Drugs indicated for the treatment of herpes zoster infection are commonly prescribed to older adults who may be at risk of dose-related adverse drug reactions, especially for those with chronic kidney disease (CKD). A new study sought to investigate whether initiation of a higher dose of an antiviral drug was associated with a greater risk of adverse drug events (neurotoxicity or mortality) within 30 days of prescription vs. a lower dose, especially for CKD patients. 27,132 patients ages ≥66 years who filled a new outpatient prescription with ≥7-day supply for oral acyclovir, valacyclovir, or famciclovir between April 2002 and December 2011 and had a confirmed herpes zoster diagnosis in the 90 days prior to or 30 days following the time of the prescription were included in the analysis. Patients taking the higher dose of the antiviral drug did not have an increased risk of hospitalization with an urgent CT scan of the head (proxy for acute neurotoxicity) or all-cause mortality. The results were consistent across all subgroups, including patients with and without CKD. These results support the safety of these medications in older patients as they are currently prescribed in clinical practice, the authors conclude.
Higher vs. lower doses of antiviral drugs used to treat herpes zoster infection may lead to more adverse drug events in older adults, particularly those with chronic kidney disease.