ジドブジン
ジドブジン（AZT）は**ヌクレオシド系逆転写酵素阻害薬（NRTI）**であり、獣医学においては主に猫免疫不全ウイルス（FIV）や猫白血病ウイルス（FeLV）の補助治療として使用されます。 * **臨床的有用性**：感染した猫のウイルス量を減らし、臨床症状（口内炎や神経症状など）を改善する可能性がありますが、完治させるものではなく、疾患の長期的な自然経過を大きく変えるものではありません。 * **臨床のポイント**：レトロウイルスは宿主のゲノムに組み込まれるため、ジドブジンのようなNRTIは、すでに感染した細胞を排除するのではなく、新しい細胞への感染を防ぐのに最も効果的です。
作用機序: 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).
動物種別の用量
- 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
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Patients with a history of life-threatening hypersensitivity reactions to zidovudine
有害事象
- Non-regenerative anemia (most common in cats, dose-dependent)
- Reductions in RBCs, PCV, and hemoglobin
- Diarrhea
- Weakness
- Granulocytopenia (reported in humans)
- Gastrointestinal effects
薬物相互作用
- 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
モニタリング
- 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
過量投与
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.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。