Computer graphics space-filling representation of salbutamol (trade name ventolin) a drug used to relive the symptoms of breathlessness in asthma, bronchitis and allergy sufferers. Salbutamol was developed from the drug isoprenaline, a substance analogous to adrenaline, a hormone whose effects include speeding up breathing and heart rates. The structural modificaton of isoprenaline to salbutamol had the effect of increasing the molecule's affinity for acting on the lung and decreasing its effect on the heart - a failing of isoprenaline had been its potency on the heart which had resulted in a number of deaths.