Evaluation of NSAID saturation levels in silicone hydrogel soft contact lenses

Background. Only a limited number of studies have reported the clinical use of soft contact lenses pre-soaked in non-steroidal anti-inflammatory drug (NSAID) solutions. Within these studies, various soaking durations, drug types, and saturation methods have been proposed. However, a standardized protocol for NSAID loading into contact lenses – taking into account the sorptive properties of the lens material and drug concentration – has not yet been established, underscoring the relevance of the present study. Purpose: to determine the optimal soaking duration for NSAID saturation of soft contact lenses at various stages of desorption. Materials and methods. This experimental study involved the physicochemical assessment of NSAID sorption and desorption from soft contact lenses using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS). Soaking durations were set at 30 minutes, 3 hours, and 24 hours. The study utilized silicone hydrogel lenses composed of Lotrafilcon A (FDA-approved for bandage use), with 24% water content and a refractive power of –0.5 diopters; a total of 36 lenses were tested. The NSAIDs under investigation were ketorolac tromethamine (30 mg/mL) (hereinafter referred to as ketorolac) and diclofenac sodium (25 mg/mL) (hereinafter referred to as diclofenac), both known for their potent antiinflammatory and analgesic properties. Results. The total amount of ketorolac absorbed by the lenses was comparable after 30 minutes and 24 hours of exposure, with peak uptake (0.61 ± 0.93 mg/mL) observed after 3 hours. For diclofenac, the highest absorption was also recorded at 3 hours (12.0 ± 5.1 mg/mL), which was greater than the concentration of ketorolac. Conclusion. The findings indicate that ketorolac 30 mg/mL enables more uniform saturation of soft contact lenses within clinically relevant concentration ranges, maintaining peak drug levels for up to 24 hours following a 3-hour soak, with minimal alterations to the physical properties of the lenses. In contrast, saturation with diclofenac resulted in a substantial increase in lens mass and exceeded the therapeutic ocular concentration threshold.