Abstract: No new trials were identified in the search for this review update. In total five trials involving 365 participants were included in this review. All trials compared Padma 28 with placebo for at least 16 weeks of follow-up. Pain-free and maximum walking distances both increased significantly in the groups treated with Padma 28, with no significant change in the placebo group. In general, the studies presented results comparing the treatment arms before and after treatment but made no comparisons between the Padma 28 and placebo groups. Pooled data of maximum walking distance after treatment with Padma 28 and placebo from two studies (193 participants) indicated a higher maximum walking distance (mean difference (MD) 95.97 m, 95% confidence interval (CI) 79.07 m to 112.88 m, P < 0.00001, very low quality evidence) in the Padma 28 group compared with placebo. The clinical importance of these observed changes in walking distance is unclear as no quality of life data were reported. There was no effect on ankle brachial index (ABI): change in ABI values between baseline and six months follow up MD -0.01, 95% CI -0.07 to 0.05, 1 study, 56 participants, P = 0.72, very low quality evidence). Mild side effects, especially gastrointestinal discomfort, tiredness and skin eruption, were reported but this outcome was not different between the Padma 28 and placebo groups (odds ratio 1.09, 95% CI 0.42 to 2.83, four studies, 231 participants, P = 0.86, very low quality evidence). Some evidence exists from individual trials to suggest that Padma 28 may be effective in increasing walking distances, at least in the short term (four months), in people with IC. Side effects do not appear to be a problem. However, the longer term effects of treatment are unknown and the clinical significance of the improvements in walking distance are questionable. Moreover, the quality of the evidence is limited by the small sample size of the available trials, limited reporting of statistical analyses that compared treatment groups, and relatively high withdrawal rates that were linked to the outcome. That is, patients were withdrawn if they failed to improve walking distance. There was also evidence of publication bias. We therefore feel there is currently insufficient evidence to draw conclusions regards the effectiveness of Padma 28 in the routine management of IC. Further well-designed research would be required to determine the true effects of this herbal preparation.

Plain-language summary: This review on the effects of Padma 28 includes five trials with a total of 365 participants (current until September 2015). The review showed that Padma 28 has some beneficial effects in improving maximum and pain-free walking distance. The groups treated with placebo did not show an improved maximum and pain-free walking distance. Unfortunately the studies reported insufficient data to allow the comparison of the change in walking distances in the Padma 28 group with the change in walking distances in the placebo group. Combining the data of maximum walking distance after treatment in two studies showed that there was a longer maximum walking distance in the Padma 28 group compared with the placebo group after 16 weeks of treatment. No change in ankle brachial pressure was observed. Mild side effects such as gastrointestinal discomfort, tiredness and skin eruption were also noted but these were not different between the Padma 28 and placebo groups. Quality of the evidence Overall, the quality of the studies was low, with evidence of publication bias, small number of trials, limited reporting of the analyses that compared treatment groups and bias due to a high percentage of withdrawals in the placebo groups because of lack of improvement or deterioration of the overall condition. We therefore feel there is currently insufficient evidence to draw conclusions about the effectiveness of Padma 28 in the routine management of IC. Further well-designed research would be required to determine the true effects of this herbal preparation.