When are peak and trough drug levels typically checked?

Peak and trough drug levels are typically monitored to determine if a drug is in the therapeutic range. This practice is essential in ensuring that the plasma concentration of the drug is effective for treatment while minimizing the risk of toxicity. The peak level is measured after the drug administration, at the point where the drug concentration is expected to be highest, to confirm that it reaches its desired efficacy without exceeding toxicity thresholds. Conversely, the trough level is assessed just before the next dose is due, ensuring that the drug concentration is still within a therapeutic range as it approaches the next administration.

Monitoring these levels helps clinicians adjust dosages accurately, assess the effectiveness of the medication, and determine how well the patient is responding to the therapy. It is particularly critical for drugs with narrow therapeutic indices, where the margin between therapeutic and toxic effects is small. Overall, checking peak and trough levels is a standard part of the therapeutic drug monitoring process to ensure optimal patient outcomes.