Oclacitinib Maleate

Janus kinase (JAK) inhibitor Immunomodulatory agent

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 0.4-0.6 mg/kg q12h for up to 14 days, then q24h for maintenance Duration: For allergic dermatitis: initial 14 days, then maintenance as needed; for atopic dermatitis: long-term use as needed
Notes: Administer on an empty stomach or with food; if used for long-term, monitor for infections and hematologic changes.
Cat PO 0.4-0.6 mg/kg (extrapolated) q12h for up to 14 days, then q24h Duration: Limited studies; use with caution and monitor for adverse effects
Notes: Off-label use; not FDA-approved for cats.

Clinical Indications & Species Uses

General Indications
  • Control of pruritus and inflammation in allergic skin conditions (primarily dogs)
Dog (Canine)
  • Control of pruritus associated with allergic dermatitis
  • Control of atopic dermatitis

Pharmacology & Mechanism of Action

Drug Class: Janus kinase (JAK) inhibitor | Pharmacological Group: Immunomodulatory agent

Mechanism of Action: Oclacitinib is a selective inhibitor of Janus kinase 1 (JAK1), which is involved in the signaling of multiple pro-inflammatory and pruritogenic cytokines, including IL-2, IL-4, IL-6, IL-13, and IL-31. By inhibiting JAK1, oclacitinib reduces the phosphorylation and activation of signal transducers and activators of transcription (STATs), thereby decreasing the production of inflammatory mediators and cytokines that drive pruritus and inflammation in allergic skin diseases. It has selectivity for JAK1 over JAK2 and JAK3, which helps minimize effects on hematopoiesis and immune function.

Pharmacodynamics: Oclacitinib rapidly reduces pruritus in dogs with allergic dermatitis, with significant improvement observed within 24 hours. It also reduces skin lesions associated with atopic dermatitis. The drug modulates the immune response by inhibiting cytokine signaling, but does not directly inhibit histamine release or mast cell degranulation. Its effects are reversible upon discontinuation, and it does not cause significant immunosuppression at therapeutic doses, though it may affect certain immune responses.

⚡ Pharmacokinetics Summary

Absorption: Oclacitinib is well absorbed after oral administration in dogs, with peak plasma concentrations reached within 1-2 hours. Food does not significantly affect absorption.
Distribution: Oclacitinib has a moderate volume of distribution, indicating distribution into tissues. It is approximately 64-70% bound to plasma proteins in dogs.
Metabolism: Oclacitinib is extensively metabolized in the liver, primarily by cytochrome P450 enzymes (CYP3A4 and CYP2D6) and other pathways. Multiple metabolites are formed, but they are not pharmacologically active.
Excretion: Oclacitinib is eliminated primarily via metabolism, with metabolites excreted in urine and feces. In dogs, the terminal half-life is approximately 4-5 hours after oral administration.
Half-Life: Dogs: ~4-5 hours; Cats: ~4-6 hours (extrapolated); Horses: not well studied.
Bioavailability: Oral bioavailability is high (approximately 80-90% in dogs).
Protein Binding: 64-70% in dogs

Available Formulations & Strengths

Oral Tablet 3.6 mg, 5.4 mg, 7.2 mg, 10.8 mg, 16 mg (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to oclacitinib or any component of the formulation
  • Dogs with serious infections (should be treated for infection before starting therapy)
  • Dogs with demodicosis (should be treated for mites before starting therapy)
  • Use in breeding, pregnant, or lactating dogs is not recommended (safety not established)
Warnings & Clinical Precautions:
  • Use with caution in dogs with a history of seizures or neurologic disorders
  • May increase susceptibility to infections (e.g., demodicosis, pyoderma, fungal infections); monitor for new infections
  • Monitor complete blood count and serum biochemistry periodically during long-term therapy
  • Do not use in dogs with pre-existing immunosuppression
  • Use with caution in dogs with hepatic or renal impairment
  • Not for use in cats (safety and efficacy not established)
  • Keep out of reach of children; avoid skin contact with broken tablets

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Decreased appetite
  • Lethargy
  • Increased thirst (polydipsia)

Serious / Severe:

  • New or worsening infections (e.g., pyoderma, demodicosis, fungal infections)
  • Hematologic abnormalities (anemia, leukopenia, thrombocytopenia)
  • Pancreatitis (rare)
  • Seizures (rare)

Rare:

  • Hepatotoxicity
  • Cutaneous drug eruptions
  • Interstitial lung disease (reported in humans, not confirmed in dogs)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Corticosteroids (e.g., prednisone) Concurrent use may increase the risk of immunosuppression and gastrointestinal ulceration; use with caution and monitor closely. Moderate
Other immunosuppressive agents (e.g., cyclosporine, azathioprine) Additive immunosuppressive effects; increased risk of infections and bone marrow suppression. High
CYP3A inhibitors (e.g., ketoconazole, itraconazole) May increase oclacitinib plasma concentrations; monitor for increased adverse effects. Moderate
CYP3A inducers (e.g., phenobarbital) May decrease oclacitinib efficacy; monitor therapeutic response. Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Lethargy
  • Anorexia
  • Ataxia
  • Tremors
  • Seizures (in severe cases)

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce emesis if ingestion is recent and the animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluids, antiemetics, and anticonvulsants as needed. Monitor for hematologic and hepatic abnormalities.

Food Animal Withdrawal Times

Not approved for use in food-producing animals; no withdrawal times established. Do not use in animals intended for food.

Storage, Handling & Regulatory Information

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

Handling & Special Conditions: Keep in a tightly closed container. Protect from moisture.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved by FDA for use in dogs for control of pruritus associated with allergic dermatitis and control of atopic dermatitis (Apoquel®).

Extra-Label (Off-Label) Use: In the US, extra-label use in food animals is prohibited. For non-food animals, extra-label use may be permitted under AMDUCA with veterinary oversight, but safety and efficacy may not be established.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Oclacitinib is a first-line therapy for managing pruritus in dogs with allergic dermatitis and atopic dermatitis. It provides rapid relief, often within 24 hours, and is generally well-tolerated. It is important to rule out and treat underlying infections (bacterial, fungal, parasitic) before initiating therapy. Long-term use requires periodic monitoring of CBC and serum chemistry, especially in dogs with concurrent disease. Oclacitinib is not recommended for use in cats due to lack of safety and efficacy data. It should be used with caution in dogs with a history of seizures or immunosuppression. The drug is not approved for food animals, and withdrawal times are not established.

References & Literature

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