Analgesic-associated nephropathy

Risk of tobacco-related multiple primary cancers in Bavaria, Germany

BACKGROUND

With the prospect of increasing prevalence of cancer, the issue of multiple primary cancers becomes more relevant. The aim of this study was to estimate the risk of developing a tobacco-related subsequent primary cancer (TRSPC) in persons with a tobacco-related first primary cancer (TRFPC) compared with the general population in Bavaria, Germany.

METHODS

Using data from the Population-Based Cancer Registry Bavaria, we analyzed TRFPC and TRSPC diagnosed in Bavaria between 2002 and 2008 to estimate the relative and absolute risk of developing TRSPC using standardized incidence ratios (SIR) and excess absolute risks (EAR).

RESULTS

121,631 TRFPC in men and 75,886 respective cancers in women were registered, which in 2.5% of male and 1.2% of female cancer patients were followed by at least one TRSPC. In both males and females, the highest increased risks compared to the general population were found within the group of cancer in the mouth/pharynx, oesophagus, larynx, and lung/bronchus.

CONCLUSIONS

With respect to cancer in the mouth/pharynx, oesophagus, larynx, lung/bronchus, kidney, urinary bladder and urinary tract, smoking was confirmed as a shared risk factor based on our finding of mutually significantly increased risks of TRSPC. The results of this study illustrate the importance of smoking cessation and of continued follow-up care especially of smokers with the aforementioned TRFPC to detect TRSPC at an early stage.

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

Role of quercetin on hepatic urea production in acute renal failure

Acute renal failure (ARF) is a serious damage of renal function induced by various nephrotoxic drugs, ischemia, bilateral urethral obstruction, trauma and unilateral nephrectomy. Dramatic clinical syndrome, azotemia, develops as a result of hypovolemia, oliguria, reduced glomerular filtration and acidosis. In addition to classic medications recent studies give more attention to beneficial effect of natural plant products as bioflavonoids. We have studied the influence of bioflavonoid, quercetin, on hepatic urea production in glycerol induced ARF in the rats. Male Sprague Dawley rats were used in the experiment. The value of urea production in the liver was determined by measuring of liver arginase activity, the terminal enzyme of urea cycle. Arginase activity was increased (p < 0.01) as well as urea level (p < 0.001) 48 h after glycerol administration. Pretreatment by quercetin suppressed the arginase activity in the liver (p < 0.05) and plasma levels of urea (p < 0.01). So, we have concluded that quercetin may be beneficial in glycerol induced ARF.

A safety assessment of fixed combinations of acetaminophen and acetylsalicylic acid, coformulated with caffeine

Overuse and abuse of phenacetin-containing mixed analgesics has contributed to end-stage renal disease. Combination analgesics, especially those coformulated with caffeine, have been implicated as imparting a greater risk of analgesic-associated nephropathy (AAN) than single or coformulated analgesics without caffeine. This has led to a recommendation that the sale of "two plus caffeine" analgesic mixtures be reclassified from over-the-counter to prescription only availability. There is a rational basis for coformulating acetylsalicylic acid (ASA) and acetaminophen (paracetamol) as this reduces the dose of each, without altering efficacy. The coformulation of caffeine with these analgesics has a significant adjuvant effect and increases analgesic efficacy 1.4-1.6-fold. Currently available animal and human data do not support the notion that the nephrotoxic risk from coformulated ASA and acetaminophen is higher than the risk from either ASA or acetaminophen alone, in equivalent analgesic doses. There are no epidemiological data that implicate caffeine in AAN, and only limited evidence that links excessive acetaminophen usage to renal disease. There is no evidence that caffeine increases analgesics papillotoxicity directly. The presence of caffeine in mixtures of analgesics are no more addictive than other sources of caffeine. There is no evidence to suggest that adding caffeine to analgesic mixtures enhances the potential for promoting analgesic misuse in the general population. Thus distinct therapeutic benefits of ASA, acetaminophen and caffeine appear to outweigh any known risk. It is doubtful if preventing the availability of these products will significantly affect the role of analgesic abuse/overuse in end-stage renal disease. Better risk management would come from a focused educational program, developed in a close collaboration between industry, healthcare professionals and consumer organizations, such a program must warn against the potential dangers of analgesic and non-steroidal anti-inflammatory drug misuse.

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.

Renal papillary necrosis--40 years on

Analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs) are well recognized as a major class of therapeutic agent that causes renal papillary necrosis (RPN). Over the last decade a broad spectrum of other therapeutic agents and many chemicals have also been reported that have the potential to cause this lesion in animals and man. There is consensus that RPN is the primary lesion that can progress to cortical degeneration; and it is only at this stage that the lesion is easily diagnosed. In the absence of sensitive and selective noninvasive biomarkers of RPN there is still no clear indication of which compound, under what circumstances, has the greatest potential to cause this lesion in man. Attempts to mimic RPN in rodents using analgesics and NSAIDs have not provided robust models of the lesion. Thus, much of the research has concentrated on those compounds that cause an acute or subacute RPN as the basis by which to study the pathogenesis of the lesion. Based on the mechanistic understanding gleaned from these model compounds it has been possible to transpose an understanding of the underlying processes to the analgesics and NSAIDs. The mechanism of RPN is still controversial. There are data that support microvascular changes and local ischemic injury as the underlying cause. Alternatively, several model papillotoxins, some analgesics, and NSAIDs target selectively for the medullary interstitial cells, which is the earliest reported aberration, after which there are a series of degenerative processes affecting other renal cell types. Many papillotoxins have the potential to undergo prostaglandin hydroperoxidase-mediated metabolic activation, specifically in the renal medullary interstitial cells. These reactive intermediates, in the presence of large quantities of polyunsaturated lipid droplets, result in localized and selective injury of the medullary interstitial cells. These highly differentiated cells do not repair, and it is generally accepted that continuing insult to these cells will result in their progressive erosion. The loss of these cells is thought to be central to the degenerative cascade that affects the cortex. There is still a need to understand better the primary mechanism and the secondary consequences of RPN so that the risk of chemical agents in use and novel molecules can be fully assessed.

Normal ultrastructure of the kidney and lower urinary tract

The mammalian urinary tract includes the kidneys, ureters, urinary bladder, and urethra. The renal parenchyma is composed of the glomeruli and a heterogeneous array of tubule segments that are specialized in both function and structure and are arranged in a specific spatial distribution. The ultrastructure of the glomeruli and renal tubule epithelia have been well characterized and the relationship between the cellular structure and the function of the various components of the kidney have been the subject of intense study by many investigators. The lower urinary tract, the ureters, urinary bladder, and urethra, which are histologically similar throughout, are composed of a mucosal layer lined by transitional epithelium, a tunica muscularis, and a tunica serosa or adventitia. The present manuscript reviews the normal ultrastructural morphology of the kidney and the lower urinary tract. The normal ultrastructure is illustrated using transmission electron microscopy of normal rat kidney and urinary bladder preserved by in vivo perfusion with glutaraldehyde fixative and processed in epoxy resin.

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.

Habitual use of acetaminophen as a risk factor for chronic renal failure: a comparison with phenacetin

Six epidemiologic studies in the United States and Europe indicate that habitual use of phenacetin is associated with the development of chronic renal failure and end-stage renal disease (ESRD), with a relative risk in the range of 4 to 19. As a result of these and other studies, phenacetin has now been withdrawn from the market in most countries. However, three case control studies, one each in North Carolina, northern Maryland, and West Berlin, Germany, showed that habitual use of acetaminophen is also associated with chronic renal failure and ESRD, with a relative risk in the range of 2 to 4. These studies suggest that both phenacetin and acetaminophen may contribute to the burden of ESRD, with the risk of the latter being somewhat less than that of the former. This apparent difference in risk may not be due to differences in nephrotoxic potential of the drugs themselves. A lower relative risk would be expected for acetaminophen if the risk of both drugs in combination with other analgesics was higher than the risk of either agent alone. Thus, acetaminophen has been used both as a single agent and in combination with other analgesics, whereas phenacetin was available only in combinations. The possibility that habitual use of acetaminophen alone increases the risk of ESRD has not been clearly demonstrated, but cannot be dismissed.

Investigation of regional glutathione levels in a model of chemically-induced renal papillary necrosis

The effect of diphenylamine on renal cortical, outer medullary and inner medullary glutathione (GSH) concentrations and the effect of GSH depletion on the nephrotoxicity of diphenylamine were investigated in male Syrian hamsters. A dose-dependent decrease in renal cortical GSH was observed within 1 hr of a single oral dose of diphenylamine (200, 400 or 600 mg/kg body weight), but statistically significant changes in outer medullary or papillary GSH were not observed. Reduction of renal papillary GSH to 29% of basal concentration [by prior treatment with L-buthionine sulfoxime (500 mg/kg body weight, ip)] did not increase the papillotoxicity of a non-toxic dose of diphenylamine (400 mg/kg) administered orally. The findings indicate that diphenylamine-induced renal papillary necrosis in the Syrian hamster is not associated with a decrease in renal papillary or outer medullary GSH nor mediated by oxidative cell injury.

Irreversible damage to the medullary interstitium in experimental analgesic nephropathy in F344 rats

Renal papillary necrosis (RPN) and a decreased urinary concentrating ability developed during continuous long-term treatment with aspirin and paracetamol in female Fischer 344 rats. Renal structure and concentrating ability were examined after a recovery period of up to 18 weeks, when no analgesics were given, to investigate whether the analgesic-induced changes were reversible. There was no evidence of repair to the damaged medullary interstitial matrix, or proliferation of remaining undamaged type 1 medullary interstitial cells after the recovery period following analgesic treatment. The recovery of urinary concentrating ability was related to the length of analgesic treatment and the extent of the resulting inner medullary structural damage. During the early stages of analgesic treatment, the changes in urinary concentrating ability were reversible, but after prolonged analgesic treatment, maximum urinary concentrating ability failed to recover. This study shows that prolonged analgesic treatment in Fischer 344 rats causes progressive and irreversible damage to the interstitial matrix and type 1 interstitial cells leading to RPN. The associated urinary concentrating defect is reversible only during the early stages of structural damage to the inner medulla.

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.

[The effect of various factors on the progression of kidney insufficiency cause by analgesic nephropathy]

In a retrospective study of 33 patients the influence of different anamnestic, clinical and laboratory parameters on the progression of renal failure was investigated. The analysis of progression of renal failure was evaluated in terms of a reasonable criterium intuitively suggesting itself which is based on a non-linear fitting of the serum creatinine profile. Follow-up serum creatinine levels showed that renal function became worse in 28 cases, with terminal renal failure developing in 6 cases. In 5 patients significant improvement in kidney function was observed. The variables systolic and diastolic blood pressure, total amount of ingested analgesics, continued abuse and cessation of analgesics, frequency of urinary tract infections and amount of proteinuria had no significant influence on progression of renal failure. However, a strong relationship between the initial serum creatinine level and the progression of renal failure could be established. In conclusion our results indicate that long-term prognosis of analgesic nephropathy mainly depends on early diagnosis.

Morbidity of patients with analgesic-associated nephropathy on regular dialysis treatment and after renal transplantation

In a retrospective study, patients with end-stage renal failure from analgesic-associated nephropathy - 55 on regular dialysis treatment and 12 after renal transplantation - were under observation for 57 and 33 months, respectively. Of these 34 patients on chronic hemodialysis had suffered from different cardiovascular diseases. Hypertriglyceridemia was diagnosed in 62% of the patients, arterial hypertension requiring antihypertensive therapy in 44%. In three patients (5%) carcinoma of the urinary bladder were diagnosed. The leading causes of death in 21 patients included cardiovascular diseases (29%), hyperkalemia (19%), sepsis, and malignant tumors (14% each). Rejection occurred in 3 out of 12 patients after renal transplantation. Again, cardiovascular morbidity was high (58%) with coronary heart disease being present in 33% of the patients. Hypertriglyceridemia was observed in 5 out of 6 patients, antihypertensive therapy was needed in 50%. One patient died from primary pulmonary hypertension.

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.

Epidemiology and mechanistic basis of analgesic-associated nephropathy

End-stage renal failure (ESRF) due to analgesic nephropathy is still a common clinical condition in several countries, but the prevalence in dialysis patients shows large geographical differences. The frequency of ESRF of unknown aetiology is the inverse of that linked to analgesic abuse, and data suggest that the occurrence of analgesic nephropathy may be underestimated. The study of analgesic nephropathy is difficult because the earliest damage to the kidney is a renal papillary necrosis (RPN), which cannot easily be diagnosed. Continued analgesic abuse generally leads to a progressive secondary cortical degeneration which is easier to diagnose. If analgesic abuse is stopped at an early enough stage in nephropathy, clinical symptoms stabilize or improve, and ESRF may be averted. A high incidence of upper urothelial carcinoma (UUC) is also observed in individuals with a history of analgesic abuse, but it is still not clear if the two have a related pathogenesis. Study of the mechanism of RPN in animals administered analgesics and nonsteroidal antiinflammatory drugs (NSAID) has been difficult owing to their extrarenal toxicity. Several model compounds cause identical clinical changes and have as their selective target the renal medullary interstitial cells; subsequently, other changes (including cortical and glomerular degeneration) develop as a secondary cascade. A number of mechanisms have been proposed to explain RPN (e.g., counter-current concentrating mechanism, ischaemic injury, altered prostaglandin metabolism, immunological changes), but peroxidative metabolism of papillotoxic chemicals within the interstitial cells seems to be the most likely cause. Analgesic abuse is a costly socioeconomic condition for which there is currently no clinical treatment. If it is diagnosed early enough, severe renal degeneration can be prevented. Additional epidemiological information is needed to establish the causative role of analgesics and other chemicals, in order to determine the relative risk of each. Additional animal experiments are needed in order to clarify the molecular pathogenesis of RPN and UUC, to differentiate the stages in progression to ESRF and to develop more sensitive and selective diagnostic criteria.