Cinchona genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (antifever) agent especially useful in treating malaria. Cinchona alkaloids include: They find use in organic chemistry as organocatalysts in asymmetric synthesis. Alongside the alkaloids, many cinchona barks contain cinchotannic acid, a particular tannin, which by oxidation rapidly yields a dark-coloured phlobaphene called red cinchonic, cinchono-fulvic acid or cinchona red. In 1934, efforts to make malaria drugs cheap and effective for use across countries led to the development of a standard called "totaquina" proposed by the Malaria Commission of the League of Nations.
Analgesic tolerance, which may be of particular concern regarding patients suffering with chronic pain and requiring an analgesic over long periods. Opioid tolerance is often addressed with opioid rotation therapy in which a patient is routinely switched between two or more non-cross-tolerant opioid medications in order to prevent exceeding safe dosages in the attempt to achieve an adequate analgesic effect. Opioid tolerance should not be confused with opioid-induced hyperalgesia. The symptoms of these two conditions can appear very similar but the mechanism of action is different. Opioid-induced hyperalgesia is when exposure to opioids increases the sensation of pain (hyperalgesia) and can