Preliminary safety and efficacy of liquid-type polycaprolactone for neck rejuvenation in Asian adults in a prospective pilot study

Abstract The neck is a challenging area for aesthetic rejuvenation due to its thin dermis and the risk of nodule formation associated with traditional particulate fillers. A novel, liquid-type polycaprolactone (PCL) offers a potential alternative by mitigating these risks. To evaluate the clinical efficacy and safety of liquid-type PCL for the treatment of horizontal neck lines in Asian patients. In this prospective, open-label, single-arm pilot study, 30 Asian subjects received three sessions of liquid-type PCL (GOURI; 210 mg/mL, 21% PCL) injections at one-month intervals using a subdermal cannula technique. All participants completed the treatment series; follow-up data were available for 29 participants at 1 month and 28 participants at both 3 and 6 months after completion of treatment. Objective biophysical parameters, including skin elasticity (Cutometer) and skin texture/wrinkle depth (Antera 3D), were assessed over a 6-month follow-up period. Subjective satisfaction and safety were also evaluated. Visual and quantitative assessments demonstrated measurable improvement in horizontal neck lines and skin quality over 6 months. In participant-level paired analyses, skin distensibility (R0) decreased from 0.214 ± 0.089 at baseline to 0.102 ± 0.091 at 6 months (mean change, −0.109; 95% CI, −0.152 to −0.066; standardized mean change [Cohen’s dz], −1.03; p < 0.001). Gross elasticity (R2) changed from 66.66 ± 15.72 to 38.16 ± 29.35 (mean change, −28.68; 95% CI, −40.70 to −16.67; dz, −0.93; p < 0.001). Skin roughness, volume of depression, and melanin index also decreased significantly. At 6 months, 85% of participants with available follow-up data reported ≥ 51% improvement. The treatment was generally well tolerated; one participant developed mild bruising that resolved spontaneously within 8 days. Liquid-type PCL may represent a safe and minimally invasive option for neck rejuvenation in appropriately selected patients. These pilot data suggest measurable improvement in neck skin texture, firmness-related parameters, and pigmentation; however, controlled studies with longer follow-up and blinded evaluation are required to confirm efficacy, durability, and optimal candidate selection.