Combination use of nonsteroidal antiinflammatory drugs

Predictivity and sensitivity of animal models of arthritis

Arthritis literally means joint inflammation. Arthritis is not a single disease. Arthritis refers to a group of rheumatic diseases and other conditions that can cause pain, stiffness and swelling in the joints. The forms range from those related to wear and tear of cartilage (such as osteoarthritis) to those associated with inflammation resulting from an overactive immune system (such as rheumatoid arthritis). Arthritis is more heterogeneous and this is an important starting point when discussing animal models for arthritis. Animal models are instrumental in understanding the etiology and pathogenetic mechanisms of rheumatoid arthritis. Several new mouse models have either been produced. Various methods have been applied to induce in animals experimental models of arthritis which would provide important insights into the aetiopathogenetic mechanisms of human RA.

Pharmacokinetic interaction between indomethacin and diflunisal

The effect of treatment with diflunisal on the steady-state pharmacokinetics of indomethacin has been studied in 16 healthy volunteers. The steady-state plasma concentration and AUC of indomethacin were significantly increased two- to threefold during treatment with diflunisal and its total clearance and total volume of distribution were significantly decreased. The urinary recovery of total indomethacin (unchanged + glucuronides) was significantly lower during administration of diflunisal, whereas excretion of the indomethacin metabolites desmethylindomethacin and desbenzoylindomethacin and their glucuronides was not significantly altered. The results can be explained by selective inhibition of glucuronidation of unchanged indomethacin by diflunisal. The interaction appears clinically relevant as potentially dangerous side effects of indomethacin are related to its plasma concentration.

Impact of non-narcotic oral analgesics on pain management

Of the four categories of oral analgesics, three have been available since the 19th century. Although adequate doses of the more potent oral opioids such as morphine and methadone are effective even in severe pain, the commonly used "weak" narcotics such as codeine and propoxyphene are no more effective than usual doses of aspirin or acetaminophen. Furthermore, the opioids produce gastrointestinal and central nervous system adverse effects, and, during long-term administration, tolerance may develop and there is a risk of drug dependence. Aspirin and acetaminophen are the traditional agents of choice for oral analgesic therapy; until 10 years ago, there were no single-entity, oral analgesics--with the exception of large doses of oral narcotics--that were more effective than usual doses of aspirin or acetaminophen. However, there is a ceiling on the analgesic effect attainable with safe doses of these drugs, which may in part be overcome through the use of the third category of oral analgesics, combinations of aspirin or acetaminophen with oral opioids. The fourth category of oral analgesics constitutes the most important recent development in pain management with analgesic drugs: the newer peripherally acting, nonsteroidal anti-inflammatory analgesics, some of which are clearly more efficacious than aspirin or acetaminophen and compare favorably not only with full doses of narcotic combination products but even, in some cases, with strong injectable opioids. On repeated dosing, some nonsteroidal anti-inflammatory drugs are better tolerated than aspirin and some have a much longer duration of analgesic effect than aspirin or acetaminophen. Further study is needed to compare nonsteroidal anti-inflammatory drugs among themselves and to determine their value in chronic pain and in combination therapy.

Plasma protein binding of dipyrone metabolites in man

Four metabolites of dipyrone, 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA) can be identified in human plasma after its oral administration. The plasma protein binding of the metabolites in samples from 20 healthy volunteers was determined by ultrafiltration. None of the metabolites were found to be extensively bound to plasma proteins. The binding of MAA and AA was relatively higher than of FAA and AAA, as expected from their chemical structure. The mean percentage plasma protein binding was 57.6% for MAA, 47.9 for AA, 17.8 for FAA and 14.2% for AAA. The correlation between the unbound concentration in plasma and the total concentrations of MAA, AA, FAA and AAA was linear. No association was evident between the total protein plasma concentration and the extent of binding. The possible therapeutic implications related to protein binding of several analgesic and non-steroidal anti-inflammatory drugs are discussed.

Combination analgesics

Six rationales for using combination analgesics are identified, but most combinations are formulated with two rationales in mind: enhancement of analgesia and reduction of adverse effects by combining two analgesics with different mechanisms of action. Acetaminophen and aspirin are the mainstays of oral analgesic combinations. There is substantial evidence that combining an optimal dose of acetaminophen or aspirin with an oral opioid such as codeine, hydrocodone, or oxycodone produces an additive analgesic effect greater than that obtained by doubling the dose of either constituent administered alone. There is also some evidence that the adverse effects produced by such combinations are less than would be produced by an equi-analgesic dose of a single constituent. The physician need not be confined to existing fixed-ratio combinations; he or she may extemporize to the patient's advantage by co-administering acetaminophen, aspirin, or other nonsteroidal anti-inflammatory drugs with available oral opioids and, in select situations, co-administering oral or injectable analgesics with psychoactive drugs.

Factors determining efficacy of NSAIDs

This article reviews the efficacy of NSAIDs and their pharmacokinetic and pharmacodynamic properties. The assumption that classic pharmacokinetic dose/plasma concentration response relationships can be applied to NSAIDs has tenuous support in the biomedical literature. Comparative efficacy studies, using ASA and indomethacin as the standards for comparison, ignore the fact that the major outcome variables are subjective responses among patients, not among drugs. Comparing inhibition of platelet malonyldialdehyde, synovial drug concentrations, urinary prostaglandin metabolites, and plasma free and total concentration with the clinical outcome provides no guidelines to serve as predictors of response. The individual agents, indomethacin, salicylates, sulindac, piroxicam, and naproxen, illustrate the complexities of NSAID pharmacotherapy. Recent proliferation of newer NSAIDs will not add significantly to the efficacy of these agents in the treatment of pain and inflammatory disease states. However, knowledge of pharmacokinetic population parameters for the individual NSAIDs will increase the likelihood of therapeutic success and diminish the possibilities for adverse reactions.

Comparison of three slow-release acetylsalicylic acid preparations in rheumatoid arthritis

Nine patients suffering from chronic rheumatoid arthritis were each given single doses of 1 g acetylsalicylic acid, in the form of each of the preparations studied: an enteric-coated tablet, a microcrystalline tablet, and a capsule containing enterosoluble granules. Absorption from each preparation was good in all patients. Onset of absorption varied to some degree, but similar salicylate levels were reached within 5 hours with all preparations. In the case of enteric-coated tablets, relatively high salicylate levels persisted 12 hours after dosing, which would seem to permit twice daily dosage, regardless of the total daily dose.

Gastrointestinal consequences of treatment with drugs in elderly patients

The aging process affects many organs of the gastrointestinal tract. The most common effect is decreased motility, which may result in patient discomfort and various alterations in absorption. Concurrent pathologic conditions, common in the elderly, can lead in turn to the use of many pharmaceuticals, either alone or in combination. Untoward reactions to these drugs, when they occur, are often manifest in the gastrointestinal tract. Agents that may cause gastrointestinal bleeding include aspirin, corticosteroids, anticoagulants, antimetabolites, and agents used in cancer chemotherapy. Ethanol or aspirin or other drugs can cause erosive gastritis.