Lecture 4 Flashcards
Why are muscarinic antagonists used in opthamology? Which drug is preferred
- dilate the eye for exam: Mydriasis
- administered directly into eye
- Produce cycloplegia
- Tropicamide preferred
when would you not use a muscarinic antagonists in an opthamology exam
- in a patient with glaucome
- it will increase intraocular pressure
Why is atropine used after an MI
- atropine used to decrease bradycardia due to excessive vagal stimulation and/or reverse heart block
Which muscarinic antagonist is used in surgery to prevent excessive vagal reflexes
Glycopyrrolate
Which muscarinic antagonist is used in the treatment of COPD and in acute asthma
- Ipatropium (Atrovent)
- Tiotropium (Spiriva)
Which muscarinic antagonist is used to treat overactive bladder
Tolterodine (Detrol)
- selective M3 receptor antagonist
Which muscarinic receptor is used to treat bladder spasms after prostate surgery
Oxybutynin (Ditropan)
- blocking muscarinic receptors decreases bladder tone and spasm
what is the main side effect of Oxybutynin
dry mouth
what are the main side effects of Tolterodine (Detrol)
- dry mouth
- blurred vision
which muscarinic antagonist is used to treat motion sickness
Scopolamine
Scopolamine has what CNS effects
- sedation
- short term memory loss
- euporia
- toxicity: hallucinations
List the side effects of muscarininc antagonists
- dry mouth
- decreased bronchial secretions
- tachycardia
- mydriasis, cycloplegia
- decreased GI motility
- urinary retention
- dry skin
- decreased sweating
atropine overdose: use mneumonic
- dry as a bone, blind as a bat, red as a beet, mad as a hatter”
- dry mouth, mydriasis, tachycardia, hot flushed skin, agitation and delirium.
treatment for atropine poisoning
- Treatment is supportive and symptomatic
- cholinesterase inhibitor, diazepam (Valium) to prevent seizures
- ice bags and ethanol to reduce body temperature
- assist respiration
Many classes of drugs have anticholinergic effects, and poisoning may occur with these drugs. Name these classes of drugs
- tricyclic antidepressants
- antihistamines
- phenothiazine antipsychotics.
Treatment of choinergic agonist or AChE inhibitor toxicity (e.g. pesticide, nerbe gas, or mushroom poisonint)
-
Atropine used to block muscarininc effects
- inject until pupils dilate and mouth is dry
Describe what happens at the neuromuscular junction when a nerve is depolarized
- The motor nerve terminal releases ACh when a stimulus travels down the axon
- ACh diffuses to the nicotinic receptor (NM) located on the skeletal muscle
- ACh binds and the Na+ channel opens and Na+ enters the cell
- This causes depolarization of the end plate membrane, resulting in a change in the end plate potential
- If the postjunctional end plate potential is sufficient, the adjacent muscle will depolarize, and the action potential will be propagated along the muscle fiber, and the muscle contracts
- ACh is rapidly broken down by acetylcholinesterase (AChE)
- If the action of ACh is prolonged sufficiently, the nicotinic receptors desensitize. At that point, the membrane can no longer be depolarized by ACh