Why is Cl better in measuring drug elimination than Rate of Loss
Bc 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)
Rate of Loss (Rate of Elimination) Formula
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
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 functions
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 process
T or F? In any given case, the increase in plasma concentration of drug will not influence (positively or negatively) the Clearance of the drug
True. 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.
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]
intrinsic activity of an enzyme
Blood flow (perfusion) of organ
Plasma protein binding
Total body clearance
elimination of drug from the body, aka systemic clearance (CL3)
Total 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
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 CL
False, 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
T or F? Knowing CLt and not CLr can be determine experimentally from urinary excretion data
False, knowing CLt and CLr can be determined experimentally from urinary excretion data.
CL in terms of Dose and AUC
CL = (Dose / AUC)
How do you determine Renal RoE (Rate of Elimination)
(CLr * Cp), OR fe = (CLr)/(CLt) or CLr = feCL
Fraction of an IV bolus dose eliminated/excreted unchanged
(Total amt excreted unchanged in urine) / (Dose). The Fe value lies btw 0-1
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