How should dosing be adjusted in renal impairment based on creatinine clearance?

• A. Reduce dose or extend dosing interval based on CrCl thresholds or guidelines
• B. Increase dose
• C. Dose remains the same
• D. Stop all dosing when CrCl is reduced

Answer: (A)

When kidney function declines, the drug’s clearance drops, so keeping the same dose and interval causes the drug to accumulate and exposure (AUC) to rise. To keep therapy effective but not toxic, dosing must be adjusted according to creatinine clearance using thresholds from guidelines or labeling. This adjustment usually means either lowering the amount given per dose or extending the time between doses, or both, depending on how renally cleared the drug is and how narrow its therapeutic window is. The exact changes are guided by CrCl and the drug’s properties, ensuring the exposure stays within the desired range.

Increasing the dose would worsen accumulation; keeping the dose the same ignores reduced clearance; and stopping dosing entirely isn’t appropriate unless specifically contraindicated by guidelines.