Yeung (1985), in a short monograph on Qing Hao gives A. apiacea Hance as a synonym for A. annua and describes the taste and property of the herb as bitter, pungent and cold. Its functions are antimalarial, to reduce the heat caused by deficiency of Yin, and to clear the summer heat. The medicinal uses of Qing Hao are given as malaria, febrile diseases, tidal fever, low grade fever and summer heat stroke. Although Qing Hao may be used as a cooling herb for the relief of symptoms, TCM places great emphasis on treating the underlying cause of an illness and as explained above, diagnosis is often much more precise than it is in western medicine. This helps to explain why complex combinations of Chinese herbs are used; additional herbs (which may be referred to as "minister", " assistant" or "guide" herbs are added to the principal (or "emperor" herb) in order to complement or modify its action so that the TCM prescription is tailored for the needs of the individual patient.
An example of a prescription for the treatment of malaria using TCM is the classical formula Qing Hao Bie Jia Tang (decoction of Carapax Trionycis and Qing Hao) which is found in the "Wen Bing Tiao Bian" (Detailed analysis of febrile diseases) of 1798. It is composed of the following: Herba Artemisia Annuae, Carapax Trionycis (fresh water turtle shell), Folium Mori (Morus alba leaf), Pollen (species not specified), Rhizoma Anemarrhenae (Anemarrhenae asphodeloides rhizome) and Cortex Moutan (Paeonia suffruticosa bark). Herba Artemisia Annuae is used to clear the heat from the channels so as to lower the fever and Carapax Trionycis has the effect of nourishing Yin and lowering the fever. The combination of the two expels heat without injuring Yin and these are the principal ingredients but Herba Artemisia Annuae may also act as the "guiding herb". Cortex Moutan may also cool the blood and help Herba Artemisia Annuae to eliminate the heat while Rhizoma Anemarrhenae serves to benefit Yin and help Carapax Trionycis to lower the fever so that they are considered to be minister herbs. Folium Mori and Pollen are assistant herbs in the formula.
Although it is well established that artemisinin itself is a highly effective antimalarial, to date there have been no published reports of clinical trials in which A. annua herb has been used alone for the treatment of malaria. One reason for this is that, as illustrated above, TCM is individualised for each patient so that different combinations of herbs are used. Currently however, there is interest in Africa in growing the herb and using it as a locally available and inexpensive antimalarial, but before this practise can be recommended, studies demonstrating the efficacy of A. annua will be needed. However, studies in which a crude ethanolic extract of A. annua was formulated with oil in a soft gel capsule and administered to mice and tried clinically in man have been reported (Yao-De et al., 1992). In mice infected with Plasmodium berghei the soft gel capsule was found to be superior to a tablet formulation of the extract; for the capsule the EDJ0 value was 11.9 g/kg (with reference to the raw herb) and 35.1 mg/kg (with respect to the artemisinin content) while the corresponding values for the tablet were 46.8 g/Kg and 124 mg/kg respectively. Artemisinin itself was found to have an ED50 of 122 mg/kg. The soft gel capsule was administered to 103 patients with malaria (P. falciparum or P. vivax) and compared with the tablet formulation which was given to 41 malaria patients. Both formulations were effective in reducing fever and clearing parasites at doses equivalent to 73.6 g raw herb (for the capsule), and 80.8 g (for the tablet), given over 3 days, but recrudescent rates were high with both dosage forms although they were reduced by increasing the duration of treatment. Recrudescence (which arises because not all of the parasites have been killed by the drug and is not due to drug resistance), may also occur when artemisinin and its derivatives are used to treat malaria (see chapter 13), but the high rate of recrudescence reported in the above study suggests that crude extracts alone may not give an acceptable cure rate and additional drug therapy may need to be given.
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