Early intervention with ColdZyme mouth spray after self-diagnosis of common cold: a randomized, double-blind, placebo-controlled study

Background A glycerol throat spray containing cold-adapted cod trypsin creates a protective barrier and is known to deactivate common cold virus in vitro and decrease pharyngeal rhinovirus load after inoculation in humans. Early self-diagnosis and use of the medical device ColdZyme indicate a safe alternative for treatment in naturally occurring common colds. Methods This was a double-blind, randomized, parallel-group, placebo-controlled study conducted at ten German sites to evaluate the efficacy of the medical device ColdZyme, a glycerol mouth spray containing cold-adapted cod trypsin, for naturally occurring common cold, versus placebo. Adults experiencing a minimum of three common colds during the previous year, but otherwise healthy, were enrolled to begin treatment with the mouth spray or placebo six times daily at first sign of a common cold. Jackson’s symptom scale and the 9-item Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21) quality of life (QoL) domain and sore throat scale were recorded daily by subjects, as well as any use of allowed rescue treatment. The trial is registered at ClinicalTrials.gov , number NCT03794804 . Results Between January and April 2019, 701 subjects were enrolled and randomly assigned to the ColdZyme group (n=351) or the placebo group (n=350). Of the 701 subjects, 438 (62.5%) subjects developed symptoms typical of common cold, and all 438 started study treatment (n=220 in the ColdZyme group and n=218 in the placebo group). There were no differences between the groups in primary and major secondary endpoints, however, the assessment using the WURSS-21 QoL domain and Jackson score suggests a slightly faster recovery with ColdZyme, as symptoms and complaints affecting the quality of life were shortened about 1 day. The beneficial effect of ColdZyme was particularly noticeable on the fifth day of the common cold. A positive difference between treatment groups was also seen for the subjects’ assessments of global efficacy of the investigational product, and a robust safety profile for ColdZyme was demonstrated throughout the study. Conclusion The safety and tolerability of ColdZyme have been confirmed in a larger study population, while establishing evidence of a slightly faster recovery from common cold symptoms.