A blood sample drawn in the middle of the dosing interval should give a conc that reflects the average steady state conc and could be used to estimate clearance in this individual and perhaps a dose change might be warranted. Theophylline sustained release TDM Janet, There are ways to estimate the average concentration of theophylline, with many assumptions. Now this value could be quite different for many reasons in this patient. CHF decreases the clearance. There are other factors that effect the clearance.
Renal clearance is minimal for theophylline.
Of course, the patient should be monitored for response and toxicity. If the response is adequate and toxicity is not an issue, whatever concentration is present, is fine. The concentration in this individual should represent the influence of any patient characteristics, e.g., CHF, smoking, ect. Theophylline sustained release TDM Dear Janet, The answer to your question is yes. Theophylline is a classic linear compound at concentration within the therapeutic range.