If too small a peak-trough difference is seen for a drug given orally, what should be done?

A small peak-trough difference for an orally administered drug generally indicates that the drug's peak concentration (after administration) and trough concentration (before the next dose) are quite close together. This situation can suggest that the drug is being eliminated more rapidly than anticipated or that its therapeutic range is narrow.

Increasing the dose interval allows the drug levels to have a longer duration to fall, potentially maximizing the time spent at therapeutic concentrations without approaching toxicity. By spreading the doses further apart, there’s a better opportunity for the drug to exert its effects at appropriate therapeutic levels. This adjustment can help stabilize the drug levels in the patient's system and avoid rapid fluctuations that can occur with short dose intervals.

In contrast, decreasing the dose or the time between doses could potentially lead to toxicity or saturation of the liver and kidney that manage drug clearance. Such actions would likely not address the issue of the small peak-trough difference effectively. Thus, adjusting the dose interval to a longer one can be a sound clinical strategy in this scenario.