Drugs Flashcards
What is the mechanism of orlistat?
Reacts with serine residues at the active sites of gastric and pancreatic lipase, irreversibly inhibiting the enzyme and preventing breakdown of fat.
What is the mechanism of hexamethonium?
Selective antagonist (at ganglia) for the neuronal subtype of nicotinic receptor, not competitive, blocks all effects of autonomic stimulation.
What are the effects of parasympathomimetics?
Cardiovascular- decreased heart rate and cardiac output, smooth muscle contracts, vascular muscle dilates via endothelium, exocrine glands secrete.
Give examples of muscarinic agonists
ACh, carbachol, methacholine, bethanecol, muscarine, pilocarpine, oxytremorine
What are the effects pf muscarine poisoning and how are they treated?
-bradycardia, vasodilation (secondary to NO), leading to falling BP
– increased gut motility (colicky pain), bronchoconstriction, pupillary constriction (miosis).
– Salivation, lacrimation, airway secretions
Treated with muscarinic antagonist, atropine
What is the use, administration and action of pilocarpine?
Treats glaucome, topical to the eye. Acts on M3 receptors on ciliary muscle, improving aqueous humour drainage, dropping intraocular pressure.
Give examples of an M1, M2 and M3 antagonists.
M1- Pirenzepine, stomach and salivary glands
M2- Gallamine, cardiac
M3- glycopirellate, smooth muscle
What are the clinical uses of antimuscarinic drugs?
-Asthma- ipratropium- dilates bronchi
-To treat bradycardia- atropine
-To decrease gut motility; decrease secretions
(pirenzapine)
- During operations: decrease secretions, decrease
AChEI side-effects (atropine)
-To dilate pupils (tropicamide)
-Urinary incontinence (oxybutynin)
- Motion sickness (hyoscine)
What are the effects of sympathetic stimulation?
- Tachycardia
- Decreased salivary production
- Vasoconstriction and vasodilation
- Decreased gut motility
- Ejaculation
- Sweating
- Bronchodilation
- Tremor
What are the 5 main types of adrenoceptors?
a1- contract smooth muscle, vasoconstriction
a2- vasoconstriction and presynaptic
b1- increase heart rate and contractility
b2- relax smooth muscle, bronchodilation and vasodilation
b3- relax smooth muscle in the bladder and stimulate lipolysis
What are the signal transduction mechanisms for autonomic receptors?
a1- Gq- PLC, increases IP3 and DAG
a2- Gi- decreases adenylyl cyclase and decreases cAMP
b(all)- Gs- increases adenylyl cyclase and increases cAMP
M1, M3- Gq- PLC, increases IP3 and DAG
M2- Gi- decreases adenylyl cyclase and decreases cAMP
What are the uses of beta receptor agonists?
Cardiogenic shock- b1- adrenaline and dobutamine
Anaphylactic shock- (alpha or beta)- adrenaline
Asthma- b2- salbutamol
ALL delay early labour
What are the main alpha antagonist uses?
Hypertension- a1- doxazosin
Benign prostatic hyperplasia- a1- tamsulosin
What are the main uses of beta antagonists?
Propanolol (b1/2), Metroprolol (b1).
Angina, cardiac arrhythmias, hypertension, anxiety, chronic heart failure, glaucoma (timolol)
What are NET inhibitors?
They enhance the effect of NA as it is not reuptaken. eg.. cocaine and desipramine- antidepressants, tachycardia, euphoria