Hi all, I'm pretty new to (the mathematical aspect of) pharmacology.

Question about the asthma medication aminophylline word for word as follows:

Ms. Nicholls is a 30 year old, 65 kg non-smoker who is to receive intravenous aminophylline for treatment of her asthma.

The bioavailability of aminophylline, F = 1; Vd = 0.5 L/kg; Cl = 40 ml/hr/kg

Each ml of the drug contains 25 mg aminophylline, which dissociates to form 21 mg of theophylline. The pharmacological effects of aminophylline are entirely attributed to that of theophylline.

The patient is administered a loading dose of 6 mg/kg of aminophylline, i.v. Calculate the anticipated plasma concentration of theophylline following this dose.

I somehow managed to conclude that Cp = 0.655 mg / kg but It doesn't look quite right to me.

6 mg/kg aminophylline = 15.6 ml drug solution.

15.6 x 21 = 327.6 mg aminophylline.

C = D/Vd

C = 327.7 / 500

0.655 mg/ kg

Any help would be much appreciated.

Cheers