A pilot study comparing the efficacy of two formulations of botulinum toxin type A for muscular calves contouring

Summary Background Enlarged, hypertrophy calf muscles are common in Asian women and can cause psychological burden. Botulinum toxin A (BTA) has been widely used in treating masseteric muscle hypertrophy and it's efficacious as a noninvasive method for calf‐contouring has been reported. Food and Drug Administration has approved onabotulinumtoxin A (ONA, Botox; Allergan Inc, Irvine, CA, USA) for upper face rejuvenation and it has off‐label uses for calf‐contouring. A recently introduced Prabotulinumtoxin A (NABOTA®, PRA; Daewoong Pharmaceutical, Seoul, Korea) demonstrated a comparable efficacy and safety to ONA for masseter reduction. Objective To compare the efficacy and safety of PRA and ONA gastrocnemius muscle reduction. Methods This is an experimental, randomized, controlled double‐blind study. Twenty‐two patients were randomized to receive 100 units PRA and ONA on each calf and were asked to come for follow‐up visit for up to 6 months. Clinical photographic documentation, calf circumference measurement (upright position and tiptoe), isokinetic analysis, and ultrasonographic imaging were performed to evaluate the treatment result. In addition, patients’ satisfaction and side effect were also recorded. Results All patients completed the study without serious side effect occurred during the whole study period. The mean calf circumference of the ONA‐ and PRA‐treated patients in upright position at baseline was 35.42 ± 1.35 cm and 36.49 ± 2.98 cm, respectively (P = 0.137). The mean calf circumference in upright position decreased significantly as early as 2 weeks after treatment, both in ONA group and in PRA group (P = 0.004 and P = 0.003, respectively), and continued to decrease until 6 months after treatment (P = 0.002 and P