Capsaicin topical cream (8%) for the treatment of myofascial pain syndrome / Creme tópico de capsaicina (8%) para o tratamento da síndrome da dor miofascial

Abstract Background: Myofascial pain syndrome is a common cause of musculoskeletal pain. The objective of this study was to evaluate the potential analgesic action of 8% capsaicin cream for topical use in patients with myofascial pain syndrome. Methods: Initially, cream formulations of PLA (Placebo) and CPS (Capsaicin 8%) were developed and approved according to the current requirements of the health authority agency. The 40 participating patients were randomly assigned to the PLA and CPS groups in a double-blind fashion. Before the creams were topically administered, according to the allocation group, the local anesthetic was used for a period of 50 minutes directly in the area of interest. The cream was applied to the area of the skin over the trigger point, represented by the area with pain at palpation, in an amount of 10 g for 30 minutes in a circular area of 24 mm diameter. Subsequently, the cream was removed and the skin tolerability parameters were evaluated. The pain was measured before and during the formulation application, as well as at 1 hour, 7 days, 30 days, and 60 days after the procedure, evaluated using a verbal numerical scale (from 0 to 10: with 0 = no pain and 10 = worst pain imaginable). Results: No patient in PLA Group had hyperemia or burning sensation at the site of application, while 85% of patients in CPS Group had hyperemia or burning sensation at 15 minutes. These complaints disappeared 24 hours after the cream was removed. The pain score in CPS Group decreased steadily up to the 60th day of evaluation (p < 0.0001). Conclusion: Application of the formulations did not cause macroscopic acute or chronic skin lesions in patients, and the 8% capsaicin formulation was beneficial and well tolerated.

Resumo Justificativa: A síndrome da dor miofascial é uma causa comum de dor musculoesquelética. O objetivo deste estudo foi avaliar a potencial ação analgésica de 8% do creme de capsaicina para uso tópico em pacientes com síndrome da dor miofascial. Métodos: Inicialmente, as formulações de creme de PLA (Placebo) e CPS (Capsaicina 8%) foram desenvolvidas e aprovadas de acordo com os requisitos atuais da agência de autoridade de saúde. Os 40 pacientes participantes foram distribuídos aleatoriamente e de forma duplo-cega para os grupos PLA e CPS. Antes dos cremes serem administrados topicamente, de acordo com o grupo de alocação, o anestésico local foi usado por um período de 50 minutos diretamente na área de interesse. A administração ocorreu na área da pele sobre o ponto-gatilho, o qual apresentou a área dolorida à palpação, em uma quantidade de 10 g por 30 minutos em área circular com diâmetro de 24 mm. Posteriormente, o creme foi removido e os parâmetros de tolerabilidade à pele foram avaliados. A dor foi medida antes e durante a aplicação da formulação, bem como 1 hora, 7 dias, 30 dias e 60 dias após o procedimento avaliado pela escala numérica verbal (0 a 10, com zero sem dor e dez a pior dor imaginável). Resultados: Nenhum paciente no grupo PLA experimentou hiperemia ou sensação de queimação no local de aplicação do creme, enquanto 85% dos que experimentaram no grupo CPS apresentaram hiperemia ou sensação de queimação 15 minutos. Essas queixas desapareceram 24 horas após a remoção do creme. O escore de dor no grupo CPS diminui de forma sustentada até o 60° dia de avaliação (p < 0,0001). Conclusão: A administração das formulações não causou lesões cutâneas agudas ou crônicas macroscópicas nos pacientes e a formulação de 8% de capsaicina foi benéfica e bem tolerada.

[Capsaicin topical cream (8%) for the treatment of myofascial pain syndrome]. / Creme tópico de capsaicina (8%) para o tratamento da síndrome da dor miofascial.

BACKGROUND: Myofascial pain syndrome is a common cause of musculoskeletal pain. The objective of this study was to evaluate the potential analgesic action of 8% capsaicin cream for topical use in patients with myofascial pain syndrome. METHODS: Initially, cream formulations of PLA (Placebo) and CPS (Capsaicin 8%) were developed and approved according to the current requirements of the health authority agency. The 40 participating patients were randomly assigned to the PLA and CPS groups in a double-blind fashion. Before the creams were topically administered, according to the allocation group, the local anesthetic was used for a period of 50minutes directly in the area of interest. The cream was applied to the area of the skin over the trigger point, represented by the area with pain at palpation, in an amount of 10g for 30minutes in a circular area of 24 mm diameter. Subsequently, the cream was removed and the skin tolerability parameters were evaluated. The pain was measured before and during the formulation application, as well as at 1 hour, 7 days, 30 days, and 60 days after the procedure, evaluated using a verbal numerical scale (from 0 to 10: with 0=no pain and 10=worst pain imaginable). RESULTS: No patient in PLA Group had hyperemia or burning sensation at the site of application, while 85% of patients in CPS Group had hyperemia or burning sensation at 15minutes. These complaints disappeared 24hours after the cream was removed. The pain score in CPS Group decreased steadily up to the 60th day of evaluation (p <0.0001). CONCLUSION: Application of the formulations did not cause macroscopic acute or chronic skin lesions in patients, and the 8% capsaicin formulation was beneficial and well tolerated.