Salmeterol stimulates intracellular adenyl cyclase, the enzyme that catalyses the conversion of ATP to cyclic-3',5'-adenosine monophosphate (cAMP) resulting in relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from mast cells.

Inhaled Salmeterol exerts a significant bronchodilating effect within 10 to 20 minutes of single-dose administration with asthma and this effect lasts for up to 12 hours or more.

Salmeterol has a beneficial effect on airway mucociliary clearance that will reduce the incidence of respiratory tract infections.

Salmeterol produces a significant protective effect against Exercise Induced Asthma (EIA) for up to 9 to 12 hours in both adolescents and adults.

Salmeterol improves the overnight PEFR (Peak Expiratory Flow Rate) and controls the symptoms of the patients with nocturnal asthma. The use of Salmeterol avoids exposure of children to theophylline or high-dose corticosteroid, with their attendants risks.

Addition of Salmeterol to inhaled corticosteroid therapy is significantly more effective in terms of an improvement in lung function, symptom control and a reduction in the use of rescue bronchodilator therapy (use of short acting beta2-agonist).

Addition of Salmeterol to inhaled corticosteroid therapy also significantly reduces the use of inhaled corticosteroids

Inhalation/Respiratory-

Chronic asthma:

• Adult: As metered dose aerosol or dry powder inhaler: 50 mcg bid, or up to 100 mcg bid if necessary, in asthma patients with more severe airways obstruction.
• Child: 4-12 yr 50 mcg bid.

Prophylaxis of exercise-induced asthma:

• Adult: As metered dose aerosol or dry powd inhaler: 50 mcg at least 30 min prior to exercise.
• Child: ≥4 yr Same as adult dose.

Chronic obstructive pulmonary disease:

• Adult: As metered dose aerosol or dry powder inhaler: 50 mcg bid.

Administration

Using an Inhaler seems simple, but most patients do not know how to use it in the right way. If the Inhaler is used in the wrong way, less medicine can reach the lungs. Correct and regular use of the Inhaler will prevent or lessen the severity of asthma attacks.

Following simple steps can help to use Inhaler effectively (According to "National Asthma Guidelines for Medical Practitioners" published by Asthma Association):

1. Take off the cap.
2. Shake the inhaler (at least six times) vigorously before each use.
3. If the inhaler is new or if it has not been used for a week or more, shake it well and release one puff into the air to make sure that it works.
4. Breathe out as full as comfortably possible & hold the inhaler upright.
5. Place the actuator into mouth between the teeth and close lips around the mouthpiece.
6. While breathing deeply and slowly through the mouth, press down firmly add fully on the canister to release medicine.
7. Remove the inhaler from mouth. Continue holding breath for at least for 10 seconds or as long as it is comfortable.
8. If doctor has prescribed more than one inhalation per treatment, wait 1 minute between puffs (inhalations). Shake the inhaler well and repeat steps 4 to 7.
9. After use, replace the cap on the mouthpiece. After each treatment, rinse mouth with water.
10. Check your technique in front of a mirror from time to time, if you see a white mist during the inhalation, you may not have closed your lips properly around mouthpiece, or you may not be breathing in as you press the can. This indicates failure of technique. If this happens, repeat the procedure from step 4 carefully.

Instructions for Cleaning Inhaler: Clean your Inhaler at least once a week. Remove canister and rinse the plastic actuator and cap in warm water but do not put the metal canister into water. Dry the actuator and cap thoroughly and gently replace the metal canister into the actuator with a twisting motion. Put the cap on the mouthpiece.

Monotherapy in the treatment of asthma. Treatment of status asthmaticus, other acute episodes of asthma or COPD.

Dose related tremor, subjective palpitations and headaches are usually mild and transient. Skin reactions, muscle cramps, non-specific chest pain, local irritation and arthralgia have been reported.

Overdose Effects

Symptoms: Dizziness, HTN or hypotension, tremor, headache, tachycardia, hypokalaemia, seizures, angina, arrhythmias, nervousness, muscle cramps, dry mouth, palpitations, nausea, fatigue, malaise, insomnia, hyperglycaemia, metabolic acidosis.

Patient with CV disease, CNS disorders, DM, hyperthyroidism, hypokalaemia, seizure disorders, ketoacidosis. Not intended for the relief of acute bronchospasm. Hepatic impairment. Pregnancy and lactation.

Use in Special Populations

Hepatic Impairment: Because Salmeterol is extensively metabolised by the liver, patients with hepatic impairment receiving the drug should be closely monitored.

Pregnancy & Lactation

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.