BPC 157 for Acute Hamstring Muscle Strain Repair

Inclusion Criteria: * Age 18 to 45 years. * Acute posterior thigh pain consistent with hamstring strain with onset within 72 hours prior to screening. * MRI-confirmed grade II hamstring strain of the biceps femoris, semitendinosus, or semimembranosus, with measurable lesion. * Pre-injury physical activity \>= 3 sessions/week or participation in organized recreational sport. * Willingness to follow the standardized rehabilitation protocol and attend all study visits. * For participants of childbearing potential: negative pregnancy test at baseline and agreement to use effective contraception during dosing and for 30 days after last dose. Exclusion Criteria: * Grade III hamstring tear, tendon avulsion, or injury requiring surgical management. * Concomitant lower extremity injury that would interfere with rehabilitation or outcome assessment. * Prior hamstring strain on the index limb within the past 6 months. * Use of systemic corticosteroids, anabolic agents, platelet-rich plasma, stem-cell products, or investigational peptides/growth factors within 30 days prior to screening. * Known bleeding disorder or current therapeutic anticoagulation. * Significant uncontrolled medical illness (e.g., severe cardiovascular, hepatic, or renal disease) that increases study risk. * Known allergy or hypersensitivity to components of the investigational product or placebo. * Pregnant or breastfeeding. * Current participation in another interventional clinical study or participation within 30 days prior to screening. * Currently subject to a formal anti-doping testing program (e.g., WADA/USADA-aligned) where use of an investigational peptide could create a regulatory conflict, unless explicitly approved by the relevant authority