Salmeterol is a long-acting beta2-agonist bronchodilator that works by relaxing the smooth muscles of the airways, thereby opening up the airways and making it easier to breathe.

Budesonide is a corticosteroid that works by reducing inflammation in the airways, thereby helping to improve airflow and reduce symptoms such as wheezing, coughing, and shortness of breath.

Dextromethorphan is an anti-tussive drug that works by suppressing the cough reflex in the brain, thereby reducing the frequency and severity of coughs.

Guaifenesin is an expectorant drug that works by increasing the production of mucus in the airways and making it thinner and easier to cough up.

Advair is a combination drug that contains salmeterol, a long-acting beta2-agonist bronchodilator, and fluticasone propionate, a corticosteroid.

Tachycardia, or rapid heart rate, is a common adverse effect of beta2-agonist bronchodilators, especially when they are used in high doses.

Hoarseness, or a change in voice, is a common adverse effect of corticosteroids, especially when they are used in high doses or for a long period of time.

Drowsiness is a common adverse effect of anti-tussive drugs, especially when they are used in high doses or for a long period of time.

Nausea is a common adverse effect of expectorant drugs, especially when they are used in high doses or for a long period of time.

Beta2-agonist bronchodilators are contraindicated in patients with heart failure because they can worsen the condition by increasing heart rate and blood pressure.

Corticosteroids are contraindicated in patients with tuberculosis because they can suppress the immune system and make the infection worse.

Anti-tussive drugs are contraindicated in patients with pneumonia because they can suppress the cough reflex and make it more difficult to clear mucus from the lungs.

Expectorant drugs are contraindicated in patients with asthma because they can increase the production of mucus in the airways and make it more difficult to breathe.

Montelukast is a leukotriene modifier that works by blocking the action of leukotrienes, which are inflammatory mediators that contribute to the symptoms of asthma and COPD.

Cromolyn sodium is a mast cell stabilizer that works by preventing the release of inflammatory mediators from mast cells, which are immune cells that play a role in the development of asthma and allergic rhinitis.