Opiates are the most effective pain reliever. Opiates, name derived from the word "opium”, which in turn is derived from the Greek oipon, oznaczającego ‘sok makowy’.
Their natural source is the poppy seed Papaver somniferum. The best known opium derivatives are codeine, morphine, diamorphine and hydromorphone. All these compounds are effective painkillers, but they have side effects, for example constipation. Two of them, morphine and diamorphine, they are addictive – even a week of taking the drugs may be enough for this. The overuse of hydromorphone has a similar effect.
However, we are mainly interested in the painkilling aspects of opiates. One of the great successes of modern chemistry is undoubtedly the synthesis of new substances that relieve pain, though only a few of the new drugs can match opiates. The raw material for obtaining opiates are unripe poppies, from which white comes out when the sides are cut, milky juice. After drying, it can be scraped off – it is the traditional form of opium. For the needs of the pharmaceutical industry, opium is obtained mechanically. Its main ingredient is morphine, complex organic compound. It affects the central nervous system, by blocking opioid receptors, responsible for the registration of pain sensations. By taking some opiates, like for example. morphine or diamorphine (heroin), even if we feel no pain, we experience their well-known narcotic effects.
Morphine is effective, because it works like natural pain relievers, produced by the body. Unlike them, however, The morphine starts working seconds after the injection, putting an end to even the most excruciating pain. Unfortunately, causes addiction. This problem can be solved, since the morphine molecule can be slightly modified, replacing one hydrogen atom with a methyl group. New relationship, called codeine, it is indeed less effective, but not addictive – it's safe enough, that it was among the commonly available painkillers.
Morphine can also be converted into an even faster-acting pain reliever, replacing its two hydrogen atoms with acetyl groups. Then diamorphine is formed (abbreviation for diacetylmorphine), a substance that reaches the brain more easily. Once in it, it loses both acetyl groups and is converted to morphine. Diamorphine relieves pain in cancer patients. In Europe, it is prescribed to patients in the last months of their lives. For them, it doesn't matter anymore, that diamorphine is more addictive than morphine. Its narcotic effects can even make you, that they will feel better temporarily. To relieve cancer patients, hydromorphone may also be administered, approved for use in the United States. It is the most effective painkiller of all opiates (Look: table below).
Table. Effectiveness of opiates.
* Maximum safe single dose. The smaller the dose, the more effective the substance.
** Rozpuszczalność w wodzie odnosząca się do soli fosforanowej w przypadku kodeiny i chlorowodorków w przypadku pozostałych związków. The more soluble the substance, the easier it is to give it to patients, and thus its effectiveness is greater.
In year 1992 a report was published, that there is a compound with more analgesic properties than morphine, wytwarzany przez ekwadorską żabę Epipedobates tricolor. W niewielkiej ilości wyekstrahował go John Daly z National Institutes of Health w Bethesdzie w stanie Maryland i nazwał epibatydyną. Turned out, that in standard rat tests there are approx 200 times stronger than morphine. In addition, the molecule of this substance is a relatively simple organochlorine compound. Does it mean, that opens a new era of non-toxic, extremely effective, not addictive, commonly available painkillers? The question remains open. Before we know the answer, epibatidine must pass a series of tests to check its effectiveness and safety. As we will see, there is a high probability, that he would not pass these tests.