### T05) Find k from C0, Ct and t.

50. Pharmacokinetics 50.2) Plasma concentrations over time 50.2.1) Plasma concentrations over time

T01: Later plasma concentration Normal 1

Total tried:       Correct:       Wrong:

For an intravenously administered drug, if the concentration at 2 hr is 2.85 mg/mL, and concentration at 6.7 hr is 1.018 mg/mL, then determine the elimination rate constant of the drug. Assume that the drug follows a first order kinetics. Click on the button below to see the answer and explanations

Notice: Undefined variable: input_value1 in /home/jshzub/web/rxcal.org/public_html/practice/practice/includes/body.php on line 220
lb equals 0.219 h-1 kg

For a first order process,
C_{t}=C_{0}×e^(-kt)
It may be re-organized as:
ln(C_{t})=ln(C_{0})-kt
∴ k = ln(C_{0}/C_{t})/t
Difference between two time points (6.7 hr and 2 hr) is 4.7 hr.
\implies k =(ln(2.85/1.018))/4.7
Or, k = 0.219
Thus, the rate constant is 0.219 \quad h^{-1}. (Ans).

#### 123 ,Lorem Ipsum dummy Text E-mail: [email protected]

Notice: Undefined index: TOTALTRY in /home/jshzub/web/rxcal.org/public_html/practice/practice/includes/body.php on line 675