Phenacetin nephropathy, with particular reference to the effect of surgery

Toxic nephropathy: Adverse renal effects caused by drugs

This is a brief overview of toxic nephropathy, which is an increasingly recognised problem with the continual introduction of new drugs and novel drug modalities, especially in oncology, and the risks associated with polypharmacy in many patients; although it is important to remember that it may not always be caused by a drug. It is also important to note that several possibly harmful drugs are now available without prescription ('over-the-counter') and can be purchased easily over the internet, including some poorly characterised herbal remedies. Knowing exactly what our patients are taking as medication is not always easy and patients often fail to mention drugs that may not have been prescribed by a doctor or recommended by a pharmacist. Moreover, patients with several comorbidities often require care from more than one doctor in other specialties, which can also lead to drug prescribing in isolation. This article will summarise some key aspects of drug nephrotoxicity and provide a few clinical pointers to consider, bearing in mind that there is rarely any antidote available, and effective treatment relies on early detection, prompt drug withdrawal, and supportive care. This short review is intended only as a primer to highlight some of the more practical aspects of toxic nephropathy; its content is based on a lecture delivered during the 2021 European Congress of Internal Medicine.

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.

Hepatotoxicity of phenacetin and paracetamol in the Gunn rat

Both phenacetin and paracetamol produce acute centrilobular liver necrosis in the homozygous Gunn rat. Paracetamol is more hepatotoxic than phenacetin, and both are more hepatotoxic to the homozygous Gunn rat than to the heterozygous Gunn rat or to the albino rat. These findings have relevance to the role of the compounds in the clinical syndromes of paracetamol induced liver necrosis and analgesic nephropathy.

Unsuspected analgesic nephropathy in transitional cell carcinoma of the upper tract: a morphological study

Analgesic nephropathy is known to have a high incidence in Australia where, following the experience in Scandinavia, reports have been published for some time recording the association between analgesic nephropathy and urothelial malignancies. The morbid anatomical features of analgesic nephropathy are now sufficiently well accepted to allow a retrospective study of unselected nephrectomies for transitional cell carcinoma of the renal pelvis and ureter, in order to assess the incidence of analgesic-type changes in this well defined group of malignancies. The records of a large general histopathology department between 1972-1978 were searched and 24 consecutive transitional cell carcinomas in these sites treated by nephrectomy were selected for study. Of these, 21 were suitable for assessment and on review were shown to comprise II cases with papillary changes acceptable as analgesic in type and five which were suggestive of early analgesic change. Of these 16, seven were female, only two were known analgesic abusers and five were recorded as consuming analgesics on a regular basis. These findings suggest that analgesics may play a significant role in the pathogenesis of urothelial malignancy in the general population.

Drug-induced renal disease

The clinical manifestations of drug-induced renal disease may include all the manifestations attributed to natural or spontaneous renal diseases such as acute renal failure, chronic renal failure, acute nephritic syndrome, renal colic, haematuria, selective tubular defects, obstructive nephropathy, etc. It is therefore vital in any patient with renal disease whatever the clinical manifestations might be, to obtain a meticulous drug and toxin inventory. Withdrawal of the offending drug may result in amelioration or cure of the renal disorder although in the case of severe renal failure it may be necessary to utilise haemodialysis or peritoneal dialysis to tide the patient over the period of acute renal failure. Analgesic nephropathy is an important cause of terminal chronic renal failure and it is therefore vital to make the diagnosis as early as possible. The pathogenesis of some drug-induced renal disorders appears to be immunologically mediated. There are many other pathogenetic mechanisms involved in drug-induced renal disorders and some drugs may under appropriate circumstances be responsible for a variety of different nephrotoxic effects. For example, the sulphonamides have been incriminated in examples of crystalluria, acute interstitial nephritis, acute tubular necrosis, generalised hypersensitivity reactions, polyarteritis nodosa and drug-induced lupus erythematosus.

The nephrotoxicity of p-aminophenol. I. The effect on microsomal cytochromes, glutathione and covalent binding in kidney and liver

p-Aminophenol administration lowered the microsomal cytochrome P-450 and b5 content and decreased the activity of NADPH cytochrome c reductase in kidney, but not in liver. Kidney GSH was depleted to 29% of the control value at 2 h, and only partly restored (50% of control) at 24 h. Liver GSH was transiently decreased, the lowest levels (77% of control) occurring at 30 min. The maximum level of covalently bound radioactivity was at two hours when 16.8% of the total radioactivity in kidney, 1.5% in liver and 3.6% in plasma was protein bound. At this time 81% of the total radioactivity in kidney and 95% of that in the liver was present in the soluble fraction.

Liver and kidney damage induced by N-hydroxyparacetamol

1. Liver and kidney glutathione are depleted in rats and mice following administration of N-hydroxyparacetamol. 2. Centrilobular hepatic necrosis and necrosis of renal proximal convoluted tubules were also found, the liver lesion predominantly in mice and the renal lesion predominantly in rats. Glutathione depletion was not responsible for this species difference. 3. These results indicate that N-hydroxyparacetamol is the metabolic precursor of the reactive toxic intermediate of paracetamol. They are also relevant to the pathogenesis of the renal damage associated with long term abuse of phenacetin containing compound analgesics.

Genesis of analgesic nephropathy in the United Kingdom

Analgesic nephropathy is more common in Western Scotland than elsewhere in the United Kingdom. This appears to be a consequence of the frequency with which local people take Askit, a preparation different from most other British analgesics in that they contain more caffeine and in their presentation as powders. Surveys of different populations in Glasgow suggest that while aspirin and paracetamol tend to be taken relatively infrequently and for appropriate reasons such as pain, Askit is more likely to be taken with excessive frequency for its supposed mood-altering properties. Working-class women with psychiatric problems are especially prone to daily self-medication. Study of individuals with analgesic nephropathy reveals that in Western Scotland, at least, the cause is dependence on analgesics. The characteristics of this include a need to continue taking and to slowly increase the dose of analgesics, partly owing to tolerance and partly to treat symptoms the analgesic ingestion has caused, as well as a psychic dependence resulting from appreciation of the psychotropic effects of the compound analgesics. When compared with matched controls, those who develop the "analgesic abuse syndrome" are more likely to have a family history of analgesic abuse, alcoholism, and psychiatric disorder. They tend to be introverted and neurotic, are prone to abuse other drugs and many have had previous psychiatric treatment.

Analgesic abuse and kidney disease

The analgesic syndrome, comprising renal disease, hypertension, peptic ulcer, anaemia and recurrent headache, accounts for wide-spread morbidity and mortality especially in Queensland and New South Wales. Epidemiological and clinical evidence gathered from many Western societies implicates unsupervised consumption of compound analgesic preparations, particularly those containing phenacetin, in the causation of the majority of cases. Laboratory experiments so far have failed to produce an entirely satisfactory model of clinical analgesic nephropathy. In small animals, papillary necrosis results from prolonged feeding with large doses of aspirin and a number of other anti-inflammatory agents more readily than when phenacetin, paracetamol or phenazone is given alone. The apparently conflicting deductive and experimental data may be reconciled if, as indicated by preliminary observations, salicylates enhance the toxicity of phenacetin derivatives. In planning a programme of prevention for the analgesic syndrome, the central aetiological role of non-narcotic drug dependency must be recognized. As the analgesics to which addiction commonly occurs are the compound powders and tablets, or those containing a stimulant, these preparations should be available only in circumstances where their use can be monitored. Suspected unsupervised and unwarranted consumption of analgesics should be checked by urinary testing for drug metabolites. Because the underlying problem of analgesic dependency is behavioural and environmental in origin rather than medical, the physician must combine forces with the social engineer to devise a definitive solution for this condition.

Analgesic abuse nephropathy

Analgesic abuse nephropathy is seldom considered as a cause in patients presenting with chronic renal disease. In a three-year period 450 patients were seen with chronic renal failure. Of these 103 had interstitial renal disease as the cause of their failure. Twenty of these 103 were due to chronic analgesic abuse, which indicates that need for a greater awareness of this problem. The spectrum of clinical and roentgenographic aspects of analgesic abuse nephropathy are discussed. What constitutes analgesic abuse, helpful clinical findings, frequency of other medical illnesses, and the low incidence of documented renal infection prior to onset of renal failure are discussed. Intravenous pyelographic findings related to visualization, renal size, corticomedullary margins and pelvicalyceal changes are also discussed and demonstrated.

Neoplasia in the rat induced by N-hydroxyphenacetin, a metabolite of phenacetin

N-hydroxyphenacetin, a phenacetin metabolite, was fed to rats as a 0.05-0.5% dietary supplement. After 9 months, tumours of the liver were found in 36 of 64 animals. One animal also developed a renal tumour. No tumours were found in control animals. The findings implicate phenacetin as a carcinogen and suggest that N-hydroxyphenacetin may be the metabolite responsible.

The radiological diagnosis of analgesic nephropathy

A study was made of the radiological findings in 57 patients with a clinical diagnosis of analgesic nephropathy. The ages of the patients ranged from 27 to 72 years, and females predominated over males in the ratio 4-7 to 1. Renal failure varied from mild to very severe and the patients showed the usual high incidence of analgesic-induced gastro-intestinal, haematological and neurological disorders. In 82% of cases, kidneys were of normal size, but there was radiological evidence of reduced renal function in 85%. Thus, a small kidney with good renal function was unlikely to be due to analgesic nephropathy. Medullar necrosis was observed in 65%, and papillary atrophy and papillary necrosis each in 46%. Although usually gradual, acute massive sloughing of necrotic papillae could occur and occasionally led to ureteric obstruction. Papillary cavitation was seen in 39% but fistulae and ring shadows were observed in only 11% and 14% respectively, while renal calcification occurred in 26%. With the use of high dose techniques and retrograde pyelography, it is almost always possible to make a positive radiological diagnosis of analgesic nephropathy, even in patients with markedly reduced renal function.

Analgesic abuse syndrome: a frequently overlooked cause of reversible renal failure

The incidence of analgesic nephropathy in the United States is greater than previously reported. Because of the characteristic radiographic features of papillary necrosis, this diagnosis may be made while it is still clinically unsuspected. Early diagnosis is extremely important because cessation of analgesic abuse may avert progressive renal damage. Uncovering the diagnosis calls for special care in obtaining the telltale history. This must be sought in patients with radiographic evidence of papillary necrosis when a history of diabetes mellitus, obstructive uropathy, or sicle cell anemia is absent, or in patients with unexplained nephrocalcinosis or nephrolithiasis.

Urinary enzymes and kidney damage by aspirin and phenacetin

Two groups of rats were given aspirin and phenacetin in their food at daily doses similar to those taken by humans suffering from analgesic abuse. Both drugs damaged the kidney proximal tubules although phenacetin affected the kidney more severely than aspirin. At the start of the experiment aspirin increased the urinary excretion of lactate dehydrogenase (LDH) while phenacetin raised the excretion of all four enzymes studies (acid phosphatase, alkaline phosphatase, glutamate dehydrogenase (GDH), LDH indicating generalised cellular injury. Subsequent samples of urine collected from rats up to seven weeks showed normal urinary enzyme levels. The value of urinary enzyme measurements in detecting renal damage by drugs is discussed.

Analgesic abuse in urological practice

Thirty-three patients seen in a urological department had taken large doses of analgesic for prolonged periods of time. In 9 cases a diagnosis of pyramidal necrosis was established, while 4 other had pyelographic evidence of pyelonephritis, and analgesic abuse was probably an important aetiological factor in their renal condition. Analgesic nephropathy is easily overlooked unless patients are questioned routinely regarding their intake of analgesic. It is important to identify the group of patients without evidence of serious renal disease who are taking excessive quantities of analgesic and to urge them to abandon the practice.

Analgesic nephropathy

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Possible role of laxatives in analgesic nephropathy

Eight out of ten of patients with analgesic nephropathy were regular and usually heavy laxative takers compared with 12 out of 200 controls from the general population and four out of 70 patients attending a renal clinic. The finding that regular laxative taking was greatly increased in patients with analgesic nephropathy suggests that this condition may often be due to the combined abuse of both laxatives and analgesics. In a series of 40 patients with rheumatoid arthritis all were found to have normal renal function and no patient took laxatives regularly. This finding would explain why analgesic nephropathy is so uncommon in patients with rheumatoid arthritis despite the fact that they are regular and heavy analgesic takers.

Aspirin and analgesic nephropathy

Renal function was studied in 17 patients with rheumatoid arthritis who had each consumed between 5 and 20 kg of aspirin. After an interval of two years 14 of these patients-seven of whom had consumed a further mean of 2 kg of aspirin-had their renal function retested. No relation was found between total dose, rate, or duration of ingestion and any aspect of renal function that was studied. All patients had plasma creatinine levels within the normal range, though slight depression in creatinine clearance was not uncommon.From this study and other published data we conclude that aspirin rarely if ever causes analgesic nephropathy when prescribed alone in doses appropriate to the treatment of rheumatoid arthritis.

Aspirin and the kidney. New Zealand Rheumatism Association Study

A survey of 763 patients with rheumatoid arthritis and 145 with osteoarthritis in six clinics in New Zealand showed no association between aspirin intake and a score designed to detect analgesic nephropathy. Analgesic nephropathy was diagnosed clinically in three patients taking APC (aspirin, phenacetin, and caffeine or codeine or both) and in one who took aspirin and phenylbutazone and was suspected in one who took aspirin and paracetamol. Isolated aspirin was not implicated. The study showed that most people can take large quantities of salicylates without renal injury.The findings are, however, consistent with the view that there is a risk from APC compounds taken in large quantity, but the numbers at risk in this study were small. Aspirin may have an additive effect with other analgesics in causing renal damage. An increased frequency of urinary tract symptoms in those taking analgesics requires further investigation.

Personality factors in analgesic nephropathy

Forty-five patients with analgesic nephropathy showed a trend towards introversion and neuroticism on the Eysenck Personality Inventory. Other analgesic abusers without renal impairment also showed these traits, while controls with renal disease not due to analgesie abuse were significantly less introverted and neurotic. It is suggested that these personality traits predisposed the patients to analgesie abuse and therefore to renal damage.

The surgical management of acute renal papillary necrosis

Analgesic nephropathy can present as an obstructive uropathy by ureteric impaction of a sloughed renal papilla. Five out of 12 patients admitted with analgesic nephropathy presented with obstructive renal failure. Endoscopic surgery to deal with the obstruction was successful in every case. Removal of the necrotic renal papilla with a Dormia ureteric stone basket was performed six times whilst ureteric catheterization was sufficient to restore urine flow on two occasions. Two of the 5 patients had had a previous nephrectomy for obstructive pyelonephritis. These results suggest that endoscopic surgery is safe and effective in the treatment of acute obstructive renal papillary necrosis.

Analgesic nephropathy

Sixty-six patients were seen from January 1963 to December 1970 in whom a diagnosis of analgesic nephropathy was made. The ratio of women to men was 2.7:1 and women presented at an earlier age. Over 60% of patients had or developed urinary tract infection and over one-third presented with serum urea levels over 300 mg/100 ml. Hypertension was present in 60% of patients and almost 20% had a history of peptic ulcer; hysterectomy had been done in 35% of the women. Most patients improved initially but more than half of those followed up died within five years of presentation. A direct relation was found between prognosis and the degree of functional renal impairment at presentation. Hypertension appeared to have an adverse effect on prognosis but no relation of prognosis to papillary necrosis, infection, or surgical procedures was found.

The use and abuse of analgesics

Of 740 Glasgow citizens studied 13.6 per cent denied ever taking analgesics while 12.3 per cent took them weekly and a further 5.0 per cent daily. Three fifths of those taking daily analgesics did so without reference to a doctor. Aspirin and paracetamol were most popular in social classes I and II while Askit were mainly used by social classes IV and V. Aspirin was the preparation of choice of those who rarely took analgesics but its popularity declined the more frequently analgesics were taken. Askit, however, were twice as popular amongst the daily self-medicators as amongst those who rarely took analgesics. Patients with renal disease, psychiatric patients, and those with psychogenic pain were much more likely to have abused analgesics than the general population. Although the risks of excessive analgesic ingestion are considerable, in Glasgow alone over 8,000 people may be abusing analgesics.

Analgesic nephropathy: removal of phenacetin from proprietary analgesics

Since phenacetin was withdrawn from Askit Powders and Beecham's Powders in 1966 these preparations have declined in importance as a cause of analgesic nephropathy in Western Scotland. In most patients with analgesic nephropathy who persist in abuse of compound analgesics renal function continues to decline. The deterioration, however, is less rapid among those taking aspirin and caffeine mixtures than in those taking preparations which also contain phenacetin.