Pharmacology Flashcards
What is the elimination constant?
The fraction of the amount of drug in the body that is eliminated per unit time
What is first order kinetics?
Rate of elimination is directly proportional to drug concentration
(concentration falls exponentially)
What is clearance?
‘The volume of plasma cleared of drug in unit time’
How long does it take to reach a steady state in drug administration?
Roughly 5 half lives
What is volume of distribution?
The volume into which a drug appears to be distributed with a concentration equal to that of plasma
What is a loading dose?
A loading dose (LD) is an initial higher dose of a drug given at the beginning of a course of treatment before stepping down to a lower maintenance dose
What is half life?
The time for the concentration of drug in plasma (or the amount of drug in the body) to halve
What is zero order (saturation) kinetics?
Eliminated at a constant rate, rather than at a rate that is proportional to their concentration
Examples of drugs showing zero order kinetics?
Ethanol
Phenytoin
Which drugs should always be avoided in gout as it exacerbated, and why?
Diuretics (e.g. furosemide, benzoflumethazide)- elevates levels of serum urate by competing for entry into proximal tubule
Which drug must you avoid with grapefruit juice as it may cause muscle pains? (very rare!)
Simvastatin (due to inhibition of CYP3A4 which metabolises simvastatin- making it more bioavailable)
The effectiveness of which drug may be decreased by impaired renal function?
- Metformin
- Simvastatin
- Furosemide
- Aspirin
- Bisoprolol
- Furosemide
Due to reduced GFR, reduced secretion of furosemide in the proximal tubule
Treatment of acute gout?
Colchicine
Naproxen (other NSAIDs)
Oral/IM prednisolone
What is the ‘triple whammy’ that can cause AKI?
ACE inhibitor
Diuretic
NSAID
In a patient on warfarin who is seeking pain relief, which drug should be avoided and why?
NSAIDs due to risk of GI bleeding (ulcers)
Choose paracetamol etc.
