A nephrologist and longtime reader of The Medical Letter wrote us to say that our recent article entitled Drugs for Anxiety Disorders should have said more about the need for dosage adjustment of gabapentin (Neurontin, and others) and pregabalin (Lyrica, and others) in patients with renal impairment. Both drugs, he pointed out, are exclusively renally eliminated and can accumulate in patients with diminished renal function. Symptoms, which can include altered mental status, may develop so slowly that neither the patient nor the practitioner connect them to the drug. The resolution of adverse effects upon discontinuation can be slow.