Pharmacokinetics Parameters, CL

alchemist04's version from 2016-06-23 05:25


Question Answer
Cl is used forquantitating the rate of drug elimination from the body
What does CL depends on(1) Plasma protein binding (2) Hepatic enzyme activity (3) Blood flow
Why is Cl better in measuring drug elimination than Rate of LossBc in Rate of Loss, the value is always changing with time after a single or multiple dose administration, if it follows First Order Kinetics
T or F? If Plasma drug concentration increase (e.g double from 2mg/mL to 4mg/mL), the Rate of Loss of drug will increase (and double from 10mg/min to 20mg/min)True
Rate of Loss (Rate of Elimination) FormuladC/dt
Why is CL better than Elimination Rate Constant (K)?Elimination Rate Constant (k) only describe the elimination of drug from the plasma and not from body. It is also affected by changes in distribution as well as elimination


Question Answer
T or F? Clearance is an excellent measure of the efficiency of elimination of metabolized (free drug, Fu) from an organ (Liver, Kidney etc). It is used to assess organ functionsTrue
T or F? Cl is the Volume of plasma in the vascular compartment cleared of drug per unit.True (i.e. it is the volume of blood plasma or cell plasma w/o drug per time (e.g. 15 mL/min or 30 mL/min)
T or F? CL is independent of 1st order processTrue
T or F? In any given case, the increase in plasma concentration of drug will not influence (positively or negatively) the Clearance of the drugTrue. If plasma concentration is 5 mg/mL and the clearance equals 3 mL/min, the clearance will remain 3 mL/min when plasma concentration increases to 60 mg/mL.


Question Answer
RoE (Rate of Elimination formula)(CL) (Cp) where Cp is the Plasma Concentration of Drug substance
CL formula is[Fu * CLi * Q] / [(Fu * CLi) + Q]
CLiintrinsic activity of an enzyme
QBlood flow (perfusion) of organ
FuPlasma protein binding


Question Answer
Total body clearanceelimination of drug from the body, aka systemic clearance (CL3)
CLhHepatic clearance
CLrRenal Clearance
CLtTotal Clearance = CLh + CLr + CL others
What is the difference btw Hepatic and Renal Clearance?(1) Hepatic clearance is drug metabolism in the liver. The drug is eliminated by biotransformation (2) Renal clearance are the drug substance that are excreted, they are the free drug substance. This drug are unchanged and cleared via nephron/kidney and urine


Question Answer
If renal clearance is reduced due to kidney disease, what will happen to hepatic clearance? Would it reduce in clearance or increased in clearance?The reduced in renal clearance will not affect hepatic clearance. Hence, hepatic clearance will function normally.
T or F? One organ CL is dependent of another organ CLFalse, one organ clearance is independent of another organ clearance.
T or F? Total Clearance (clearance from the entire body) is determined from the total exposure (AUC) ff an IV dose: True
Question Answer
T or F? Knowing CLt and not CLr can be determine experimentally from urinary excretion dataFalse, knowing CLt and CLr can be determined experimentally from urinary excretion data.
CL in terms of Dose and AUCCL = (Dose / AUC)


Question Answer
How do you determine Renal RoE (Rate of Elimination)(CLr * Cp), OR fe = (CLr)/(CLt) or CLr = feCL
fe isFraction of an IV bolus dose eliminated/excreted unchanged
Fe formula(Total amt excreted unchanged in urine) / (Dose). The Fe value lies btw 0-1