Anticholinergics Flashcards
Anticholinergic drugs competitively antagonize the effects of what?
Ach
What terms are commonly used interchangeably when blocking the parasympathetic nervous system?
- Antimuscarinic and anticholinergic
- although truly an anticholinergic can have effects at Nicotinic cholinergic sites as well
What drug is a naturally occurring alkaloid of the Belladonna plant or synthetic derivatives?
Atropine
What drug occurs in Hyoscyamus or “Henbane”?
Scopolamine
Antihistamines, antipsychotic and antidepressant drugs may also have what type of effects do to similar structures of anticholinergics?
antimuscarinic effects (anti parasympathetic)
How do anticholinergics cause parasympatholytic effects?
Combine reversibly with muscarinic receptors preventing Ach from activating site
How can anticholinergics effects be overcome or reversed?
increasing Ach concentration = (muscarinic receptor activation= parasympathetic effects “rest and digest”)
Where are the effects of muscarinic receptor M1 activation seen?
CNS and stomach
Where are the effects of muscarinic receptor M2 activation seen?
airway smooth muscle, heart, CNS
Where are the effects of muscarinic receptor M3 activation seen?
CNS, glands, airway smooth muscle
Where are the effects of muscarinic receptor M4 activation seen?
CNS, heart
Where are the effects of muscarinic receptor M5 activation seen?
CNS
Low dose anticholinergics will inhibit which muscarinic receptor?
M3 receptors (glands-bronchial and salivary)
Slightly higher dose anticholinergics will stimulate which muscarinic receptor?
M2 receptors (heart and eye)
High dose anticholinergics will inhibit which muscarinic receptor?
M1 cholinergic control of GI motility and secretion and urination,
Which anticholinergic drugs will produce CNS effects?
- Mainly scopolamine
- minimal from atropine at normal doses
- none from Glycopyrrolate
What are the CNS effects seen with scopolamine and atropine?
-Sedation (usually first, especially with Scopolamine), followed by stimulation, hallucinations
– Amnesia
– Decreases tremor from Parkinson’s (decreased dopaminergic activity, relative excess of cholinergic activity)