East Asian Arch Psychiatry 2024;34:14-7 | https://doi.org/10.12809/eaap2344

CASE REPORT

Prazosin for trauma-related nightmares in civilians at a Singapore hospital: a case series 

Keng Chuan Soh, Yi Hang Tay

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Key words: Prazosin; Psychological trauma; Sleep

Keng Chuan Soh, Department of Psychological Medicine, Khoo Teck Puat Hospital, Singapore
Yi Hang Tay, Department of Psychological Medicine, Khoo Teck Puat Hospital, Singapore

Submitted: 14 September 2023; Accepted: 28 December 2023

Prazosin was patented in 1965 and initially used as an antihypertensive, before being used to treat urinary hesitancy in benign prostatic hyperplasia.¹ Its effects on nightmares associated with post-traumatic stress disorder (PTSD) were first discovered in veterans of the Vietnam War who were prescribed prazosin for benign prostatic hyperplasia and reported reduction, and in certain cases even resolution, of combat trauma-related nightmares.²

The mechanism of this effect is considered to be associated with a decrease in arousal mediated by α-1 adrenoceptor antagonism,³ with a resultant blunting of the response to disturbing dreams. This decreased stress response can also lead to a reduced recall of nightmare content.

Recent systematic reviews and meta-analyses^4,5 support the efficacy of prazosin in treating nightmares associated with PTSD, as indicated by the reduction in frequency and intensity of nightmares, as well as improvement in sleep quality and scores on PTSD scales. Most of these data are drawn from veteran populations. However, one randomised controlled trial did not find such beneficial effects of prazosin in a veteran population.⁶

The use of prazosin in civilians of Asian ethnicity is much less studied. Treatment requirements and responses may vary in different populations, given inherent differences in demographics, contexts and numbers of traumatic events, clinical factors, and social supports following trauma disclosure.⁷ We therefore collated a case series of outpatients treated with prazosin for trauma-related nightmares to determine its efficacy and tolerability.

Medical records were retrospectively reviewed for psychiatry clinic outpatients, from a public hospital in Singapore, who were treated with prazosin for nightmares associated with PTSD between 1 January 2021 and 30 September 2021.

Data collected included age, ethnicity, sex, psychiatric diagnoses, nature of psychological trauma (if any), prazosin dosage and duration, other psychiatric medications and dosage, any concurrent psychotherapy, clinical observations pertaining to sleep and nightmares, and total and trauma- related nightmare scores on the PTSD Checklist for DSM-5 (PCL-5) before and after taking prazosin.

The self-report 20-question PCL-5 measures the extent to which each DSM-5 symptom of PTSD has bothered the patient over the previous month. Responses are measured on a five-point Likert scale from 0 (not at all) to 4 (extremely). The total score ranges from 0 to 80; higher scores indicate more frequent and intense symptoms of PTSD. The trauma-related nightmare question reads “In the past month, how much were you bothered by repeated, disturbing dreams of the stressful experience?”

Seven patients with 93 line-item prescriptions of prazosin were identified (Table).

Patient 1

A 25-year-old Chinese woman was diagnosed with PTSD and major depressive disorder (MDD). She had traits of borderline personality disorder (PD) but did not meet the threshold for the diagnosis. She experienced a traumatic sexual event and had recurrent nightmares of being either sexually violated or killed. She also reported being in a state akin to sleep paralysis. Her total PCL-5 score was 70, and she reported that her nightmares bothered her ‘quite a bit’ during the previous month. She declined antidepressants but agreed to try prazosin. Despite an episode of near-syncope when the dosage was increased from 4 mg/day to 5 mg/day, she tolerated a maintenance dosage of 6 mg/day and reported no adverse effects. Her clinical psychologist had originally planned for nightmare re-scripting, but this was no longer indicated owing to the decreased frequency and intensity of her nightmares.

Patient 2

A 25-year-old Malay woman who identified as non-binary was diagnosed with complex PTSD, borderline PD, and MDD. She had a history of multiple sexual traumas and reported frequent nightmares that resulted in night terrors and nocturnal enuresis, which embarrassed her greatly. Antidepressant trials were not well-tolerated; she was on an off-label antipsychotic to facilitate sleep. Prazosin was prescribed, with the dosage gradually increased to 6 mg/day. She responded well and reported no adverse effects. The frequency and intensity of the nightmares reduced and the nocturnal enuresis resolved. She reported improved energy levels and reduced anxiety such that she was able to return to employment.

Patient 3

A 20-year-old Malay woman was diagnosed with borderline PD, MDD, persistent depressive disorder (PDD), and social anxiety disorder. Although she did not have a diagnosis of PTSD, she reported being extremely affected by a traumatic sexual event of questionable veracity. The nightmares involved re-experiencing of this event. Her total PCL-5 score was 49, and she reported that the nightmares bothered her ‘quite a bit’ during the previous month. She received psychotherapy that focused on sleep initiation rather than addressing the nightmares. She was prescribed prazosin, and the dose was gradually increased to 7 mg/day. She reported that the frequency of nightmares reduced from daily to not more than three times a week and that she had only a partial recollection of their content.

Patient 4

A 26-year-old Malay-Thai woman was diagnosed with PTSD and PDD. She had experienced trauma related to a sexual assault. Her total PCL-5 score was 73, and she reported that her nightmares bothered her ‘extremely’ during the previous month. These nightmares evolved from vague feelings of ‘someone was there’ to witnessing her own sexual assault from a third-person perspective. She was prescribed prazosin, and the dose was gradually increased to 7 mg/day. The nightmares resolved but later recurred when the police investigations were concluded without any charges pressed. Approximately a year after the initiation of prazosin, her total PCL-5 score had reduced to 56, and she reported that the nightmares bothered her ‘quite a bit’.

Patient 5

A 36-year-old Thai woman was diagnosed with complex PTSD, MDD, and PDD. She had experienced multiple episodes of sexual assault and physical violence, which led to near-daily nightmares involving fighting off unfamiliar men. Her nightmares caused her to wake up shouting; she also reported occasional sleep paralysis. Her total PCL-5 score was 44, and her nightmares bothered her ‘moderately’ during the previous month. She was prescribed prazosin, with the dose gradually increased to 8 mg/day. 14 months later, her total PCL-5 score had reduced to 23, although she still reported that her nightmares bothered her ‘moderately’ during the previous month. At the earlier time when she was taking prazosin 6 mg/day, the nightmares had initially resolved and only recurred when she ran out of medication. Although these nightmares persisted, they were less frequent and appeared more distant. She reported that “[It is] happening to me, but I’m another person”. She experienced less resultant distress such that she no longer woke up kicking and shouting.

She overdosed on prazosin twice. In the first episode, she took 78 mg of prazosin together with 250 mg of quetiapine and alcohol. She was crying and vomiting when paramedics arrived. At 4.5 hours after the overdose, she was noted to be drowsy, and her lowest blood pressure reading was 87/66 mmHg. In the second episode, she took 30 tablets of prazosin, but the exact dosage could not be ascertained. There was no co-ingestion of alcohol or other substances. She experienced dizziness and slept for most of the day. She presented to the emergency department more than 36 hours after the overdose. By then, she was asymptomatic and normotensive.

Patient 6

A 57-year-old Malay transgender woman was diagnosed with complex PTSD and MDD. She had a history of multiple sexual traumas and was a victim in a road traffic accident. Her nightmares involved both themes. She was taking antidepressants and benzodiazepines when prazosin was prescribed. She reported a vague feeling of being ‘unwell’ when taking 1 mg/day of prazosin and was therefore maintained on 0.5 mg/day, which she subjectively found helpful for sleep maintenance.

Patient 7

A 20-year-old Chinese-Malay woman was diagnosed with complex PTSD and MDD. She had a history of multiple sexual assaults and reported vivid nightmares of being pursued or attacked by male strangers or being sexually assaulted by her mother, although the latter had never occurred. Her PCL-5 total score was 53, and she reported that her nightmares bothered her ‘quite a bit’. She reported various adverse effects from numerous antidepressants. She had an episode of near-syncope when prazosin was increased from 0.5 to 1 mg/day. She eventually discontinued prazosin while on a dose of 2 mg/day, owing to palpitations and bilateral tinnitus.

Our cases offered insights to real-world usage of prazosin for trauma-related nightmares in Asian civilians. Prazosin appears to be effective in the treatment of nightmares related to PTSD in civilians of Asian ethnicity. Of the seven patients, five reported reduced frequency and intensity of nightmares and improved sleep. They could tolerate prazosin doses of 6 to 8 mg/day.

The two remaining patients had varying clinical outcomes. Patient 6 had a vague feeling of being ‘unwell’ when taking prazosin at 1 mg/day but reported improvements in sleep at 0.5 mg/day, although it was unlikely to be pharmacologically mediated. Patient 7 experienced near- syncope when prazosin was increased from 0.5 to 1 mg/day; she reported intolerable adverse effects with prazosin at 2 mg/day, with no clinically discernible benefit.

Patient 5 who took an overdose (up to 78 mg) of prazosin together with 250 mg of quetiapine and alcohol was noted to be drowsy, and her lowest blood pressure reading was 87/66 mmHg at 4.5 hours after the overdose. However, it is difficult to delineate the effect of prazosin given the co-ingested substances.

The average daily dosage of prazosin suggested in an Australian publication is 19.6 mg in men and 8.7 mg in women.⁸ According to the Monthly Index of Medical Specialties,⁹ in the context of treating hypertension and congestive heart failure, the upper limit of prazosin dosage is 20 mg/day in divided dosages. However, a study has documented successful treatment of PTSD-related nightmares with dosages of 30 mg/day and 45 mg/day, which were reported to be safe, tolerable, and effective.¹⁰

In our patients, beneficial effects were observed at a dose of 6mg/day to 8 mg/day.

Prazosin should be considered in patients with frequent and disruptive nightmares, especially for those with difficulty maintaining sleep and those who remain disturbed by their nightmares during waking hours. Prazosin is underutilised in our settings. It is well- tolerated and not known to have problems with misuse or tolerance. This makes it useful for those with substance use histories and those who do not respond to conventional pharmacotherapy such as diazepam or Z-drugs. A step-by- step guide on initiating prazosin treatment, together with potential adverse effects, is recommended for psychiatrists and family physicians.¹¹

There are limitations to the present study. All patients were female and had experienced sexual traumas, which is not representative of the overall population and spectrum of trauma-related nightmares. Trauma in other contexts, including those that emerge within healthcare settings such as at inpatient psychiatric wards¹² and intensive care units¹³, were not considered. Four of the seven patients had traits of borderline PD or borderline PD. Comorbid physical illnesses and general anxiety levels were not recorded, and PCL-5 scores before and after prazosin treatment were not evaluated for all patients.

Prazosin is efficacious and well-tolerated for the treatment of trauma-related nightmares among Asian civilians.

Both authors designed the study, acquired the data, analysed the data, drafted the manuscript, and critically revised the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

Both authors have disclosed no conflicts of interest.

This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

All data generated or analysed during the present study are available from the corresponding author on reasonable request.

The study was approved by the National Healthcare Group Domain Specific Review Board (reference: 2022/00551). The patients were treated in accordance with the tenets of the Declaration of Helsinki.

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