Pharmacology quiz Flashcards
Mathematically how can you quantify therapeutic index?
Looking at the curves, the dose at which half of the toxic effects occur divided by dose at which half the good effects occur. Ie if the curves are far apart, there is a good therapeutic window, and this division value will be higher.
Cimetidine is a potent _____ of CYP450?
Inhibitor
Old H2 antagonist
Verapamil does what to which enzyme system?
Inhibits CYP3A4
Azoles do what to which enzyme system?
Inhibits CYP3A4
Erythromycin does what to which enzyme system?
Inhibits CYP3A4
Diltiazem does what to which enzyme system?
Inhibits CYP3A4
What effect do alcohol and amiodarone have on warfarin metabolism?
Inhibit metabolism
How does codeine get to morphine?
CYP2D6
Fluoxetine does what to which enzyme?
Inhibits CYP 2D6
What are the notable exceptions that decrease INR? Most increase INR.
Carbamazepine(also increase but mostly decrease)
Phenytoin (also increase but mostly decrease)
Rifampicin
Cholystyramine
St Johns wort
What is the function of P-glycoprotein?
Efflux protein- leads to less absorption from GIT.
What are some susceptible drugs when there are others that affect P glycoprotein?
Digoxin- a renally excreted drug but still loads of interactions due to P glycoprotein
SJS in asian carbamazepine users assoc with which HLA?
HA B*1502
Fluclox liver failure associated with which HLA?
HLA-B *5701
Abdo pain + neuro signs, think…
Acute intermittent porphyria
Lead poisoning
Mechanism of Tryptans
5Ht1 agonists used in acute treatment of migraine
Should take as soon as possible after onset of HEADACHE not aura
AE tingling, heat, tightness in throat and chest, pressure. DONT give if signif RF for IHD
beta blockers and glucose- what points to consider?
Can slightly impair glucose tolerance
Can interfere with metabolic and autonomic responses to hypoglycaemia
Varenicline MOA?
Nicotinic receptor partial agonist
Avoid in patients with psych history or self harm history
Bupropion MOA?
Norepinephrine and dopamine reuptake inhibitor and nicotinic antagonist
Small risk seizures, dont use in epilepsy
What are some muscarinic antagonists and how are they used?
Tolterodine, oxybutuynin, and solifenacin are muscarinic antagonists for urinary incontinence
Ipratropium is for COPD
Procyclidine is for Parkinson’s disease
What is the mechanism of azathioprine?
Metabolised to mercaptopurine which is a purine analogue that inhibits purine synthesis.
MOA phenytoin?
Increases refractory period of voltage gated Na channels, decreasing sodium influx into neurons which decreases excitability
What type of anaemia does phenytoin cause?
Megaloblastic anaemia- alters folate metabolism
Also can cause anaplastic anaemia (idiosyncratic)
What are the chronic side effects of phenytoin?
Gingival hyperplasia secondary to increased PDGF
Megaloblastic anaemia
Peripheral neuropathy
Osteomalacia from enhanced Vit D metabolism
Lymphadenopathy
Dyskinesia
Dupytren’s contracture
Can also cause hepatitis, aplastic anaemia, drug induced lupus, bad rashes like TENS
Do you need to monitor phenytoin levels?
Not routinely, but check trough level if want to adjust dose, suspect toxicity, or nonadherence
What is GLP-1?
A hormone released by the small intestine in response to an oral glucose load.
Exenatide is a GLP-1 mimetic –>increase insulin, reduced glucagon
What is the incretin effect?
Same amount of glucose PO will cause an increase in insulin load compared with same amount of glucose IV. This is mediated by GLP-1 which is decreased in DM2
Weight loss or weight gain with exenatide?
Loss
MOA sitagliptin and vildagliptin?
oral preparations, NO weight gain, do NOT cause hypos
DPP-4 usually inactivates GLP-1. Sitagligliptin inhibits enzyme–>increased GLP-1 levels
Leukotriene receptor antagonists are associated with the development of which vasculitis?
Churg Strauss
Ondansetron MOA?
5-HT3 receptor antagonist
Explain the receptor 5-HT in migraine? (confusing)
5-HT receptor agonists in acute TREATMENT of migraine eg sumitriptan (5HT1D)
5-HT receptor antagonists are used in PROPHYLAXIS eg pizotifen (5HT2)
MOA of pioglitazone
A thaiazolidinedione
Agonists to PPAR-gamma receptor (an intracellular nuclear receptor)- thought to control adipocyte differentiation and function. Causes a reduction in peripheral insulin resistance.
What is a contraindication to pioglitazone?
Heart failure- causes fluid retention.
More of a risk if patient is also on insulin
Also has increased risk of fractures, bladder cancer.
Get weight gain and LFT derangement.
MOA of octreotide
Long acting analogue of somatostaatin. Somatostatin is released from pancreatic D cells and inhibits the release of growth hormone, glucagon, and insulin
Which drugs can be cleared with dialysis? BLAST
barbituate
lithium
alcohol (incl methanol and ethylene glycol)
salicylates
theophyllines (charcoal haemoperfusion is best)
Digoxin, trycyclics, beta blockers, benzos CANNOT
TCA ECG changes
Sinus tachycardia
Wide QRS
Prolonged QT interval
CORRECTION OF ACIDOSIS IS FIRST LINE IV lipid emulsion can be used to bind free drug Dialysis does not work Avoid 1a, 1c, III antiarrhythmics Response to lignocaine is variable
How much steroid does someone need to be on before they score osteoporosis prophylaxis?
7.5mg pred 3 or more months
What effect does metformin have on B12?
Reduces B12 absorption
Why does ethanol cause polyuria?
Inhibits ADH secretion
