Here is the design of a clinical trial:

Official Title: Lithium for Fracture Treatment: a Double Blind Randomized Controlled Trial

Included conditions:
- Fractures

Study Armgroups:
- {'label': 'Lithium carbonate', 'type': 'EXPERIMENTAL', 'description': 'Lithium carbonate 300mg capsule; once per day for 2 weeks.', 'interventionNames': ['Drug: Lithium Carbonate']}
- {'label': 'Lactose placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Lactose placebo capsule; once per day for 2 weeks.', 'interventionNames': ['Drug: Lactose Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'Lithium Carbonate', 'description': 'Intervention begins 14 days after injury for non-surgical participants and 2 weeks after surgery for participants who have surgical treatment of their fractures.', 'armGroupLabels': ['Lithium carbonate'], 'otherNames': ['Lithium']}
- {'type': 'DRUG', 'name': 'Lactose Placebo', 'description': 'Intervention begins 14 days after injury for non-surgical participants and 2 weeks after surgery for participants who have surgical treatment of their fractures.', 'armGroupLabels': ['Lactose placebo'], 'otherNames': ['placebo']}

Primary Outcomes:
- {'measure': 'radiographic healing of fracture', 'description': 'radiographic healing using the RUST score at 8 weeks', 'timeFrame': '8 weeks after injury (non-surgical participants) or 8 weeks after surgery (surgical participants)'}

Please estimate the sample size based on the assumption: 
A two-sample two-sided t-test with 80% power at an alpha of 0.05, assuming a drop-out rate of 10%-15%. The O'Brien-Fleming function partitions the alpha for interim and final analysis to approximately 0.003 and 0.047, respectively.
Sample size considerations
        The sample size calculation was based on pilot data analysis previously completed comparing mean Radiographic Union Scores (RUSTs) between treatment and placebo at 24 weeks in the pilot study. With the mean RUST of the placebo taken to be 8.25 and an SD of 2.6 based on our pilot data, a two-sample two-sided t-test with 70 per group has 80% power at alpha of 0.05 to test a difference in means of 1.24 or greater. Assuming a drop-out rate of 10%â15%,âthis sample size will be inflated to 80 per group, or 160 participants in total. The participants will be randomised 1:1 into the two groups and stratified according to long bone and smoking. The sample size calculation was run using PASS V.12 (Hintze, J. (2014), NCSS; Kaysville, Utah, USA). A single interim analysis will be carried out at 50% recruitment. The OâBrien-Fleming function was used with the sample size estimates to partition the alpha for the interim and final analysis to approximately 0.003 and 0.047, respectively.