Zidovudine
Zidovudine (AZT) is a **nucleoside reverse transcriptase inhibitor (NRTI)** used primarily in veterinary medicine as an adjunctive treatment for **feline immunodeficiency virus (FIV)** and **feline leukemia virus (FeLV)**. * **Clinical Utility**: While it can reduce the viral load in infected cats and improve clinical signs (such as stomatitis or neurological manifestations), it is not a cure and may not significantly alter the natural long-term course of the disease. * **Clinical Pearl**: Because retroviruses integrate into the host genome, NRTIs like zidovudine are most effective at preventing the infection of new cells rather than clearing already infected cells.
กลไกการออกฤทธิ์: Zidovudine is a synthetic thymidine analogue. * **Mechanism**: It is converted *in vivo* by cellular kinases into its active metabolite, **zidovudine triphosphate**. * **Pathway**: Zidovudine triphosphate competes with natural thymidine triphosphate for incorporation into viral DNA by **viral RNA-directed DNA polymerase** (→ **reverse transcriptase**). * **Effect**: Because zidovudine lacks a 3'-OH group, its incorporation prevents the formation of phosphodiester linkages, leading to **DNA chain termination** and a virustatic effect against retroviruses. * It also possesses some activity against gram-negative bacteria and can exhibit host cell cytotoxicity (particularly in rapidly dividing cells like bone marrow).
ขนาดยาตามชนิดสัตว์
- Adjunctive therapy of FeLV and FIV · 5-10 mg/kg PO or SC q12h · PO, SC · q12h · Higher dose should be used carefully as side effects can develop. For SC injection, dilute lyophilized product in isotonic sodium chloride to prevent local irritation. For PO, syrup or gelatin capsules can be used.
- Adjunctive therapy of FeLV and FIV · 5-10 mg PO or SC q12h · PO, SC · q12h · Note: Dose is in mg per cat, not mg/kg. Higher dose should be carefully used in FeLV-infected cats because side effects, particularly non-regenerative anemia, can develop.
- FeLV · 5 mg/kg PO or SC q12h · PO, SC · q12h · If giving SC, dilute in sterile normal saline to prevent local irritation. Check CBC weekly the first month.
- FIV encephalopathy · 20 mg/kg PO q12h · PO · q12h
ขนาดยาเป็นข้อมูลอ้างอิงทางคลินิกสำหรับสัตวแพทย์ผู้มีใบอนุญาต โปรดตรวจสอบกับฉลากล่าสุดและผู้ป่วยแต่ละรายเสมอ
วิธีการให้ยา
ข้อห้ามใช้
- Patients with a history of life-threatening hypersensitivity reactions to zidovudine
อาการไม่พึงประสงค์
- Non-regenerative anemia (most common in cats, dose-dependent)
- Reductions in RBCs, PCV, and hemoglobin
- Diarrhea
- Weakness
- Granulocytopenia (reported in humans)
- Gastrointestinal effects
อันตรกิริยาระหว่างยา
- Azole Antifungals (e.g., ketoconazole) · May increase zidovudine levels
- Atovaquone · May increase zidovudine levels
- Doxorubicin · May antagonize each other's effects; avoid concurrent use. Also increases risk of hematologic toxicity.
- Interferon alfa · Increased risk for hematologic and hepatotoxicity
- Probenecid · May increase zidovudine levels
- Myelo-/Cytotoxic Drugs (e.g., chloramphenicol, flucytosine, vincristine, vinblastine) · Administered with zidovudine may increase the risk of hematologic toxicity
- Rifampin · May decrease blood levels (AUC) of zidovudine
การติดตาม
- CBC (Complete Blood Count): Weekly for the first month of treatment (non-regenerative anemia is common, especially at higher doses). If stable, monthly checks are sufficient.
- Hematocrit: If PCV drops below 20%, treatment should be discontinued (anemia usually resolves within a few days).
- CD4/CD8 ratios (if possible)
- Clinical efficacy and improvement of signs
การได้รับยาเกินขนาด
Human adults and children have survived massive oral overdoses (up to 50 grams) without permanent sequelae. * **Clinical Signs**: Vomiting and transient hematologic effects (e.g., bone marrow suppression) are the most consistent adverse effects reported with acute overdoses. * **Management**: Treatment is largely supportive and symptomatic, focusing on gastrointestinal decontamination if caught early, and monitoring hematologic parameters.
ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต