INTRODUCTION:

Salbutamol is a drug used in the treatment of asthma, a chronic lung disease caused by inflammation of the lower airways. Asthma causes the airways to become sensitive, swollen and inflamed, even when there are no visible symptoms and thus causes hyper-responsiveness of tissues lining the bronchi to certain triggers. The most serious symptom is the constriction of the smooth muscle lining the bronchi of the lungs. This symptom was so important that asthma was previously characterised as a periodic bronchospasm. This reduces airflow and thus makes breathing hard or, in fatal cases, impossible. Affecting some 15 million Americans¹ and more than 3 million in the UK⁶, asthma continues to increase in both incidence and severity despite vast improvements in both therapeutic options and understanding of the disease over the years.

These increases have yet to be adequately explained, but the number and frequency of hospitalisations due to asthma, along with the attendant expenditures, continue to escalate. More people of all ages are being treated for asthma now than ever, and the number of children receiving treatment continues to escalate.

Salbutamol Crystals Under a Polarized Light Microscope:

Reproduced with the permission of Michael W. Davidson

The cost of asthma to the community is truly staggering. An estimated $6 billion⁴ is spent on treating asthma in the USA alone. Other expenses such as and estimated $1 billion⁵ for the loss in productivity by working parents caring for children who miss school due to asthma mean that asthma treatment is a very  important area.

With asthma affecting 1 in 7 school children in the UK⁶ (1 in 25 adults) asthma has an affect on a huge number of families in the United Kingdom.

An idea of the huge scale of asthma world-wide can be seen from a  more comprehensive list of asthma statistics (and their sources), to numerous to be usefully include in this section:  ASTHMA STATISTICS

The causes of asthma are not fully understood however,  like its related allergic conditions eczema and hay fever, asthma often runs in the family and may be inherited. It is thought there are probably several other, environmental, factors that contribute to someone developing asthma, such as housing and diet. It is hypothesised that intense exposure to allergens and triggers (notably airborne chemical irritants or particles) can precipitate asthma. It is also known that smoking during pregnancy increases the chance of a child developing asthma. Contrary to one common misconception there is no evidence that traffic pollution causes asthma, although poor air quality can be a trigger
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Although the cause of asthma is not fully understood the mode of action of most triggers is better understood. A trigger is any object or action  which causes an asthma attack.  Common triggers include:

• Tobacco smoke
• Exercise
• Animal hair, fur or feathers
• Animal danders
• House-dust mites
• Pollen
• Indoor fungi
• Air Pollution & Irritants (fumes from gas, oil, kerosene, perfumes)
• Rhinitis-Sinusitis
• Gastroesophageal reflux
• Aspirin Sensitivity
• Sulphite Sensitivity
• Beta-Blockers
• Infections (such as colds or ëflu)
• Food additives
• Weather changes

Salbutamol can be taken either orally or more commonly using an inhaler device. The inhaler ensures that very small amounts of medication are delivered directly into the lungs.

 
There are two main types of asthma medication:

• Quick Relief medications:
• Long-term control or preventive medications

Inhaled Salbutamol  is the most commonly used quick-relief medication. First market by Galaxo in 1969 and now by Allen & Hanburys it is  in the top 150 prescribed drugs.

One of the most interesting factors in the chemistry and biochemistry of salbutamol is the opposite biological effect observed for the R and S isomer of the drug. The R isomer effects dilation of the smooth muscle whereas the S isomer, via a different pathway, causes constriction of this same muscle.