Long-term oral azithromycin in chronic plaque psoriasis: a controlled trial.

Continued sub-clinical streptococcal infection might be responsible for chronic plaque psoriasis. Considering the beneficial effect of benzathine penicillin in chronic plaque psoriasis, but due to the risk of penicillin sensitivity and to its painful parenteral route of administration, we tried oral azithromycin in this single blind randomized case-control trial. 50 patients with moderate to severe chronic plaque psoriasis were enrolled. Of these, 30 randomly selected patients received azithromycin for 48 weeks as a single oral 500 mg daily dose for 4 days with a gap of 10 days (total 24 such courses). The remaining 20 patients received a vitamin C tablet (non-chewable) in the same dosage schedule. Informed consent was obtained from all patients enrolled. Though the trial concluded at 48 weeks, patients in the azithromycin-arm were followed for another year to observe any relapse. A significant improvement in PASI score was noted from 12 weeks in the majority of patients in the azithromycin group. At the end of 48 weeks, 18 patients (60%) showed excellent improvement, while 6 patients (20%) showed good improvement and 4 patients (13.33%) showed mild improvement. PASI 75 was 80%. No significant change was seen in lesions in the control group. 2 patients in the study group and 5 patients in the control group did not complete the prescribed duration of study. An exacerbation in lesions was reported in 5 cases (16.66%) in the group receiving azithromycin. These exacerbations also responded by continuing the same treatment. At the end of another one year follow up in the azithromycin-arm, 6 patients (20%) developed a recurrence of lesions. Relevant investigations and clinical assessments were done at regular intervals to observe any side-effects and to check progress of the disease. Data were analysed statistically by using the student t-test. Patients tolerated the therapy well.