Amino Acids, Dicarboxylic/therapeutic use; Amino Acids, Sulfur/therapeutic use; Bromhexine/therapeutic use; Bronchitis/drug therapy; Expectorants/therapeutic use; Lung Diseases, Obstructive/drug therapy; Administration, Oral; Adult; Aged; Amino Acids, Dicarboxylic/administration & dosage; Amino Acids, Dicarboxylic/adverse effects; Amino Acids, Sulfur/administration & dosage; Amino Acids, Sulfur/adverse effects; Bromhexine/adverse effects; Chronic Disease; Clinical Trials as Topic; Female; Humans; Male; Middle Aged; Nausea/chemically induced; Respiration/drug effects; Spirometry; Sputum/drug effects; Sputum/metabolism; Viscosity; Vital Capacity/drug effects; Vomiting/chemically induced