Posted: December 21st, 2015

Calculate the maximum, minimum and average plasma concentrations of the drug if the oral dose was repeated at 6 hourly intervals. Do the maximum and minimum concentrations fall within the therapeutic range?

Following intravenous administration of 200 mg of a drug to a healthy volunteer the plasma concentration versus time curve may be described by the equation:

C_t = 4.17e^–0.24t

Where the plasma concentration (C_t) is in units of micrograms per millilitre (μg/mL) and the time (t) post drug administration is in hours.

The drug was subsequently given orally at a dose of 300 mg to the same volunteer yielding an area under the plasma concentration time curve of 23.2 mg L^–1 h.

• Using the above information, calculate the following pharmacokinetic parameters of the drug:

• elimination half-life;
• volume of distribution,
• area under the plasma concentration time curve,
• oral bioavailability.

(50% Marks)

• Further examination of the properties of the drug indicate that it has a therapeutic range between 2.0 and 8.0 mg/L in plasma concentration. Calculate the maximum, minimum and average plasma concentrations of the drug if the oral dose was repeated at 6 hourly intervals. Do the maximum and minimum concentrations fall within the therapeutic range?