スルファジメトキシン/オルメトプリム
これは**強化サルファ系抗菌薬**であり、感受性ブドウ球菌や大腸菌による犬の皮膚および軟部組織の感染症治療薬としてFDAに承認されています。他のサルファ剤に比べて副作用が少ない可能性があり、1日1回の投与が可能です。**注意**: 前立腺への移行性が低いため、前立腺感染症には無効です。
作用機序: 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*).
動物種別の用量
- 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.
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
- 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)
有害事象
- 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
薬物相互作用
- 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).
モニタリング
- 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)
過量投与
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 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。