Description
Firocoxib is a selective inhibitor of COX-2 (IC
50s = 0.13 and 7.5 μM for COX-2 and COX-1, respectively, in isolated cat blood). It inhibits LPS-induced production of prostaglandin E
2 (PGE
2; ) in isolated dog, horse, and cat whole blood
ex vivo. Firocoxib decreases lameness, induces analgesia, and improves range of motion in dogs and horses with osteoarthritis when administered at doses of 5 and 0.1 mg/kg per day, respectively. Formulations containing firocoxib have been used in dogs and horses with osteoarthritis.
Chemical Properties
White Solid
Uses
A selective cyclooxygenase-2-(COX-2) inhibitor. Anti-inflammatory; analgesic.
Definition
ChEBI: An enol ether that is the cyclopropylmethyl ether of 3-hydroxy-5,5-dimethyl-4-[4-(methylsulfonyl)phenyl]furan-2-one. A selective cyclooxygenase 2 inhibitor, it is used in veterinary medicine for the control of pain and inflammation associated with osteoart
ritis in horses and dogs.
brand name
Equioxx (Merial).
Mechanism of action
Firocoxib is a non-steroidal anti-inflammatory drug (NSAID) belonging to the Coxib group, which acts by selective inhibition of cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis. Cyclooxygenase is responsible for the generation of prostaglandins. COX-2 is the isoform of the enzyme induced by pro-inflammatory stimuli and has been postulated to be primarily responsible for synthesizing prostanoid mediators of pain, inflammation, and fever. Coxibs, therefore, display analgesic, anti-inflammatory, and antipyretic properties. COX-2 is also thought to be involved in ovulation, implantation, and closure of the ductus arteriosus and central nervous system functions (fever induction, pain perception, and cognitive function).
Pharmacokinetics
Firocoxib has a half-life of 7.8 hours in dogs, 9-12 hours in cats, 11 hours in foals, 30-40 hours in adult horses, and 6.7 hours in calves. Because of shorter half-life, the concentrations are lower in foals compared to adult horses. It is highly protein bound (96%-98%). Oral absorption is 38% in dogs, 79%-100% in horses, approximately 100% in calves, and 54%-70% in cats. Feeding delays absorption but does not diminish overall absorption. In horses, oral absorption is 79%-100% with oral paste at a dose of 0.1 mg/kg, and 88% when the canine tablets are administered (no significant difference in absorption between oral paste and tablets). Fasted horses have higher absorption than fed horses[1].
Veterinary Drugs and Treatments
Firocoxib is indicated in dogs and horses for the control of pain
and inflammation associated with osteoarthritis. A chewable tablet
form for dogs and an oral paste for horses are available.
Like other NSAIDs, firocoxib can be useful for treating fever,
pain, and/or inflammation associated with other conditions, postsurgery,
trauma, etc.
Firocoxib may also be useful in other species, but information is
scant regarding its safety and efficacy. One study in cats (McCann,
Rickes et al. 2005) evaluating firocoxib in experimentally induced
pyrexia, demonstrated that the drug was effective after a single
oral dose in preventing or attenuating pyrexia at all doses studied
(0.75 – 3 mg/kg).
References
[1] Mark G. Papich DVM. “Firocoxib.”Saunders Handbook of Veterinary Drugs (Fourth Edition) (2016): 324-327.
