Table 5 Clinical efficacy studies: Upper respiratory tract infections

Robinson (1977)

To confirm that guaifenesin was superior to placebo in facilitating expectoration of sputum and ameliorating dry cough in patients with an acute upper respiratory infection

Randomized double-blind parallel-group study:

200 mg guaifenesin in 10-mL doses vs placebo, 4× daily for 3 days

Subjective measures compared to placebo:

• Cough frequency reduced at 48 h, 72 h (all: p < 0.01)

• Cough intensity reduced at 48 h, 72 h (all: p < 0.01)

• Chest discomfort reduced at 24 h, 48 h, 72 h (all: p < 0.01)

• Sputum volume increased (only in patients with productive cough) at 48 h (p < 0.01)

• Ease of raising sputum increased at 24 h, 48 h, 72 h (all: p < 0.01)

Kuhn (1982)

To evaluate the efficacy of guaifenesin in reducing cough frequency in adults with acute respiratory disease

Double-blind study:

2400 mg guaifenesin vs placebo syrup vehicle in 30-mL doses every 6 h for 30 h

• Objective cough counts: No significant differences between guaifenesin and placebo

• Significantly greater decrease in sputum viscosity compared to baseline in patients with productive cough (p = 0.001)

• Greater decrease in sputum quantity (p = 0.07)

Albrecht (2012)

Pilot study to determine the efficacy of extended-release (ER) guaifenesin with placebo for treatment of URTI, using objective and subjective efficacy assessments

Randomized double-blind study:

1200 mg ER guaifenesin vs placebo 2× daily for 7 days

Subjective measures of efficacy (patient-reported outcomes; PROs) showed the most prominent differences between treatment groups at Day 4, in favor of guaifenesin. Based on post-hoc analyses focusing on subsets of these PROs, an 8-question PRO tool (SUM8) was validated.