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Papaver somniferum, the opium poppy, has been used medicinally for over 5000 years. When the unripe seed capsule is incised a milky fluid runs out and when dried this constitutes opium (Greek opus = juice). This contains three important alkaloids—morphine, codeine, and papaverine. Morphine is unrivalled for the relief of severe pain with myocardial infarction. Before modern diuretics were introduced in 1958, it was the most valuable drug for the treatment of acute left ventricular failure. Heroin is diamorphine. Papaverine, unlike the other two alkaloids, is not an analgesic or narcotic. It acts by relaxing smooth muscle, and in animals it depresses conduction in cardiac muscle and prevents chloroform induced ventricular fibrillation. In the 1930s it was tried without success in angina, hypertension, and arrhythmias. However, it was popular for the relief of intestinal colic and this led in 1957 to the German pharmaceutical firm Knoll producing a very active synthetic analogue D365. D for their chemist, Ferdinand Dengel. This became known as verapamil and in 1963 Albrecht Fleckenstein made a seminal discovery of calcium antagonism as its mode of action. In 1972 Schamroth, Krikler, and Garrett were the first to link the arrhythmia terminating action of verapamil with the concept of calcium channel blockade.
The stamp illustrated comes from the 1961 medicinal plants set of eight issued by Hungary. Other plants featured included the blue iris, purple hollyhock, and the thorn apple.