Mirtazapine Therapy for Posttraumatic Stress Disorder: Implications of Alpha-Adrenergic Pharmacology on the Startle Response

Pharmacotherapy of 1,044 inpatients with posttraumatic stress disorder: current status and trends in German-speaking countries

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder with limited approved pharmacological treatment options and high symptom burden. Therefore, real-life prescription patterns may differ from guideline recommendations, especially in psychiatric inpatient settings. The European Drug Safety Program in Psychiatry ("Arzneimittelsicherheit in der Psychiatrie", AMSP) collects inpatients' prescription rates cross-sectionally twice a year in German-speaking psychiatric hospitals. For this study, the AMSP database was screened for psychiatric inpatients with a primary diagnosis of PTSD between 2001 and 2017. N = 1,044 patients with a primary diagnosis of PTSD were identified with 89.9% taking psychotropics. The average prescription rate was 2.4 (standard deviation: 1.5) psychotropics per patient with high rates of antidepressant drugs (72.0%), antipsychotics drugs (58.4%) and tranquilizing drugs (29.3%). The presence of psychiatric comorbidities was associated with higher rates of psychotropic drug use. The most often prescribed substances were quetiapine (24.1% of all patients), lorazepam (18.1%) and mirtazapine (15.0%). The use of drugs approved for PTSD was low (sertraline 11.1%; paroxetine 3.7%). Prescription rates of second-generation antipsychotic drugs increased, while the use of tranquilizing drugs declined over the years. High prescription rates and extensive use of sedative medication suggest a symptom-driven prescription (e.g., hyperarousal, insomnia) that can only be explained to a minor extent by existing comorbidities. The observed discrepancy with existing guidelines underlines the need for effective pharmacological and psychological treatment options in psychiatric inpatient settings.

Relationship between mirtazapine dose and incidence of adrenergic side effects: An exploratory analysis

INTRODUCTION

Mirtazapine is an antidepressant with US Food and Drug Administration approval for management of major depressive disorder. Low doses of mirtazapine are often used for management of insomnia, with higher doses expected to provide more noradrenergic effect, and thus a higher degree of activation. If so, use of higher doses at bedtime may not be advisable and may worsen certain neuropsychiatric symptoms. No studies have been performed to evaluate these outcomes.

METHODS

This study consisted of a retrospective review of data submitted to the US Food and Drug Administration's Adverse Event Reporting System from January 1, 1995, to August 1, 2015. Cases that were deemed by study authors to represent activation of the noradrenergic system, and for which other confounders could not be identified, were included in the final analysis. The frequency of each specific adverse event was evaluated based on dose and compared to recent prescribing rates to determine if likelihood of a side effect increased with higher dose.

RESULTS

The study identified 308 incidences of anxiety, agitation, delusion, hallucination, hypertension, insomnia, nightmare, or tachycardia. After controlling for frequency of prescribing at a given dose, there was a statistically significant increase in rates of tachycardia which correlated with dose. However, after correction for multiple comparisons, results were no longer significant.

DISCUSSION

This study failed to support the hypothesis that mirtazapine is more activating at higher doses and appears to support the safety of increasing dose without increasing risk of noradrenergic side effects. Prospective studies will be necessary to confirm these findings.