Final answer:
After discontinuing the IV theophylline, the first dose of the oral medication should be given immediately to maintain therapeutic levels and avoid any gap in medication coverage.
Step-by-step explanation:
The question posed is about the scheduling of the first dose of an immediate-release oral form of theophylline after discontinuing its intravenous (IV) administration. Based on pharmacokinetic principles regarding drug plasma concentration curves, as the graph in the provided text outlines, there is a difference in how quickly IV versus oral medications achieve peak plasma concentrations. IV medications produce peak concentrations rapidly, then diminish over time, while oral medications require more time to reach their peak.
For safety and effectiveness, oral medication should be scheduled to maintain therapeutic drug levels without causing unnecessary side effects or a lapse in medication coverage. Thus, after discontinuing the IV form of theophylline, the first dose of the oral medication should be administered immediately on discontinuing the IV form to maintain appropriate theophylline levels while avoiding gaps in therapy.
When determining the dosage of a drug, factors to consider include the patient's age, body mass, liver and kidney function, and history of allergic reactions. These factors help to select the optimum dosage that minimizes risk while still achieving the desired effect. As theophylline is typically administered on a fixed schedule, immediate conversion from IV to oral form helps in maintaining the therapeutic levels required for clinical effectiveness.