Cyclosporine is a calcineurin inhibitor immunosuppressant that is FDA-approved for the treatment of atopic dermatitis in dogs (as Atopica, manufactured by Elanco). It modulates the immune system rather than broadly suppressing it like corticosteroids, making it useful for chronic conditions requiring long-term management. In addition to allergic skin disease, cyclosporine is used off-label for a wide range of immune-mediated conditions in both dogs and cats. The human brand Neoral is sometimes used interchangeably with Atopica, though only the modified (microemulsion) formulation should be used for pets.
What Is Cyclosporine Used For?
Cyclosporine is prescribed for immune-mediated and inflammatory conditions:
- Atopic dermatitis in dogs — FDA-approved indication (Atopica); long-term management of chronic allergic skin disease
- Perianal fistulas (anal furunculosis) — one of the most effective treatments for this painful condition
- Immune-mediated diseases — immune-mediated hemolytic anemia (IMHA), immune-mediated thrombocytopenia (ITP), immune-mediated polyarthritis
- Inflammatory bowel disease (IBD) — in dogs and cats with steroid-refractory disease
- Keratoconjunctivitis sicca (KCS/dry eye) — ophthalmic formulation (Optimmune) stimulates tear production
- Feline allergic dermatitis — off-label but widely used
- Feline stomatitis — severe oral inflammation in cats
- Sebaceous adenitis — a skin disease affecting hair follicle glands
How Does Cyclosporine Work?
Cyclosporine works by binding to an intracellular protein called cyclophilin. The cyclosporine-cyclophilin complex inhibits calcineurin, an enzyme critical for activating T-lymphocytes. T-cells are a type of white blood cell central to the immune response that drives allergic inflammation and autoimmune disease. By blocking T-cell activation, cyclosporine reduces the production of inflammatory cytokines (especially interleukin-2) and dampens the immune response driving the disease.
Unlike corticosteroids, cyclosporine does not broadly suppress all immune cell types and does not cause the polydipsia, polyuria, and muscle wasting associated with chronic steroid use. However, it does reduce immune surveillance, which means monitoring for infections is important during treatment.
Dosage
Your veterinarian will determine the exact dose.
Dogs
| Dog’s Weight | Typical Starting Dose | Frequency |
|---|---|---|
| 10 lbs (4.5 kg) | 23 mg | Once daily |
| 25 lbs (11.3 kg) | 57 mg | Once daily |
| 50 lbs (22.7 kg) | 113 mg | Once daily |
| 75 lbs (34 kg) | 170 mg | Once daily |
| 100 lbs (45 kg) | 227 mg | Once daily |
Standard dose: 5 mg/kg once daily for atopic dermatitis. After 4-8 weeks of good control, many dogs can be stepped down to every-other-day dosing. Immune-mediated diseases may require higher doses initially.
Cats
| Cat’s Weight | Typical Dose | Frequency |
|---|---|---|
| 6-12 lbs (2.7-5.4 kg) | 25-50 mg | Once daily |
Standard feline dose: 5-7 mg/kg once daily. Atopica for Cats is available as an oral solution.
How to Give Cyclosporine to Your Dog or Cat
- Give on an empty stomach (at least 1-2 hours before or after food) for optimal absorption.
- Atopica capsules (dogs): Available in 10 mg, 25 mg, 50 mg, and 100 mg capsules.
- Atopica solution (cats): Oral liquid administered directly or mixed with a small amount of food.
- Do NOT use non-modified cyclosporine (Sandimmune) — it has unpredictable absorption. Only use modified formulations (Atopica, Neoral, or their generics).
- GI side effects (vomiting) are common in the first 1-2 weeks and often improve with continued use. Freezing the capsules before administration may reduce nausea.
- If your pet has been stable for 4-8 weeks, your veterinarian may try tapering to every-other-day dosing.
Side Effects
| Common Side Effects | Serious Side Effects (Contact Your Vet) |
|---|---|
| Vomiting (most common, especially early) | Opportunistic infections |
| Diarrhea or soft stool | Persistent vomiting or severe GI distress |
| Decreased appetite (transient) | Gum overgrowth (gingival hyperplasia) |
| Excessive hair growth (hypertrichosis) | |
| Papillomatosis (wart-like growths) | |
| Signs of serious infection (fever, lethargy) |
Vomiting is the most common side effect, affecting up to 25-30% of dogs in the first few weeks. Strategies to reduce nausea include giving the capsule frozen, giving a small bland meal 30 minutes before the dose, or temporarily splitting the dose into twice daily.
Drug Interactions
- Ketoconazole: Commonly used intentionally to increase cyclosporine blood levels (allows lower cyclosporine doses and reduced cost). However, this must be done under veterinary supervision with blood level monitoring.
- Other CYP3A4 inhibitors (itraconazole, erythromycin, grapefruit juice): Increase cyclosporine levels.
- Phenobarbital, rifampin: Decrease cyclosporine levels by increasing metabolism.
- NSAIDs: May increase kidney stress when combined.
- Other immunosuppressants (azathioprine, corticosteroids): Additive immunosuppression.
- Vaccines: Cyclosporine may reduce immune response to vaccines. Discuss vaccination timing with your veterinarian.
Contraindications
- Known hypersensitivity to cyclosporine
- Active serious infections — immunosuppression can worsen infections
- Dogs under 6 months of age or weighing less than 4 lbs
- Pregnant or lactating animals — safety not established
- Malignant neoplasia — immunosuppression may theoretically promote tumor growth (though clinical evidence is limited)
Storage
- Store at controlled room temperature, 68-77degF (20-25degC).
- Do not refrigerate or freeze (unless freezing capsules briefly before dosing to reduce nausea).
- Keep in original packaging.
- Keep out of reach of children and pets.
Cost & Availability
Cyclosporine is available as both veterinary (Atopica) and generic human (modified cyclosporine) formulations.
- Atopica (brand): $50-$150+ per month depending on dog size
- Generic modified cyclosporine: 30-50% less expensive than brand
- Ketoconazole co-administration strategy: Can reduce cyclosporine cost by 50% or more by allowing lower doses (veterinary supervision required)
- Available forms: Capsules (10, 25, 50, 100 mg); oral solution (cats); ophthalmic ointment (Optimmune for dry eye)
Frequently Asked Questions
How does cyclosporine compare to Apoquel? Both treat atopic dermatitis in dogs, but they work differently. Apoquel (JAK inhibitor) provides faster itch relief (within hours vs. weeks for cyclosporine) and is easier to administer. Cyclosporine has a broader immunomodulatory effect and may be preferred for some immune-mediated conditions. Cyclosporine causes more GI side effects initially but may be better for certain patients. Your veterinarian will help choose based on your dog’s specific situation.
What is the ketoconazole “boost” strategy? Ketoconazole inhibits the liver enzyme that metabolizes cyclosporine, causing higher blood levels from a given dose. This allows veterinarians to prescribe a lower dose of cyclosporine while maintaining therapeutic levels. This strategy can significantly reduce the monthly cost of treatment. It must be done under veterinary supervision with blood level monitoring.
Will cyclosporine make my pet more susceptible to infections? As an immunosuppressant, cyclosporine does reduce immune surveillance, which can increase susceptibility to infections. However, at the doses used for atopic dermatitis, the risk is relatively modest compared to high-dose corticosteroids. Your veterinarian will monitor for signs of infection and may recommend periodic wellness exams and blood work.
Sources & References
- FDA - Atopica (Cyclosporine) Approval
- Merck Veterinary Manual - Immunosuppressive Agents
- VCA Hospitals - Cyclosporine
- PetMD - Cyclosporine for Dogs and Cats
- Plumb’s Veterinary Drug Handbook - Cyclosporine
Verification Notes
Cyclosporine’s description as “Calcineurin inhibitor. Atopica is FDA-approved for canine atopic dermatitis. GI upset is common initially. Do not use modified and non-modified forms interchangeably. Monitor kidney/liver function.” is confirmed by the research corpus. The ketoconazole drug interaction and cost-reduction strategy are well-documented in veterinary dermatology practice.