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Pharmacological particulars
ATCvet code: QM01AG90
Pharmacotherapeutic group:
Anti-inflammatory and anti-rheumatic products; non-steroids; fenamates; flunixin.
Pharmacodynamic properties
The active substance flunixin (as a meglumine salt) is a carboxylic acid, non-steroidal anti-inflammatory drug (NSAID) with non-narcotic analgesic and antipyretic activities. It demonstrates potent inhibition of the cyclo-oxygenase system (COX-1 and COX-2). COX converts arachidonic acid to instable cyclic endoperoxides, which are converted to prostaglandins, prostacyclin and tromboxane. The inhibition of the synthesis of such components is responsible for the analgesic, antipyretic and anti-inflammatory properties of flunixin meglumine.
In one study, Finadyne Transdermal was investigated in 64 cows with mastitis and efficacy for reducing rectal temperature was compared to placebo, which was used in 66 cows. At six hours post-treatment 95.3% of cows treated with Finadyne Transdermal showed a decrease in rectal temperature of more than 1.1°C, compared with 34.9% in the placebo group. After 6 hours, when antibiotic treatment had been added, there were no differences in rectal temperature between the groups.
Pharmacokinetic properties
After dermal application, flunixin is moderately absorbed through the skin of cattle (bioavailability about 44%). In cattle (except for calves), volumes of distribution are generally low due to the high degree (approximately 99%) of plasma protein binding. The apparent plasma elimination half-life following pour-on administration is about 7.8h. The metabolism of flunixin is rather limited, most of the drug corresponding to the unchanged parent compound and the remaining metabolites derived from hydroxylation. In cattle, elimination occurs primarily through biliary excretion.
After pour-on treatment, faster absorption of flunixin was observed in warmer conditions compared to colder conditions. In warm conditions (environmental temperatures between 13 °C and 3 0°C) the Tmax was about 2 hours whereas it was about 6 hours in cold conditions (environmental temperatures between -3 °C and 7 °C).
Anti-pyretic effect has been demonstrated from 4 hours after application of the product.