Pharmacology quiz Flashcards by alice Sawka

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.

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Cimetidine is a potent _____ of CYP450?

Inhibitor

Old H2 antagonist

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Verapamil does what to which enzyme system?

Inhibits CYP3A4

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Azoles do what to which enzyme system?

Inhibits CYP3A4

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Erythromycin does what to which enzyme system?

Inhibits CYP3A4

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Diltiazem does what to which enzyme system?

Inhibits CYP3A4

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What effect do alcohol and amiodarone have on warfarin metabolism?

Inhibit metabolism

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How does codeine get to morphine?

CYP2D6

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Fluoxetine does what to which enzyme?

Inhibits CYP 2D6

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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

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What is the function of P-glycoprotein?

Efflux protein- leads to less absorption from GIT.

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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

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SJS in asian carbamazepine users assoc with which HLA?

HA B*1502

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Fluclox liver failure associated with which HLA?

HLA-B *5701

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Abdo pain + neuro signs, think…

Acute intermittent porphyria

Lead poisoning

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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

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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