Pharma MCQ 2 Flashcards
How many quaternary amines has succinylcholine?
2
It’s two acetylcholines joined via an acetyl group
How is succinylcholine broken down?
Rapidly hydrolysed by plasma cholinestrase in the plasma to succinic acid and choline.
What enzyme can prolong the action if succinylcholine?
Inhibitors of plasma and acetylcholinesterases
Elimination half life of succinylcholine
4-5 mins
Which the following do not inhibit COX:
Azapropazone Phenazocine Benorylate Levorphanol Paracetamol
Azapropazone - NSAID derivative
Phenazocine - opioid agonist
Benorylate - ester of paracetamol and aspirin
Levorphanol - pure opioid agonist
Paracetamol - COX-3 and COX-1 inhibitor
Aspirin metabolised by?
Esterases in the intestinal mucosa and liver to acetic acid and salicylate
Aspirin protein binding?
80-90%
Aspirin pKa
Less ionised in plasma or stomach?
Aspirin is a weak acid
pKa 3.5
More unionised in stomach at pH1-2.
Therefore less ionised in the stomach.
How does morphine cause hypotension after an IV bolus?
Histamine release
Vagal stimulation
Arteriolar dilation- local vasc smooth muscle effects and inhibition CNS.
Decreased sympathetic activity
Pethidine:
Half life compared to morphine?
Lipid solubility compared to morphine?
- Longer terminal half life. Morphine: 2-3 hours
Pethidine: 3-5 hours - More lipid soluble than morphine
Pethidine:
- Relation to atropine?
- Metabolites? Active/ inactive?
- Relation to local anaesthetics?
- Atropine like chemical and has atropine like actions.
- Active metabolite- norpethidine
- Relation to local anaesthetic- LA membrane stabilising properties.
Which of these are MAO inhibitors?
Amitryptyline Tranylcypromine Diazepam Ephedrine Phenelzine
Tranylcypromine
Ephedrine
Phenelzine
Neostigmine:
Is orally well absorbed?
False, permanently charged quaternary amine, limited absorption.
Shortest duration of action: order of anticholinesterases?
Edrophonium
Neostigmine
Pyridostigmine
Neostigmine mechanism of action
Carbamylates acetylcholinesterase therefore increasing concentration of acetylcholine
How does dopexamine affect cardiac contractility?
Beta-adrenergic sympathomimetic
Increases contractility
How does theophylline affect myocardial contractility? The
NON-specific phosphodiesterase inhibitor.
Increases cAMP.
Therefore increases Ca in myocytes.
Increases contractility.
How does epinephrine influence myocardial contractility?
Increases contractility through B-agonist activity.
How does glucagon affect myocardial contractility?
Through G-protein-coupled receptor.
Increases adenylate cyclase activity.
Increases cAMP.
Increases Ca in myocytes.
Increases contractility.
How does Digoxin affect myocardial contractility?
Increases intracellular Na.
By inhibiting Na/K ATPase.
This increases Na/Ca exchanger activity.
Increases Ca in myocyte.
Increases contractility.
Nifedipine effect on myocardial contractility?
Calcium channel blocker.
Reduces intracellular Ca, reduces myocardial contraction.
Nifedipine effect on arteriolar dilation/ contraction?
Vasodilation - blocks Ca channel, reduced Ca in cell for contraction.
Nifedipine is completely absorbed sublingually? T/F?
True- sublingual avoids first pass metabolism.
Which is more effective in SVT: verapamil or nifedipine?
Verapamil.
Nifedipine (dihydropyridine) does not delay AV node conduction, Verapamil (phenylalkylamines) does.
Verapamil should not be given with b-blocker why?
Delays AV node conduction and will cause severe Brady.
What is disopyramide? And what is it used for?
Class 1a anti-arrhythmic
Negative ionotropy and reduces BP,
(prolongs PR interval and duration of action potential).
No effect peripherally, only centrally.
What arrhythmias can disopyramide trigger?
VT, VF or torsades de pointes. No extrasystoles.
