that is a alkaloid that acts like ACH
Pilocarpine
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What is Bethanechol used for
It is one of the few ACH drugs that are not short acting. It is administered orally to stimulate the urinary and intestinal tracts. Because of general anesthetics, elderly or other conditions they may have bowel or bladder retention
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What does overstimulation by Bethanechol cause
Urinary frequency and diarrhea
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Why are cholinergic drugs used locally
During Ophthalmic examination (To Constrict the pupil) and in treatment of Glaucoma
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What does glaucoma do
Glaucoma will cause blindness by gradually destroying the retina which causes blindness
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how will Cholinergic drugs help glaucoma
Will produce miosis which promotes better drainage of intraocular fluid and this lowers pressure
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What are indirect-acting cholinergic drugs known as
The anticholinesterases
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What do Direct-acting cholinergic drugs do
Inhibit the enzyme acetylcholinesterase and allow accumulation of ACH at all cholinergic receptor sites
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What are anticholinesterase drugs subdivided into
- Reversible inhibitors
- Irreversible inhibitors
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What is the main use of acetylcholine
Miotic in cataract surgery
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What does Bethanechol for
Nonobstructive urinary retention
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What does carbachol for
Treatment of glaucoma
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What is Pilocarpine for
Treatment of glaucoma
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What is Ambenonium for
Treatment of myasthenia gravis
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What is demacarium for
Treatment of glaucoma
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What is edroponium for
Diagnosis of myasthenia gravis, antidote for curare-type drugs
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What is galantamine for
Treatment of Alzheimer's disease
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What is Neostigmine for
Treatment of myasthenia gravis, antidote for curare-type drugs
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What is Physostigmine for
Antidote to Anticholinergic drugs, treatment of glaucoma
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What are pyridostigmine for
Treatment of myasthenia gravis, antidote for curare-type drugs
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What is tacrine for
Treatment of alzheimer's disease
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What is donepezil for
Treatment of alzheimer's disease
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What are reversible inhibitors used for
diagnosis and treatment of myasthenia gravis, and as antidotes to reverse the effects that block cholinergic and Nicotinic receptors
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What is myasthenia gravis
It affects the skeletal muscle, it is characterized by insufficient Acetylcholine activity
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What is the duration of neostigmine
2-4 hours
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What Is the duration of pyridostigmine
3-6 hours
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What is the duration of ambenonium
4-8 hours
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Neostigmine, pyridostigmine, and Ambenonium are administered orally for what treatment
Treatment of myasthenia gravis
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Neostigmine, pyridostigmine, and Ambenonium are administered IV for what
Reverse the effects of excessive cholinergic blockade
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What are Quaternary amines
Charged compounds, they do not cross the blood-brain barrier and produce affects only at peripheral receptor sites. Examples are Neostigmine, pyridostigmine, and ambenonium
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What is Physostigmine
Not a charged compound, and does not produce effects on the brain. Used parenterally to revers the CNS effects of excessive Anticholinergic blockade and as eyedrops in the treatment of Glaucoma
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What are the irreversible inhibitors of acetylcholinesterase
Derivatives of organophosphate compounds widely used as insecticides, pesticides, and as chemical warfare agents. Have extremely long durations of action because they form irreversible bonds with the acetylcholinesterase enzyme
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What is echothiophate used for
In very small doses usually used as eye drops of glaucoma, in larger doses these drugs produce severe toxicity.
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What is cholinergic crisis
Caused by large dose of echothiophate it can quickly cause respiratory paralysis and death
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What is the most common adverse effects of cholinergic drugs
Nausea, vomiting, diarrhea, blurred vision, excessive sweating, muscular tremors, bronchoconstriction, bradycardia, and hypotension.
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What happens in toxic overdose of cholinergic drugs
Muscular paralysis and respiratory depression that may cause death
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What is the main antidote for cholinergic drugs
Administration of Anticholinergic drugs, such as atropine, which compete with ACH for the muscarinic receptor and reverse the effects
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What is Cholinergic crisis
Term used to describe the effects of excessive drug dosage in patients with myasthenia gravis
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What does ACH cause at high concentrations
Excessive stimulation of muscarinic receptors, but blockade of nicotinic receptors. This causes respiratory paralysis because respiratory muscles are voluntary in nature
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In ACH overdose what can be used to bring the acetylcholinesterase levels to normal
Atropine or pralidoxime
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What can farmers that spray there fields with Derivatives of anticholinesterase experience
Cholinergic crisis, unless masks or enclosed tractor cabs are used
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What does pralidoxime do
A drug that can reactivate the acetylcholinesterase enzyme after it has been inhibited by an irreversible inhibitor, most effective immediately after exposure. Also the antidote to organosphate chemical warfare agents.
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What are anticholinesterase drugs used for
Treatment of Glaucoma, myasthenia,gravis, urinary retention, intestinal paralysis, alzheimer's disease, and as antidotes to the curaretype skeletal blockers and the Anticholinergic drug
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What is myasthenis gravis believed to be due to
An Autoimmune reaction where the body produces antibodies that attack the Nm receptor, thus you loose muscle tone and strength
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What is used to increase the ACH levels for myasthenis gravis
Pyridostigmine and ambenonium
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What is another name for urinary retention
Atony of the bladder
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What is another name for Intestinal Stasis
Paralytic ileus
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What are Urinary retention and Paralytic ileus usually treated by
Neostigmine, it increases level of ACH to stimulate bladder contraction and intestinal peristalsis
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What is Alzheimer disease
A degenerative brain condition that occurs in some individuals with advanced age. A loss of neuronal synapses and a reduction of ACH levels in the brain, which cause memory loss, dementia, and general deterioration of mental function
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What drugs are used to help treat alzheimer's disease
- Two reversible anticholinesterase drugs:
- Tacrine
- Donepezil
- They both increase activity in the brain, the effects are more notable in the beginning and lessen as the disease progresses. Lecithin is a precursor of ACH and is usually administered to further increase ACH levels
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What are skeletal muscle blockers used for
In surgery to produce paralysis of skeletal muscle, at high doses it may cause respiratory paralysis
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What do you do if you administer too much skeletal muscle blockers
If that does happen administer neostigmine to increase ACY and antagonize the action of the skeletal muscle blockers
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What do Anticholinergic drugs do
Block the cholinergic receptors and produce effects similar to decreasing the activity of the parasympathetic system. This includes urinary and intestinal inhibition, cardiac stimulation, and central effects in the brain of stimulant and depressant effects
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What is the antidote for anticholinergic drugs
Usually physostigmine, because it can pass the blood-brain barrier, the increase ACH produced compete with the anticholinergic drugs for the receptor
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What are anticholinergic drugs
Cholinergic blocking drugs that bind to the muscarinic receptors, they act by competitive antagonism of ACH
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What are the oldest anticholinergic drugs
atropine and scopolomine
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Where were Atropine and Scopolamine obtained from
The Belladonna Plant and are usually called Belladonna alkaloids
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What is the Vagus nerve
The Parasympathetic nerve of the hear
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What is used to increase heart rate
anticholinergic drugs, they decrease the activity of the vagus nerve thus hear rate increases
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What drug is administered pre-op to inhibit secretion that may interfere with general anesthetics
Anticholinergic drugs, ACH increases the secretions and anticholinergic drugs produce brochodilation and so can also be used in asthma
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What do anticholinergic drugs do to the GI system
Reduce salivary and GI secretions so don't administer if intestinal obstruction. They are used as antispasmodics in GI disorders such as irritable bowel syndrome or peptic ulcers
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What do anticholinergic drugs do to the genitourinary system
Inhibit urinary peristalsis and the voiding of urine. May be used on people suffering from enuresis. Contraindicated in males with hypertrophy of the prostate gland.
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What do most anticholinergic drugs that gain access to the brain do
Give a depressant effect. usually drowsiness and sedation, can be used as sleep aids
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What will Scopolamine do
In little amounts it Act as a sleep aid, in larges doses there can be a mixture of both CNS stimulant and depressent
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What will both atropine and scopolamin produce at toxic doses
Produce excitation, delirium, hallucinations, and profound CNS depression that can lead to respiratory arrest and death
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What are anticholinergic actions useful for
Parkinson's disease and as antiemetics for motion sickness
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What is the Main use and common dosage of Atropine
- To increase heart rate, preop medication, enuresis, GI and Biliary colic, antidote to cholinergic drugs Mydriatic and Cycloplegic
- .4-.6 mg PO,IV,IM,SC Topical Eyedrops
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What is the Main use and common dosage of Hyoscyamine
- Same as Atropine
- .25-1.0 mg PO, IV
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What is the Main use and common dosage of Scopolamine
- Motion sickness
- 1 Patch every 3 days
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What is the Main use and common dosage of Homatropine
- Mydriatic
- Ophthalmic Solution
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What is the Main use and common dosage of Dicylomine
- Treatment of GI disorders such as ulcers, colitis
- 80-160 mg PO
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What is the Main use and common dosage of Glycopyrrolate
- Treatment of ulcers
- 2-6mg PO
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What is the Main use and common dosage of methscopolamine
- Treatment of GI disorders such as ulcers, colitis
- 2.5-10 mg PO
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What is the Main use and common dosage of Oxybutynin
- Treatment of overactive bladder
- 5-15 mg PO
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What is the Main use and common dosage of propantheline
- Treatment of GI disorders such as ulcers, colitis
- 22.5-60mg PO
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What is the Main use and common dosage of tolterodine
- Treatment of overactive bladder
- 2-4 mg PO
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What is cycloplegia
loss of accommodation
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What are the drugs used in ophthalmology to facilitate examination of the retina or lens
Anticholinergic drugs
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What type of drug should not be given to a patient with glaucoma
Anticholinergic because it will increase pupillary dilation and closure of the drainage pathway
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What is the most frequent adverse effect of anticholinergic
Caused by excessive blockade of the PNS, symptoms include, dry mouth, visual disturbances, urinary retention, constipation, flushing and dryness of skin, fever, tachycardia, symptoms of both CNS stimulation and depression
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What are the effect on the skin from anticholinergic drugs caused by
Anticholinergic effect that inhibit sweating mechanism and the vasodilate certain blood vessels causing flushing
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What happens to children who mistakenly eat the Belladonna berries
Fever, tachycardia, dryness, mydriasis and flushing of skin in severe cases respiratory paralysis, coma, and death may occur withing hours
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What is treatment for overdose of belladonna
Induce emesis or performing gastric lavage to limit absorption. Can use activated charcoal and saline cathartics are used to inactivate the drug. Physostigmine given IV antagonizes the action and useful if delirium and coma are present
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