Abstract
The objective of this trial was to investigate the efficacy of a Comfrey root extract cream in patients with acute upper or lower back pain. The study was conducted as a double-blind, multi-centre, parallel group design RCT over a period of 5 ± 1 days. The patients (n=120, mean age 36.9 years, 46.7 % female) were treated three times a day, 4 g cream per application. The trial included four visits.
The primary efficacy variable was the area-under-the-curve (AUC) of the Visual Analogue Scale (VAS) on active standardised movement values at visits 1 to 4. Among the secondary objectives were back pain at rest (VAS), pressure algometry (pain-time curve; AUC over 5 days), global assessment of efficacy by the patient and investigator, and functional impairment measured with the Oswestry Disability Index.
There was a significant treatment difference between verum and placebo. In the course of the trial the primary variable decreased on average (median) about 95,2 % in the Comfrey extract group and 37.8 % in the placebo group. The results separated by pain location show an equivalent effect of comfrey extract: Regarding pain at rest, in lower back pain a reduction of 98% were observed, in upper back pain 96.9%.
The results of this RCT were clear-cut and consistent across all variables. Comfrey root extract cream showed a remarkably potent and clinically relevant effect in reducing acute back pain. For the first time a fast-acting effect of the ointment (1 hour) was also witnessed in this trial.
Conflicts of interest and sources of funding
CS and MT are employees of Merck Selbstmedikation GmbH, the sponsor of the presented clinical trial. BMG is CEO of CRM Pharmaberatung GmbH, the CRO of the presented clinical trial.
