D-Penicillamine: The State of the Art in Humans and in Dogs from a Pharmacological and Regulatory Perspective

Chelant agents are the mainstay of treatment in copper-associated hepatitis in humans, where D-penicillamine is the chelant agent of first choice. In veterinary medicine, the use of D-penicillamine has increased with the recent recognition of copper-associated hepatopathies that occur in several breeds of dogs. Although the different regulatory authorities in the world (United States Food and Drugs Administration-U.S. FDA, European Medicines Agency-EMEA, etc.) do not approve D-penicillamine for use in dogs, it has been used to treat copper-associated hepatitis in dogs since the 1970s, and is prescribed legally by veterinarians as an extra-label drug to treat this disease and alleviate suffering. The present study aims to: (a) address the pharmacological features; (b) outline the clinical scenario underlying the increased interest in D-penicillamine by overviewing the evolution of its main therapeutic goals in humans and dogs; and finally, (c) provide a discussion on its use and prescription in veterinary medicine from a regulatory perspective.

The effect of various avocado oils on skin collagen metabolism

The effects of various avocado oils on collagen metabolism in skin were studied in growing rats fed diets containing 10% (w/w) of the tested oils. Rats fed the unrefined avocado oil extracted with hexane from the intact fruit, its unsaponifiables or the avocado seed oil, showed significant increases in soluble collagen content in skin, though total collagen content was not affected. The increased soluble collagen content appears to be a consequence of the inhibition of lysyl oxidase activity. The active factor was found to be present in the unrefined avocado oil and probably originated from the avocado seed, since collagen metabolism was affected only by fractions which contained lipids fraction from the seed. In comparison rats fed the refined or unrefined soybean oils showed no effects.

Changes in the growth and metabolism of cells cultured from normal, sclerotic and rheumatoid connective tissue brought about by D-penicillamine and by sodium salicylate

D-penicillamine and sodium salicylate were equally effective in suppressing the proliferation of fibroblasts from normal and scleroderma skin and rheumatoid synovial cells. The effects were concentration-dependent, beginning at around 100 microgram/ml, and proliferation was almost halted at 1600 microgram/ml. Individual cell strains of each type showed differences in drug susceptibility but there was no consistent difference between cells from normal and abnormal tissues. Acid mucopolysaccharide secretion was more clearly inhibited in scleroderma fibroblasts than in synovial cells, and penicillamine produced greater inhibition than salicylate, beginning at 10 microgram/ml and reaching almost 50% at 500 microgram/ml. Confluent cultures of scleroderma fibroblasts showed 23% less incorporation of 3H-proline into collagenase-sensitive protein in the presence of 1600 microgram/ml penicillamine, without significant effect on other protein synthesis; sodium salicylate had no effect. These data suggest that D-penicillamine may affect connective tissue metabolism in other ways than by interfering with collagen synthesis or cross-linking.