The toxicity of three gold compounds in laboratory animals

The role of conventional pathology and toxicology in evaluating the immunotoxic potential of xenobiotics

Investigating the immunotoxic potential of candidate drugs as part of a preclinical safety evaluation poses several problems. These include the need for practical, validated tests, the difficulty in establishing the toxicologic significance of positive findings, and a poor understanding of the predictive value such findings hold for drug effects in man. A key component of this investigation is the toxicologic profile generated through preclinical toxicity and safety studies. As this "routine" assessment becomes increasingly comprehensive and sophisticated, most toxicologically significant drug-associated effects are revealed. Such findings may serve as "triggers" for investigating possible immune mechanisms. Decisions to test specifically for immunotoxicity may also be influenced by the molecular structure and pharmacologic profile of the compound, as well as the intended use of the drug. Examples of such indications and follow-up studies are discussed in this review. We are presently poorly equipped to effectively screen drugs indiscriminately for an immunotoxic potential. We are better prepared, however, to investigate whether a drug-associated change is due to an adverse effect on the immune system. This problem-oriented approach to immunotoxicology challenges us as diagnosticians and immunopathologists, and requires a close working relationship among the toxicologic pathologist, the basic immunologist, the immunopharmacologist, and the clinician.

Lymphadenopathy and lymph node infarction in the course of gold therapy

Lymphadenopathy, as a complication of gold therapy, appears to be an uncommon occurrence. Lymph node infarction has not been previously documented in this setting. The unique pathologic features in this case may reflect: a phenomenon specific to gold; early examination of the infarcted node; or underlying leukocytoclastic angiitis secondary to gold toxicity. Polymorphonuclear leukocytic infiltration of an infarcted lymph node has apparently not been previously reported.

Auranofin: a unique oral chrysotherapeutic agent

Auranofin is a chemically unique gold coordination complex with demonstrated antiarthritic properties on oral administration. Its pharmacokinetic and immunologic profiles are distinct from injectable gold compounds. When auranofin is added to a regimen of salicylates and/or a nonsteroidal antiinflammatory drug for the treatment of RA, significant additional therapeutic benefit is observed. Published studies indicate that auranofin given 6 mg per day approaches the efficacy of parenteral gold salts in the treatment of rheumatoid disease. Noticeable improvement in clinical and laboratory parameters of disease activity has been observed by the third month of auranofin therapy. Further benefit occurs in some patients during the remainder of the first year of treatment. In the more than 3,000 patients treated with auranofin, the most frequently reported side effects were gastrointestinal (mainly diarrhea) and mucocutaneous. Most side effects were mild in nature and the withdrawal rate due to all adverse reactions averaged 11%. Auranofin differs from injectable gold by producing more gastrointestinal but fewer mucocutaneous reactions. The severity of these reactions is less with auranofin and causes fewer withdrawals from therapy.

Effects of various substances on two types of inflammatory reaction in animals

The effects of 16 substances, including non-steroidal anti-inflammatory agents, a corticoid, phenols, immunomodulators and gold salts, were studied using two types of acute inflammatory reaction, a non-specific reaction (carrageenan-induced oedema) and an immune reaction (reversed passive Arthus reaction in the rat or active Arthus reaction in the mouse). Results revealed that the active Arthus model appears to be more selective than the passive reversed Arthus model, which is itself less sensitive than the carrageenan model. The active Arthus reaction might be useful for secondary screening of molecules that act on mechanisms modulating the intervention of complement and the various functions of polymorphonuclear leucocytes, and the passive Arthus reaction appears to be more suitable for preliminary screening. The activities of the different substances studied are discussed in terms of their modes of action and toxicity.

Effect of aurothioglucose on liver and kidney concentrations of copper, iron, manganese and zinc

Sixty male Swiss-Webster mice were given intraperitoneal injections of the gold-containing drug aurothioglucose in saline at 3 dose levels: 50, 200, and 400 mg/kg. Controls received i.p. injections of saline. Ten injections were administered over a 3-week period. After sacrifice, kidney and liver concentrations of gold, copper, zinc, iron, and manganese were determined by atomic absorption spectrophotometry and tissues were examined by light microscopy. Dose related increases in liver and kidney gold were found and kidney copper also increased significantly with increasing renal gold content. Kidney copper was 5.05 +/- 0.80 ppm in control animals, and 7.81 +/- 1.11 ppm, 13.01 +/- 2.49 ppm, and 17.11 +/- 4.02 ppm in mice receiving 50, 200, and 400 mg/kg aurothioglucose respectively. Renal zinc and liver zinc and copper were also significantly (P less than 0.01) increased in mice receiving the highest dose of aurothioglucose. There were no other statistically significant differences in tissue concentrations among the various groups of animals for the other liver and kidney metal concentrations determined. Tubular epithelial cells of aurothioglucose-dosed animals often had cytoplasmic vacuoles which contained granular brown-gold material; this effect was dose-related.