Supercritical CO₂-Assisted Impregnation of Absorbable Surgical Sutures with Carvacrol and Benzydamine Hydrochloride: Comparative In Vitro Release Profiles and Drug Release Kinetics

The development of bioactive surgical sutures capable of delivering therapeutic agents directly at the wound site has gained increasing attention in biomedical research. Functionalized sutures may provide localized antimicrobial or anti-inflammatory activity, potentially reducing postoperative complications and promoting tissue healing. In this study, absorbable surgical sutures were impregnated with carvacrol, a natural phenolic compound with well-known antimicrobial properties, using supercritical carbon dioxide (scCO₂) technology. The impregnation process was carried out at 35 °C and 10 MPa for 120 min, allowing for the incorporation of carvacrol into the polymeric matrix of the sutures. The in vitro release behavior of the impregnated sutures was evaluated in phosphate-buffered saline (PBS, pH 7.4) at 37 °C over an 8-day period. The concentration of released compounds was determined by UV-Vis spectrophotometry using previously established calibration curves. An analysis of the experimental release data demonstrated that both carvacrol and benzydamine hydrochloride (HCl) (Tantum Verde^®) exhibited a sustained release profile throughout the incubation period. Carvacrol release increased progressively from 2.02 ± 0.15 ppm on day 1 to 7.45 ± 0.15 ppm on day 7, followed by a slight stabilization on day 8 (7.25 ± 0.31 ppm). Similarly, benzydamine HCl (Tantum Verde^®) release increased from 1.83 ± 0.11 ppm on day 1 to 3.29 ± 0.13 ppm on day 8. Release kinetics were analyzed using the Korsmeyer-Peppas model, indicating that the release mechanism was predominantly diffusion-controlled during the initial stage of the experiment. The results demonstrate that supercritical CO₂ impregnation is an effective solvent-free technique for incorporating bioactive compounds into absorbable sutures, enabling controlled release under physiological conditions.