Liver reactions from trimethoprim

Sulfonamide Hypersensitivity

Sulfonamides, particularly antimicrobial sulfonamides, have been implicated as a common cause of a spectrum of hypersensitivity reactions. Immediate IgE-mediated reactions have been reported but are much less common than delayed cutaneous reactions. Delayed cutaneous reactions range from benign exanthems to severe cutaneous reactions such as Stevens Johnson syndrome, toxic epidermal necrolysis, or drug reaction with eosinophilia and systemic symptoms. Sulfonamides can be subclassified as antimicrobial sulfonamides and non-antimicrobial sulfonamides, which are also distinguished by key structural differences, resulting in very low risk of cross-reactivity between these two subclasses. Immediate and delayed skin testing and in vitro testing remain limited as options in evaluating antimicrobial sulfonamide hypersensitivity. Drug challenges continue to play an important role in the evaluation of both immediate and delayed reactions, with a growing body of evidence for the safety of direct challenges regardless of human immunodeficiency virus infection status. While numerous "desensitization" protocols have been described for the management of antimicrobial sulfonamide hypersensitivity, there is limited evidence that such procedures are successful because of an induction of tolerance.

Investigating the Mechanism of Trimethoprim-Induced Skin Rash and Liver Injury

Trimethoprim (TMP)-induced skin rash and liver injury are likely to involve the formation of reactive metabolites. Analogous to nevirapine-induced skin rash, 1 possible reactive metabolite is the sulfate conjugate of α-hydroxyTMP, a metabolite of TMP. We synthesized this sulfate and found that it reacts with proteins in vitro. We produced a TMP-antiserum and found covalent binding of TMP in the liver of TMP-treated rats. However, we found that α-hydroxyTMP is not a substrate for human sulfotransferases, and we did not detect covalent binding in the skin of TMP-treated rats. Although less reactive than the sulfate, α-hydroxyTMP was found to covalently bind to liver and skin proteins in vitro. Even though there was covalent binding to liver proteins, TMP did not cause liver injury in rats or in our impaired immune tolerance mouse model that has been able to unmask the ability of other drugs to cause immune-mediated liver injury. This is likely because there was much less covalent binding of TMP in the livers of TMP-treated mice than TMP-treated rats. It is possible that some patients have a sulfotransferase that can produce the reactive benzylic sulfate; however, α-hydroxyTMP, itself, has sufficient reactivity to covalently bind to proteins in the skin and may be responsible for TMP-induced skin rash. Interspecies and interindividual differences in TMP metabolism may be 1 factor that determines the risk of TMP-induced skin rash. This study provides important data required to understand the mechanism of TMP-induced skin rash and drug-induced skin rash in general.

Scandinavian epidemiological research in gastroenterology and hepatology

In the last decades, a large number of epidemiological studies in gastroenterology and hepatology have originated from the Scandinavian countries. With the help of large health databases, with good validity and other registries related to patient outcomes, researchers from the Scandinavian countries have been able to make some very important contributions to the field. These countries, Sweden, Norway, Finland, Denmark and Iceland, have all universal access to health care and have shown to be ideal for epidemiological research. Population-based studies have been frequent and follow-up studies have been able to describe the temporal trends and changes in phenotypes. Our ability in Scandinavia to follow up defined groups of patients over time has been crucial to learn the natural history of many gastrointestinal and liver diseases and often in a population-based setting. Patient-related outcomes measures will probably gain increasing importance in the future, but Scandinavian gastroenterologists and surgeons are likely to have a better infrastructure for such endeavors compared to most other populations. Thus, there is a bright future for international competitive research within the field of gastrointestinal and liver diseases in Scandinavia.

ADVERSE REACTIONS OF NITROFURANTOIN, TRIMETHOPRIM AND SULFAMETHOXAZOLE IN CHILDREN

PURPOSE

Many children with urological disease require long-term treatment with antibiotics. In many cases the choice of medical instead of surgical management hinges on the implied safety of certain drugs. Recently some groups have advocated subureteral injection procedures to avoid long-term antibiotics for low grade reflux. We present a concise and relevant review on the use and adverse reactions of nitrofurantoin, trimethoprim and sulfamethoxazole in children.

MATERIALS AND METHODS

We reviewed the literature regarding the safety and toxicity of these drugs. Information regarding absorption, excretion and dosing was also gathered to explain better the mechanisms of toxicity.

RESULTS

Adverse reactions in children reported in the literature related to nitrofurantoin are gastrointestinal disturbance (4.4/100 person-years at risk), cutaneous reactions (2% to 3%), pulmonary toxicity (9 patients), hepatoxicity (12 patients and 3 deaths), hematological toxicity (12 patients), neurotoxicity and an increased rate of sister chromatid exchanges. Adverse reactions in children related to trimethoprim/sulfamethoxazole are almost exclusively due to the sulfamethoxazole component, including cutaneous reactions (1.4 to 7.4 events per 100 person-years at risk), hematological toxicity (0% to 72% of patients) and hepatotoxicity (5 patients). The majority of adverse reactions were found in children on full dose therapy and not prophylaxis.

CONCLUSIONS

The use of nitrofurantoin, trimethoprim and sulfamethoxazole is safe in children for long-term prophylactic therapy. The antibiotic safety issue should not be misconstrued as an argument for surgical therapy, whether minimally invasive or not. Adverse reactions exist to these medicines but they are less common than seen in adults, presumably because of the lower dose used for therapy, and the lack of significant comorbidities and drug interactions in children. Serious side effects are extremely rare and most are reversible by discontinuing therapy. The extremely low potential for significant adverse reactions should be discussed with parents.

Idiosyncratic toxicity associated with potentiated sulfonamides in the dog

Idiosyncratic toxicity to potentiated sulfonamides occurs in both humans and dogs, with considerable clinical similarities. The syndrome in dogs can consist of fever, arthropathy, blood dyscrasias (neutropenia, thrombocytopenia, or hemolytic anemia), hepatopathy consisting of cholestasis or necrosis, skin eruptions, uveitis, or keratoconjunctivitis sicca. Other manifestations seen less commonly include protein-losing nephropathy, meningitis, pancreatitis, pneumonitis, or facial nerve palsy. The pathogenesis of these reactions is not completely understood, but may be due to a T-cell-mediated response to proteins haptenated by oxidative sulfonamide metabolites. Our laboratory is working on tests to characterize dogs with possible idiosyncratic sulfonamide reactions, to include ELISA for anti-drug antibodies, immunoblotting for antibodies directed against liver proteins, flow cytometry for drug-dependent anti-platelet antibodies, and in vitro cytotoxicity assays. The management of idiosyncratic sulfonamide toxicity involves client education to identify clinical signs early and allow rapid drug discontinuation, supportive care to include possibly ascorbate and glutathione precursors, and avoidance of subsequent re-exposure. It is important to realize that only antimicrobial sulfonamides, such as sulfamethoxazole, sulfadiazine, and sulfadimethoxine, share this clinical syndrome. There is no evidence for cross-reactivity with drugs that have different underlying structures but share a sulfonamide moiety, such as acetazolamide, furosemide, glipizide, or hydrochlorthiazide.

Antibiotic-associated hepatitis: update from 1990

OBJECTIVE

To review the literature on the recent available evidence of antibiotic-associated acute liver injury.

DATA SOURCES

All published articles from January 1990 to July 1995 were extracted from the monthly updated HEPATOX database. Additional articles were found using MEDLINE, EMBASE, and PASCAL searches. Hepatic injuries associated with antituberculous, antimycotic, antiviral, antiprotozoal, and antiseptic compounds were excluded form this review.

STUDY SELECTION

As the amount of literature was large, only case reports, series and epidemiologic data were used. Results from clinical trials were reviewed only when other information was available.

DATA EXTRACTION

Original articles were reviewed to select relevant material. Information regarding the clinical description, histologic features, severity, outcome, and possible risk factors was extracted. Data on incidence were provided by epidemiologic studies or spontaneous reporting to regulatory agencies.

DATA SYNTHESIS

Antibiotic-associated acute injury is rare, with an incidence not exceeding 1 case 10,000 users for most drugs. Among beta-lactams, amoxicillin/clavulanic acid and penicillinase-resistant penicillins are associated with predominant and sometimes protracted cholestasis. The hepatotoxic potential of all available erythromycin salts is confirmed, and recent evidence suggests that roxithromycin could be added to the list of antibiotic-induced liver injury. Among fluoroquinolones, only ciprofloxacin has been associated with serious hepatitis. Trimethoprim/sulfamethoxazole-induced hepatitis often reported, but trimethoprim alone also appears as a possible cause of acute liver injury. Finally, acute bile duct injuries and ductopenia have been described with several antibiotics.

CONCLUSIONS

The most important recent information is the possibility of protracted liver cholestasis with bile duct injuries induced by several antibiotics, particularly penicillinase-resistant penicillins, and the identification of new potentially hepatotoxic antibiotics, namely, roxithromycin, ciprofloxacin, and trimethoprim.