Oral Chinese herbal medicine for psoriasis vulgaris

Background: Psoriasis vulgaris is a common chronic immunological inflammatory skin disease without cure. Psoriasis is associated with increased risk of serious co-morbidities such as cardiovascular disease and diabetes. Current conventional therapies can be expensive and commonly have adverse effects. Hence further effective and safe therapies are needed. Chinese herbal medicine (CHM) has been utilised for centuries for the management of psoriasis. This thesis reviewed its current clinical and experimental psoriasis evidence and aimed to develop and test an evidence based CHM formulation.<br><br>Methods: Firstly, two systematic reviews and meta-analyses were conducted using the Cochrane Library Systematic Review Method to examine published CHM research for psoriasis. 1) Randomised controlled trials (RCTs) of oral CHM for psoriasis vulgaris compared with placebo. 2) RCTs combining oral CHM with conventional therapy for psoriasis vulgaris. Secondly, in vitro and in vivo data for commonly used CHM phytochemicals were reviewed to evaluate their potential biological psoriatic mechanisms. Lastly based on the review findings and available treatment guidelines an optimised oral CHM formulation (PSORI-CM01) was developed for psoriasis vulgaris and then clinically evaluated via a rigorous designed pilot placebo double-blind RCT.<br><br>Results: Literature review indicated mild–moderate psoriasis is undertreated, and topical treatments have limited efficacy. Systematic review found oral CHM has benefit compared with placebo; however, the effect size is relatively small. Further systematic review of CHM combined with conventional therapy indicated it increases effects and reduces adverse events. Subsequent in vitro and in vivo review recognised Paeonia. lactiflora Pallas and Paeonia veitchii Lynch constituents and those of other CHM act on pathways similar to conventional psoriasis drugs. The pilot RCT investigates PSORI-CM01 in a mild to moderate psoriasis vulgaris (psoriasis area severity index (PASI) 7–12) population. Thirty participants undergo a two-week run-in phase then receive 12-weeks of PSORI-CM01 plus calcipotriol or placebo plus calcipotriol. The pilot study is to determine the feasibility for an adequately powered RCT. Primary outcome is PASI change (%) and secondary measures include: PASI 75 rate, QoL change (dermatology life quality index (DLQI) and Skindex 29), acceptability of treatment, change to psoriasis-related cytokines (such as TNF-α and IL-23) and adverse events. Blood plasma specimens are collected at weeks –2, 12 and 24 then concentrations of inflammatory cytokines measured via multi-assay technique (Bio-Plex® Multiplex System). The pilot RCT is ongoing, interim results indicated baseline analysis (n=11) mean PASI score 9.0±2.4, and DLQI score 10±7.6.<br><br>Conclusion: Oral CHM has promising efficacy for psoriasis and combined with conventional treatments enhances effects. Evidence suggests combined treatment is safe; however, long-term follow-up data are limited. Efficacy of CHM is related to the mechanistic actions of contained constituents, some of which coincide with conventional drug treatment targets. PSORI-CM01 has in vitro and in vivo evidence indicating its therapeutic benefit is via modulation of known psoriatic biological pathways. The current pilot will provide data on the feasibility of a larger-scale study and provide preliminary data for PSORI-CM01 efficacy and safety.