bioavailability 4 relationships

CLr > fu x GFR

secretion

CLr < fu x GFR

reabsorption

CLr = fu x GFR

filtration

more renal clearence

secreting more stuff

less renal clearance

reabsorbing stuff mainly

secretion

occurs in proximal tubules

secretion

active carrier mediated process

saturable

transporters for acid and basic drugs

no neutral drug secretion

high Er

good substrates for renal transporters

dependent on renal blood flow (Qr)

low Er

poor substrates

transportation is the limiting step

depends on unbound drug

secretion depends on

fu + Qr 

(plasma protein binding and kidney blood flow)

penicilian

acidic drug

probenecid

acidic drug

how does probenecid dec CLr of amoxicillian

probenecid shares the same renal transporter as amoxicilian so not as much is getting secreted

reabsorption

occurs in the nephron

passive process

exogenous drugs + drugs

active process

endogenous cmpds (vitamins, aa, glucose)

polarity

properties of drug

ionization

properties of drug

urine flow

physiological factors

urine pH

physiological factor

factors affecting renal reabsorption

drug properties + physiological factors

polar cmpds

not absorbed

high plasma protein binding

dec drug excretion

faster urine flow

inc drug excretion

CLr = fu x urine flow

alkaline urine

sodium bicarbonateal

alkaline drug

acetazolamide

acidic drug

ammonium chloridea

acidic drug

vitamin C

inc pH of urine (greater #)

reabsorb WB and inc elimination of WA

dec pH of urine (smaller #)

reabsorb WA and excrete WB

no reabsorption

SA, SB, polar drug in unionized form`

methamphetamine

basic drug so acidifying the drug will eliminate it

salicylic acid 

is acidic so alklanizing the urine will secrete it [give acetazolamide]

phenobarbital

acidic drug so alkalinizing the urine will excrete it [give acetazolamide]

theophylline

low Eh drug

warfarin

low Eh drug

verapamil

high Eh drug

there is no upper limit for CL

true

phenobarbital

inducer

rifampin

inducer

erythromycin

inhibitor

cimetidine

inhibitor

inc free fraction of low Eh drugs like warfarin

has significant effects on Eh bc more fu and this is a low Eh drug

inc free fraction of high Eh drugs like verapamil

has INSIGNIFICANT effects on Eh bc fu does not influence Eh of high Eh drugs

anything affecting CL

affects AUC iv

changes in oral CL

change AUC oral

low Eh drugs

F=1 so its not rlly affected by much

high Eh drugs

F is affected by CLint, fu, Qh

inc CL

dec AUC iv

factors affecting AUC iv in low Eh drugs

fu, CLint

factors affecting AUC iv in high Eh drugs

Qh

factors affecting AUC po for low and high Eh drugs

fu, CLint

changes in oral CL changes AUC po

true

AUC iv is goverened by CL so CLint changes have no effect

truecirroh

cirrhosis

dec CLint