Effects of nonsteroidal anti-inflammatory drugs on prostaglandins and renal function

Role of glomerular prostanoid in control of glomerular filtration rate in rats

It is generally accepted that the main action of glomerular prostanoids (GPs) on glomerular filtration rate (GFR) is to modulate the activity of different vasoconstrictors, specially in states of renal hypoperfusion. However it was also suggested that GPs may directly affect GFR. The present study was focused on this last hypothesis, in different experimental models, in rats. In adriamycin induced acute renal failure, the transient decrease of GFR is associated with higher levels of thromboxane B2. Later on, when GFR returns to normal, vasodilator prostaglandins synthesis was also increased. In captopril induced renal failure in Na depleted rats (where GPs synthesis remained normal), stimulation of PGE2 and PGI2 production by K and NaCl was associated with a significant improvement of GFR. Furthermore, the increase in GFR induced by NaCl was prevented by inhibition of prostaglandin synthesis. Infusion of atrial natriuretic peptide in euvolemic rats induce a marked elevation both of GFR and PGE2 synthesis. It was abolished by previous administration of prostaglandin synthesis inhibitor. In conclusion, glomerular prostanoids may influence GFR, either directly, or as mediator or modulator of other vasoactive hormones.

The basis for variability of response to anti-rheumatic drugs

The reasons for variability of response to anti-rheumatic drugs are myriad. All the factors that contribute to kinetic variability, for example, contribute to differences in response between individuals. Thus, differences in drug formulation, protein binding, drug metabolism and excretion, all contribute to variable responses. Further, factors which contribute to differential clinical response/toxicity must be considered. Here, age, gender, genetic background, weight, concomitant diseases and numerous environmental factors come into play. Among the environmental factors are such diverse elements as smoking, activity and diet. Finally our ability to measure change, be it in response or toxicity, is limited, introducing apparent variability (as much as real variability) into the equation. While we cannot, at present, delineate the contribution of each factor to individual variability, it is hoped that systematic, persistent effort will help us understand and then control these elements, leading to improved ability to individualize therapy and decrease the variability of response to anti-rheumatic drugs.

Side-effects of non-steroidal anti-inflammatory drugs

Despite a continuing lack of good quality epidemiological studies, our knowledge of the side-effects of NSAIDs has advanced in recent years. The most important reactions are those which are related predictably to the pharmacology of the drugs and these need to be considered whenever a NSAID is prescribed, particularly for patients who can be identified as belonging to high-risk groups. The important reactions are: 1. Gastrointestinal damage, which is now known to extend to some degree from the oesophagus to the rectum, although the acid contact areas of the stomach and duodenum are the most important. Although the studies have produced heterogeneous results, NSAIDs probably double or triple the risk of an individual developing serious gastrointestinal haemorrhage or perforation. The risk increases with age and previous history of ulceration, and, in communities with particularly high use of NSAIDs, the drugs may account for up to 30% of all cases of ulcer complications. 2. Renal syndromes, of which functional renal impairment is the most important. This may precipitate cardiac failure, and hyperkalaemia is an additional hazard. Antagonism of the action of diuretics may contribute to the fluid retention, and antagonism of antihypertensive therapy is probably quite common and may result in additional unnecessary therapy. Patients at risk of functional renal impairment from NSAIDs can be identified readily and in these subjects the drugs have to be used with great care and with appropriate monitoring. 3. Respiratory effects, in particular acute bronchospasm in subjects with a history of aspirin sensitivity. NSAIDs should be used with caution in asthmatics, and patients purchasing NSAIDs without prescriptions need to be warned of these effects. Other uncommon serious reactions include hepatocellular damage, acute interstitial nephritis, agranulocytosis and aplastic anaemia, Stevens-Johnson syndrome and toxic epidermal necrolysis. These are unpredictable reactions which generally need not be considered before prescribing. However, in patients who present with any of these conditions, NSAIDs, because of their wide use, should always be considered as a possible cause.

Clinical aspects of renal prostaglandins and NSAID therapy

Nonsteroidal antiinflammatory drugs (NSAIDs) can have a variety of effects on renal function. Excluding allergic phenomena, these are directly related to NSAID-induced inhibition of renal synthesis of prostaglandins (PGs). For the most part, renal PGs play important physiological roles only in certain pathologic conditions. Thus, patients without these diseases (such as cardiac, hepatic, or renal compromise) manifest no or only trivial effects on renal function when NSAIDs are administered. This feature is to the advantage of the clinician because it allows prospective identification of patients who are at risk for an adverse renal effect; hence, such effects can be minimized or avoided altogether. To do so requires an understanding of the various roles of PGs in the kidney and thereby the effects that one can observe from NSAIDs. This review focuses on these various roles of renal PGs and on identification of patient groups at risk for adverse renal effects of NSAIDs.

A multicenter study of the safety and efficacy of naproxen: analysis of blood pressure

A multicenter study was conducted to determine safety and efficacy of naproxen, 500 mg twice daily, administered for 4 weeks to osteoarthritis (OA) patients. OA symptoms improved in the study population. The study population included 97 patients, 43 of whom were 65 years of age or older. Forty-four of the 97 patients had a history of hypertension; 42 of these took antihypertensive medication before and during the study. Baseline blood pressure (BP) was measured in most patients while they were receiving their prior nonsteroidal antiinflammatory drug (NSAID) therapy; from that baseline, no increase in BP was seen in the hypertensive or normotensive patients after 4 weeks of naproxen therapy. In patients whose BP was controlled by antihypertensive agents, BP remained under control during naproxen therapy.

Hepatic and renal tolerability of long-term naproxen treatment in patients with rheumatoid arthritis

Clinical and laboratory assessments of hepatic and renal function in rheumatoid arthritis (RA) patients who received naproxen for up to 6 months during two randomized, double-blind studies comparing naproxen 375 mg twice daily (n = 286) with naproxen 750 mg twice daily (n = 300) were analyzed. Patient groups were segregated by dosage, duration of treatment, and age at entry (less than 65 years v greater than or equal to 65 years), and laboratory measurements of SGOT, SGPT, serum creatinine (Scr), and BUN were examined. Records of individual patients with clinically meaningful abnormalities in laboratory tests or adverse events of hepatic or renal origin were examined in detail. Over the duration of these studies, there were no clinically meaningful changes in mean laboratory values or differences in occurrences of abnormal values among the different patient groups. In both dosage groups, pretreatment incidences of clinically meaningful abnormalities in laboratory tests were similar to those in serial observations during treatment. Six patients who received naproxen 375 mg twice daily and four patients who received naproxen 750 mg twice daily had a hepatic or renal clinical event or distinctly abnormal laboratory value, but only three of these withdrew because of these problems. Occasional transient abnormalities of conventional laboratory tests of hepatic and renal function occurred in some patients during naproxen treatment. Such abnormalities called for careful patient monitoring but generally did not warrant immediate drug withdrawal.

Kidney function during naproxen therapy in patients at risk for renal insufficiency

The effects of naproxen on renal function in 34 patients with minimally elevated serum creatinine (Scr) or subnormal creatinine clearance (Ccr) were evaluated in a parallel-design study. All patients received open-label naproxen 375 mg twice daily for 2 weeks (phase I); patients were then randomly assigned to receive naproxen 750 mg twice daily (n = 26) or to continue naproxen 375 mg twice daily (n = 8) double-blind for an additional 2 weeks (phase II). Renal function was assessed by Scr, Ccr, and BUN measurements at baseline and at the end of each treatment phase. Neither treatment group had a clinically meaningful change in median laboratory values between baseline and the end of phase I, or between baseline and the end of phase II. During the first 2 weeks of treatment with naproxen 375 mg twice daily, there was no change in Scr. At the time of the first Scr measurement following the increase in naproxen dose to 750 mg twice daily, 13 of 26 patients had Scr levels of 1.1 mg/dL or higher, but four days later, only three patients had Scr levels of 1.1 mg/dL or higher, suggesting that a transient increase in Scr may accompany dosage increase. Chronic administration of naproxen 375 mg twice daily in patients at risk for renal insufficiency based on laboratory evidence of renal impairment was not associated with further deterioration in renal function. An increase in dosage to 750 mg twice daily in such patients appeared to be associated with only small, transient changes in laboratory measures of renal function.

Nonsteroidal antiinflammatory drug-induced renal dysfunction related to inhibition of renal prostaglandins

This article reviews the role of prostaglandins (PG) in maintaining renal function in the face of vasoconstrictive substances and decreased renal blood flow. Inhibition of the synthesis of renal PG by nonsteroidal antiinflammatory drugs (NSAID) may lead to the development of hemodynamically induced renal dysfunction in patients with a decreased effective plasma volume or chronic renal insufficiency. The importance of stimulation of renal PG activity to the action of diuretics and a pharmacodynamic mechanism for NSAID-induced diuretic resistance are presented. Evidence for the relative selectivity of sulindac in inhibiting systemic PG without inhibiting renal PG is also reviewed. Inhibition of renal PG synthesis has been postulated to be a contributing factor for other forms of NSAID-induced renal dysfunction (interstitial nephritis, analgesic-associated nephropathy). The relationship between renal PG inhibition by NSAID and these syndromes is briefly discussed. Considering the frequent use of NSAID, it is important that practitioners are aware of the mechanisms whereby patients may develop NSAID-induced renal dysfunction and that they are able to identify patients at risk.

Aspirin, paracetamol and non-steroidal anti-inflammatory drugs. A comparative review of side effects

Non-steroidal anti-inflammatory drugs (NSAIDs) effectively control the symptoms of many of the rheumatic diseases although they have little effect on the underlying causes. Their effect is mainly on the mediators of the inflammatory process. Unfortunately, these mediators have important physiological roles in the maintenance of health, particularly in the gastrointestinal tract and the kidney, so that their inhibition results in many unwanted reactions of varying severity. The mechanisms underlying these reactions are described. Their occurrence varies, both qualitatively and quantitatively, and an attempt is made to assess these differences, although it may be that they are related directly to differences in dosage and therapeutic efficacy. In addition, immunologically mediated adverse reactions occur. These mechanisms are outlined and related to the clinical picture. There are considerable differences in frequency of reactions between the compounds: in particular there is a wide variation in the rate of dermatological reactions of this type. Agranulocytosis has been particularly associated with the pyrazolone compounds, although it has been reported with most others. Aplastic anaemia, which may not be an immune-mediated reaction, is also thought of as a pyrazolone reaction, but the incidence with indomethacin approaches a similar level. Although all drugs analysed may cause hepatic reactions, these are rare except with the now withdrawn benoxaprofen. Several types of immunologically mediated renal reactions occur and these rarities are also described. Paracetamol does not have any effect on the inflammatory mediators. Anxieties about this substance relates to the parent compound phenacetin and its necrotic effect on the renal papillae. There is extensive literature on this subject concerning not only paracetamol, but also aspirin and other NSAIDs. This is also assessed and summarised. The danger of paracetamol as a direct hepatic toxin in self-poisoning is discussed. Novel NSAIDs are introduced and others withdrawn with frequent and monotonous regularity. Sometimes the reasons have some medical or scientific plausibility, but often they are over-reactions by registration authorities or pharmaceutical companies in response to uninformed media publicity. The problems of the numerically and scientifically accurate collection and assessment of adverse reaction data are legion and as a result useful agents have been lost. Some of these difficulties are described, and some non-drug 'adverse reactions' are described.(ABSTRACT TRUNCATED AT 400 WORDS)

Renal involvement in juvenile chronic arthritis: clinical and pathologic features

Over an 18-year period, renal involvement was diagnosed in 13 patients, who represent 1% of the total juvenile chronic arthritis population referred to us. All had severe arthritis. This study illustrates the importance of renal biopsy and indicates that renal involvement in juvenile chronic arthritis is a heterogeneous group of diseases, with a variety of causes. In eight patients with nephrotic syndrome, renal biopsy revealed amyloidosis. One rapidly died of diffuse amyloidosis and infection. The other seven received chlorambucil. Disappearance of proteinuria was noted in three of them. Four patients have persistent proteinuria but normal serum creatinine. It is suggested that, despite the long-term oncogenic risk of the drug, chlorambucil may be beneficial in patients with amyloid deposits. In one patient, the nephrotic syndrome was attributed to systemic lupus erythematosus, and in another, the chance association of an arthritis and nephrotic syndrome with minimal glomerular changes was considered. Although drug responsibility is difficult to determine in these patients receiving several medications in association, the renal involvement presented by the remaining three patients was probably related to drug(s). Moreover, it is possible that the effect of the association of medications is deleterious to the kidney. Drug-induced nephropathy is usually reversible when drugs are stopped. Unfortunately, because of persistent joint pain, these patients will continue to require pain-relieving drugs over prolonged periods.

Analgesic-associated nephropathy

Although the question of whether or not analgesic abuse leads to a certain type of nephropathy has been investigated since 1953, no conclusive answer has been forthcoming. Epidemiologic investigations on the correlation between analgesic abuse and renal function as well as experimental animal studies have given contradictory results concerning the possibility of analgesic-associated kidney damage. However, studies on the correlation between analgesic abuse and papillary necrosis have demonstrated that this lesion coincides in 69% of the cases with an analgesic history. Follow-up studies of patients with analgesic nephropathy have shown that renal function deteriorates in 60% of the patients with continued abuse and that it stabilizes in 80% of the patients after cessation of abuse. Studies on the legislative restriction of phenacetin/acetaminophen, carried out mostly in Scandinavian countries since 1965, show a 50%-90% decline in signs of analgesic nephropathy (papillary necrosis) following a reduction in the sale of these drugs. The prevalence of analgesic abuse may be underestimated, since up to 80% of the abusers tend to deny their analgesic intake. Obviously, only a small percentage of analgesic abusers (approximately 1%) finally develop nephropathy. Even though the results of epidemiologic and experimental studies are contradictory, the results of investigations on papillary necrosis and on legislative prevention as well as of patient follow-ups tend to indicate a correlation between analgesic abuse and a well-defined type of nephropathy.

The effects of naproxen and sulindac on renal function and their interaction with hydrochlorothiazide and piretanide in man

We have studied the effect of a single dose challenge of naproxen (500 mg) and sulindac (200 mg) on renal function in five volunteers, and the effect of a single dose challenge of the thiazide, hydrochlorothiazide (100 mg), and loop diuretic, piretanide (6 mg) on renal function when the diuretics were given alone or when superimposed on chronic therapy of either naproxen or sulindac. None of the nonsteroidal anti-inflammatory drug (NSAID) or diuretic exposures significantly influenced glomerular filtration rate, as measured by creatinine clearance. Over the first 4 h of the study, both naproxen and sulindac reduced fractional excretion of sodium by approximately 50%. Sulindac also caused a significant uricosuria whilst naproxen promoted urate retention. Similar changes were observed over 8 h. Superimposition of either hydrochlorothiazide or piretanide on top of chronic sulindac therapy resulted in a blunting of the natriuresis by approximately 30% compared to when these diuretics were given alone: the action of the diuretics was unchanged by naproxen. Sulindac pretreatment did not alter the urinary excretion of either hydrochlorothiazide or piretanide; naproxen did not alter hydrochlorothiazide excretion. On the basis of these findings, it is concluded that NSAIDs exert direct tubular effects that do not necessarily interfere with the delivery of diuretics to their sites of action within the nephron.

Renal side effects of nonsteroidal antiinflammatory drugs: clinical relevance

Nonsteroidal antiinflammatory drugs (NSAIDs) induce a variety of renal side effects. We review their prevalence and clinical relevance, and identify the patients who are most at risk for these complications. NSAIDs induce hemodynamic renal failure in states of compromised renal perfusion and in the presence of a preexisting nephropathy. Association of triamterene and indomethacin is especially nephrotoxic and should be avoided. NSAIDs cause sodium retention and impair the natriuretic effect of diuretics: this side effect is clinically relevant in edema-forming states. Hyperkalemia induced by NSAIDs is harmful in case of renal failure and hypoaldosteronism. NSAIDs may induce an acute interstitial nephritis often associated with the nephrotic syndrome; the event is rare and unpredictable, and mainly propionic acid derivatives have been incriminated. NSAIDs are reported to attenuate the hypotensive effect of various drugs; further studies are warranted to better delineate the clinical relevance of this observation.

Benefits and risks of nonsteroidal antiinflammatory drugs in steroid-resistant nephrotic syndrome

In this paper we discuss the effects of nonsteroidal antiinflammatory drugs on proteinuria and the specific risks of these drugs in patients with nephrotic syndrome. We summarize the results of a prospective uncontrolled trial of meclofenamate in severe steroid-resistant nephrotic syndrome secondary to focal glomerular sclerosis and idiopathic membranous nephropathy. This study examined the effect of meclofenamate on proteinuria, serum albumin levels, serum cholesterol, serum triglycerides, renal function, BP, liver function tests, and hematologic values. We also sought and evaluated adverse reactions due to this medication. We offer some suggestions for selective use and careful supervision of NSAIDs in the nephrotic syndrome.

Effects of 1 gram oral or intravenous aspirin on urinary excretion of thromboxane B2 and 6-keto-PGF1 alpha in healthy subjects

Aspirin inhibits cyclo-oxygenase, thus preventing prostanoids formation. After oral administration aspirin is hydrolysed to inactive salicylate partly within the gastrointestinal tract, partly during first pass in the liver, partly in the circulation by plasma esterases. Intravenous aspirin, in contrast, mainly undergoes plasma esterase-catalysed deacetylation. Six healthy male subjects were given 1 g aspirin orally and intravenously two weeks apart according to a cross-over randomized design. Whereas serum TxB2 generation reflecting platelet cyclo-oxygenase activity was suppressed by aspirin by both routes, urinary excretion of TxB2 and 6-keto-PGF1 alpha was not affected by oral aspirin, but was partially though significantly reduced by the i.v. drug. Drug disposition seems therefore to be essential in determining the "biochemical selectivity" of aspirin as related to platelet and renal prostanoids generation.

Acute effects of clometacin on renal prostaglandin biosynthesis in healthy subjects

In 6 healthy subjects the effect of clometacin on renal function, sodium and water excretion, plasma renin activity and urinary excretion of prostaglandins has been studied. After four days of treatment with clometacin, the excretion of urinary prostaglandins E2, F2 alpha and 6 keto F1 alpha and thromboxane B2 were reduced by 61.2, 41.2, 59 and 42%, respectively. 62% reduction in plasma renin activity was also observed. There was no significant change in mean blood pressure, heart rate, body weight, creatinine clearance or urinary excretion of sodium. It is concluded that clometacin is an efficient cyclooxygenase inhibitor in healthy individuals with a normal sodium intake, and that caution is required when giving clometacin to patients at risk of developing renal failure during treatment with a cyclooxygenase inhibitor.

Effect of non-steroidal anti-inflammatory drugs on control of hypertension by beta-blockers and diuretics

The effect of sulindac on renal function and blood pressure was compared with those of placebo, piroxicam, and naproxen in 20 patients with primary hypertension being treated with a diuretic and a beta-blocker. Although the three non-steroidal anti-inflammatory drugs (NSAIDs) did not differ in their effect on renal function (weight, glomerular filtration rate, creatinine clearance) or on serum thromboxane and plasma 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha), blood pressure was significantly lower with sulindac than with placebo, piroxicam, or naproxen. These differences were associated with less renal cyclooxygenase inhibition by sulindac (reflected by urinary thromboxane B2 and 6-keto PGF1 alpha) than by other NSAIDs. The findings suggest that the blood pressure differences reflect vasodilation due to differences in the balance between systemic and renal effects of the NSAIDs.

Implications of nonsteroidal anti-inflammatory drug therapy

This panel considered the clinical implications of nephrotoxicity due to nonsteroidal anti-inflammatory drugs. Although the clinical benefits and safety of these agents are well established, the drugs may adversely affect renal perfusion, electrolyte balance, and blood pressure in susceptible patients. The renal effects of these agents are directly related to their potency in inhibiting renal prostaglandins as reflected by inhibition of urinary prostaglandin excretion; however, none of the nonsteroidal anti-inflammatory drugs is completely free of the risk. Hyperkalemia is the most frequently observed adverse effect, most commonly occurring in patients with diabetes mellitus, patients with mild to moderate renal insufficiency, and patients receiving beta blockers, angiotensin converting enzyme inhibitors, or potassium-sparing agents. Patients at risk for the development of fluid retention and acute reductions in glomerular filtration rate include those with congestive heart failure, systemic lupus erythematosus, chronic glomerulonephritis, or liver failure with ascites, those receiving diuretics, premature infants, and possibly the elderly. Monitoring of serum creatinine and electrolyte levels, blood pressure, and body weight is suggested for susceptible patients receiving these agents.

Non-steroidal anti-inflammatory drugs and renal failure

In 3 years seventeen patients presented to one unit with renal failure associated with the use of non-steroidal anti-inflammatory drugs (NSAID). Seven patients presented with acute renal failure, in four due to acute tubular necrosis and in three to acute interstitial nephritis; all recovered when NSAID treatment was stopped. Four patients presented with symptomless renal impairment discovered during routine follow-up in a rheumatology clinic; again all improved on withdrawal of NSAID. The remaining six patients presented with chronic renal failure, a disorder not previously associated with NSAID treatment. The pattern of renal disease associated with NSAID may be more extensive than has previously been recognised. A history of NSAID use should be sought in all patients presenting with unexplained renal failure.

The arthritic patient with hypertension: selection of an NSAID

Vasodilator prostaglandins produced in the renal medulla have a role in blood pressure regulation, beyond modulation of sodium and water retention. Systemic vasodilation resulting from effects of renomedullary prostaglandins lowers systemic vascular resistance, and administration of NSAIDs elevates blood pressure in hypertensive patients treated with diuretics and/or beta blockers, in patients with myocardial infarction, and in patients taking sympathomimetic agents such as phenylpropanolamine. Aspirin, which appears in the urine as salicylic acid (which has no effect on cyclooxygenase) has not been implicated as a drug which attenuates blood pressure control. Similarly, sulindac, the active sulfide metabolite of which is not filtered, does not inhibit renal synthesis of prostaglandins, though given in doses sufficient to inhibit serum thromboxane and 6-keto PGF 1-alpha. In a double-blind complete crossover study of blood pressure and renal function in hypertensive patients controlled with timolol-hydrochlorothiazide, sulindac lowered blood pressure significantly, whereas naproxen and piroxicam significantly raised blood pressure, in the absence of any effect on GFR, plasma renin, weight, creatinine clearance, or urinary sodium. It is suggested that for arthritic patients with hypertension, the NSAIDs of choice are aspirin and sulindac.