Continuous Intravenous Acyclovir as Outpatient Parenteral Antimicrobial Therapy for HSV and VZV Neurological Infections: A Case Series With Pharmacokinetic and Cost Evaluation, and Review of Literature

ABSTRACT Varicella zoster virus (VZV) and herpes simplex virus (HSV) are major causes of viral meningitis and encephalitis. Standard intermittent intravenous acyclovir requires hospitalisation, reducing patient comfort and prolonging admissions. Continuous infusion may maintain therapeutic plasma and cerebrospinal fluid (CSF) concentrations while enabling treatment through Outpatient Parenteral Antimicrobial Therapy (OPAT). Objectives to evaluate the feasibility, pharmacokinetic target attainment, and cost reduction of continuous intravenous acyclovir for HSV and VZV neurological infections in an OPAT setting. We conducted a case series of eight patients with HSV or VZV neurological infections who received continuous intravenous acyclovir through our OPAT programme after initial hospital‐based therapy. Steady‐state plasma concentrations were measured to assess pharmacokinetic target attainment. Costs were calculated based on daily costs of discontinued inpatient care and OPAT. Existing literature on continuous intravenous acyclovir and acyclovir in OPAT was reviewed. No persistent complications associated with continuous intravenous acyclovir administration were observed. All patients completed treatment with good clinical responses; one had persistent ptosis, and another developed postherpetic neuralgia. Acyclovir plasma concentrations remained above the therapeutic threshold in all seven measured cases, suggesting adequate CSF exposure. Hospital admissions were shortened, with no readmissions. The acyclovir OPAT programme led to cost savings of 3486 EUR per patient. Despite this small case series, continuous intravenous acyclovir appears to be feasible for treating HSV and VZV neurological infections in an OPAT setting, with potential benefits in patient comfort, healthcare costs, and hospital resource utilization. Larger studies are warranted to assess safety and efficacy.