頭孢維星
**頭孢維星 (Cefovecin)** 是一種專為犬貓設計的長效注射型第三代頭孢菌素類抗生素。 **主要臨床特徵：** * **提高依從性：** 其主要臨床優勢在於解決飼主難以按時餵藥的問題，或適用於對口服抗生素耐受性差、吸收不良的病患。 * **抗菌譜：** 作為第三代頭孢菌素，具有廣效抗菌活性。對常見的皮膚病原體（如假中間葡萄球菌、犬鏈球菌G群及多殺性巴斯德桿菌）高度有效。 * **局限性：** 對綠膿桿菌 (Pseudomonas spp.) 或腸球菌 **無效**。此外，由於其高蛋白結合率，在標準標籤劑量下，無法達到足夠的血清濃度來治療全身性（非泌尿道）的大腸桿菌感染。 * **藥代動力學特點：** 其極長的半衰期歸因於對血漿蛋白的高親和力及緩慢的解離率，使得單次注射即可根據目標病原體的最低抑菌濃度 (MIC) 提供數天至數週的治療性抗菌濃度。
作用機制: Cefovecin is a **time-dependent, bactericidal** beta-lactam antibiotic. * **Mechanism:** Like other cephalosporins, cefovecin mimics the D-alanyl-D-alanine terminal of the peptidoglycan chain. It binds to and irreversibly inhibits bacterial **Penicillin-Binding Proteins (PBPs)**, specifically **transpeptidases** and **carboxypeptidases**. * **Pathway:** Inhibition of PBPs → Prevents cross-linking of peptidoglycan chains → Weakens the bacterial cell wall → Osmotic instability → **Bacterial cell lysis and death**. * **Efficacy:** Because it is a time-dependent antibiotic, maintaining free (unbound) drug concentrations above the Minimum Inhibitory Concentration (MIC) of the target pathogen for a significant portion of the dosing interval is critical for its bactericidal efficacy.
各物種劑量
- Skin infections due to S. intermedius or S. canis (Group G) (USA Label) · 8 mg/kg SC once. A second injection (same dose/route) may be administered if response to therapy is not complete 7 days later (for S. intermedius infections) and 14 days later for S. canis (Group G) infections. Maximum treatment should not exceed 2 injections. · SC · once (may repeat in 7-14 days) · Maximum 2 injections
- Skin and soft tissue infections (UK Label) · 8 mg/kg SC once. If required, treatment may be repeated at 14 day intervals up to a further three times. · SC · once (may repeat q14d) · Up to 4 injections total · Treatment of pyoderma should be extended beyond complete resolution of clinical signs.
- Severe infections of the gingival and periodontal tissues (UK Label) · 8 mg/kg SC once. · SC · once · Single dose · Used as adjunctive treatment to mechanical or surgical periodontal therapy.
- Urinary Tract Infections (UK Label) · 8 mg/kg SC once. · SC · once · Single dose
- Skin, soft tissue, urinary tract infections, and severe periodontal disease · 8 mg/kg · SC · every 14 days · up to 3 times · Equivalent to 1 ml/10 kg of reconstituted drug.
- Skin infections (wounds and abscesses) caused by susceptible strains of Pasteurella multocida (USA Label) · 8 mg/kg SC as a single, one-time subcutaneous injection. · SC · once · Single dose · Therapeutic concentrations are maintained for approximately 7 days for P. multocida infections.
- Skin and soft tissue abscesses and wounds (UK Label) · 8 mg/kg SC once. If required, an additional dose may be administered 14 days after the first injection. · SC · once (may repeat in 14 days) · Up to 2 injections
給藥途徑
禁忌症
- Known allergy or hypersensitivity to cefovecin, other cephalosporins, or penicillins (beta-lactams)
- Small herbivores (e.g., guinea pigs, rabbits) due to risk of fatal dysbiosis
- Dogs or cats less than 4 months of age (USA label) or less than 8 weeks of age (UK label)
不良反應
- Lethargy and depression
- Anorexia
- Vomiting
- Mild to moderate increases in liver enzymes (ALT, GGT)
- Increases in BUN and moderately elevated serum creatinine (observed in cats)
- Injection site irritation, vocalization, and transient edema
- Hypersensitivity reactions and anaphylaxis (rare but potentially fatal)
- Myelotoxicity creating toxic neutropenia (rare class effect)
- Anemia, thrombocytopenia, and prolonged coagulation times (rare class effect)
藥物相互作用
- Carprofen · May compete for plasma protein binding sites, potentially increasing the free (active) concentrations of either drug.
- Furosemide · May compete for plasma protein binding sites. · moderate
- Doxycycline · May compete for plasma protein binding sites.
- Ketoconazole · May compete for plasma protein binding sites.
- NSAIDs, Propofol, Cardiac, Anticonvulsant, and Behavioral medications · Concurrent use of highly protein-bound drugs may compete with cefovecin binding and cause adverse reactions, though actual clinical significance is not fully established.
- NSAIDs · Competition for plasma protein binding, potentially altering free drug concentrations · moderate
監測
- Clinical efficacy (resolution of clinical signs of infection)
- Adverse effects (e.g., gastrointestinal upset, lethargy, injection site reactions)
- Renal and hepatic parameters in patients with pre-existing organ dysfunction
過量
Acute overdoses are generally well tolerated and relatively safe. * **Dogs:** Administered SC up to 180 mg/kg (22.5X the labeled dose) showed only injection site irritation, vocalization, and transient edema (which resolved within 8-24 hours). * **Cats:** Administered the same 22.5X dose showed similar injection site signs. However, 10 days post-injection, treated cats had lower mean white blood cell counts compared to controls, and one cat exhibited a small amount of bilirubinuria on day 10. * **Treatment:** If massive overdose occurs or severe adverse effects are noted, treatment is symptomatic and supportive. Due to the long half-life, prolonged monitoring may be required.
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