Here is the design of a clinical trial:

Official Title: Naltrexone Treatment for Prolonged Grief Disorder: A Pilot Study

Included conditions:
- Prolonged Grief Disorder

Study Armgroups:
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': '24 randomized patients will take placebo daily for 8 weeks.', 'interventionNames': ['Drug: Placebo']}
- {'label': 'Naltrexone', 'type': 'ACTIVE_COMPARATOR', 'description': '24 randomized patients will take naltrexone daily for 8 weeks', 'interventionNames': ['Drug: Naltrexone HCl 50 MG Oral Tablet']}

Interventions:
- {'type': 'DRUG', 'name': 'Naltrexone HCl 50 MG Oral Tablet', 'description': 'Generic, oral tablet.', 'armGroupLabels': ['Naltrexone']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'Composed of filler material and encapsulated to appear identical to naltrexone.', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'Change in Prolonged Grief Disorder Symptom Severity as Assessed by Prolonged Grief-13 (PG-13)', 'description': 'Prolonged Grief Disorder (PGD) is a newly defined syndrome that is a specific reaction to the loss of a loved one. Change in PGD symptom severity will be measured by using Prolonged Grief-13-R (PG-13-R), a self-rated scale consisting of 11 items. The validity and reliability of the scale were tested and validated in previous studies.\n\nMinimum Score: 11 - reflecting the lowest level of PGD symptom severity (distress) Maximum Score: 55 - reflecting the highest level of PGD symptom severity (distress) Diagnostic Criteria PGD symptom severity of ≥30 is the threshold for "syndromal" level PGD.\n\nProlonged Grief (PG-13-R) is a diagnostic tool. If a respondent meets the diagnostic criteria for PGD, this suggests that they should seek more thorough evaluation from a mental health professional. Only an in-person assessment by a mental health professional can determine for certain the clinical significance of the reported symptoms, and provide recommendations or referrals for treatment.', 'timeFrame': 'Baseline and 8 Weeks'}
- {'measure': 'Change in Prolonged Grief Disorder Symptom Severity as Assessed by Prolonged Grief-13', 'description': 'Prolonged Grief Disorder (PGD) is a newly defined syndrome that is a specific reaction to the loss of a loved one. Change in PGD symptom severity will be measured by using Prolonged Grief-13-R (PG-13-R), a self-rated scale consisting of 11 items. The validity and reliability of the scale were tested and validated in previous studies.\n\nMinimum Score: 11 - reflecting the lowest level of PGD symptom severity (distress) Maximum Score: 55 - reflecting the highest level of PGD symptom severity (distress) Diagnostic Criteria PGD symptom severity of ≥30 is the threshold for "syndromal" level PGD.\n\nProlonged Grief (PG-13-R) is a diagnostic tool. If a respondent meets the diagnostic criteria for PGD, this suggests that they should seek more thorough evaluation from a mental health professional. Only an in-person assessment by a mental health professional can determine for certain the clinical significance of the reported symptoms, and provide recommendations or referrals for treatment.', 'timeFrame': 'Baseline and 12 weeks'}
- {'measure': 'Change in Number of Participants With Prolonged Grief Disorder as Assessed by Structured Clinical Interview for PGD (SCIP)', 'description': 'Eligibility for the study and change in symptom severity will be measured by SCIP. This structured clinical interview is adapted to the DSM-5-TR criteria for PGD. Interviewers will be trained to standard which will be a κ \\> 0.8 agreement between trainee and trainer.', 'timeFrame': 'Every 4 weeks for 8 weeks'}

Please estimate the sample size based on the assumption: 
80% power (Type II error < 0.2) to detect a significant difference (Type I error < 0.05); interim analysis at 50% information fraction; accrual rate of 6 participants per month over 9-12 months.
Sample size {14}
        According to previous studies tracking grief intensity changes across time among the bereaved sample [5, 26], we estimate a natural decline of 1.0 in PG-13-R scores during a period of 2âmonths with a standard deviation of 6.0, for patients 12 to 18âmonths post bereavement. Meanwhile, we propose a 20% decline from baseline PG-13-R for the treatment group. The effect size (Cohenâs d) was then assumed to be 0.83. The null hypothesis is that comparing to the placebo-controlled group, naltrexone treatment at 50âmg mitigates grief intensity among patients with prolonged grief disorder in a 2-month period. With 48 participants (nâ=â24 naltrexone arm; nâ=â24 placebo arm) and an interim analysis at 50% information fraction, we expect to have 80% power (Type II errorâ<â0.2) to detect a significant difference (Type I errorâ<â0.05) in PG-13-R baseline-to-2-month scores comparing the intervention and control groups. The accrual rate is expected to be 6 participants per month with the recruitment period spanning over 9â12âmonths.