Anti-Muscarinic drugs-Lecture Flashcards
What effect do anti-muscarinics have on salivary secretion?
They decrease salivary secretion, with less effect on intestinal secretion.
Intestinal secretion is controlled by the non-cholinergic enteric nervous system and intestinal hormones.
What is ‘Atropine fever’?
Inhibition of thermoregulatory sweating that may increase body temperature.
It is a side effect of anti-muscarinic drugs.
What are the durations of action for Atropine and Tropicamide?
Atropine: 7-10 days, Tropicamide: < ¼ day.
This refers to their mydriatic action duration.
What is the mechanism by which mydriatics cause pupil dilation?
They block M receptors in the sphincter pupillae muscle, leading to unopposed contraction of the dilator pupillae muscle.
This results in relaxation of the sphincter pupillae muscle.
What are the effects of anti-muscarinics on the eye?
They produce mydriasis, cycloplegia, inhibition of lacrimation, and may increase intraocular pressure (IOP).
These effects are due to competitive blockade of M receptors.
List some anti-muscarinic agents used for urinary symptoms.
- Oxybutynin
- Flavoxate
- Tolterodine
- Solifenacin
What are the cardiovascular effects of atropine?
It corrects bradycardia by blocking pre-junctional M1 receptors, reducing vagal tone, increasing AV conduction, and decreasing PR interval.
This results in tachycardia.
What is the effect of anti-muscarinic drugs on bronchial secretion?
They decrease bronchial secretion and can make mucus viscous, inhibiting mucociliary clearance.
Ipratropium bromide does not inhibit mucociliary escalatory movement.
What therapeutic uses do anti-muscarinic agents have in the respiratory system?
- Pre-anesthetic medication
- Treatment of COPD
- Reduce bronchial secretion
What are some therapeutic uses of antimuscarinic agents?
- Ophthalmic: Mydriatics for examination
- Cardiovascular: Atropine for bradycardia
- Respiratory: Pre-anesthetic
- Gastrointestinal: Anti-spasmodic
- Genitourinary: Dysuria treatment
- CNS: Motion sickness
- OPC poisoning: Atropine
- Anesthetic pre-medication
What are the adverse effects of anti-muscarinic drugs related to the eyes?
- Decreased lacrimation
- Cycloplegia
- Blurring of vision
- Increased IOP
Fill in the blank: Anti-muscarinic drugs may cause _______ retention, particularly in elderly males with BPH.
urinary
What are the classifications of anti-muscarinic drugs?
- Natural alkaloids
- Semisynthetic analogues
- Quaternary ammonium compounds
What is the primary action of anti-muscarinic agents?
They competitively block M-cholinergic receptors, antagonizing the action of acetylcholine.
This includes both muscarinic and nicotinic actions.
What is the effect of anti-muscarinics on gastric emptying?
They prolong gastric emptying time and decrease gastric acid, pepsin, and mucus secretion.
Long-term use may lead to constipation.
What are some examples of natural alkaloids that are anti-muscarinic?
- Atropine
- Scopolamine (Hyoscine)
These are derived from plants like Atropa belladonna and Hyoscyamus niger.
True or False: Quaternary ammonium compounds of anti-muscarinic drugs hardly cross the BBB.
True
What is the effect of anti-muscarinic agents on the gastrointestinal system?
They decrease intestinal tone, peristaltic movement and may cause gastric outlet obstruction.
Long-term use may lead to constipation.
