Answer Happy

5 marks 2. A patient with chronic obstructive pulmonary disease is given a dose of 0.57g of theophylline, and plasma samples taken at various time intervals are analysed. The data obtained are shown in Table 1. Table 1. Plasma concentrations of theophylline in CPOD patient. Time /h Plasma Concentration (Cp) /mg L-1 5 10 10 7 20 3 a) On semi-log (i.e. log Y axis) graph paper, plot the data above, and label accordingly. (Note: you are plotting Cp on a log scale, so do not further transform data using logs). 15 marks b) Estimate the initial plasma concentration Cp(0) at time zero. 10 marks c) ...and using this, calculate the volume of distribution for theophylline. 10 marks d) What does this tell us about the distribution of the drug to the tissues, and what might we infer concerning theophylline's physicochemical nature? 10 marks VD - Volume of distribution la = dose/cPlo)= Plasma Concentration at time zero. cl= clearence th=half-tin formula vo= a/cp (o) = 0.693 x VD cl e) Why can Vd be a useful parameter for a prescriber? for az t늘 5 marks f) From your graph, estimate the half-life of the drug in this patient. 10 marks g) Now calculate the clearance of drug X in this person. 10 marks h) Explain in words what your answer to (g) means. 5 marks