Doxycycline as an initial treatment of bullous pemphigoid in Japanese patients

Objectives Tetracycline antibiotics have been used in bullous pemphigoid (BP) for their anti‐inflammatory effects. In Japan, tetracycline and minocycline, but not doxycycline, have been generally used in BP, although doxycycline has a better side‐effect profile than other tetracycline antibiotics. To determine the effectiveness and safety of doxycycline in Japanese BP patients, we performed a retrospective cohort study. Methods We analyzed 27 Japanese BP patients in whom doxycycline was used as a first‐line treatment at Kido Hospital between April 1, 2014, and August 31, 2019. We estimated time to prednisolone treatment as a primary measure of effectiveness of doxycycline, because second‐line prednisolone treatment was initiated when each physician judged that disease activity could not be controlled with doxycycline alone. Results During the median follow‐up of 63 weeks, second‐line prednisolone treatment was initiated in 22 of 27 patients. Median time to prednisolone treatment was 7 weeks. Severe disease based on the Bullous Pemphigoid Disease Area Index (BPDAI) and eosinophilia were the risk factors for prednisolone treatment. At 6 weeks, 14 of 27 patients were under doxycycline treatment without prednisolone, and significant decreases of BPDAI scores were achieved. In 9 of these 14 patients, prednisolone treatment was started after 6 weeks, but the recurrent or mild remaining lesions could be controlled with relatively low‐dose prednisolone in combination with doxycycline. No severe adverse events related to doxycycline occurred. Conclusions Doxycycline has short‐term effectiveness, potential corticosteroid‐sparing effect, and long‐term safety in Japanese BP patients with mild to moderate disease and no eosinophilia.