Treating Nightmares in Posttraumatic Stress Disorder with Clonidine and Doxazosin

Inclusion Criteria:

1. Diagnosis of posttraumatic stress disorder (PTSD) according to DSM 5 with a 20 itemCAPS-5 total score ≥ 26

2. At least two nightmares a week, an intensity score ≥ 2, with a CAPS-IV B2 (frequencyand intensity for the last week) score ≥ 5

3. Men and women between 18 and 65 years of age

4. Written informed consent

5. The patient has the capacity to give consent (He/she is able to understand thenature and anticipated effects/side effects of the proposed medical intervention)

6. The patient is not breastfeeding

7. Women of child-bearing potential must have a negative urine or serum pregnancy test

8. All participants must use highly effective contraception

9. The patient received stable pharmacological medication for at least 4 weeks or atleast five times the value of a elimination half-life prior to study baseline (anychanges in medication dose or frequency of therapy must be answered with no).

Exclusion Criteria:

1. Disturbances of cardiac impulse formation and conduction, for example sick sinussyndrome or atrioventricular block second and third degree

2. Bradycardia, with a heart rate less than 50 beats per minute

3. Current major depressive episode and a MADRS score > 34

4. The patient does have a known allergy, hypersensitivity or contraindication againstclonidine, doxazosin, or other types of quinazolines

5. History of severe orthostatic hypotension

6. Benign prostatic hyperplasia and concomitant congestion of the upper urinary tract,chronic urinary tract infection or bladder stones, hypotension (for benign prostatehyperplasia only)

7. Either overflow bladder or anuria with or without progressive renal insufficiency

8. Planned cataract surgery (risk of 'Intraoperative Floppy Iris Syndrome')

9. Intake of phosphodiesterase-5-inhibitors

10. Intake of methylphenidate

11. Severe hepatic impairment (ASAT or ALAT greater than two times normal)

12. Acute or unstable medical illness

13. Known HIV- and/or active Hepatitis-B- or Hepatitis-C-infection

14. Current or past malignant illness

15. The patient does have clinically significant abnormalities in 12-lead ECG

16. The patient does have clinically significant laboratory abnormalities

17. Epilepsy

18. Dementia

19. Current substance/alcohol use disorder (≤ 3 months)

20. Psychotic disorder

21. Bipolar disorder

22. Current anorexia nervosa

23. Acute suicidality (any suicidal ideation of type of 5 in the C-SSRS in the pastmonth)

24. Intake of alpha adrenergic agents (Clonidine, doxazosin, or others) within 4 weeksprior to baseline (randomization)

25. Trauma-focused psychotherapy four weeks before the trial

26. Initiation of sleep medication 4 weeks prior to baseline

27. The patient is unwilling to consent to saving, processing and propagation ofpseudonymized medical data for study reasons

28. Patients, who may be dependent on the sponsor, the investigator or the trial sites

29. The patient is legally detained in an official institution

30. The patient did participated in other interventional trials during the 3 monthsbefore and at the time of this trial