HISTORY OF DEVELOPMENT IN ASTHMA DRUG COMPOUNDS
In finding the treatment of asthma, more than hundred years of research has been put into the development of introducing the right agent triggering a specific response; Salbutamol as a ventolin inhaler, a β2-adrenoceptor agonist. This research report addresses the main compound that was considered as a “hit” in reversing the airway obstruction and why other compounds such as epinephrine and isoprenaline were neglected over salbutamol.
A compound known as epinephrine in adrenaline injection was first addressed for the treatment of asthma in 1903 by Bullowa & Kaplan. Few years later its usage soon came to an end when it had been found to cause unwanted effects on cardiovascular system. After numerous tests and development, in 1940 Konzett identified isoprenaline; a remedy which replaced adrenaline. The effect on treating airway obstruction was promising however like the epinephrine effect on cardiovascular system was still seen. Salbutamol was then introduced by Allen & Hanburys in 1969, which is currently the most suited remedy for asthma. They are highly effective, had much longer duration than the previous drugs and had little or no cardiovascular side effects. It was the subdivision of β-receptors into 2 β1 (cardiac muscle) and β2 (bronchial smooth muscle) that allowed salbutamol inhaler to be developed (Lands et al., 1967. By understanding the existence of these subdivisions, salbutamol was made with more selectivity on β2 receptor and hence showing hardly any side effects on cardiovascular system. Tests to show the specificity of salbutamol have been conducted on an isolated guinea pig, salbutamol showed 1/10 activity of adrenaline on trachea and 1/2000 activity on atria (Cullum et al., 1969). Isoprenaline and epinephrine were neglected over salbutamol since they are both β1 and β2 non-selective agent, they activate the β2-adrenoceptors and they would also non-selectively activate the...
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