Effects and cost of glycyrrhizin in the treatment of upper respiratory tract infections in members of the Japanese maritime self-defense force: Preliminary report of a prospective, randomized, double-blind, controlled, parallel-group, alternate-day treatment assignment clinical trial

Background: Upper respiratory tract infections (URTIs) account for at least half of all acute illnesses. Specific antiviral therapy has not been developed against most respiratory viruses thought to cause URTIs. The pharmacologic action of glycyrrhizin has been shown to produce anti-inflammatory activity, modulation of the immune system, inhibition of virus growth, and inactivation of viruses. Objective: The aim of this study was to assess the tolerability, efficacy, and cost of glycyrrhizin in improving the severity and duration of signs and symptoms of URTIs. The primary end point was tolerability, and the secondary and points included improvement in signs and symptoms of URTI and cost. Methods: Members of the Japanese Maritime Self-Defense Force (SDF) treated for URTIs from January 2002 to May 2002 in the SDF Etajima Hospital (Hiroshima, Japan) were eligible for this prospective, randomized, double-blind, controlled, parallel-group, alternate-day treatment assignment study. All patients in this study fulfilled the following enrollment criteria: admitted to the hospital on the first arrival day as an outpatient; fever (body temperature <38.0°C) with signs and symptoms of URTI (headache, sore throat, rhinorrhea, pharyngitis); and had not received antibiotics or oseltamivir phosphate for 4 weeks before the study. Patients who were admitted on an even day received an IV drip infusion of 40 mL of glycyrrhizin (0.2%) and 500 mL of lactated Ringer's solution daily during hospitalization (glycyrrhizin group). Patients who were admitted on an odd day received an IV drip infusion of 500 mL/d of lactated Ringer's solution only (control group). Adverse effects were assessed by the physicians during hospitalization, using patient interview and laboratory analysis. Results: Forty-one consecutive patients entered the study; 15 patients (15 men, 0 women; mean [SD] age, 25.2 [1.5] years) were assigned to the glycyrrhizin group and 269 patients (24 men, 2 women; mean [SD] age, 22.6 [0.9] years) were assigned to the control group. The 2 groups were similar in terms of baseline characteristics. The mean duration of hospitalization was shorter (P = 0.01), the mean maximum body temperature 24 to 48 hours after admission was less (P = 0.05), and the cost of therapy (P = 0.03) was less in the glycyrrhizin group than the control group. No AEs were reported. Conclusions: In this study of hospitalized patients with URTIs, glycyrrhizin therapy was associated with a shorter hospitalization, lower-grade fever, and lower cost of therapy compared with controls, showing that it may be beneficial to patients with URTIs without acute bacterial infections.