THE respiratory system is the pathway that allows for the gaseous exchange. It starts from the nose and mouth, then to the trachea (windpipe), down the bronchi (main branches) and into the pair of lungs. It is further divided into smaller branches called the bronchioles and the alveoli, tiny air sacs. A network of blood capillaries surround the alveoli which has an ultra-thin membrane that allows the blood to transport oxygen for energy production in the cells and simultaneously removing the waste product, carbon dioxide.

This process of breathing is mostly an involuntary action initiated by the brain. It signals to the diaphragm when to contract and relax, causing expiration and inspiration in coordination with the intercostal muscles in the chest cavity.

Irritants such as cleaning agents, environmental pollutants, radioactive gases, cigarette smoke and other factors such as microbes and genetics, may cause functional impairment of the respiratory system at varying severity.

Respiratory diseases are categorised as obstructive (asthma, bronchitis and emphysema), infections from viral, bacterial or fungi (e.g. pneumonia and tuberculosis), environmental (asbestosis or particulate pollutant) and vascular disease (e.g. pulmonary hypertension) and restrictive (e.g. fibrosis). Some conditions like asthma are reversible with oral, inhaled, nebulise or injectable medications whilst other conditions like COPD (chronic obstructive pulmonary disease) are irreversible.

Well established research has confirmed that using inhaled formulations as the first line of treatment in mild or moderate obstructive respiratory diseases, such as asthma and COPD yielded the best outcomes. Yet, today, the inhalers are still underutilised because of various misconceptions.

A detailed illustration of the breakdown of both oral and inhaled formulations after entering the body may demonstrate why inhalers are the first choice. Generally oral formulations such as tablets, syrups and capsules must first undergo dissolution (except syrups), absorption and first pass metabolism through the liver (breaking down the formula to the active molecule) before it becomes bioavailable. In the case of salbutamol tablets, only 50 per cent of the drug becomes bioavailable for its bronchodilation mechanism of action. One salbutamol tablet has 4 milligrams or equivalent to 4,000 micrograms of active ingredient.

Comparatively, with the pressurised metered-dose inhalers, one puff (actuation) of the inhaler is 100 micrograms, since the canister is primed with active micronised molecules which go directly to the target site (lungs) and initiate its mechanism of action. No dissolution, no absorption and no first pass metabolism is engaged. So the patient can use less amount of salbutamol thereby reducing the systemic associated side effects with tablets like heart palpitations, hand tremor and nervous tension. Also it has a faster onset of action which is key in such difficult breathing conditions where time is a significant factor, especially if there is associated anxiety. So in emergency situations, short-acting inhalers are a better choice because of speed of onset action and elimination of unwanted systemic side effects.

However, combination inhalers with long-acting bronchodilators and corticosteroids are best for daily maintenance dose, thus minimising emergency situations. They are designed to work synergistically to prolong the therapeutic bronchodilation (expanding the airways) and reducing the inflammations (cleaning up the mucus build up) over a 24 hour period. However, it must be emphasised that such inhalers are not to be used in emergency attacks since their half-life is long and hence their onset of action takes some time.

The downside when using an inhaler are improper user technique, occasional stimulation of a cough reflex or a sore throat. The latter can be alleviated by taking a few sips of water about 10 minutes after using an inhaler. Or if the user engages in an improper technique, then you can rectify also by requesting a demonstration before leaving the pharmacy so that any required adjustments may be made.

There are complimentary devices such as spacers, which, when attached to the inhaler, create a one way flow of the medication at a rate which will reach the lungs. Without the spacers one has to coordinate one’s breathing with the puff of aerosol, which, if out of sync, can waste the medication or make it stick to the back of your throat causing irritation.

To ensure that your inhaled medication never runs out, you can estimate the amount remaining by extracting the canister from the case and immersing in a half-glass of water. If it sinks to the bottom then it is full, if only half submerge then it is half filled and if it floats to the top then it is empty.

For further pharmacological guidance and physician referral, contact the pharmacist of Medicine Express PHARMACY located at 223 Camp Street, between Lamaha and New Market Streets. If you have any queries, comments or further information on the above topic kindly forward them to medicine.express@gmail.com or send them to 223 Camp Street, N/burg. Tel #225-5142.