Here is the design of a clinical trial:

Official Title: Validating the Effect of Ondansetron and Mirtazapine in Treating Hyperemesis Gravidarum: A Double-Blind Randomised Placebo-Controlled Multicentre Trial

Included conditions:
- Hyperemesis Gravidarum
- Nausea Gravidarum
- Vomiting of Pregnancy

Study Armgroups:
- {'label': 'Mirtazapine', 'type': 'EXPERIMENTAL', 'description': 'Mirtazapine 15 mg oral tablet (incapsulated in gelatine to provide blinding) will be administered once daily (bedtime) for 7 days. Placebo (empty gelatine capsule) will be administered once daily (morning).\n\nOn Day 7 dosage increase is optional. If desired, mirtazapine 30 mg oral tablet (incapsulated in gelatine) will be administered once daily (bedtime) for 7 days. Placebo (empty gelatine capsule) will be administered three times daily (morning, noon and late afternoon). In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'interventionNames': ['Drug: Mirtazapine']}
- {'label': 'Ondansetron', 'type': 'EXPERIMENTAL', 'description': 'Ondansetron 8 mg oral tablet (incapsulated in gelatine) will be administered twice daily (morning and bedtime) for 7 days.\n\nOn Day 7 dosage increase is optional. If desired, ondansetron 8 mg oral tablet (incapsulated in gelatine) will be administered four times daily (morning, noon, late afternoon and bedtime) for 7 days. In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'interventionNames': ['Drug: Ondansetron']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Placebo oral tablet (empty gelatine capsule) will be administered twice daily (morning and bedtime) for 7 days.\n\nOn Day 7 dosage increase is optional. If desired, placebo oral tablet (empty gelatine capsule) will be administered four times daily (morning, noon, late afternoon and bedtime) for 7 days. In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'Mirtazapine', 'description': 'Mirtazapine 15 mg oral tablet (incapsulated in gelatine to provide blinding) will be administered once daily (bedtime) for 7 days. Placebo (empty gelatine capsule) will be administered once daily (morning).\n\nOn Day 7 dosage increase is optional. If desired, mirtazapine 30 mg oral tablet (incapsulated in gelatine) will be administered once daily (bedtime) for 7 days. Placebo (empty gelatine capsule) will be administered three times daily (morning, noon and late afternoon). In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'armGroupLabels': ['Mirtazapine'], 'otherNames': ['KRKA Mirtazapine Oral Tablet']}
- {'type': 'DRUG', 'name': 'Ondansetron', 'description': 'Ondansetron 8 mg oral tablet (incapsulated in gelatine) will be administered twice daily (morning and bedtime) for 7 days.\n\nOn Day 7 dosage increase is optional. If desired, ondansetron 8 mg oral tablet (incapsulated in gelatine) will be administered four times daily (morning, noon, late afternoon and bedtime) for 7 days. In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'armGroupLabels': ['Ondansetron'], 'otherNames': ['Bluefish Ondansetron Oral Tablet']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'Placebo oral tablet (empty gelatine capsule) will be administered twice daily (morning and bedtime) for 7 days.\n\nOn Day 7 dosage increase is optional. If desired, placebo oral tablet (empty gelatine capsule) will be administered four times daily (morning, noon, late afternoon and bedtime) for 7 days. In case dosage increase is not desired, the subject will continue the initial treatment for an additional 7 days.', 'armGroupLabels': ['Placebo'], 'otherNames': ['Placebo Oral Tablet']}

Primary Outcomes:
- {'measure': 'Change in nausea and vomiting from baseline to Day 2 (short term) in the mirtazapine group versus the placebo group.', 'description': 'Change in Pregnancy Unique Quantification of Emesis 24 score (PUQE-24 score) (patient reported) from baseline to Day 2 (short term) in the mirtazapine group versus the placebo group. PUQE-24 score ranges 3-15 with 3 being better and 15 being worse.', 'timeFrame': '2 days'}
- {'measure': 'Change in nausea and vomiting from baseline to Day 2 (short term) in the ondansetron group versus the placebo group.', 'description': 'Change in PUQE-24 score (patient reported) from baseline to Day 2 (short term) in the ondansetron group versus the placebo group.', 'timeFrame': '2 days'}
- {'measure': 'Change in nausea and vomiting from baseline to Day 14(+/-1) (long term) in the mirtazapine group versus the placebo group.', 'description': 'Change in PUQE-24 score (patient reported) from baseline to Day 14(+/-) (long term) in the mirtazapine group versus the placebo group. Only tested if outcome 1 is significant.', 'timeFrame': '14 days'}
- {'measure': 'Change in nausea and vomiting from baseline to Day 14(+/-1) (long term) in the ondansetron group versus the placebo group.', 'description': 'Change in PUQE-24 score (patient reported) from baseline to Day 14(+/-) (long term) in the ondansetron group versus the placebo group. Only tested if outcome 2 is significant.', 'timeFrame': '14 days'}
- {'measure': 'Change in nausea and vomiting from baseline to Day 2 (short term) in the mirtazapine group versus the ondansetron group.', 'description': 'Change in PUQE-24 score (patient reported) from baseline to Day 2 (short term) in the mirtazapine group versus the ondansetron group. Only tested if outcome 1 is significant.', 'timeFrame': '2 days'}

Please estimate the sample size based on the assumption: 
Each hypothesis for coprimary outcomes will be tested at a significance level of 2.5% to obtain a family-wise type I error of 5% based on a Bonferroni correction. The power calculation is based on a standard deviation of change in PUQE-24 score of 3. Expecting a dropout rate of 35%, the trial aims for a power of 80%.
Sample size
          The trial is dimensioned to detect a difference of 2 or more in the coprimary outcomes; change in PUQE-24 score from baseline to day 2 in the mirtazapine versus the placebo group, or in the ondansetron versus the placebo group. Each hypothesis for coprimary outcomes will be tested at significance level 2.5% in order to obtain at family-wise type I error of 5% based on a Bonferroni correction. The power calculation is based on a standard deviation of change in PUQE-24 score of 3, which is a conservative estimate based on a placebo-controlled trial with doxylamine-pyridoxine.26 Expecting dropout of 35%, 58 participants are required in each of the three groups to obtain a power of 80%. Rounding that up to 60 participants, we aim to include 180 participants in total.