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.
There are a variety of refernces that would be useful. Here a just a couple. Winter ME . Basic CLinical Pharmacokinetics. Theophylline chapter pp.