Following participant selection, confirmation of eligibility criteria, and completion of the baseline clinical assessment (Day 0), each participant will receive one bottle of nail lacquer containing Tofacitinib 2% for home use throughout the study period. Application of the investigational product will be the responsibility of the participant and must be performed once daily, in accordance with the instructions provided by the research team. Prior to each new application, the participant must completely remove the previous layer of nail lacquer, ensuring that the nail surface is clean and dry. After removal, a new uniform layer of the product should be applied to the affected nail(s). The product must be used daily and continuously for the entire duration of the study, in compliance with the schedule established in the study protocol.

The Nail Psoriasis Severity Index (NAPSI) evaluates nail psoriasis severity by assessing a target nail for nail matrix and nail bed involvement. The nail is divided into four quadrants. Nail matrix psoriasis includes pitting, leukonychia, red spots in the lunula, and nail plate crumbling, while nail bed psoriasis comprises onycholysis, splinter hemorrhages, oil drop (salmon patch) discoloration, and nail bed hyperkeratosis. Each component is scored from 0 to 4 according to the number of quadrants affected (1 = 1/4, 2 = 2/4, 3 = 3/4, 4 = 4/4). The total NAPSI score per nail is calculated as the sum of matrix and nail bed scores, ranging from 0 to 8. The score is directly proportional to disease severity, with higher scores indicating greater nail involvement and a score of zero representing absence of nail manifestations. In clinical studies, a decrease in NAPSI score over time indicates clinical improvement.

The Dermatology Life Quality Index (DLQI) is a validated, standardized instrument used to assess the impact of dermatological diseases on patients' quality of life over the preceding seven days. The questionnaire consists of 10 items covering symptoms and feelings, daily activities, leisure, work or school, personal relationships, and treatment-related burden. Each item is scored on a four-point scale from 0 to 3, where 0 indicates "not at all" and 3 indicates "very much." The total DLQI score is calculated as the sum of all items, yielding a minimum score of 0 and a maximum score of 30. Interpretation is directly proportional to disease impact: higher scores reflect greater impairment and worse dermatology-related quality of life, whereas lower scores indicate less impact, with a score of zero representing no effect on quality of life.

This study evaluates the use of a medicated nail lacquer for the treatment of nail psoriasis, and one of the outcome measures will be the monitoring of treatment adherence, including the frequency of application and the correct execution of the nail lacquer application technique. Adherence will be systematically monitored throughout the study period using structured records to verify whether the product is applied in accordance with the dosing regimen and protocol-defined instructions. This monitoring aims to ensure intervention fidelity and to support the accurate interpretation of the treatment's efficacy and safety outcomes.