Cyclosporine
Cyclosporine is a highly lipophilic polypeptide agent originally isolated from the fungus *Tolypocladium inflatum*. In veterinary ophthalmology, it is the cornerstone therapy for **keratoconjunctivitis sicca (KCS)**, commonly known as dry eye, and **chronic superficial keratitis (Pannus)** in dogs. Beyond its tear-stimulating properties, cyclosporine reduces corneal pigmentation and granulation associated with chronic inflammation. **Clinical Pearl:** Because it is extremely hydrophobic, ophthalmic formulations require specific vehicles (like corn/olive oil in compounded drops, or specific ointment bases) for corneal penetration. It is generally safe for long-term topical use without systemic immunosuppressive side effects.
กลไกการออกฤทธิ์: Cyclosporine is a **calcineurin inhibitor**. It binds to cyclophilin within T-lymphocytes, inhibiting the enzyme calcineurin → prevents dephosphorylation of Nuclear Factor of Activated T-cells (NFAT) → **blocks transcription of interleukin-2 (IL-2)** and other inflammatory cytokines. In the eye, this halts local inflammatory mediator production, arresting self-perpetuating lacrimal adenitis. It also acts as a **prolactin analog**, fitting onto lacrimal prolactin receptors to directly stimulate tear production. Furthermore, it increases conjunctival mucin stores, improving the overall quality of the tear film.
ขนาดยาตามชนิดสัตว์
- Keratoconjunctivitis sicca (KCS) · Not recommended · topical ophthalmic · Preliminary results have not been promising; often aggravates ophthalmic herpes virus infections.
- Keratoconjunctivitis sicca (KCS) · 0.2% ointment · topical ophthalmic · twice daily (up to 3 times a day initially in difficult cases) · Life-long · 3-8 weeks of therapy are necessary before a dramatic increase in the Schirmer tear test becomes evident.
- German Shepherd Pannus (chronic superficial keratitis) · 0.2% ointment · topical ophthalmic · twice daily · Life-long · Preferred over chronic topical corticosteroids due to lack of systemic side effects.
ขนาดยาเป็นข้อมูลอ้างอิงทางคลินิกสำหรับสัตวแพทย์ผู้มีใบอนุญาต โปรดตรวจสอบกับฉลากล่าสุดและผู้ป่วยแต่ละรายเสมอ
วิธีการให้ยา
ข้อห้ามใช้
- Feline keratoconjunctivitis sicca associated with active herpes virus infection
- Feline eosinophilic keratitis (historically, though newer evidence varies, the monograph notes it is not promising)
อาการไม่พึงประสงค์
- Mild ocular irritation upon application
- Aggravation of ophthalmic herpes virus infections (especially in cats)
อันตรกิริยาระหว่างยา
- Itraconazole · Inhibits cytochrome P450 metabolism of ciclosporin, increasing blood concentrations up to five-fold. Dose reduction (halving dose or doubling interval) is required. · major
- Ketoconazole · Inhibits cytochrome P450 metabolism of ciclosporin, significantly increasing blood concentrations. · major
- Diltiazem · Competitively inhibits enzymes involved in ciclosporin metabolism, increasing serum levels. · moderate
- Doxycycline · Inhibits enzymes involved in ciclosporin metabolism, increasing serum levels. · moderate
- Aminoglycosides · Increased risk of nephrotoxicity; concomitant use is not recommended. · major
- NSAIDs · Increased risk of nephrotoxicity; concomitant use is not recommended. · major
- Quinolones · Increased risk of nephrotoxicity; concomitant use is not recommended. · moderate
- Trimethoprim/Sulphonamides · Increased risk of nephrotoxicity; concomitant use is not recommended. · moderate
- ACE inhibitors · Increased risk of hyperkalaemia. · moderate
- Macrocyclic lactones (e.g., ivermectin, milbemycin) · Ciclosporin inhibits MDR1 P-glycoprotein, decreasing the efflux of macrocyclic lactones from the blood-brain barrier, potentially resulting in CNS toxicity. · major
การติดตาม
- Schirmer Tear Test (STT) after 1 month of therapy, then periodically
- Fluorescein staining to monitor for corneal ulceration
- Resolution of corneal pigmentation and neovascularization
การได้รับยาเกินขนาด
Systemic toxicity has **not** been noted in dogs given this drug chronically via the topical ophthalmic route. Even if 100% of the ophthalmic dose were absorbed, it is well below the systemic therapeutic/toxic dose.
ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต