Here is the design of a clinical trial:

Official Title: A Randomized, Crossover Study Comparing Adherence, Preference + Acceptability of a Dual Prevention Pill (DPP) Capsule Containing PrEP + an Oral Contraceptive Versus Two Separate Pills in Women at Risk of HIV in Harare, Zimbabwe

Included conditions:
- HIV Infections
- Contraception

Study Armgroups:
- {'label': 'Sequence 1', 'type': 'OTHER', 'description': 'This arm is a single, over-encapsulated DPP containing PrEP (200 mg of emtricitabine \\[FTC\\], 300 mg of tenofovir disoproxil fumarate \\[TDF\\]) and a COC (30 mcg of ethinyl estradiol \\[EE\\], 150 mcg of levonorgestrel \\[LNG\\]) taken once daily for three 28-day cycles followed by PrEP (FTC/TDF) and a COC (EE/LNG) taken daily for three 28-day cycles.', 'interventionNames': ['Drug: Dual Prevention Pill', 'Drug: PrEP and combined oral contraceptive (COC) as two separate tablets']}
- {'label': 'Sequence 2', 'type': 'OTHER', 'description': 'This arm is two separate tablets (PrEP \\[FTC/TDF\\] and COC \\[EE/LNG\\]) taken once daily for three 28-day cycles followed by single, over-encapsulated DPP containing PrEP (FTC/TDF) and a COC (EE/LNG) taken once daily for three 28-day cycles.', 'interventionNames': ['Drug: Dual Prevention Pill', 'Drug: PrEP and combined oral contraceptive (COC) as two separate tablets']}

Interventions:
- {'type': 'DRUG', 'name': 'Dual Prevention Pill', 'description': 'a single over-encapsulated DPP containing a PrEP tablet and a COC', 'armGroupLabels': ['Sequence 1', 'Sequence 2'], 'otherNames': ['DPP']}
- {'type': 'DRUG', 'name': 'PrEP and combined oral contraceptive (COC) as two separate tablets', 'description': 'PrEP tablet and a COC as two separate tablets', 'armGroupLabels': ['Sequence 1', 'Sequence 2'], 'otherNames': ['Truvada', 'Zinnia F']}

Primary Outcomes:
- {'measure': 'To determine preference for taking a single DPP capsule versus 2 separate tablets (PrEP and COC) once daily among women after using each regimen for three 28-day cycles.', 'description': 'Proportion of women who prefer the DPP (Regimen A) vs 2 separate tablets (Regimen B) after using each regimen for 3 28-day cycles, per self-report on computer-assisted self-interviewing (CASI).', 'timeFrame': 'at study completion (approximately 24 weeks)'}
- {'measure': 'To assess the acceptability of taking the DPP capsule versus two separate tablets once daily to prevent HIV and unintended pregnancy among women who use each regimen for three 28-day cycles.', 'description': 'Acceptability scores by regimen and overall, per a quantitative acceptability questionnaire via CASI.', 'timeFrame': 'At the 3 and 6 month visits.'}

Please estimate the sample size based on the assumption: 
In South Africa, 80% power, 50% correlation between regimens, no period effect, and 10% dropout rate. In Zimbabwe, 94% power with alpha=0.04 and 84% power with alpha=0.02, with a 10% loss to follow-up.
Sample size and power calculations
        
          South Africa
          The sample size calculation was based on comparing adherence between the two regimens. A sample size of 86 has 80% power to detect a difference between the proportion of women who are adherent to each regimen assuming 25% of women are adherent to PrEP alone, 40% are adherent to the DPP, with a correlation between regimens of 50% and no period effect. We estimated 25% of participants would be adherent to the 2-pill regimen based on findings from other PrEP studies among young women in sub-Saharan Africa.5 52 We increased the sample to 96 in case 10% of participants discontinued early while still having 86 participants complete the cross-over period.
        
        
          Zimbabwe
          The sample size was calculated based on detecting a difference in preference for the DPP versus two separate pills. A sample size of 30 has 94% power to detect a preference for one regimen over the other when the true preference for one regimen is at least 80% based on the exact binomial test (alpha=0.04). If only 27 AGYW complete the study (10% loss to follow-up), we have 84% power to detect a preference for one regimen over the other when the true preference for one regimen is at least 80%, based on the exact binomial test (alpha=0.02).