Pharmacokinetics, pharmacodynamics, metabolism, toxicology and residues of phenylbutazone in humans and horses

Abstract

The presence of horse meat in food products destined for human consumption and labelled as beef has raised several concerns of public interest. This review deals solely with one aspect of these concerns; samples of equine tissue from horses destined for the human food chain have tested positive for the non-steroidal anti-inflammatory drug, phenylbutazone. The safety of some or all such foods for human consumers is a major concern, because it was shown many years ago that phenylbutazone therapy in humans can be associated with life threatening blood dyscrasias. As an initial basis for assessing the potential toxicity of foods containing phenylbutazone and its metabolites, this article reviews (1) the pharmacokinetic, pharmacodynamic, metabolic and toxicological profiles of phenylbutazone, with particular reference to horses and humans; (2) toxicity data in laboratory animals; (3) phenylbutazone residues in food producing species, and (4) as a preliminary assessment, the potential hazard associated with the consumption of horse meat containing phenylbutazone and its metabolites. Since phenylbutazone cannot be classified as a carcinogenic substance in humans, and noting that blood dyscrasias in humans are likely to be dose and treatment duration-dependent, the illegal and erratic presence of trace amount residues of phenylbutazone in horse meat is not a public health issue.

Phenylbutazone in horses and man: Properties relevant to safety of humans consuming horse meat containing phenylbutazone and its metabolites

“…This editorial summarises and extends the contents of a recent review (Lees and Toutain 2013). (Lees et al 2004) Phenylbutazone is a nonsteroidal anti-inflammatory drug (NSAID).…”

Preparation and characterization of a composite based on polyaniline, polypyrrole and cigarette filters: adsorption studies and kinetics of phenylbutazone in aqueous media

“…1,2 The use of PBZ in human medicine is hampered because of increased risks of several diseases as agranulocytosis, aplastic anemia, hematemesis, perforation of peptic ulcer, hepatotoxicity, and renal failure. In humans, the pharmacokinetic is characterized by a slow release and the absorption is almost complete after oral dosing.…”

Toxicology for the Equine Practitioner

“…It has been hypothesized that NSAIDS that nonselectively inhibit both COX-1 and COX-2 have greater toxic potential because they not only decrease prostaglandins mediating inflammation, but also prostaglandins necessary for physiologic homeostasis. 44 NSAIDS that are selective inhibitors of COX-2 are thought to be less toxic; nonetheless, most of the NSAIDS used in horses are nonselective inhibitors of the COX enzyme, which increases the risk of adverse effects associated with their use. Although the nonselective inhibition theory is still valid, recent evidence suggests that this theory is overly simplistic.…”