On non-steroidal anti-inflammatory drugs
Non-steroidal anti-inflammatory drugs (NSAIDs) are the most widely-appointed group of medicines worldwide. Every day, more than 30 million people in the world are taking any NSAIDs, 40% of them – aged 60 years.
The prescriptive list of basic (essential) Medicines (Essential Drug List. WHO, 1999) includes only a few funds belonging to a class of non-opioid analgesics, including two NSAIDs.
The selection of these funds to the list of essential medicines is due not only to their high therapeutic activity, but, most importantly, secure, proven long-term experience of many doctors around the world. Meanwhile, WHO experts stressed that the list is not a «frozen» document, it must be regularly reviewed and adapted to the conditions of individual countries should take into account the qualifications and experience of physicians, as well as new research.
As you know, the whole class of non-opioid analgesics can be divided into two large groups – nekislotnye acid and derivatives. And if the second, more narrowly, includes tools such as acetaminophen (paracetamol), metamizole (analgin) *, with only antipireticheskoy and analgesic activity, the first – all the so-called non-steroidal anti-inflammatory drugs, possessing a full spectrum of pharmacological activity – analgesic and anti-inflammatory antipireticheskim action.
The whole group of NSAIDs is also conventionally divided into a number of key «families» (subclasses) in accordance with the active substance, which they are derived.
Experts from different countries are united in the opinion that the differences in the effectiveness of NSAIDs are relatively small (Fries JF, Williams CA, Bloch DA, 1991). Reviews of several dozen clinical trials of various NSAIDs in osteoarthritis and rheumatoid arthritis did not give grounds to rank the drugs according to their effectiveness (Fries J., 1996). Although the number of NSAIDs is increasing, none of the new drugs can not be conclusively found to be more effective than aspirin or ibuprofen. The frequency of side effects arising from the admission of these drugs, also about the same, perhaps, the exception is ibuprofen in low doses (Brooks PM, 1988). At the same time, the systematization of data from randomized trials (McQuay H., Moore A., 1998), using the criterion of maximum total pain relief, which to some extent can objectify the potential relevance of various analgesics in anesthesia, gives rise to a definite hierarchy in analgetic activity many medicines.
If the effectiveness of drugs roughly equivalent, then the reason for their choice could be the relative safety. However, with few exceptions, there is little choice. NSAIDs is one of the most common causes of adverse reactions to drug treatment. In the UK, NSAIDs account for 5% of all prescribers, but they accounted for 25% of all adverse events reported to the Committee on Safety of medicines. According to official estimates, in the UK 3-4 thousand deaths annually due to side effects of NSAIDs. In the United States each year use of NSAIDs leads to more than 70 thousand hospitalizations and 7 thousand deaths.
For NSAIDs typical four main types of side effects: gastrointestinal reactions, including stomach ulcers, hypersensitivity, renal insufficiency after prolonged use, central nervous system dysfunction, including forgetfulness, inability to concentrate, insomnia, paranoia and depression. Less commonly observed liver damage, sometimes severe.
Data on the frequency of nephrotoxic adverse reactions during treatment with NSAIDs (Current Problems in Pharmacovigilance, 1994)
The number of message here, attributable to 100,000 prescriptions per year
All medicines in varying degrees, can be associated with undesirable side reactions. NSAIDs as a class of drugs characterized by a number of adverse reactions, and the difference in their severity is extremely small. In addition, these problems are potentially important for all patients without exception, regardless of the duration of therapy and age.
Gastrointestinal reactions as a manifestation of adverse reactions to NSAIDs are the most frequent and common to this class of therapeutic drugs. Clinically, these manifestations occur most difficult and are a major risk factor for death.
NSAIDs toxic effects on two independent mechanisms – local (a narrow) and the total generalized (systemic) effect.
One of the most reasonable points of view on the pathogenesis of NSAID-induced lesions of gastrointestinal system is that these specific complications of therapy due to non-selective suppression of synthesis of prostaglandins **.
Approximately 50% of patients with NSAID-gastropathy (yazvennno-erosive lesions of mucous membrane of the stomach and duodenal ulcers, bleeding), the disease can occur with virtually no symptoms, and thus detected very late. Such vital hazardous conditions may be the first and only sign of pathological changes in the gastrointestinal tract (this feature of NSAID-gastropathy is particularly pronounced in older patients). Moreover, quite often non-steroidal anti-inflammatory agents due to the peculiarities antiprostaglandinovoy activity can «obscure» symptoms of pathology of the gastrointestinal tract, thus impeding the diagnosis and treatment of disease. At the same time, a certain part of patients (30%) gastropathy is the only symptom of abdominal pain without pathological somatic changes. Between plagues, formed as a result of taking NSAIDs, and have arisen spontaneously, at random (ulcer), there is some difference. First, ulcers, resulting from NSAIDs, most often asymptomatic. Secondly, the gastric mucosa «adapted» to long-term effects of NSAIDs, so that 2-8 weeks after taking the drug reduced the acute lesion, and a number of experiments showed that the most dangerous may be considered the first months of receiving those funds.
It is believed that the risk of gastrointestinal bleeding is high as a target short-term, and during chronic administration of NSAIDs. At the same time, there is every reason to believe that it is the duration of admission to the greatest extent due to the major threat, even OTC NSAIDs. Long-term retrospective study (Kurata JH, Abbey DE, 1984), conducted in 4524 patients found that daily use of aspirin at a dose of 1000 mg (DCI – 6000 mg) for the prevention of myocardial infarction at 4 years increases the risk of ulcerative lesions in 10.7 times compared with the control group (not taking aspirin). One must bear in mind that the minimum doses of salicylates can be quite dangerous. Research (Naschitz J., 1989) have demonstrated that even a minimum dose of aspirin as 75-250 mg, may be the main cause of bleeding in the upper gastrointestinal tract in 8.2% of patients. At the same time one of the prospective studies (Lanza F., 1984) showed that a three-day short-term regular use of the safest of the NSAIDs, the drug – ibuprofen – a daily dose of 1600 mg (DCI – 2400 mg) can not cause morphologically significant changes in gastric mucosa.
Hypersensitivity reactions. One of the most important criteria for the use of NSAIDs as an analgesic for acute pain (traumatic or surgical origin) is an allergic-immunological status of the patient, the risk of bronchospasm (Szczeklik A., 1992). Acute asthma attacks aspirinzavisimoy develops in about 8-20% of adult asthmatics. In some patients it may be the first symptom of incipient asthma disease. The observed cross-correlation between asthma and bronchospasm aspirinzavisimoy applies not only to salicylates, but almost all NSAIDs. And considering the issue more broadly, it should be recognized that the appointment of acid derivatives of NSAIDs is contraindicated in patients with a history of any manifestation of the so-called «aspirin triad» – asthma, nasal polyposis, in ducts or intolerance to aspirin (Power I., 1993).
Data on the frequency of hepatotoxic adverse reactions during treatment with NSAIDs (Current Problems in Pharmacovigilance, 1994)
The number of message here, attributable to 100,000 prescriptions per year
Renal. It is believed that the adverse reaction from the kidney may be due to systemic non-selective suppression of prostaglandin synthesis, affecting the regulation of glomerular filtration, maintenance of fluid and electrolyte balance. These reactions usually occur in patients with a history of any kidney disease. In such cases, the main symptoms of adverse reactions may be acute renal failure, fluid retention, hyperkalemia.
Furthermore, we must take into account the possibility of cross-reactivity with the appointment of NSAIDs while taking diuretic drugs, especially in elderly patients. Most NSAIDs inhibit the action and increase the nephrotoxicity «loop» diuretics reduce the hypotensive effect benzotiazidov (Johnson AG, Seideman P., Day RD, 1993), which also greatly increases the risk of adverse reactions.
Abnormal liver function. Risk of drug hepatitis while taking NSAIDs is relatively small. We describe the exclusive cases of acute hepatotoxic reactions to the development of fatal outcome (Masana P. et al., 1986). All of them are associated with significant overdose and prolonged treatment. At the same time, in 1-4% of cases there may be asymptomatic moderate increase in the level of liver enzymes (Nasonov EL, Lebedeva OV, 1991).
Violation of the central nervous system. Reactions of neurotoxicity, manifested by headaches, some disorientation, confusion may occur while taking all NSAIDs, but most often they occur, when it comes to drugs, it is easy minuyuschih blood-brain barrier (Goodwin JS, Regan. M., 1982). All these reactions are most pronounced in older patients due to their age and physiological characteristics. In addition, this category of patients in connection with violation of attention and memory are at risk for accidental overdose (the so-called «aspirin intoxication»), which is easy to ignore.
Generalized data on the safety key NSAIDs. Since prior to 1997 studies on the tolerability of aspirin, ibuprofen and acetaminophen (the most widely used in everyday practice for treatment of low / moderate acute pain in adults) has been conducted, this problem is regarded as sufficiently relevant to public health. Accordingly, in 1997-1999, was followed by a global, randomized, multicenter study focused on obtaining reliable data for objective comparison of tolerability of aspirin, ibuprofen and paracetamol in standard recommended doses and intermittent on the acute pain of various etiologies (The PAIN Study: Paracetamol, Aspirin and Ibuprofen New Tolerability Study / / Clin. Drug. Invest, 1999, vol. 18, № 2, pp. 88-98; Moore N., Van Ganse E., et al. A comparison of the tolerability of Ibuprofen, Acetominophen and Aspirin for short-term analgesia / / Proceedings of the 9th World Congress on Pain / Eds. M. Devor, MC Rowbotham, Z. Wiesenfeld-Hallin. Seatle: IASP Press, 2000, p. 809-817).
The results showed that all the main characteristics of tolerability of ibuprofen equivalent indicators tolerability of paracetamol and aspirin higher than portability. In this regard, you may need to reconsider the priorities concerning the use of first-line analgesics for short-term treatment of conditions involving pain syndrome in general practice. First recommended to prescribe ibuprofen because of poorer tolerability of aspirin and the potential dangers of paracetamol overdose.
And finally, what it is worth noting: most of the newer drugs cost much more than appeared long ago. Thus, it is known that the use of a simple reproduction of analgesic such as ibuprofen, costing 2-8 times cheaper than the use of a new, «modern» NSAIDs. If appointed NSAIDs with misoprostol to reduce the risk of ulcerative lesions of the stomach and intestines, then the cost of treatment is even higher. This proves once again that the use of long-known NSAIDs, such as aspirin and ibuprofen, is much more profitable.
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