Adjunctive treatment with rhodiola crenulata in patients with chronic obstructive pulmonary disease-a randomized placebo controlled double blind clinical trial

Chronic obstructive pulmonary disease (COPD) is a low grade systemic inflammatory disease characterized by dyspnea and exercise intolerance even under standard therapy. Rhodiola crenulata (RC) has been shown to exert anti-inflammatory effects and to enhance exercise endurance, thereby having the potential to treat COPD. In this 12-week, randomized, double-blind, placebo-controlled clinical trial, 57 patients with stable moderate-to-severe COPD aged 70±8.8 years were given RC (250 mg twice/day) (n=38) or a placebo (250 mg twice/day) (n=19) in addition to their standard regimen. There were no significant differences in anthropometrics, quality of life, lung function, six-minute walk and incremental exercise tests between the two groups at enrollment. Over the 12 weeks, RC was well tolerated, significantly reduced triceps skin thickness (Δ=-1 mm, p = .04), change of FEV1 (4.5%, p = .03), and improved workload (Δ=10%, p = .01); although there were no significant differences in these factors between the two groups. However, there were significant between-group differences in tidal volume and ventilation-CO₂-output ratio at peak exercise (both p = .05), which were significantly related to peak work rate (both p<.0001). RC tended to protect against acute exacerbation of COPD (p = .1) but not other measurements. RC did not improve the six-minute walk test distance but significantly improved tidal breathing and ventilation efficiency, most likely through improvements in work rate. Further studies with a larger patient population are needed in order to confirm these findings.