Antimuscarinics Flashcards
What is the prototype anti muscarinic?
Atropine
What Antimuscarinic is used for nausea and vomiting
Scopolamine
AKA hyoscyamin and analogs
What Antimuscarinic is used for Respiratory Disease?(2)
Ipratropium (Atrovent)
Tiotropium (Spiriva)
What Antimuscarinic is used for incontinence? (3)
Oxybutynin ( Ditropan)
Tolterodine (Detroit)
Solifenacin (Vesicare)
What Antimuscarinic is used in Opthalmology?
Tropicamide (Mydriacyl)
Define Muscarinic Agonist
Competitive agonist of ACh at Muscarinic receptor
What are the physical Effects of a Muscarinic Agonist
During if secretions:
Lacrimal, salivary, respiratory, GI decrease time and motility of GI tract.
Relaxation of the Bladder and urine retention
Bronchodilation
Increased heart rate
What are the effects of Antimuscarinic on nervous system?
Sedation and Amnesia
Excitation and seizures
Antiemetic: Reduction of Vomitting
Quaternary salts don’t penetrate CNS.
What is the Chemoteceptor trigger zone?
chemoreceptor trigger zone (CTZ) is an area of the medulla oblongata that receives inputs from blood-borne drugs or hormones, and communicates with other structures in the vomiting center to initiate vomiting.
What are the common uses of Antimuscarinics?
Motion sickness: Scopolamine
Respiratory diseases- Asthma COPD: Tiotropium, ipatropium, aclidinium
Urinary incontinence: oxybutynin, darifenacin
Ophthalmologic as mydriatic agents ( not glaucoma)
What are less common uses of antimuscarinics?
Low-dose inclusion in antidiarrheal
Antidote for poisoning with cholinesterase inhibitors or muscarinic agonists
Parkinson’s treatment: benzetropine and trihexyphenidyl
Emergency cardiac stimulation: Atropine
Pulmonary medicine
Preoperative Anesthesia
Describe the use of scopolamine
Anti-motion sickness and nausea
Transdermal patch that is most effective as a prophylactic
What are the side-effects of scopolamine?
Xerostomia- dry mouth
Drowsiness
Blurred Vision
What effect does antimuscarinics have on bronchioles smooth muscle?
They block excitatory muscarinic receptors M3 on bronchioles smooth muscle.
Bronchiodilation
Example: Tiotropium
Available as inhalants in combination with B2 agonists.
How do antimuscarinics help urinary incontinence.
Suppress premature detrusor contraction and enhance bladder storage.
Examples oxybutynin, tolterodine, solifenacin
Antimuscarinic side-effects
Why is the Urinary Incontenance drug of choice?
Oxybutynin
Cheap
Short half-life
Metabolized by CYP3A4
Transdermal gel
Causes dry mouth
Are solifenacin and darifenacin selective in the bladder?
No
How are antimuscarinics used in eye exam?
They paralyze the ciliary muscle.
Example: Tropicamide
A different drug is used if you just want mydriasis or pupil dilation
Antimuscarinics can cause glaucoma.
What type of drug us used for pupil dilation?
alpha receptor agonist
What does antimuscarinic toxicity do to the CNS?
Hallucination, coma,
Antimuscarinic poisoning makes you:
Red as a beet
Dry as a Bone
Blind as a bat
Mad as a hatter
What are contraindications for Antimuscarinics?
Glaucoma Prostatic Hypertrophy Cardiovascular instability Severe Ulcerative colitis Children most at risk
What drug classes have Antimuscarinic side effects?
Tricyclic Antidepressants
Antipsychotics 1st and 2nd generation
Antihistamine
Amantadine
How do you treat Antimuscarinic poisoning?
Physostigmine crosses BBB
Or cholinesterase inhibition
Benzodiazepines for seizures
Ice baths for hyperthermia
Keep in dark for photophobia
Why is is difficult to selectively manipulate Muscarinic Receptors:
The active sites are similar / highly conserved
So they need allosteric modulators
