磺胺二甲嘧啶/奧美普林
這是一種**增效磺胺類抗菌藥**，獲FDA核准用於治療犬隻由敏感葡萄球菌和大腸桿菌引起的皮膚及軟組織感染。與其他磺胺類藥物相比，其副作用可能較少，且可每日給藥一次。**注意**：此藥無法有效穿透前列腺，因此不適用於前列腺感染。
作用機制: Sulfadimethoxine/ormetoprim is **bactericidal** due to the synergistic, sequential inhibition of enzymes in the bacterial folic acid synthesis pathway. - **Sulfadimethoxine** (a sulfonamide) acts as a false substrate, competitively inhibiting the conversion of para-aminobenzoic acid (PABA) → dihydrofolic acid (DFA). - **Ormetoprim** (a diaminopyrimidine) blocks the subsequent conversion of DFA → tetrahydrofolic acid (THFA) by reversibly inhibiting the enzyme **dihydrofolate reductase**. This dual blockade halts bacterial thymidine synthesis, ultimately preventing DNA replication. It has a broad spectrum of activity against many Gram-positive (e.g., *Staphylococcus*, *Streptococcus*, *Nocardia*) and Gram-negative organisms (excluding *Pseudomonas aeruginosa*), as well as certain protozoa (*Pneumocystis*, *Coccidia*, *Toxoplasma*).
各物種劑量
- Susceptible infections · Medicated premix: 113.5 grams sulfadimethoxine and 68.1 grams ormetoprim per pound in 50 lb bags · PO · Continuous in feed · Varies · FDA-approved for chickens (broilers, replacements), turkeys, ducks, & Chukar partridges. 5-day slaughter withdrawal. Do not feed to chickens over 16 weeks of age, or turkeys/ducks producing eggs for food.
- Susceptible infections (skin and soft tissue) · Initially 55 mg/kg (combined drug) PO on the first day of therapy, then 27.5 mg/kg PO once daily for at least 2 days after remission of clinical signs. Not approved for treatment longer than 21 days. · PO · q24h · Up to 21 days · Dose is based on combined drug weight.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to sulfonamides, thiazides, or sulfonylurea agents
- Severe renal or hepatic impairment
- Marked liver parenchymal damage
- Blood dyscrasias
- Doberman Pinschers (highly susceptible to sulfonamide-induced poly-systemic immune complex disease)
不良反應
- Keratoconjunctivitis sicca (KCS/dry eye) - potentially irreversible
- Acute neutrophilic hepatitis with icterus
- Vomiting
- Anorexia
- Diarrhea
- Fever
- Hemolytic anemia
- Urticaria
- Polyarthritis
- Facial swelling
- Polydipsia and polyuria
- Cholestasis
- Hypersensitivity reactions (Type I anaphylaxis or Type III serum sickness)
- Hypothyroidism (with extended use)
- Crystalluria and hematuria (especially in cats)
- Leukopenias and anemias
藥物相互作用
- Various (Refer to Trimethoprim/Sulfa) · Specific interactions are not explicitly noted for this combination, but it is expected to share the interaction profile of trimethoprim/sulfa (e.g., potential antagonism with cyclosporine, increased risk of bleeding with anticoagulants).
監測
- Clinical efficacy and resolution of infection
- Adverse effects (especially signs of hypersensitivity or liver issues)
- Tear production via Schirmer Tear Test in dogs (baseline, at 5 days post-initiation, and then every 2-3 weeks)
過量
In experimental dog studies, doses **>80 mg/kg** resulted in slight tremors and increased motor activity. Higher doses may cause depression, anorexia, or seizures. **Treatment:** For very high oral overdoses, empty the gut using standard precautions and protocols. Treat clinical signs supportively and symptomatically.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。