Example : Bretylium is an antiarrhythmic drug used in the treatment of ventricular tachycardia. After administration of a single iv dose of 600 mg bretylium, the plasma conc-time profile can be described by : Cp (mg/L) = 12 e-1.38 t + 0.9 e0.087 t. Calculate bretylium AUC after a single iv dose of 600 mg, and the average steady state conc during administration of 300 mg every 6 hr.

Cp = 12 e-1.38 t + 0.9 e -0.087 t
AUC =

A

α +

B

β
Cpss average=

Dose

CLT τ

Answer :

AUC =

12 mg/L

1.38 hr-1 +

0.9 mg/L

0.087 hr -1 = 19.3 mg-hr/L
CLT =

600 mg

19.3 mg-hr/L = 31 L/hr
Cpaverage ss =

300 mg

31 L/hr 6 hr = 1.61 mg/L
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