Analgesic nephropathy: a reassessment of the role of phenacetin and other analgesics

Common Analgesic Agents and Their Roles in Analgesic Nephropathy: A Commentary on the Evidence

An association between non-opioid analgesic agents and chronic kidney disease has long been suspected. The presumed development of chronic renal impairment following protracted and excessive use of non-opioid analgesia is known as analgesic nephropathy. Many clinicians accept analgesic nephropathy as a real entity despite the paucity of scientific evidence. This narrative review aims to summarize the literature in the field. The weight of available observational literature suggests that long-term ingestion of paracetamol and combination mixtures of aspirin and paracetamol are likely to contribute to chronic renal impairment. However, there is no convincing data to implicate non-steroidal anti-inflammatory drugs or aspirin monotherapy in the development of analgesic nephropathy. In the absence of high-level evidence, while controversy persists, it may be prudent for physicians to consider all non-narcotic analgesics to be nephrotoxic with long-term use.

Paracetamol: a focus for the general pediatrician

Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever in children. This drug has multiple mechanisms of action, but its pharmacodynamic is still not well known. The central nervous system is the main site of action and it mirrors the paracetamol effect compartment. The recommended dosages and routes of administration should be different whether paracetamol is used for the treatment of pain or fever. For example, the rectal route, while being efficacious for the treatment of fever, should be avoided in pain management. Paracetamol is a safe drug, but some clinical conditions and concomitant drugs, which are frequent in clinical practice, may increase the risk of paracetamol toxicity. Therefore, it is important to optimize its administration to avoid overdoses and maximize its effect. The principal mediator of the paracetamol toxicity is the N-acetyl-p-benzo-quinone imine (NAPQI), a toxic product of the paracetamol metabolism, which could bind cysteine groups on proteins forming paracetamol-protein adduct in the liver.

CONCLUSION

Although frequently prescribed, the concept of "effect compartment concentration" and the possible co-factors that could cause toxicity at recommended doses are not familiar to all pediatricians and general practitioners. We reviewed the literature concerning paracetamol mechanisms of action, we highlighted some relevant pharmacodynamic concepts for clinical practice, and we summarized the possible risk factors for toxicity at therapeutic dosages.

Over-the-counter analgesic use

Chronic analgesic nephropathy, particularly chronic interstitial nephritis and renal papillary necrosis, results from daily use for many years of mixtures containing at least two analgesics and caffeine or dependence-inducing drugs. Computed tomography scan can accurately diagnose this disease even in the absence of reliable information on previous analgesic use. The occasion to moderate regular use of aspirin and nonsteroidal anti-inflammatory drugs is without renal risk when renal function is normal. Paracetamol use is less clear although the risk is not great. The continued use of non-phenacetin-combined analgesics with or without nonsteroidal anti-inflammatory drugs is associated with faster progression toward renal impairment. As long as high-risk analgesic mixtures are available over the counter, analgesic nephropathy will continue to be a problem.

Changes of panorama in renal disease mortality in Finland after phenacetin restriction

The purpose of the present study was to examine the effect of phenacetin consumption and its restriction on the mortality from nephropathy. Changes in this mortality in Finland during 1951-77 were investigated. The second part of the study was concerned with the frequency of papillary necrosis in cases autopsied in the Department of Medicine, Turku University Central Hospital, during 1952-79. These figures were studied in relation to increased phenacetin consumption after World War II, its restriction in 1962 and its complete banning in 1965. Both the epidemiologic survey of the mortality from nephropathy in Finland and the autopsies showed a clear and strong correlation both with increased phenacetin consumption and with its discontinuation. The banning of phenacetin led within 2-4 years to a decline in the mortality from nephropathy to its pre-phenacetin level.

Glucuronidation of fenamates: Kinetic studies using human kidney cortical microsomes and recombinant UDP-glucuronosyltransferase (UGT) 1A9 and 2B7

Mefenamic acid, a non-steroidal anti-inflammatory drug (NSAID), is used commonly to treat menorrhagia. This study investigated the glucuronidation kinetics of flufenamic, mefenamic and niflumic acid using human kidney cortical microsomes (HKCM) and recombinant UGT1A9 and UGT2B7. Using HKCM Michaelis-Menten (MM) kinetics were observed for mefenamic (K(m)(app) 23 microM) and niflumic acid (K(m)(app) 123 microM) glucuronidation, while flufenamic acid exhibited non-hyperbolic (atypical) glucuronidation kinetics. Notably, the intrinsic renal clearance of mefenamic acid (CL(int) 17+/-5.5 microL/minmg protein) was fifteen fold higher than that of niflumic acid (CL(int) 1.1+/-0.8 microL/minmg protein). These data suggest that renal glucuronidation of mefenamic acid may result in high intrarenal exposure to mefenamic acyl-glucuronide and subsequent binding to renal proteins. Diverse kinetics were observed for fenamate glucuronidation by UGT2B7 and UGT1A9. Using UGT2B7 MM kinetics were observed for flufenamic (K(m)(app) 48 microM) and niflumic acid (K(m)(app) 135 microM) glucuronidation and atypical kinetics with mefenamic acid. Similarity in K(m)(app) between HKCM and UGT2B7 suggests that UGT2B7 may be the predominant renal UGT isoform catalysing niflumic acid glucuronidation. In contrast, UGT1A9 glucuronidation kinetics were characterised by negative cooperativity with mefenamic (S(50) 449 microM, h 0.4) and niflumic acid (S(50) 7344 microM, h 0.4) while atypical kinetics were observed with flufenamic acid. Additionally, potent inhibition of the renal glucuronidation of the UGT substrate 'probe' 4-methylumbelliferone by flufenamic, mefenamic and niflumic acid was observed. These data suggest that inhibitory metabolic interactions may occur between fenamates and other substrates metabolised by UGT2B7 and UGT1A9 in human kidney.

Paracetamol: new vistas of an old drug

Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever. It occupies a unique position among analgesic drugs. Unlike NSAIDs it is almost unanimously considered to have no antiinflammatory activity and does not produce gastrointestinal damage or untoward cardiorenal effects. Unlike opiates it is almost ineffective in intense pain and has no depressant effect on respiration. Although paracetamol has been used clinically for more than a century, its mode of action has been a mystery until about one year ago, when two independent groups (Zygmunt and colleagues and Bertolini and colleagues) produced experimental data unequivocally demonstrating that the analgesic effect of paracetamol is due to the indirect activation of cannabinoid CB(1) receptors. In brain and spinal cord, paracetamol, following deacetylation to its primary amine (p-aminophenol), is conjugated with arachidonic acid to form N-arachidonoylphenolamine, a compound already known (AM404) as an endogenous cannabinoid. The involved enzyme is fatty acid amide hydrolase. N-arachidonoylphenolamine is an agonist at TRPV1 receptors and an inhibitor of cellular anandamide uptake, which leads to increased levels of endogenous cannabinoids; moreover, it inhibits cyclooxygenases in the brain, albeit at concentrations that are probably not attainable with analgesic doses of paracetamol. CB(1) receptor antagonist, at a dose level that completely prevents the analgesic activity of a selective CB(1) receptor agonist, completely prevents the analgesic activity of paracetamol. Thus, paracetamol acts as a pro-drug, the active one being a cannabinoid. These findings finally explain the mechanism of action of paracetamol and the peculiarity of its effects, including the behavioral ones. Curiously, just when the first CB(1) agonists are being introduced for pain treatment, it comes out that an indirect cannabino-mimetic had been extensively used (and sometimes overused) for more than a century.

Case-control study of regular analgesic and nonsteroidal anti-inflammatory use and end-stage renal disease

BACKGROUND

Studies on the association between the long-term use of aspirin and other analgesic and nonsteroidal anti-inflammatory drugs (NSAIDs) and end-stage renal disease (ESRD) have given conflicting results. In order to examine this association, a case-control study with incident cases of ESRD was carried out.

METHODS

The cases were all patients entering the local dialysis program because of ESRD in the study area between June 1, 1995 and November 30, 1997. They were classified according to the underlying disease, which had presumably led them to ESRD. Controls were patients admitted to the same hospitals from where the cases arose, also matched by age and sex. Odds ratios were calculated using a conditional logistic model, including potential confounding factors, both for the whole study population and for the various underlying diseases.

RESULTS

Five hundred and eighty-three cases and 1190 controls were included in the analysis. Long-term use of any analgesic was associated with an overall odds ratio of 1.22 (95% CI, 0.89-1.66). For specific groups of drugs, the risks were 1.56 (1.05-2.30) for aspirin, 1.03 (0.60-1.76) for pyrazolones, 0.80 (0.39-1.63) for paracetamol, and 0.94 (0.57-1.56) for nonaspirin NSAIDs. The risk of ESRD associated with aspirin was related to the cumulated dose and duration of use, and it was particularly high among the subset of patients with vascular nephropathy as underlying disease [2.35 (1.17-4.72)].

CONCLUSION

Our data indicate that long-term use of nonaspirin analgesic drugs and NSAIDs is not associated with an increased risk of ESRD. However, the chronic use of aspirin may increase the risk of ESRD.

Caffeine as a promoter of analgesic-associated nephropathy--where is the evidence?

Individual groups of nephrologists - in their responsibility for their patients - initiated a most controversial discussion whether or not caffeine - coformulated to analgesics - might initiate or sustain analgesic overdosing. The original sources (data) of such suspicion have got lost during the debate of the last two decades. Therefore, it seemed to be appropriate to investigate the original data background and the reasons why nephrologists started to suspect caffeine as a stimulant of analgesic overdosing by employing a systematic and exhaustive review of primary nephrological publications. Their selection followed a precise selection plan, including all epidemiological studies on analgesic-associated nephropathy, the original papers of all groups having been involved in those studies, further originals from the mainly involved countries (academically, politically), and any literature thereof cited as a proof. The following results emerged from the investigation: (i) The epidemiological studies warranted no conclusion about a role of caffeine in prompting excessive analgesic use. (ii) The identified groups of nephrologists provided not substantial data to advocate the said suspicion, except for the observation of a preferential choice of phenacetin-containing combinations, especially powder preparations. (iii) Only two cited original data sources revealed drug-seeking behaviour with phenacetin-containing preparations which subsided, after phenacetin was banned from the respective markets. Conclusively, it appears that there is no substantial data to support a pivotal role of caffeine in initiating or sustaining analgesic overdosing. However, there is strong data that phenacetin, by its psychotropic properties, may have caused drug-seeking behaviour and thus led to analgesic overdosing. This conclusion is convincingly supported by thorough pharmacokinetic investigations. Note: All caffeine-related statements within the reviewed literature have been collected in tables (referred to as Table SX) which are provided in full text for check on the following website: http://www.blackwellpublishing.com/products/journals/suppmat/FCP/FCP174/FCP174sm.htm

Regular use of analgesics is a risk factor for renal cell carcinoma

Phenacetin-based analgesics have been linked to the development of renal pelvis cancer and renal cell carcinoma (RCC). The relationship between non-phenacetin types of analgesics and kidney cancer is less clear, although laboratory evidence suggests that these drugs possess carcinogenic potential. A population-based case-control study involving 1204 non-Asian RCC patients aged 25-74 and an equal number of sex-, age- and race-matched neighbourhood controls was conducted in Los Angeles, California, to investigate the relationship between sustained use of analgesics and risk of RCC according to major formulation categories. Detailed information on medical and medication histories, and other lifestyle factors was collected through in-person interviews. Regular use of analgesics was a significant risk factor for RCC in both men and women (odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.4-1.9 for both sexes combined). Risks were elevated across all four major classes of analgesics (aspirin, non-steroidal anti-inflammatory agents other than aspirin, acetaminophen and phenacetin). Within each class of analgesics, there was statistically significant increasing risk with increasing level of exposure. Although there was some minor variability by major class of formulation, in general individuals in the highest exposure categories exhibited approximately 2.5-fold increase in risk relative to non- or irregular users of analgesics. Subjects who took one regular-strength (i.e. 325 mg) aspirin a day or less for cardiovascular disease prevention were not at an increased risk of RCC (OR = 0.9, 95% CI = 0.6-1.4).

Analgesic use and chronic renal failure: a critical review of the epidemiologic literature

Heavy use of analgesics, particularly over-the-counter (OTC) products, has long been associated with chronic renal failure. Most of the earlier reports implicated phenacetin-containing analgesics as the risk factor. Since the early 1980s. several case-control studies have reported associations between chronic renal failure and use of other forms of analgesics, including acetaminophen, aspirin, and other non-steroidal antiinflammatory drugs (NSAIDs). Findings from these studies, however. should be interpreted with caution because of a number of inherent limitations and potential biases in the study design and data collection procedures. These limitations include: failure to identify patients early enough in the natural history of their disease to collect reliable information on analgesic use at an etiologically relevant time period; selection bias due to incomplete identification of subjects or low response rates; selection of cases and controls from different population bases; failure to employ survey techniques to improve reliability of recall of analgesic use; failure to collect detailed information on analgesic use such as year started and ended and reasons for switching analgesics; lack of standardization in the definition of regular analgesic use; and failure to adjust for phenacetin use and other confounding factors when assessing associations with analgesics other than those containing phenacetin. It is our hope that this review of study design limitations will lead to improvements in future studies of chronic renal failure risk. Since use of analgesics is widespread and new OTC products are introduced frequently, the potential impact of these drugs on the development of chronic renal failure may be significant, thus warranting continued evaluation of these products for any renal toxicity.

A review of epidemiologic studies of nonnarcotic analgesics and chronic renal disease

The relationship of long-term and heavy exposure of nonnarcotic analgesics to the risk of chronic renal disease (CRD) has been the object of intensive clinical, pharmacologic, toxicologic, and epidemiologic research for 4 decades. The clinical evidence of an increased risk has been suggestive but inconclusive. The experimental evidence in animal models has been inconsistent, and in any case it cannot be generalized to humans. The epidemiologic evidence has been unsatisfactory for the most part: most of the early studies had severe methodologic limitations; moreover, they related mainly to phenacetin-containing drugs and did not have useful information on other analgesics. Since 1980, 9 analytical epidemiologic studies have attempted to confirm that a causal relationship exists between phenacetin or other analgesics and CRD. In the aggregate, despite methodologic flaws, this work suggests that excessive use of phenacetin-containing analgesics probably causes renal papillary necrosis and interstitial nephritis. In contrast, there is no convincing epidemiologic evidence that nonphenacetin-containing analgesics (including acetaminophen, aspirin, and mixtures of these two compounds) or that nonsteroidal antiinflammatory drugs cause CRD. Moreover, the nature of dose-response relationships, the types of renal disease possibly caused by analgesics, and the cofactors that might be related both to analgesic use and to the development of CRD in humans are still uncertain, and the pathologic mechanisms of analgesic-induced CRD in humans remain unclear. It may take many years before all the outstanding issues are settled. Until they are, as a matter of good clinical judgment it would be prudent to consider all analgesics as potentially nephrotoxic and, as much as possible, to avoid excessive, protracted use.

Simultaneous analysis of several non-steroidal anti-inflammatory drugs in human urine by high-performance liquid chromatography with normal solid-phase extraction

A practical and reproducible high-performance liquid chromatographic method using normal solid-phase extraction has been developed for the simultaneous analysis of twelve non-steroidal anti-inflammatory drugs (NSAIDs) in human urine. A urine specimen mixed with acetate buffer pH 5.0 was purified by solid-phase extraction on a Sep-Pak Silica cartridge. The analyte was chromatographed by a reversed-phase Inertsil ODS-2 column using a phosphate buffer-acetonitrile at pH 5.0 as the mobile phase, and the effluent from the column was monitored at 230 or 320 nm. Absolute recoveries were greater than 73% for all of the twelve NSAIDs. The present method enabled simple manipulation and isocratic HPLC with UV analysis as well as high sensitivity of 0.005 microg/ml for naproxen, and 0.05 microg/ml for sulindac, piroxicam, loxoprofen, ketoprofen, felbinac, fenbufen, flurbiprofen, diclofenac, ibuprofen and mefenamic acid as the quantitation limit in human urine using indomethacin as an internal standard.

Nonnarcotic analgesics: prevalence and estimated economic impact of toxicities

OBJECTIVE

To review and compare the risks of nonnarcotic analgesic toxicities in adults and estimate the relative healthcare costs of these toxicities, since direct comparison of costs is not possible.

DATA SOURCES

A MEDLINE search of the literature from 1969 to 1995 was used to identify pertinent data. Additional references were identified from articles obtained in the search. Information was obtained from prospective, retrospective, controlled, and uncontrolled studies; case reports; and review articles.

DATA EXTRACTION

Estimates of annual US costs of toxicities were extrapolated and synthesized from data from diagnosis-related groups, published information about the incidence of toxicity, or local data.

DATA SYNTHESIS

Chronic use of nonsteroidal antiinflammatory drugs (NSAIDs) is associated with a high incidence of acute renal toxicity and gastrointestinal toxicity. The most common problems associated with acetaminophen use are hepatoxicity after acute problems ingestion of large doses (> 10 g) or habitual use of smaller doses (< 4 g), particularly in alcoholic patients, and chronic analgesic nephropathy. Aspirin use is associated with a high incidence of gastrointestinal and acute renal toxicity in certain patient groups. Available data suggest that acetaminophen, used intermittently, remains the nonnarcotic analgesic of choice in many patient populations, including those with impaired renal function, gastrointestinal disease, and bleeding disorders. Estimated annual US costs associated with the toxicities of acetaminophen (excluding hepatotoxicity), aspirin (acute upper gastrointestinal bleeding only), and NSAIDs (excluding non-upper gastrointestinal hemorrhagic complications and hepatotoxicity) are about $51.5 million, $358.6 million, and $1.35 billion, respectively.

CONCLUSIONS

Intermittent use of most nonnarcotic analgesics produces a small risk of chronic renal or hepatic toxicity. Gastrointestinal toxicity, especially upper gastrointestinal bleeding, remains a significant problem with NSAIDs and aspirin. Acetaminophen remains the nonnarcotic analgesic of choice for intermittent use by most patient groups. The toxicities associated with NSAIDs constitute about 72.6% of the total toxicities (costs $1.86 billion) caused by NSAIDs, acetaminophen, and aspirin.

Combination analgesic involvement in the pathogenesis of analgesic nephropathy: the European perspective

Analgesic nephropathy (AN) is a chronic renal disease characterized by renal papillary necrosis and interstitial nephritis caused by excessive consumption of analgesic mixtures. In a recent study, diagnostic criteria for AN, based on a computed tomography scan investigation without contrast, were presented. The observation of a decreased renal mass of both kidneys combined with either bumpy contours or papillary calcifications was found to have a high diagnostic performance. Although several case control studies and two prospective studies demonstrated the association between analgesic abuse and nephropathy, the nephrotoxicity of the different analgesic products had not been clearly established. Analgesic abuse can be defined as a daily consumption of analgesic mixtures over a several-year period. Abuse of single analgesics is rare; it has been clearly demonstrated that abusers prefer analgesic mixtures. In Belgium, the prevalence of AN was positively related to the sales of analgesic mixtures containing two analgesic components plus caffeine and/or codeine. This relationship could not be observed for analgesics containing only one analgesic component plus caffeine and/or codeine. Moreover, during a European multicenter study, nephrotoxicity of different combinations of analgesic mixtures (all containing caffeine and/or codeine) could be documented in the absence of any previous phenacetin consumption. Epidemiologic observations in Sweden, France, and Belgium regarding incidence of AN, sales figures of analgesics, and legislative measurements concerning analgesic consumption supported the previous observations.

Acetaminophen/aspirin mixtures: experimental data

The pertinent literature concerning the experimental induction of analgesic nephropathy is reviewed. Based on the accumulated data from animal experiments that induced a pathologic lesion resembling chronic analgesic nephropathy, of the limited number of analgesics tested, aspirin seems to be the most nephrotoxic of the commonly available analgesics. When aspirin is combined with other analgesics, the limited data available suggest at least an additive nephrotoxic effect, if not a synergism. The histologic presentation of acute intoxication is substantially different from that following chronic ingestion. With improvements in pathologic analysis of experimental results, future studies may well provide more insight as to the significance, relative contribution, and risk of combination analgesic products in inducing experimental analgesic nephrotoxicity.

Aspirin or acetaminophen? A comparison from data collected by the Spanish Drug Monitoring System

To characterize and compare the toxicity profiles of aspirin and acetaminophen when used by large populations, all records of adverse drug reactions to these drugs reported to the Spanish Drug Monitoring System from 1982 to 1991 were analyzed. According to these data, aspirin-induced reactions were more serious than those reactions to acetaminophen; the severity of all the reactions in both cases was associated with time of exposure and with the accumulated dose administered. For GI reactions to aspirin no association was found between severity and time of exposure or dose, although an association with age was found. There were no differences between the proportions of deaths, malformations, and renal damage recorded for either of the two groups. Proportions of hematological and hepatic disturbances were greater with acetaminophen. Adverse drug reaction data for aspirin and acetaminophen from spontaneous reporting seem to be consistent with data coming from observational studies.

Do patients with epistaxis have drug-induced platelet dysfunction?

Aspirin and other non-steroidal anti-inflammatory drugs (NSAID) are being used increasingly. A positive correlation has been shown between epistaxis and the use of NSAID in the over 50s. This prospective study compared the NSAID intake and platelet function in 50 patients with epistaxis and 50 controls. Standard haematological parameters and the platelet response to collagen and arachidonic acid aggregation and adenosine triphosphate release were measured. The patients showed a significant increase in NSAID intake (P < 0.01, 95% confidence for the difference in the medians = 4-36%) and hypertension (for diastolic blood pressure > 100 mmHg, P < 0.01, 95% confidence for the difference in the medians = 5.9-16.1). The patients showed a significant reduction in platelet aggregation to collagen (P = 0.025). Non-steroidal anti-inflammatory drugs produce a significant platelet dysfunction which should be considered in the multifactorial aetiology of epistaxis.

Chronic renal disease and papillary necrosis associated with the long-term use of nonsteroidal anti-inflammatory drugs as the sole or predominant analgesic

The risk of renal papillary necrosis and renal dysfunction due to the chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) is unknown. In a prospective study of 259 heavy analgesic users seen in a general medical hospital over an 11-year-period beginning in January 1982, 69 new cases of analgesic nephropathy with renal papillary necrosis were confirmed by intravenous urogram (26.6%), ultrasonography (30.4%), and/or computed tomography (43%). Twenty-nine of these patients (42%) had consumed excessive quantities of NSAIDs alone; an additional nine patients (13%) had consumed NSAIDs predominantly in combinations with paracetamol, aspirin, phenacetin, caffeine, and/or traditional herbal medications. Of those patients who consumed NSAIDs alone, 17 had consumed only a single type of NSAID and the remaining 12 had consumed multiple types of NSAIDs. The amount of NSAIDs administered ranged from 1,000 to 26,600 capsules or tablets over a 2- to 25-year period. Renal impairment (serum creatinine, 126 to 778 mumol/L) was noted in 26 of these 38 patients (64.8%). The reasons given for consuming NSAIDs include gouty arthritis (18 patients), osteoarthritis (seven patients), rheumatoid arthritis (six patients), chronic headache (three patients), gouty arthritis plus chronic headache (three patients), and chronic backache (one patient). All patients were prescribed these drugs and were followed medically. The occurrence of analgesic nephropathy was predominantly in males (male to female ratio, 1.9:1). Most of the patients did not have the characteristic psychological profile attributed previously to analgesic abuse nephropathy. Associated addictive habits, such as the use of psychotropic drugs and sleeping tablets, purgative abuse, and alcoholism, were absent.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin and the prevention of colorectal cancer: a review of the evidence

In all but one of seven recent epidemiologic case-control and cohort studies directly examining the association between aspirin and colorectal cancer and polyps, regular aspirin use reduced the risk of these diseases by about half. Although these studies show a biologically plausible relationship between aspirin and colorectal cancer, information regarding dose and duration and risk change after discontinuation of aspirin is limited and contradictory. Additionally, selection bias, recall bias, and confounding cannot be completed discounted. The one randomized trial of aspirin and placebo showed that aspirin at a dose adequate for preventing myocardial infarction (325 mg every other day) did not reduce colorectal cancer incidence during five years of randomized treatment and follow-up. Further studies need to determine the biologic effects of aspirin, the minimum dose required, and whether other factors, such as age, illnesses, and reasons for aspirin use, modify or confound colorectal cancer development.

The Tromsø Study: frequency and predicting factors of analgesic drug use in a free-living population (12-56 years)

In a cross-sectional survey carried out in Tromsø in 1986-7, 19,137 men and women aged 12-56 years from the general population were asked about their use of drugs during the preceding 14 days. Use of analgesics was very common. On average 28% of the women and 13% of the men had used analgesics. Drug use due to menstruation discomfort contributed only partly to the gender difference. Drug use was independent of age from 20 years of age. Factors having an impact on analgesic drug use were analyzed by logistic regression. The most significant predictors of analgesic use were suffering from headache (OR = 14.2(women) OR = 24.4(men)) and infections (OR = 2.0(women) OR = 2.4(men)). Drug users also tended to suffer from symptoms of depression (women) and sleeplessness (men). Lifestyle and sociodemographic factors were also significant predictors, but were of marginal importance (OR < 1.5) compared with occurrence of pain and infections.

Paracetamol poisoning and the kidney

Nephrotoxicity is less common than hepatotoxicity in paracetamol overdose but renal tubular damage and acute renal failure occur even in the absence of hepatotoxicity. It is possible that antidotal therapy with agents such as N-acetylcysteine may not prevent renal toxicity and, indeed, on the basis of animal work, may actually potentiate tubular damage. Careful clinical attention should be paid to renal function in patients poisoned with paracetamol.

Different roles for phenacetin and paracetamol in cancer of the kidney and renal pelvis

A population-based case-control study of kidney cancer was carried out in New South Wales using data from structured interviews with 489 cases of renal-cell cancer and 147 cases of renal pelvic cancer diagnosed in 1989 and 1990, together with 523 controls from the electoral rolls. This study showed that the risk of renal pelvic cancer was increased by phenacetin/aspirin compound analgesics (RR = 12.2; 95% CI 6.8-22.2) to a far greater extent than by paracetamol (RR = 1.3; 95% CI 0.7-2.4; not significant). There was a doubling of risk (RR = 2.0; 95% CI 0.9-4.4) in the highest tertile of paracetamol taken in any form compared with values for non-users of any type of analgesic. By contrast, the risk of renal-cell cancer appeared to be increased to a similar degree by phenacetin/aspirin compound analgesics (RR = 1.4; 95% CI 0.9-2.3) and paracetamol taken in any form (RR = 1.5; 95% CI 1.0-2.3). When both drugs were treated as alternative forms of the same risk factor, the risk was increased by 1.7 (95% CI 1.2-2.4). On this evidence, we postulate that phenacetin/aspirin compounds are weakly carcinogenic in the renal parenchyma through the metabolic conversion of phenacetin to paracetamol, and potently carcinogenic in the renal pelvis by different or additional pathways involving renal papillary necrosis. In addition, there is an indication of a weak link between paracetamol and renal pelvic cancer.

Analgesics abuse: theoretical and practical considerations

Three important issues must be addressed in any attempt to determine whether combination painkillers play a role in analgesic nephropathy. The first issue, namely that of a causal link between the combination itself and nephrotoxicity, has never been adequately documented. On the contrary, there is much evidence that the combination as such has no influence whatsoever. The cause of the nephrotoxicity is most likely the painkilling mechanism, i.e. the antagonism to prostaglandins; the most potent prostaglandin-antagonists, the non-steroidal anti-inflammatory drugs, whether used in combination or singly, also most frequently cause renal pathology. The second issue, i.e. the safety of combination painkilling drugs in comparison with that of single substances, is intimately bound up with the advantages of the former with respect to both activity and the activity-side-effects ratio. The third issue, abuse, should be recast in a broader context. The central element here is not the painkilling drug but rather the labile personality of the user in conjunction with a more or less stressful environment in which a wide variety of drugs and stimulants are available and taken for better 'coping'. To a great extent analgesics abuse can be prevented by information (i.e. social medicine). In a broader perspective, man experiences considerable difficulty adapting to the sweeping social, technological and ideological changes of recent decades, and this transition contributes in no small measure to the analgesics problem. It should be a priority of government to find remedies for this state of affairs.

The effect of cyclophosphamide administration on the kidney of the rat

In studies primarily designed to evaluate the effectiveness of chitosan as a treatment for cyclophosphamide-induced hemorrhagic cystitis in the rat, renal papillary necrosis and pyelonephritis were observed. Cyclophosphamide alone produced relatively mild renal changes. The combination of cyclophosphamide and intravesical instillation of acetic acid induced renal papillary necrosis (38 to 83% incidence) along with pyelonephritis, hydroureter and hydronephrosis. Chitosan, instilled in place of acetic acid, partially inhibited the induction of renal papillary necrosis. It appears that the presence of vesico-ureteral reflux with or without associated hydroureter and hydronephrosis is a prerequisite for cyclophosphamide-induced renal damage.

Early sequential ultrastructural renal alterations induced by 2-bromoethylamine hydrobromide in the Swiss ICR mouse

Thirty-two male Swiss ICR mice were injected intraperitoneally with 300 mg 2-bromoethylamine hydrobromide/kg body weight, anesthetized, and perfused with glutaraldehyde-paraformaldehyde solution at 5, 15, 30, 60, 90, 120, 150, and 180 minutes after treatment. Eight control mice were injected intraperitoneally with sterile diluent, and one was perfused at each of the same time periods as the treated mice. Proximal tubule epithelial alterations progressed over time from increased secondary lysosome and myeloid body formation to cellular and mitochondrial swelling and eventually cell necrosis. The glomerular, peritubular, and vasa recta capillaries had endothelial cell swelling and desquamation and platelet aggregation. Bromoethylamine nephrotoxicosis in the male Swiss ICR mouse is an ischemic necrosis of the proximal tubules and papilla initiated by endothelial cell damage and makes an excellent model of chemically induced damage to endothelial cells and tubular necrosis.

Experimental renal papillary necrosis in the Mongolian gerbil (Meriones unguiculatus)

Sequential light microscopic and ultrastructural examination of kidneys from male and light microscopic examination of female Mongolian gerbils given 250 mg 2-bromoethylamine hydrobromide (BEA)/kg body weight ip were performed. In addition, male Mongolian gerbils were treated with both BEA and ip injections of either water, dimethyl sulfoxide, piperonyl butoxide, or reserpine. Light microscopic renal lesions in male Mongolian gerbils progressed from congestion of the vasa recta of the proximal inner medulla at 6 hr post-treatment to total renal papillary necrosis (RPN) at 24 hr post-treatment. There was no sex difference in sensitivity to BEA. Ultrastructural alterations in male gerbils were restricted to the vasa recta. Vascular lesions of endothelial swelling and pericapillary edema in the vasa recta of the proximal inner medulla was observed 2 hr post-treatment and progressed to occlusion by platelets adherent to exposed basement membranes at 6 hr post-treatment. Diuresis induced by injections of saline and injections of dimethyl sulfoxide or piperonyl butoxide did not affect the development of BEA-induced RPN. Reserpine slowed the development of BEA-induced RPN by its vasodilatory effect on the renal vasculature, not by blocking the endothelial toxicity of BEA. RPN induced by BEA in the Mongolian gerbil is apparently an ischemic necrosis of the inner medulla that develops secondary to endothelial damage of the vasa recta.

Caffeine potentiation of mefenamic acid-induced lesions in the rat renal medulla

The effect of caffeine given in combination with mefenamic acid on the renal medulla was examined. Sprague-Dawley rats were divided into four groups and gavage fed either vehicle suspension (control), mefenamic acid, mefenamic acid+caffeine or caffeine only for 4 months. Renal tissue taken from the corticomedullary junction was processed for electron microscopy. Ultrathin sections were cut after identification of vasa rectae on survey sections. On subsequent morphometric analysis, percentage interstitial tissue was calculated from the total area of vasa recta less the non-interstitial tissue. The median percentage of interstitial tissue in the mefenamic acid and caffeine group was 41 (range 33-50; n = 15) compared with 34 (20-48; n = 20) in mefenamic acid (P less than 0.01), 29 (15-42; n = 15) in caffeine only (P less than 0.001) and 32 (20-46; n = 18) in vehicle-treated animals (P less than 0.001). There were no significant differences between mefenamic acid alone and vehicle or caffeine-only groups or between caffeine-only and vehicle-treated controls. This suggests that caffeine potentiates the effect of the non-steroidal anti-inflammatory drug, mefenamic acid, on the rat renal medulla, resulting in a quantitative increase in the interstitial tissue between adjacent afferent and efferent vasa recta.

Effects of tenoxicam on renal function and the disposition of inulin and p-aminohippurate in healthy volunteers and patients with chronic renal failure

1. The effects of tenoxicam on renal function were studied in 10 patients with chronic renal failure (creatinine clearance 46.7 +/- 11.9 ml min-1 1.73 m-2) and eight healthy volunteers. A parallel treatment control group of eight healthy volunteers received placebo. Tenoxicam was given orally in a dose of 40 mg daily for 2 days followed by 20 mg daily for a further 8 days. Renal function was assessed by measurement of the renal clearances of inulin and p-aminohippurate (PAH) using the single injection technique before and during administration of tenoxicam. 2. In the healthy volunteers there were no changes in glomerular filtration rate, effective renal plasma flow, or the urinary excretion of N-acetylglucosaminidase and beta 2-microglobulin on the 3rd and 10th days of treatment with tenoxicam. The mean urinary excretion of prostaglandins E2 and 6-keto F1 alpha decreased during treatment but there was great individual variation and the differences were not statistically significant. Tenoxicam had no effect on the half-life, clearance, volume of distribution or urinary recovery of inulin and PAH. 3. There was no significant change in the clearance of inulin and creatinine after treatment with tenoxicam for 10 days in the patients with chronic renal failure. However, in this group there was a significant increase in plasma creatinine on the 3rd and 6th days with a return to pretreatment levels by the 10th day. The administration of tenoxicam for 10 days was associated with a small but significant increase in the plasma half-life and volume of distribution of inulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiologic study of analgesic abuse: mortality study in 7275 working women (1968-1987)

In a prospective, longitudinal investigation over a period of 20 years in 7275 working women 30 to 49 years old, we examined the effect of the ingestion of analgesics on cause-specific mortality. Evidence of intake of phenacetin and salicylate containing analgesics was obtained at a urine screening in 1967 and was shown to relate to intake between 1968 to 1978. Life table analysis of the effect of phenacetin intake on overall mortality showed significant differences between the groups of women with intake (N = 613) versus no intake (N = 4175): for total [relative risk (RR) = 2.1, P less than 0.001], urorenal (RR = 24.4, P less than 0.001), cardiovascular (RR = 4.5, P less than 0.001), and cancer mortality (RR = 1.9, P less than 0.001). No significant effects on overall or cause-specific mortality were found for salicylate intake. These results make a causal relationship between the amount of analgesic containing phenacetin consumed and the risk of death from urorenal disease likely. Furthermore, the data show an elevated risk for cardiovascular disease and cancer for phenacetin intake. No such relationships are demonstrable for the use of salicylate.

Decreased incidence of diphenylamine-induced renal papillary necrosis in Syrian hamsters given dimethylsulphoxide

The renal papillotoxicity of diphenylamine dissolved in dimethylsulphoxide (DMSO) was investigated in male Syrian hamsters, male Sprague-Dawley rats and female Mongolian gerbils. When diphenylamine in DMSO was administered orally to male Syrian hamsters (400, 600 or 800 mg/kg body weight/day for up to 9 days), the incidence of renal papillary necrosis was almost zero. Hamsters pretreated with DMSO (0.5 ml/100 g body weight/day) and 1 hr later given 400, 600 or 800 mg diphenylamine in peanut oil/kg body weight/day for 3 consecutive days had significantly reduced incidences of renal papillary necrosis (0/10, 0/10 and 1/10 in the low-, mid- and high-dose groups, respectively) when compared with hamsters given similar doses of diphenylamine but not pretreated with DMSO (5/10, 7/10 and 5/10 in the low-, mid- and high-dose groups, respectively). Focal, apex-limited renal papillary necrosis was observed in two Sprague-Dawley rats given 800 mg diphenylamine in DMSO/kg body weight/day orally for 9 days. Focal, intermediate renal papillary necrosis was observed in two additional rats administered 800 mg diphenylamine in DMSO/kg/day orally for 9 days. Renal papillary necrosis was not observed in any of the Mongolian gerbils. The results of these studies suggest that DMSO protects against diphenylamine-induced renal papillary necrosis in male Syrian hamsters.

Analgesic nephropathy in Fischer 344 rats: comparative effects of chronic treatment with either aspirin or paracetamol

This study has compared the relative nephrotoxicity of chronic treatment with aspirin or paracetamol in an animal model. Changes in renal structure and urinary concentrating ability were examined in female Fischer 344 rats after continuous treatment with either aspirin (120-230 mg/kg body wt/day), or paracetamol (140-210 mg/kg body wt/day), and were compared with age-matched untreated control rats. Renal morphological changes were examined after 40-83 weeks of analgesic treatment, using light and electron microscopy. Aspirin caused renal papillary necrosis and a decrease in urinary concentrating ability, whereas paracetamol alone did not cause significant renal damage. Aspirin produced damage to the interstitial cells and matrix, particularly in the mid-papillary region, followed by changes to the thin limbs of the loop of Henle and medullary capillary endothelium. These structural changes were similar to those described previously, when continuous treatment with combined aspirin and paracetamol was studied in the same animal model.

An epidemiologic study of abuse of analgesic drugs. Effects of phenacetin and salicylate on mortality and cardiovascular morbidity (1968 to 1987)

BACKGROUND

Phenacetin abuse is known to produce kidney disease; salicylate use is supposed to prevent cardiovascular disease. We conducted a prospective, longitudinal epidemiologic study to examine the effects of these drugs on cause-specific mortality and on cardiovascular morbidity.

METHODS

In 1968 we evaluated a study group of 623 healthy women 30 to 49 years old who had evidence of a regular intake of phenacetin, as measured by urinary excretion of its metabolites, and a matched control group of 621 women. Salicylate excretion was also measured. All subjects were examined over a period of 20 years.

RESULTS

Life-table analyses of mortality during the 20 years, with adjustment for the year of birth, cigarette smoking, and length of follow-up, revealed significant differences between the groups in overall mortality (study group vs. control group, 74 vs. 27 deaths; relative risk, 2.2; 95 percent confidence interval, 1.5 to 3.3), deaths due to urologic or renal disease (relative risk, 16.1; 95 percent confidence interval, 3.9 to 66.1), deaths due to cancer (relative risk, 1.9; 95 percent confidence interval, 1.1 to 3.3), and deaths due to cardiovascular disease (relative risk, 2.9; 95 percent confidence interval, 1.5 to 5.5). The relative risk of cardiovascular disease (fatal or nonfatal myocardial infarction, heart failure, or stroke) was 1.8, and the 95 percent confidence interval 1.3 to 2.6. The odds ratio for the incidence of hypertension was 1.6, and the 95 percent confidence interval 1.2 to 2.1. The effects of phenacetin on morbidity and mortality, with adjustment for base-line salicylate excretion, were similar. In contrast, salicylate use had no effect on either mortality or morbidity.

CONCLUSIONS

Regular use of analgesic drugs containing phenacetin is associated with an increased risk of hypertension and mortality and morbidity due to cardiovascular disease, as well as an increased risk of mortality due to cancer and urologic or renal disease. The use of salicylates carries no such risk.

End-stage renal disease and non-narcotic analgesics: a case-control study

1. To assess the risk of end-stage renal disease (ESRD) associated with the regular use of three classes of non-narcotic analgesics, we performed a case-control study of 340 patients with ESRD on a haemodialysis maintenance program and 673 hospital controls. 2. The overall odds ratio estimate for non-narcotic analgesics taken at least every other day for 30 days or longer before the first symptom of renal disease was 2.89 (95% CI, 1.78 to 4.68). 3. The risk increased in relation to the use duration. 4. The previous regular consumption of combinations containing phenacetin was strongly associated with ESRD (odds ratio, 19.05; 95% CI, 2.31 to 157.4). The odds ratio for previous regular consumption of salicylates was 2.54 (95% CI, 1.24 to 5.20) and for pyrazolones 2.16 (95% CI, 0.87 to 5.32). 5. An analysis for possible confounding by a history of repeated headaches, arthritis, kidney stones, hypertension, and diabetes did not alter the results. 6. The odds ratio estimates for different pathological subgroups of ESRD patients in relation to previous use of any non-narcotic analgesic were glomerulonephritis. 10.57 (95% CI, 1.25 to 89.0), interstitial nephritis, 3.33 (95% CI, 1.21 to 9.17), cystic kidney disease, 0.71 (95% CI, 0.25 to 1.97), and unknown, 5.15 (95% CI, 2.29-11.57). 7. The results of this study suggest that the regular consumption of analgesics should be routinely considered as a risk factor for any non-congenital cause of chronic renal failure. They also suggest that the risk of ESRD associated with the regular consumption of phenacetin is much higher than the risk associated with other non-narcotic analgesics.

Acute cortical tubular necrosis in the Swiss ICR mouse induced by 2-bromoethylamine hydrobromide

Dose-response and sequential studies of 2-bromoethylamine hydrobromide (BEA) nephrotoxicosis were carried out using Swiss ICR mice. For the dose-response study, 150 male mice, 30 per group, were injected intraperitoneally (ip) with 100, 200, 300, 400 or 500 mg BEA/kg and ten from each group were killed 1, 3 or 5 days after treatment. For the sequential study, 80 male mice were injected ip with 300 mg BEA/kg and ten were killed at 0.5, 1, 2, 3, 6, 12 or 18 hr, or 10 days after treatment. Control mice (10-15) in both studies were given 0.15 ml of 0.9% NaCl solution injected ip and were killed after 1, 3 or 5 days in the former study and after 18 hr of 10 days in the latter study. Mortality and the extent of the renal lesions were dose dependent. The percentage of mice with tubular necrosis varied from 0 in mice given 100 mg BEA/kg to 100 in mice given 400 mg BEA/kg. The percentage of mice with renal papillary necrosis was also dose dependent and varied from 0 in the 100 mg/kg group to 72 in the 400 mg/kg group. Degeneration of proximal tubules was detected 2 hr after treatment. Three hours after treatment, grossly, the renal cortex was diffusely pale and, microscopically, there was marked acute tubular necrosis. Epithelial cells lining the cortical tubules were regenerating 3 days after treatment. By 10 days after treatment cortical interstitial fibrosis was marked with many tubules lined by regenerating epithelium and many tubules were dilated. BEA-induced nephrotoxicosis in the mouse was primarily an acute cortical tubular necrosis.

The comparative effects of paracetamol and indomethacin on renal function in healthy female volunteers

1. Renal function was assessed in 10 healthy female volunteers during administration of placebo, paracetamol (acetaminophen) (4.0 g daily) and indomethacin (150 mg daily) for 3 days under conditions of controlled sodium and fluid intake. 2. Paracetamol and indomethacin had no significant effect on the glomerular filtration rate and effective renal plasma flow as measured by the renal clearances of inulin, creatinine and p-aminohippurate (PAH). 3. Compared with placebo, paracetamol reduced the mean urinary excretion of prostaglandin E2 by 43% on the second day and 58% on the third treatment day (P less than 0.01). With indomethacin the corresponding reductions were 73 and 80%. Paracetamol and indomethacin had much less effect on the excretion of prostaglandin 6-keto F1 alpha, and a significant decrease was observed only on the third day. 4. The decreased urinary excretion of prostaglandin E2, produced by paracetamol was associated with a reduction in sodium excretion of more than 50% (P less than 0.01) and delay in the onset of diuresis following an acute water load. 5. The renal effects of paracetamol and indomethacin appear to differ. Although indomethacin reduced prostaglandin excretion more than paracetamol it had a similar effect on sodium excretion and less initial antidiuretic action. Unlike paracetamol, indomethacin also reduced basal plasma renin activity. 6. Paracetamol reduced the total body clearance of PAH and increased its plasma half-life. This effect could be attributed to inhibition of the acetylation of PAH by paracetamol. 7. In normal use paracetamol does not appear to have the adverse renal effects associated with the non-steroidal anti-inflammatory analgesics and further studies are required to establish the clinical significance of these findings.

The effect of acetaminophen on pig kidneys with a 2-bromoethanamine-induced papillary necrosis

Large White pigs were used to investigate the effects of acetaminophen (paracetamol) on normal kidneys or those with an existing renal papillary necrosis. Pairs of young female animals were treated with either a single iv dose of 50 mg/kg 2-bromoethanamine (BEA), 100 mg/kg/day acetaminophen po for 28 days, or a combination of BEA followed by the acetaminophen treatment. Two pigs served as untreated controls. Kidney length, diameter and parenchymal thickness were measured by ultrasound scans, and glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) assessed by 99mTc-DTPA and 131I-hippuran renography prior to treatment and on day 26. Acetaminophen only caused no renal pathology. Despite the lack of a gross RPN, hyperplasia of the pelvic and ureteric urothelia (with extensive vacuolation) was observed following BEA, but BEA followed by acetaminophen for 28 days did not enhance the lesion. The BEA and BEA-acetaminophen groups (but not acetaminophen only) showed an increased ERPF compared with age-matched controls, but there was no significant difference in the overall GFR between the groups.