Robenacoxib — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	1-2 mg/kg	q24h	Duration: For osteoarthritis: up to 6 months; for acute pain: 3-7 days; for post-operative pain: 3-5 days Notes: Administer with or without food. For post-operative pain, give 1-2 hours before surgery or at the time of anesthesia induction.
Cat	PO	1-2.4 mg/kg	q24h	Duration: For musculoskeletal pain: up to 6 months; for post-operative pain: 3-5 days Notes: Administer with or without food. For post-operative pain, give 1-2 hours before surgery or at the time of anesthesia induction.
Cat	SC	2 mg/kg	Single dose	Duration: For post-operative pain: single injection before surgery Notes: Use only for peri-operative pain management. Do not repeat within 24 hours.

Clinical Indications & Species Uses

General Indications

Pain and inflammation management in dogs and cats

Dog (Canine)

Treatment of pain and inflammation associated with osteoarthritis
Management of acute musculoskeletal pain
Post-operative pain relief following soft tissue and orthopedic surgery

Cat (Feline)

Treatment of pain and inflammation associated with musculoskeletal disorders
Post-operative pain relief following ovariohysterectomy and other soft tissue surgery

Pharmacology & Mechanism of Action

Drug Class: NSAID | Pharmacological Group: Coxib (selective COX-2 inhibitor)

Mechanism of Action: Robenacoxib is a non-steroidal anti-inflammatory drug (NSAID) of the coxib class, which selectively inhibits the cyclooxygenase-2 (COX-2) enzyme. COX-2 is induced at sites of inflammation and produces prostaglandins that mediate pain, inflammation, and fever. By selectively inhibiting COX-2, robenacoxib reduces the synthesis of pro-inflammatory prostaglandins while sparing COX-1, which is constitutively expressed and responsible for producing prostaglandins that protect the gastrointestinal mucosa, maintain renal blood flow, and support platelet function. This selectivity is dose-dependent and is more pronounced in dogs and cats than in other species, contributing to a favorable gastrointestinal safety profile compared to non-selective NSAIDs.

Pharmacodynamics: Robenacoxib exhibits potent anti-inflammatory, analgesic, and antipyretic effects. In animal models, it has been shown to reduce inflammation and pain associated with acute and chronic musculoskeletal disorders. Its selectivity for COX-2 is high, with a selectivity ratio (COX-1/COX-2) of approximately 100-fold in dogs and cats. The onset of analgesia is rapid, with peak effects observed within 1-2 hours after oral administration. The duration of action is approximately 24 hours, allowing once-daily dosing. Robenacoxib does not significantly affect platelet aggregation at therapeutic doses, and it has minimal effects on gastrointestinal mucosal integrity and renal function when used at recommended doses.

⚡ Pharmacokinetics Summary

Absorption: Robenacoxib is well absorbed after oral administration in dogs and cats. In dogs, the oral bioavailability is approximately 70-80%, with peak plasma concentrations reached within 1-2 hours. In cats, bioavailability is slightly lower, around 50-60%, with peak concentrations at 1-2 hours. Absorption is not significantly affected by food, but administration with food may reduce the rate of absorption. After subcutaneous injection, absorption is rapid and complete, with peak concentrations achieved within 30 minutes.

Distribution: Robenacoxib is highly bound to plasma proteins (greater than 99%) in dogs and cats. It distributes widely into tissues, with high concentrations found in inflammatory exudate and synovial fluid. The volume of distribution is relatively small, approximately 0.2-0.3 L/kg, indicating limited tissue binding. It crosses the blood-brain barrier to a minimal extent.

Metabolism: Robenacoxib is extensively metabolized in the liver, primarily by cytochrome P450 enzymes (CYP2C and CYP3A) and glucuronidation. The major metabolic pathways include hydroxylation and O-demethylation, followed by conjugation. In dogs, the primary metabolite is a hydroxylated derivative, while in cats, glucuronide conjugates are more prominent. The metabolism is species-specific, with cats having a slower rate of glucuronidation, which may affect the half-life.

Excretion: Robenacoxib is eliminated primarily via the biliary route, with a significant portion excreted in feces. In dogs, approximately 70% of the dose is recovered in feces and 20% in urine. In cats, fecal excretion is also predominant. The elimination half-life is approximately 1-2 hours in dogs and 2-3 hours in cats after oral administration, but the pharmacodynamic effect lasts longer due to sustained concentrations at the site of inflammation.

Half-Life: Dog: 1-2 hours; Cat: 2-3 hours; Horse: not established; Cattle: not established; Small ruminants: not established; Rabbit: not established; Birds: not established.

Bioavailability: Dog: 70-80% oral; Cat: 50-60% oral; Subcutaneous injection: 100%.

Protein Binding: Greater than 99% in dogs and cats.

Available Formulations & Strengths

Oral Tablet 5 mg, 10 mg, 20 mg, 40 mg (PO)

Injectable Solution 20 mg/mL (SC)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to robenacoxib or any other NSAID
Gastrointestinal ulceration or bleeding
Renal or hepatic impairment
Dehydration, hypovolemia, or hypotension
Concurrent use of other NSAIDs or corticosteroids
Pregnancy, lactation, or breeding animals (safety not established)
Animals less than 2.5 kg body weight (for tablets)
Cats with chronic renal disease (use with caution)

Warnings & Clinical Precautions:

Use with caution in animals with pre-existing renal, hepatic, or cardiac disease
Monitor for signs of gastrointestinal intolerance (vomiting, diarrhea, decreased appetite)
Avoid use in dehydrated, hypovolemic, or hypotensive animals
Do not exceed recommended dose or duration
In cats, subcutaneous injection should be given only once; subsequent doses should be oral
Safety in young animals (<6 months) has not been fully established
Use with caution in geriatric animals
May mask signs of infection due to anti-inflammatory effects

Adverse Effects & Reactions

Common:

Vomiting
Diarrhea
Decreased appetite
Lethargy
Injection site pain (after SC injection)

Serious / Severe:

Gastrointestinal ulceration or perforation
Renal toxicity (acute renal failure)
Hepatic toxicity
Bleeding disorders

Rare:

Idiosyncratic reactions
Allergic reactions (skin rash, facial swelling)
Neurological signs (ataxia, seizures)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Other NSAIDs (e.g., carprofen, meloxicam)	Increased risk of gastrointestinal ulceration and renal toxicity	High
Corticosteroids (e.g., prednisone, dexamethasone)	Increased risk of gastrointestinal ulceration and renal toxicity	High
ACE inhibitors (e.g., enalapril, benazepril)	Reduced renal blood flow, increased risk of renal toxicity	Moderate
Diuretics (e.g., furosemide)	Increased risk of dehydration and renal toxicity	Moderate
Anticoagulants (e.g., warfarin, heparin)	Increased risk of bleeding	Moderate
Methotrexate	Increased methotrexate toxicity	Moderate

Overdose & Toxicity Management

Signs of Toxicity:

Vomiting
Diarrhea
Gastrointestinal ulceration
Renal failure
Lethargy
Depression
Seizures (in severe cases)

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Induce vomiting if ingestion is recent (within 2 hours) and the animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluid therapy to maintain renal perfusion. Monitor renal and hepatic function. Administer gastroprotective agents (e.g., misoprostol, omeprazole) if gastrointestinal signs occur. In severe cases, consider hemodialysis or peritoneal dialysis. There is no specific antidote.

Food Animal Withdrawal Times

Robenacoxib is not approved for use in food-producing animals. Withdrawal times are not established. Do not use in animals intended for human consumption.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), excursions permitted between 15-30°C (59-86°F).

Handling & Special Conditions: Protect from moisture. Keep in original container. Do not remove desiccant.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved by FDA for use in dogs and cats (Onsior).

Extra-Label (Off-Label) Use: In the United States, robenacoxib is approved for use in dogs and cats. Extra-label use in other species is permitted under AMDUCA only with a valid veterinarian-client-patient relationship and must follow established withdrawal times if used in food animals, but since it is not approved for food animals, extra-label use is highly discouraged and may be prohibited.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Robenacoxib is a highly selective COX-2 inhibitor that provides effective pain relief and anti-inflammatory activity in dogs and cats. It is particularly useful for managing chronic osteoarthritis and acute post-operative pain. Its selectivity for COX-2 over COX-1 results in a lower risk of gastrointestinal adverse effects compared to non-selective NSAIDs, but it is not without risk. It is important to use the lowest effective dose for the shortest duration necessary. In cats, the subcutaneous formulation is convenient for peri-operative use, but it should be used as a single injection. Robenacoxib should be used with caution in animals with renal or hepatic impairment, and renal function should be monitored during long-term therapy. It is contraindicated in animals with known hypersensitivity to NSAIDs. As with all NSAIDs, concurrent use with other NSAIDs or corticosteroids should be avoided. Client education should include signs of adverse effects and the importance of regular veterinary check-ups during long-term therapy.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)