Session 11.3 Pharmacokinetics 5 Flashcards
what happens during distal tubular reabsorption
passive reabsorption of drugs through OAT and OCT which are lipid soluble and unionised and at a high concentration
most frug
not reabsorbed and enter unrine if ionised and lipid insoluble
if DCT acidic
weak acids become protonated and become charge neutral so re absorbed
if DCT basic
weakbases lose proton and become charge neutral so re absorbed
acidic urine
decrease absorption of weak bases
alkaline urine
decreases absorption of weak acids
what is clearance
the rate of elimination of a drug from the body…the volume of plasma (Vd) that is completely cleared of the drug per unit time, in ml/min or ml.min-1
both hepatic and renal clearance
why is it apparent rate of elimination
as real volume of plasma never completely cleared of drug
what is the clinical relevance of clearance and Vd
how long drug stays in body and does any therapeutic good - dosage schedule, therapeutic regime level, minimising ADR’s
what does clearance aand Vd estimate
drug half life, t1/2
what is drug half life
the amount of time over which the concentration of a drug in plasma decreases to one half of that concentration value it had when it was first measured
if clearance stays the same and Vd increases
t1/2 increases
if clearance increases but vd stays the same
t1/2 decreases
t1/2=
(0.7 x Vd) / clearance
