If a patient is on Drug A for 10 years and Drug B is added, which drug’s dose should typically be lowered?

In situations where a patient has been on a medication for an extended period, such as 10 years, and another medication is introduced, it is usually advisable to consider decreasing the dose of the long-standing medication. This is particularly true if the two drugs have overlapping effects or if Drug B has the potential to interact with or enhance the effects of Drug A.

The rationale behind lowering the dose of Drug A often revolves around minimizing the risk of adverse effects, especially if Drug A is known to cause toxicity or has a narrow therapeutic index. Introducing Drug B could change the pharmacodynamics or pharmacokinetics of Drug A, necessitating a reduction to maintain safe and effective therapy.

For example, if Drug A is an antihypertensive and Drug B is also an antihypertensive added for better blood pressure control, continuing both at their original doses could lead to hypotension. This principle helps ensure patient safety and comfort, while also optimizing therapeutic outcomes.