某些药物露置空气中遇光线及空气中氧气会迅速变色而引起变质。例如肾上腺素遇空气中氧气及光线迅速变成红色、橘红色、最后变为棕色及黑色物质。这是肾上腺素氧化生成邻醌肾上腺素,再变为肾上腺色素进而氧化及聚合是生成黑素(Melanine)。肾上腺素的这种氧化作用,通常叫自动氧化作用(也称自氧化作用)。 Certain drugs exposed to light in the air and oxygen in the air will rapidly discolourize and cause deterioration. For example, adrenaline meets the oxygen and light in the air quickly turns red, orange, and finally into brown and black substances. This is the adrenergic oxidation of o-quinone epinephrine, and then into the adrenal pigment oxidation and polymerization is the formation of melanin (Melanine). This oxidation of epinephrine, usually called auto-oxidation (also known as auto-oxidation).