Aspirin
Aspirin (USAN), also known as acetylsalicylic acid (/əˌsɛtəlˌsælɨˈsɪlɨk/ ə-set-əl-sal-i-sil-ik; abbreviated ASA), is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatorymedication. Aspirin was first isolated by Felix Hoffmann, a chemist with the German company Bayer, under the direction of Arthur Eichengrün.[1][2]
Salicylic acid, the main metabolite of aspirin, is an integral part of human and animal metabolism. While in humans much of it is attributable to diet, a substantial part is synthesized endogenously.[3]
Aspirin also has an antiplatelet effect by inhibiting the production of thromboxane, which under normal circumstances binds platelet molecules together to create a patch over damaged walls of blood vessels. Because the platelet patch can become too large and also block blood flow, locally and downstream, aspirin is also used long-term, at low doses, to help prevent heart attacks, strokes, and blood clot formation in people at high risk of developing blood clots.[4] It has also been established that low doses of aspirin may be given immediately after a heart attack to reduce the risk of another heart attack or of the death of cardiac tissue.[5][6] Many people take a daily aspirin to reduce their risk of heart attack. New evidence suggests that aspirin may be a powerful tool in cancer prevention as well.[7][8][9][10]
The main undesirable side-effects of aspirin taken by mouth are gastrointestinal ulcers, stomach bleeding, and tinnitus, especially in higher doses. In children and adolescents, aspirin is no longer indicated to control flu-like symptoms or the symptoms of chickenpoxor other viral illnesses, because of the risk of Reye's syndrome.[11]
Aspirin is part of a group of medications called nonsteroidal anti-inflammatory drugs(NSAIDs), but differs from them in the mechanism of action. Though it, and others in its group called the salicylates, have similar effects (antipyretic, anti-inflammatory, analgesic) to the other NSAIDs and inhibit the same enzyme cyclooxygenase, aspirin (but not the other salicylates) does so in an irreversible manner and, unlike others, affect more the COX-1 variant than the COX-2 variant of the enzyme.[12]
Today, aspirin is one of the most widely used medications in the world, with an estimated 40,000 tonnes of it being consumed each year.[13] In countries where Aspirin is a registered trademark owned by Bayer, the generic term is acetylsalicylic acid (ASA).
Pain
In general, aspirin works well for dull, throbbing pain; it is ineffective for pain caused by most muscle cramps, bloating, gastric distension, and acute skin irritation.[16] The most studied example is pain after surgery, such as tooth extraction, for which the highest allowed dose of aspirin (1 g) is equivalent to 1 g of paracetamol (acetaminophen), 60 mg of codeine, or 5 mg of oxycodone. A combination of aspirin and caffeine, in general, affords greater pain relief than aspirin alone. Effervescent aspirin alleviates pain much faster than aspirin in tablets (15–30 min vs. 45–60 min).[17]
Nevertheless, as a postsurgery painkiller, aspirin is inferior to ibuprofen and has higher gastrointestinal toxicity. The maximum dose of aspirin (1 g) provides weaker pain relief than an intermediate dose of ibuprofen (400 mg), and this relief does not last as long.[17] A combination of aspirin and codeine may have a slightly higher analgesic effect than aspirin alone; however, this difference is not clinically meaningful.[18] It appears ibuprofen is at least equally, and possibly more, effective than this combination.[19]
According to a 1998 meta-analysis of clinical trials for menstrual pain, aspirin demonstrated higher efficacy than placebo, but lower than ibuprofen or naproxen, although maximum doses of aspirin were never used in these trials. The authors concluded ibuprofen has the best risk-benefit ratio.[20]
Aspirin did not ease pain during cycling exercise,[21] while caffeine was very effective.[22][23] Likewise, aspirin, codeine, or paracetamol was not better than placebo for muscle soreness after exercise.
Tramadol
Tramadol hydrochloride (trademarked as Conzip, Ryzolt, Ultracet, Ultram in the USA,Ralivia and Zytram XL in Canada) is a centrally-acting syntheticanalgesic used to treat moderate to moderately-severe pain. The drug has a wide range of applications, including treatment of rheumatoid arthritis,restless legs syndrome and fibromyalgia. It was launched and marketed asTramal by the German pharmaceutical company Grünenthal GmbH in 1977.[1][2]
Tramadol is a very weak μ-opioid receptor agonist, induces serotoninrelease, and inhibits the reuptake of norepinephrine.[3][4] Tramadol is converted to O-desmethyltramadol, a significantly more potent μ-opioid agonist. The opioid agonistic effect of tramadol and its major metabolite(s) is almost exclusively mediated by such μ-opioid receptors. This further distinguishes tramadol from opioids in general (including morphine), which do not possess tramadol's degree of receptor subtype selectivity and which are much stronger opiate-receptor agonists. Similarly, the habituating properties of tramadol (such as they are) are arguably mainly due to μ-opioid agonism with contributions from serotonergic and noradrenergic effects.
