|Medicinal plants: An expanding role in development (WB, 1996, 32 p.)|
|4. Toward a strategy|
There is increasing concern regarding the quality of medicinal plant material being delivered to local pharmaceutical industries and the length of storage prior to processing. The storage time is of particular concern because of loss of efficacy. Any future strategy should encourage better handling and prompt deliveries.
Therapeutic products from plants differ crucially in one particular aspect from those from a laboratory: they are subject to the vagaries of nature. A compound from a chemical reactor inside a factory is identical batch after batch, but the amount of product in living plants can change with such factors as the weather, the time of harvest, and the way the crop is harvested and handled.
Any strategy must address this variability. Investigations should be made into the stability of each herbal product, taking into account such practices as the effects of sunlight, temperature, humidity, plant husbandry, and packaging.
Box 5 Box 5: The 200-year Treatment
One of the great complaints in the late 1 700s, was dropsy. People in later life came down with sodden, flesh fluid-filled chests and grossly swollen bellies. Physicians of that era spent much of their efforts attempting to rid patients of the burden of excess fluid. All seemed in vain until, in 1775 William Withering visited an old Shropshire woman suffering from dropsy. She was seemingly far gone but a few weeks later, the good doctor, who spent much of his time treating the poor, found her much improved. He discovered she had taken a local folk-remedy that included more than 20 different herbs. Upon consideration, Withering decided that the active herb was the European wild flower known as foxglove.
He then used foxglove extracts on his own patients with dramatic effect, achieving a high proportion of cures. One man, for instance, shed 40 pints (about 10 liters) of fluid in two weeks. Withering, quite logically, thought the drug worked through the kidneys. He spent 10 years looking into that potential but only after his death was the real story recognized: foxglove acts not on the kidneys but on the heart. Its components improve the circulation of the blood, which in turn flushes out the accumulation of excess fluids.
Today, the common foxglove provides the world's major heart medicines, digitoxin and digoxin. These have so far resisted attempts at commercial synthesis, it is still necessary to use plant material for every dose administered. Each year American doctors write more than 16 million prescriptions for these compounds as well as 2 5 million prescriptions for the undifferentiated extract of foxglove leaves. All are still derived from the dried leaves, sometimes from the British foxglove Digitalis purpurea but mostly from the European Digitalis lanata
Millions of-heart sufferers owe their lives to this. Digoxin and
digitoxin, strengthen and regulate their heartbeat This success and the
consequent relief of human misery is thanks to the inquisitive and insightful
country doctor. who established beyond doubt the great value of various foxglove
samples the poor folk of Shropshire were employing two centuries ago. We have
now benefited from William Withering's wisdom for two centuries.