Table 4 Clinical efficacy studies: Chronic bronchitis and chronic respiratory conditions
From: Role of guaifenesin in the management of chronic bronchitis and upper respiratory tract infections
| Author (Year) | Objectives of study | Intervention | Results |
|---|---|---|---|
| Hayes (1956) | To determine the effectiveness of Robitussin® as an expectorant in productive cough due to chronic pulmonary disease | 1–2 g Robitussin® (containing 100 mg guaifenesin and 1 mg desoxyephedrine HCl per 5 mL) vs placebo every 2–3 h, as required |
Statistically significant changes compared to placebo: • Reduction in chronic productive cough • Decreased frequency of cough and sputum viscosity |
| Chodosh (1964) | To investigate the efficacy and mechanism of action of guaifenesin in bronchopulmonary diseases |
Double-blind study: 100 mg guaifenesin tablet 4× daily vs placebo for 14 days (after placebo run-in) |
Statistically significant changes compared to placebo: • Increase in ease of expectoration • Decrease in the measured sputum surface tension |
| Hirsch (1973) | To investigate the expectorant effect of guaifenesin in patients with chronic bronchitis |
Single-blind crossover study: 800 mg or 1600 mg guaifenesin vs placebo alternating for 5 weeks Double-blind crossover study: 1600 mg guaifenesin vs placebo daily for 5 days | No significant difference between guaifenesin and placebo in reducing sputum consistency, increasing sputum volume, improving ventilatory function or ease of expectoration |
| Wojcicki (1975) |
To investigate the effect of guaifenesin on: (i) Severity and frequency of cough, and (ii) Tenaciousness of sputum |
Double-blind crossover study: 120 mg guaifenesin vs 17 mg narcotine HCl, vs combination (120 mg guaifenesin +17 mg narcotine HCl), vs placebo, 3× daily for 7 days (per treatment) |
Guaifenesin + narcotine HCl combination associated with statistically significant decreases in: • Cough severity • Cough frequency |
| Finiguerra (1982) (unpublished; data on file) |
To determine the efficacy of guaifenesin for: (i) Modifying the volume and viscosity of tracheobronchial secretions, and in (ii) Providing symptomatic relief of difficult expectoration and cough in chronic bronchitis |
Randomized double-blind parallel-group study: 190 mg guaifenesin vs placebo, 3× daily for 15 days |
Statistically significant changes: • Decrease in sputum volume and viscosity • Decrease in cough severity • Improvement in ease of expectoration |
| Parvez (1996) | To determine the usefulness of a multidimensional cough quantitation system for evaluating guaifenesin’s effects on cough and sputum |
Randomized double-blind parallel-group study: 300 mg guaifenesin vs placebo, 4× daily for 14 days |
Differences between guaifenesin and placebo groups: • Guaifenesin significantly increased sputum volume; 37% difference on day 14 (p < 0.05) • Significant reduction in fucose, a biomarker for sputum glycoprotein, in the guaifenesin group at day 14 (p < 0.01) • Subjective measure of average intensity/cough at day 4 (p < 0.05) • Trend for greater improvement in ease of expectoration at days 10 and 14 in the guaifenesin group but did not reach significance in the subgroup with productive cough (p < 0.01) |