Nonsteroidal anti-inflammatory drugs pyrazolones

Little information is available regarding tissue distribution or metabolic products of nonsteroidal anti-inflammatory drugs in cattle. The early synthetic compounds were simple derivatives either of salicylic acid such as acetylsalicylic acid and methylsalicylic acid, or of pyrazolone such as metamizole, oxyphenbuta-zone, phenylbutazone, propylphenazone, and suxibuzone. Modern nonsteroidal anti-inflammatory drugs are derivatives either of anthranilic acid such as dido-... 

The eight groups of nonsteroidal anti-inflammatory drugs are salicylates, parachlorobenzoic acid derivatives, pyrazolone derivatives, propionic acid derivatives, fenamates, oxicams, phenylacetic acid, and selective COX-2 inhibitors. 

However, a patient sensitized to another prodrug, pyrazinobutazone, a piperazine salt of phenylbutazone, reacted with a flare-up to oral provocation (Dorado Bris et al. 1992). Benzydamine, a topical and systemic nonsteroidal anti-inflammatory drug has caused two cases of occupational sensitization (Foti et al. 1992). An unusual case of a multilocular fixed drug eruption upon inhalation of pyrazolones with positive oral provocation has also been described (Vanuytrecht-Henderickx et al. 1986). 

Fig. 9.4 Some important pyrazolone nonsteroidal anti-inflammatory drugs showing the 1-phenyl-2,3-dimethyl-3-pyrazoline-5-one common core structure in bold...

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