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Effect of colestimide therapy for glycemic control in type 2 diabetes mellitus with hypercholesterolemia.

Colestimide is a new anion-exchange resin used to lower serum cholesterol in Japan. Because of its excellent compliance, colestimide can replace cholestyramine. To clarify the effect of colestimide on glycemic controls, colestimide (3 g/day) or pravastatin (10 mg) was given orally to patients with type 2 diabetes treated with oral hypoglycemic agents or insulin who had low-density lipoprotein (LDL) cholesterol levels exceeding 3.6 mmol/l. In the colestimide groups, fasting plasma glucose concentrations had decreased significantly from 8.5 +/- 1.4 to 7.7 +/- 1.5 mmol/l at 3 months (P<0.05), as had glycated hemoglobin (HbA1c) from 7.7 +/- 0.7% to 6.8 +/- 0.5%, for an 8% reduction (P<0.01). Fasting plasma glucose and HbA1c did not change in the pravastatin group. Total cholesterol and LDL-cholesterol decreased significantly (P<0.01) with either medication, with similar reduction rates for both drugs. Doses of oral hypoglycemic agents and insulin did not change during the study, and body weight remained stable. Considering that patients with type 2 diabetes often have hyperlipidemia, colestimide therapy may have a clinically useful dual action in such patients.

Aged↗

Pharmacology for renal calculi.

Stone disease is as old as recorded history but despite advances in diagnosis and treatment, it continues to cause significant morbidity. This review summarises the current pharmacologic management of urinary calculi based upon the stone type. All patients with stone disease are advised to increase fluid intake, limit dietary protein and limit sodium. Calcium oxalate stones can be managed on a selective or non-selective basis depending on the cause of the hypercalciuria or hyperoxaluria. Agents currently in use include sodium cellulose phosphate, thiazides, orthophosphates, oral calcium supplements, pyridoxine, cholestyramine, citrate, magnesium and allopurinol. Classically, struvite stones occur in the presence of urea splitting organisms and are composed of magnesium, ammonium phosphate and carbonate apatite. The goal of treatment is to make patients stone free as bacteria retained in stone fragments lead to stone growth. Urease inhibitors, aluminium hydroxide gel, hemiacidrin, and Suby G and M solutions are infrequently used in treatment. Cystine stones are the result of an autosomal recessive disorder. D-Penicillamine, captopril and alpha-mercaptopropionylglycine (MPG) are all oral agents that have proven to be efficacious. As more randomised trials are conducted and the understanding of endogenous stone inhibitors progresses, the medical management of stone disease will continue to improve.

Calcium Oxalate↗

Meloxicam: a reappraisal of pharmacokinetics, efficacy and safety.

The discovery of two distinct isoenzymes of COX has led to the development and clinical introduction of COX-2 inhibitors with increased selectivity onto the market. Meloxicam is a non-steroidal anti-inflammatory drug (NSAID) of the oxicam class, and is a preferential inhibitor of COX-2, demonstrating effectiveness with anti-inflammatory, analgesic and antipyretic activity. Meloxicam is therapeutically utilised in the management of osteoarthritis and rheumatoid arthritis. Trials have examined the risk of gastrointestinal ulceration of meloxicam when compared with traditional non-specific COX-inhibiting NSAIDs with mixed results; meloxicam seems to have a greater gastrointestinal risk than the highly specific COX-2 NSAIDs. Meloxicam has a plasma half-life of approximately 20 h and is convenient for once daily administration. Neither moderate renal nor hepatic insufficiency significantly alters the pharmacokinetics of meloxicam in short-term studies. Furthermore, dose adjustment is not required in the elderly. Recent drug-drug interaction studies have demonstrated that meloxicam interacts with some medications, including cholestyramine, lithium and some inhibitors of cytochrome P450 -2C9 and -3A4. Consequently, increased clinical vigilance should be maintained when coprescribing some medications with meloxicam. Concentration-dependent therapeutic and toxicological effects have yet to be extensively elucidated for meloxicam. Long-term safety in various organ systems, especially in the heart and vascular system and with concomitant drug administration, remains to be proven. The pharmacokinetics of meloxicam enables once daily application, which increases compliance compared with some shorter acting NSAIDs; however, long-term clinical data clearly demonstrating safety and efficacy advantages are lacking.

Anti-Inflammatory Agents, Non-Steroidal↗

Familial cholestasis with gallstone, ataxia and visual disturbance.

Two siblings with progressive intrahepatic cholestasis were reported. The brother died at 4 years of age because of hepatic failure followed by persistent obstructive jaundice starting at 4 months of age. The sister had unique clinical features, including recurrent obstructive jaundice since early infancy, radiopaque gallstone and neurological abnormalities which were cerebellar ataxia, bilateral ptosis, hyporeflexia and visual disturbance involving retinal degeneration and optic atrophy. She had a coarse facial appearance, camptodactyly and sclerotic skin with many scratch marks. Persistent high levels of serum bile acids were found while the patient was icteric and even anicteric, though serum cholesterol levels were approximately within normal limits. The serum lipoprotein-X was negative whenever examined. Cholestyramine treatment gave incomplete relief from pruritus but resulted in no improvement in her clinical course.

Cerebellar Ataxia↗

Adverse drug interactions with nonsteroidal anti-inflammatory drugs (NSAIDs). Recognition, management and avoidance.

The prevalence and incidence of adverse drug interactions involving nonsteroidal anti-inflammatory drugs (NSAIDs) remains unknown. To identify those proposed drug interactions of greatest clinical significance, it is appropriate to focus on interactions between commonly used and/or commonly coprescribed drugs, interactions for which there are numerous well documented case reports in reputable journals, interactions validated by well designed in vivo human studies and those affecting high-risk drugs and/or high-risk patients. While most interactions between NSAIDs and other drugs are pharmacokinetic, NSAID-related pharmacodynamic interactions may be considerably more important in the clinical context, and prescriber ignorance is likely to be a major determinant of many adverse drug interactions. Prescribing NSAIDs is relatively contraindicated for patients on oral anticoagulants due to the risk of haemorrhage, and for patients taking high-dose methotrexate due to the dangers of bone marrow toxicity, renal failure and hepatic dysfunction. Combination NSAID therapy cannot be justified as toxicity may be increased without any improvement in efficacy. Where lithium or anti-hypertensives are coprescribed with NSAIDs, close monitoring is mandatory for lithium toxicity and hypertension, respectively, and aspirin (acetylsalicylic acid) or sulindac are preferred. Phenytoin or oral hypoglycaemic agents may be administered with NSAIDs other than pyrazoles and salicylates provided that patients are monitored carefully at the initiation and cessation of NSAID treatment. Digoxin, aminoglycosides and probenecid may be coprescribed with NSAIDs, but close monitoring is required, particularly for high-risk patients such as the elderly. Indomethacin and triamterene should be avoided due to the risk of renal failure. High dose aspirin should be replaced by naproxen in patients on valproic acid (sodium valproate) and care is required when corticosteroids are administered to patients taking salicylates long term in high dosage. Interactions between NSAIDs and antacids or cholestyramine are generally avoidable. Adverse drug interactions involving NSAIDs may be limited by rational prescribing and by careful monitoring, particularly for high-risk patients, drugs and therapy periods.

Animals↗

Class III antiarrhythmics in overdose. Presenting features and management principles.

Class III (Vaughan-Williams classification) antiarrhythmic drugs prolong the cardiac action potential without affecting depolarisation. The 3 class III drugs currently in general use are amiodarone, sotalol and bretylium. The presenting features of acute toxicity are different for each agent and are, therefore, discussed separately. Several new class III antiarrhythmic agents are under development, including dofetilide and d-sotalol, but specific data on overdoses of these potent class III drugs are not yet available. Amiodarone toxicity following acute overdose is rare because poor bioavailability and a large volume of distribution limit the peak serum concentration. Toxicity is low even if high serum concentrations are reached. The major risks from acute overdose are hypotension (intravenous administration only) and arrhythmia if other factors, such as hypokalaemia or additional antiarrhythmic agents are present. Management is chiefly directed at reducing absorption with activated charcoal or cholestyramine, and monitoring for arrhythmia. Sotalol is a beta-blocker with additional class III activity. Oral bioavailability is high, and overdosed patients can present with bradycardia, hypotension and major haemodynamic collapse. The combination of bradycardia and prolongation of the QT interval is associated with malignant arrhythmias such as torsade de pointes. Management principles include observation and correction of bradycardia with endocardial pacing, intravenous adrenergic drugs and glucagon. The risk of arrhythmia can be substantially reduced by intravenous potassium and magnesium supplements. d-Sotalol is a potent class III drug devoid of beta-blocking activity and may be expected to share the proarrhythmic affects of the racemic mixture in overdose, without pronounced hypotension and bradycardia. Intravenous bretylium in overdose causes an initial hypertensive effect, followed by profound hypotension from systemic vasodilation. Management is directed at controlling hypotension with volume expansion and norepinephrine (noradrenaline).

Amiodarone↗

Adverse effects of drugs used in the management of constipation and diarrhoea.

Most laxatives, if used intermittently in the absence of contraindications, are relatively safe. Bulking agents may diminish absorption of some minerals and drugs, but this is not usually clinically significant. Ispaghula can cause serious allergic reactions. The chronic ingestion of stimulant laxatives has been blamed for the development of the 'cathartic colon', but there are no definitive studies which have demonstrated this. Dantron (danthron) preparations should only be used in older patients and the terminally ill because of the risk of hepatotoxicity with this drug. Oral oxyphenisatine should no longer be used. Senna would appear to be the stimulant laxative of choice during pregnancy and lactation. Bisacodyl is the polyphenolic derivative of choice. Lactulose, sorbitol and lactilol rarely cause significant adverse effects. Magnesium salt laxatives and phosphate enemas can cause serious metabolic disturbances in babies and young children. Liquid paraffin is contraindicated if there is any risk of aspiration. Interference with the absorption of fat soluble vitamins would not appear to be clinically significant. Docusate sodium may potentiate the hepatotoxicity of other drugs, but reports of this are rare. The role of cisapride in constipation has not been established. Antidiarrhoeal drugs are second line drugs whose use is aimed at minimising inconvenience and discomfort. No antidiarrhoeals can be recommended for children under 4 years of age. Loperamide is the drug of choice in older children and adults. The atropine component of diphenoxylate/atropine combinations can cause significant adverse effects. Bismuth salicylate is an inconvenient treatment for travellers' diarrhoea as large frequent doses of the liquid formulation are needed. Some bismuth can be absorbed and there is the potential to cause encephalopathy. Octreotide, methysergide and cholestyramine have a role for specific causes of diarrhoea only. Octreotide is effective in high output states from the small or large bowel, with few adverse effects. Clonidine and lidamidine may have a role in the treatment of chronic diabetic diarrhoea. The role of lidamidine in nondiabetic chronic diarrhoea has not been established.

Antidiarrheals↗

Clinically significant drug interactions with new immunosuppressive agents.

Tacrolimus (FK506), mycophenolate mofetil, sirolimus (rapamycin), gusperimus, and monoclonal antibody preparations are new immunosuppressive agents, some of which are already approved for clinical use, while others are currently undergoing clinical trials. The present article provides an overview of adverse drug interactions between these immunosuppressants and other drugs which may be used concomitantly. Preliminary data suggest that a pharmacodynamic interaction can occur between tacrolimus and nonsteroidal anti-inflammatory drugs, associated with an increased risk of nephrotoxicity. Erythromycin, clarithromycin, clotrimazole, fluconazole, ketoconazole, and danazol have been shown to increase tacrolimus blood concentrations, while rifampicin (rifampicin) was found to decrease tacrolimus blood concentrations. Evidence from experimental studies suggest that several other drugs also known to affect cytochrome P450 activity may have significant effects on the pharmacokinetics of tacrolimus. On the other hand, tacrolimus itself may inhibit the metabolism of coadministered drugs. This interaction may be attributed to the enhanced renal impairment which has been observed in patients treated with tacrolimus and cyclosporin. The bioavailability of mycophenolic acid, the active metabolite of mycophenolate mofetil, has been reported to be reduced by aluminium/magnesium hydroxide-containing antacids and cholestyramine. Mycophenolic acid, sirolimus and gusperimus may impair bone marrow function and this adverse effect may be enhanced by concomitant administration of other myelosuppressive drugs. There is some evidence that coadministered sirolimus and cyclosporin cause an increase in each other's blood concentrations. An increased risk of central nervous system adverse effects has been described following the combined use of indomethacin and the monoclonal antibody muromonab CD3 (OKT3).

Anti-Inflammatory Agents, Non-Steroidal↗

Drug interactions of lipid-altering drugs.

The use of lipid-altering drugs has been shown to reduce the progression of atherosclerotic lesions and reduce the risk of atherosclerotic events (such as myocardial infarction and stroke). In general, these lipid-altering drugs are well tolerated but there is the potential for drug interactions. For example, HMG-CoA reductase inhibitors may interact with macrolides, azalides, azole antifungals and cyclosporin. Resins (such as cholestyramine and colestipol) may impair the absorption of many concurrent medications. Fibrates have potential drug interactions with warfarin, furosemide (frusemide), oral hypoglycaemics and probenecid. Nicotinic acid (niacin) may have potential drug interactions with high dose aspirin (acetylsalicylic acid), uricosuric agents (such as sulfapyrazone) and alcohol (ethanol). Finally, probucol may have potential drug interactions with antidysrhythmics, tricyclic antidepressants and phenothiazines. In addition, lipid-altering drugs, used in combination, may have the potential for drug interactions, enhancing some of the risks of adverse effects, such as myositis and hepatotoxicity. Therefore, in order to use lipid-altering drugs in the most effective, and safest manner, it is important for the clinician to have an understanding of the mechanisms of potential drug interactions, which drug interactions may theoretically occur, and specifically, which spe cific drug interactions have already been described.

Contraindications↗

Pravastatin: a review of its use in elderly patients.

UNLABELLED: Pravastatin (Pravachol) is a competitive, reversible HMG-CoA reductase inhibitor that lowers serum cholesterol levels by inhibiting de novo cholesterol synthesis and has antiatherogenic effects that appear to be partially independent of its lipid-lowering effects. Pravastatin 10-40 mg/day produced significant reductions (vs baseline or placebo) in serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels in elderly patients (aged >or=60 or >or= 65 years) with hypercholesterolaemia or normal cholesterol levels. Serum triglyceride and high-density lipoprotein cholesterol levels also improved in some studies, but not in others. Coadministration of cholestyramine, another lipid-lowering agent, further enhanced the lipid-lowering effects of pravastatin in elderly patients. Data from the large, long-term (3-6 years) PROspective Study Of Pravastatin in the Elderly at Risk (PROSPER), Cholesterol And Recurrent Events trial (CARE) and Long term Intervention with Pravastatin in Ischaemic Disease (LIPID) trials demonstrated that pravastatin 40 mg/day reduces coronary events in elderly patients with hypercholesterolaemia or normal cholesterol levels, with or at high risk of developing coronary heart disease (CHD). In these trials, the incidence of death from CHD or the combined endpoint of death from CHD or nonfatal myocardial infarction was significantly lower in pravastatin than in placebo recipients. Pravastatin is well tolerated in the elderly, and adverse effects considered related to therapy are minimal. The most commonly occurring adverse events included gastrointestinal events, renal or genital system events, respiratory disorders, headaches and musculoskeletal pain. CONCLUSION: Pravastatin effectively lowers serum TC and LDL-C levels and, as demonstrated in major clinical outcome trials, reduces coronary events in elderly patients with hypercholesterolaemia or normal cholesterol levels. Pravastatin is well tolerated and as such should be considered a first-line agents for primary or secondary prevention in older individuals with evident CHD or multiple risk factors for CHD.

Adult↗

Digitalis. An update of clinical pharmacokinetics, therapeutic monitoring techniques and treatment recommendations.

The intestinal absorption of digoxin is essentially a passive non-saturable diffusion process, although a saturable carrier-mediated component also plays an important role. The bioavailability varies between 40 and 100%: the presence of food may reduce the peak serum concentration, but does not reduce the amount of digoxin absorbed. Recent development of a capsule containing a hydroalcoholic vehicle may reduce interindividual variations in absorption. Pharmacokinetic analysis of the distribution of digoxin suggests 3 compartments, the slow distribution phase accounting for the lag time between the inotropic effects and the plasma concentration profile. Digoxin is extensively bound to tissues such as myocardium, renal, skeletal muscle as well as red blood cells, but not to adipose tissue. Plasma protein binding varies between 20 and 30%: displacement of digoxin from protein binding sites does not cause significant clinical effects. As expected, haemodialysis or exchange transfusions do not significantly alter the body load of digoxin. The apparent volume of distribution of digoxin varies between 5 and 7.3 L/kg; this may be reduced by, for example, electrolyte abnormalities which reduce digoxin binding to the myocardium. The elimination half-life of digoxin is 36 hours, with 60 to 80% being excreted unchanged, by passive glomerular filtration and active tubular secretion. The remainder is excreted non-renally. Clearance is therefore dependent on renal function and declines in renal disease and in elderly patients. Digoxin interacts with other drugs at any stage of absorption (e.g. cholestyramine), distribution (e.g. quinidine), metabolism (e.g. phenytoin) or elimination (e.g. diltiazem). Patients should, therefore, be carefully monitored when changing a therapeutic regimen which includes any drugs known to interact with digoxin. Clinical monitoring is more important than therapeutic drug monitoring which should be reserved for suspected toxicity, doubts about efficacy, or in cases of poor compliance. With the advent of newer treatment modalities, digoxin is no longer the treatment of first choice in supraventricular arrhythmias and congestive heart failure. However, with careful monitoring, digoxin remains an important therapeutic option.

Digitalis Glycosides↗

Pharmacokinetic interactions with digoxin.

Numerous pharmacological agents have been shown to produce clinically significant pharmacokinetic interactions with digoxin. Drugs which reduce digoxin absorption include the antacids aluminium hydroxide, magnesium hydroxide and magnesium trisilicate, the antidiarrhoeals kaolin and pectin, the hypocholesterolaemic agent cholestyramine and the chemotoxins cyclophosphamide, vincristine and bleomycin. Certain antibiotics including sulphasalazine, neomycin and aminosalicylic acid reduce digoxin absorption while others, including erythromycin and tetracycline, increase the bioavailability of digoxin in some patients. Capsule preparations of digoxin in solution are less subject to several of the interactions which affect the absorption and bioavailability of digoxin tablets. Various drugs induce alterations in the volume of distribution and clearance of digoxin. Cardiac patients receiving digoxin therapy are particularly prone to interactions with commonly co-administered medications such as the antiarrhythmics quinidine and amiodarone, the calcium channel blockers verapamil and nifedipine, and possibly some vasodilating agents. Studies of digoxin interactions have yielded discrepant results, indicating the need for careful analysis of investigational design before arriving at clinical conclusions.

Digoxin↗

Clinical pharmacokinetic considerations in the control of oral anticoagulant therapy.

Aspects of the pharmacokinetics of warfarin that are clinically relevant are reviewed here. Since warfarin is normally completely absorbed, resistance to treatment due to impaired absorption is unusual, even in severe short bowel syndrome. Warfarin is highly albumin-bound; thus, hypoalbuminaemic states result in an increased free fraction of the drug and a decreased half-life but, as might be expected, there is no evidence of altered response at steady-state. Warfarin is completely metabolised by the liver to hydroxy-warfarins and warfarin alcohols, and although the latter have some biological activity they do not contribute significantly to the drug effect. No information is available concerning the metabolism of warfarin in chronic liver disease, but there is evidence of increased sensitivity due to impaired vitamin K-dependent clotting factor synthesis. Impaired renal function does not appear to alter the effect of warfarin. Lowered response to the drug may be secondary to poor compliance, kinetic resistance or pharmacodynamic resistance. These factors can be identified using algorithms based on population values for plasma warfarin concentrations and clearances at steady-state. The pharmacokinetics and pharmacodynamics of warfarin indicate that several days' overlap with heparin on initiation of warfarin, and gradual (rather than sudden) discontinuation of warfarin, might theoretically be necessary. However, those studies which have been performed have indicated that a long overlap and gradual discontinuation are not associated with greater safety or efficacy of the drug. Because of the long elimination half-life of warfarin and the short elimination half-life of vitamin K, many days' treatment with phytomenadione may be required after warfarin overdose. The elimination half-life and therefore the duration of therapy may be reduced by regular oral cholestyramine, although the means by which the latter enhances warfarin elimination is still unknown.

Animals↗

Drug interactions involving aspirin (acetylsalicylic acid) and salicylic acid.

Aspirin (acetylsalicylic acid) is metabolically converted to salicyclic acid by the action of carboxylesterases. Although metabolic drug interactions involving aspirin are theoretically possible, there appear to have been no studies to date which have shown conclusively that aspirin hydrolysis is altered by coadministered drugs. However, a number of treatments are known to affect the rate or extent of aspirin absorption, including activated charcoal, antacids, cholestyramine and metoclopramide. Caffeine and metoprolol have been reported to increase peak salicylic acid concentration following aspirin administration, and coadministration of dipyridamole and aspirin results in higher plasma aspirin concentrations. The mechanism(s) responsible for these latter observations remains unknown. Salicylic acid is extensively bound to plasma albumin, and many of the reported drug interactions involve displacement of the coadministered drug from plasma protein. Protein binding displacement appears to be the basis of salicylic acid interactions with diclofenac, flurbiprofen, ibuprofen, isoxicam, ketoprofen, naproxen, phenytoin and tolmetin. Following displacement of these agents increased clearance of total drug occurs, and consequently the plasma concentration of total drug decreases. Although generally not measured, unbound concentration of the interacting drug should not be markedly altered. Salicylic acid also increases total plasma clearance of fenoprofen but, unlike the interactions with the other propionic acid non-steroidals, plasma protein binding displacement does not appear to be involved. Induction of fenoprofen metabolism is a possibility, although there is no firm evidence from other studies that salicylate is able to induce the metabolism of coadministered drugs. Since salicylic acid is extensively metabolised, it is not surprising that it is able to inhibit the metabolism of certain coadministered drugs and chemicals, an effect which has been reported for salicylamide, valproic acid, m-xylene, and zomepirac. The interactions with salicylamide, m-xylene and zomepirac are probably competitive in nature since mutual inhibition of salicylic acid metabolism occurs. There is an additional component of protein binding displacement in the interactions with valproic acid and zomepirac, resulting in increased unbound drug concentration. Certain coadministered drugs (or chemicals) may alter the metabolism of salicylic acid; inhibition of its metabolism has been demonstrated following treatment with benzoic acid, salicylamide, m-xylene, zomepirac and possibly cimetidine. In contrast, salicylic acid elimination is enhanced in oral contraceptive steroid users and by corticosteroid treatment. Oral contraceptive steroids induce both salicylic acid glucuronidation and salicylurate formation. Induction of metabolism has also been proposed to account for the effects of corticosteroids, but this is still to be proven.(ABSTRACT TRUNCATED AT 400 WORDS)

Antacids↗

Pharmacokinetic drug interactions with nonsteroidal anti-inflammatory drugs.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs. Drug interactions with this class of compounds are frequently reported and can be pharmacokinetic and/or pharmacodynamic in nature. The pharmacokinetic interactions can be divided into 3 classes: (1) drugs affecting the pharmacokinetics of an NSAID. (2) an NSAID interfering with the pharmacokinetics of another NSAID and (3) NSAIDs altering the pharmacokinetics of another drug. Although the pharmacokinetics of some NSAIDs may be significantly affected by the concurrent administration of certain other drugs (including other NSAIDs), this type of interaction only occasionally leads to serious complications. Concurrent administration of antacids or sucralfate may delay the rate of oral absorption of NSAIDs but generally has little effect on the extent. Use of antacids increases urinary pH, leading to increased renal excretion of unchanged salicylic acid and decreased plasma concentrations of this antirheumatic agent. The H2-receptor blocking agent cimetidine inhibits the oxidative metabolism of many concurrently administered drugs, including certain NSAIDs. Probenecid inhibits the renal secretion of drug glucuronides and this will lead to accumulation in plasma of those NSAIDs eliminated primarily by the formation of labile acyl glucuronides such as naproxen, ketoprofen, indomethacin, carprofen. Cholestyramine decreases the oral absorption of many concurrently administered drugs, including NSAIDs. It may also decrease plasma concentrations of those NSAIDs undergoing enterohepatic circulation (e.g. piroxicam, tenoxicam) by interrupting the enterohepatic cycle. Corticosteroids stimulate the clearance of salicylic acid, leading to low plasma salicylate concentrations. Plasma concentrations of many NSAIDs are significantly reduced when the NSAID is coadministered with aspirin. The clinical relevance of most of these interactions is not well established. However, in those cases where the interaction results in elevated plasma concentrations of the NSAID, special caution should be exercised to avoid excessive accumulation of the NSAID especially in elderly and/or very sick patients who may be more sensitive to the more serious gastroduodenal and renal side-effects of these agents. By virtue of their pharmacokinetic and pharmacodynamic properties, NSAIDs may significantly affect the disposition kinetics of a number of other drugs. They can displace other drugs from their plasma protein binding sites, inhibit their metabolism or interfere with their renal excretion. If the affected drug has a narrow therapeutic index, the interaction may be clinically significant. The pyrazole NSAIDs (phenylbutazone, oxyphenbutazone, azapropazone) inhibit the metabolism of many drugs such as the coumarin anticoagulants, oral antidiabetics and anticonvulsants such as phenytoin. Salicylates displace oral anticoagulants from their plasma protein binding sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Inflammatory Agents, Non-Steroidal↗

Clinical pharmacokinetics of sulindac. A dynamic old drug.

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) of the indene acetic acid class. The absorption of sulindac is rapid when given orally. Sulindac is reversibly metabolised to sulindac sulphide which has anti-inflammatory and analgesic properties and is irreversibly metabolised to sulindac sulphone which has been suggested to possess antiproliferative effects against tumours. Sulindac and its sulphide and sulphone metabolites bind extensively to plasma albumin. Sulindac is eliminated following bio-transformation; sulindac and sulindac sulphone and their respective glucurooconjugated metabolites are excreted in urine; however only a small amount of the sulindac sulphide metabolite is eliminated in urine. Following long term twice daily administration both sulindac and its metabolites accumulate in plasma. Both patients with cirrhosis and the elderly demonstrate elevated concentrations of all species upon long term sulindac administration as compared with a single dose. The disposition of sulindac and its metabolites may be tied to renal function. In end-stage renal disease, increased free fractions of all species and accumulation of the sulphide and sulphone metabolites, and to a lesser extent sulindac, occurs. Significant drug interactions have been demonstrated for dimethylsulphoxide, cyclosporin, furosemide (frusemide), hydrochlorothiazide, methotrexate and cholestyramine.

Absorption↗

Clinical pharmacokinetics of diclofenac. Therapeutic insights and pitfalls.

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid class. When given orally the absorption of diclofenac is rapid and complete. Diclofenac binds extensively to plasma albumin. The area under the plasma concentration-time curve (AUC) of diclofenac is proportional to the dose for oral doses between 25 to 150 mg. Substantial concentrations of drug are attained in synovial fluid, which is the proposed site of action for NSAIDs. Concentration-effect relationships have been established for total bound, unbound and synovial fluid diclofenac concentrations. Diclofenac is eliminated following biotransformation to glucoroconjugated and sulphate metabolites which are excreted in urine, very little drug is eliminated unchanged. The excretion of conjugates may be related to renal function. Conjugate accumulation occurs in end-stage renal disease; however, no accumulation is apparent upon comparison of young and elderly individuals. Dosage adjustments for the elderly, children or for patients with various disease states (such as hepatic disease or rheumatoid arthritis) may not be required. Significant drug interactions have been demonstrated for aspirin (acetylsalicylic acid), lithium, digoxin, methotrexate, cyclosporin, cholestyramine and colestipol.

Administration, Oral↗

Clinical pharmacokinetics of ibuprofen. The first 30 years.

Ibuprofen is a chiral nonsteroidal anti-inflammatory drug (NSAID) of the 2 arylpropionic acid (2-APA) class. A common structural feature of 2-APANSAIDs is a sp3-hybridised tetrahedral chiral carbon atom within the propionic acid side chain moiety with the S-(+)-enantiomer possessing most of the beneficial anti-inflammatory activity. Ibuprofen demonstrates marked stereoselectivity in its pharmacokinetics. Substantial unidirectional inversion of the R-(-) to the S-(+) enantiomer occurs and thus, data generated using nonstereospecific assays may not be extrapolated to explain the disposition of the individual enantiomers. The absorption of ibuprofen is rapid and complete when given orally. The area under the plasma concentration-time curve (AUC) of ibuprofen is dose-dependent. Ibuprofen binds extensively, in a concentration-dependent manner, to plasma albumin. At doses greater than 600mg there is an increase in the unbound fraction of the drug, leading to an increased clearance of ibuprofen and a reduced AUC of the total drug. Substantial concentrations of ibuprofen are attained in synovial fluid, which is a proposed site of action for nonsteroidal anti-inflammatory drugs. Ibuprofen is eliminated following biotransformation to glucuronide conjugate metabolites that are excreted in urine, with little of the drug being eliminated unchanged. The excretion of conjugates may be tied to renal function and the accumulation of conjugates occurs in end-stage renal disease. Hepatic disease and cystic fibrosis can alter the disposition kinetics of ibuprofen. Ibuprofen is not excreted in substantial concentrations into breast milk. Significant drug interactions have been demonstrated for aspirin (acetylsalicylic acid), cholestyramine and methotrexate. A relationship between ibuprofen plasma concentrations and analgesic and antipyretic effects has been elucidated.

Animals↗

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