Low-Dose Naltrexone Use in Postural Orthostatic Tachycardia Syndrome: A Case Series.

Introduction In recent years, low-dose naltrexone has emerged as a novel off-label therapy for many chronic conditions including postural orthostatic tachycardia syndrome (POTS), however, there is little evidence for its efficacy. Methods In this institutional review board (IRB)-approved case series, the charts of six tilt table-confirmed patients with POTS who underwent a trial of low-dose naltrexone (LDN) at our institution were reviewed. Medical history, subjective description of symptom severity, the continuation of therapy, tolerability, and scores on patient-reported outcome measures (Patient-Reported Outcomes Measurement Information System {PROMIS} Fatigue, PROMIS physical and mental health, Generalized Anxiety Disorder Assessment {GAD}-7, Patient Health Questionnaire {PHQ}-9, and Composite Autonomic Symptom Score {COMPASS}) were collected at therapy initiation and six to 12 months after the start of LDN. Results Three out of six reviewed patients reported an improvement in their POTS after the initiation of LDN. Two patients discontinued the therapy due to a lack of perceived benefit. No side effects or adverse outcomes were reported. The patient-reported outcome measures of PROMIS Fatigue, PROMIS physical and mental health, GAD-7, PHQ-9, and COMPASS showed inconsistent changes over the course of therapy, with some patients showing improvement or stability and others showing worsening. The small sample size and incomplete response rate did not allow for extensive statistical analysis. Conclusion As seen in its use in other conditions, LDN appears to have a favorable safety and side effect profile in patients with POTS but has little evidence for efficacy. Although some patients noted benefit, patient-reported outcome measures show a variable response profile. High-quality randomized controlled trials are needed to determine if the treatment is efficacious and should be used outside of a trial basis.