Safety evaluation of pirfenidone gel 8% w/w: Assessing comedogenicity, skin irritability, allergenicity, and photoirritation

Objectives: Hypertrophic scars are a pathological outcome of disrupted wound healing. These scars significantly affect the quality of life due to their esthetic, functional, and psychological impacts. Topical pirfenidone, a broad-spectrum antifibrotic agent, has shown potential in regulating collagen synthesis and reducing established scars. This study aimed to assess the safety profile of pirfenidone gel 8% w/w through standardized evaluations of its comedogenic potential, skin irritation on normal and sensitive skin, allergenicity, and photoirritation potential. Materials and Methods: The study employed a monocentric, evaluator-blinded design to assess the safety of pirfenidone in 281 participants. Comedogenicity was evaluated using follicular biopsy and microscopic grading. Skin irritation was measured with a patch test on sensitive and normal skin types, and outcomes were graded using the Draize and Contact Dermatitis Research Group scales. Allergenicity was assessed through a Human Repeat Insult Patch Test, while photoirritation was evaluated using a photo patch test. Results: Pirfenidone gel 8% w/w was noncomedogenic, with a mean comedone grade significantly lower than the positive control ( P = 0.005). The patch test confirmed the gel’s non-irritant nature, with mean scores considerably lower than the positive control across sensitive and normal skin types. Allergenicity testing in 211 participants confirmed the gel as non-irritant and hypoallergenic, with no weak or strong positive reactions observed. Photoirritation testing classified the gel as a non-photo irritant, with mean scores for ultraviolet-exposed and ultraviolet-unexposed sites below the irritation threshold. Conclusion: This study demonstrates that pirfenidone gel 8% w/w is safe for topical application, with no significant adverse reactions observed concerning comedogenicity, skin irritability, allergenicity, and photoirritation. These findings support its use, although further research is warranted to evaluate its long-term safety.