A Controlled Trial of Oral Rifampin in Chronic Plaque Psoriasis

Abstract

Group A Streptococcal infection in the throat is responsible for causing initial and recurrent attacks of acute guttate psoriasis (AGP). Up to 70% of these AGP patients go on to develop chronic plaque psoriasis (CPP). We hypothesized that chronic sub-clinical, on-going streptococcal infection might solely be responsible for CPP in a genetically predisposed individual. Rifampin, a useful drug for several types of bacterial infections including Group A Streptococci (GAS) because of its broad spectrum, excellent tissue penetration, low side-effect profile and its salivary concentrations after oral administration greatly exceeds the minimum inhibitory concentration for most GAS, thus helpful in eradicating pharyngeal carriage of GAS, was considered for long term use in CPP. Fifty patients with moderate to severe CPP were enrolled. Of these 25 were randomly selected to receive rifampin for 36 weeks as a single oral morning dose of 10 mg/kg body weight (approx. patient weighing <50 kg received 450mg per day and patients >50 kg received 600mg per day). Remaining 25 patients received placebo. Rifampin group was further followed-up to one more year. Significant improvement in PASI score was noted from 12 weeks in majority of patients in Rifampin group. Relevant investigations and clinical assessment was done at regular intervals to observe any side effects and check progress of the disease. Data were analyzed statistically using the t-test. As psoriasis is a chronic disorder that waxes and wanes over time, withdrawal of treatments usually is accompanied by relapse of skin manifestations so a follow-up with one year drug-free period was added to verify treatment consistency. Patients tolerated the therapy well.