Question

1. Metabolic Drug Interactions

Drug E has the following phamacokinetic parameters:

Systemic Clearance: 3L/hr

Fraction Unbound in Blood: 0.9

Fraction Excreted unchanged in Urine: 0.02

Determine the impact of similtaneously administering a drug that inhibits the enzymes involved in the metabolism of Drug E on the following pharmacokinetic parameters:

Bioavailability : Increased / Decreased /Essentially Unchanged

Systemic Clearance : Increased / Decreased /Essentially Unchanged

Half-life : Increased / Decreased /Essentially Unchanged

2. Systemic Clearance Extended Calculation

A pharmaceutical company is developing a new drug ‘FCP-17' and has just determined the following pharmacokinetic parameters from a Phase I human study:

Fraction unbound (f_u): 0.5

Clearance by active secretion (CL_sec): 2L/hr

Fraction reabsorbed (FR): 0.25

Hepatic Extraction Ratio (E_H): 0.25

Question:

Showing all working out, and stating all assumptions, Calculate the total SYSTEMIC CLEARANCE for 'FCP-17'.

*That's the all information I got in the question. May I know what kind of information you need for this two questions? The first question only need to answer is either Increased / Decreased /Essentially Unchanged.

Answer 1

1 Bioavailability :Essentially unchanged

Systemic Clearance :Increased

Half life:Essentially unchanged

2.SYSTEMIC CLEARANCE

The systemic clearance, CL, is a measure of the efficiency with which a drug is irreversibly removed from the body.The clearance of substance x (Cx) can be calculated as

Cx = Ax/Px,

where Ax is the amount of x eliminated from the plasma, Px is the average plasma concentration, and Cxis expressed in units of volume per time.

Systemic Clearance =Hepatic extraction ratio/

Fraction rebound

=0. 5/0.25

=2L/hr