A randomized, double-blind, parallel-group, multicenter, placebo-controlled study of the safety and efficacy of extended-release guaifenesin/pseudoephedrine hydrochloride for symptom relief as an adjunctive therapy to antibiotic treatment of acute respiratory infections

Purpose: This study assessed the efficacy and safety of guaifenesin 600 mg and pseudoephedrine hydrochloride 60 mg extended-release bilayer tablets in providing relief of acute respiratory symptoms when used as an adjunct to antibiotics in patients with an acute respiratory infection (ARI). Methods: Adult patients experiencing symptoms of ARI and meeting the physician's usual diagnostic criteria for oral antibiotic treatment were prescribed an antibiotic and randomized to adjunctive guaifenesin/pseudoephedrine hydrochloride or matching placebo twice daily for 7 days. Patients completed symptom diaries and treatment assessments twice daily and attended office visits on Days 4 and 8. Results: The safety/intent-to-treat (ITT) population analysis included 601 patients (guaifenesin/pseudoephedrine, n = 303; placebo, n = 298). Mean symptom scores were lower with guaifenesin/pseudoephedrine from Day 3 for every symptom assessed, with statistically significant improvements in total symptom score from Day 3 (P = 0.026). The greatest effects of treatment with guaifenesin/pseudoephedrine were observed for nasal congestion and sinus headache. Time to overall relief was shorter with guaifenesin/pseudoephedrine (P = 0.038). Significantly more patients reported "the medication was helping during the day" on Day 2 with guaifenesin/ pseudoephedrine (P = 0.002). Patient assessments of symptom relief showed a significant preference for guaifenesin/pseudoephedrine versus placebo (P = 0.021). Treatment with guaifenesin/ pseudoephedrine was well tolerated. Insomnia (2.6%), nausea (2.3%), and headache (1.3%) were the most common treatment-related adverse effects. Conclusions: As adjunctive therapy for symptom relief for patients taking antibiotics for ARIs, guaifenesin/pseudoephedrine shortened time to relief and improved bothersome respiratory symptoms better than placebo, with greatest effects seen for nasal congestion and sinus headache.