テトラサイクリン
Tetracycline
Tetracycline hydrochloride
別名: Aquadrops · Panmycin · Sumycin · Polyotic · Delta Albaplex · Tetracycline HCl · tetracyclini hydrochloridum
VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス
監査済み v13 用量エビデンス
構造化された用量計算エビデンスSusceptible infections (extra-label)
- q8-12h
NA
必ず考慮する臨床コンテキスト (2)
- ■ This medicine is best given without food. Avoid giving this medicine orally within 1 to 2 hours of milk or other dairy products.
- Unless otherwise instructed by the manufacturer, tetracycline oral tablets and capsules should be stored in tight, light-resistant containers at room temperature (15°C-30°C [59°F-86°F]).
用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。
概要
テトラサイクリンは、プロトタイプとなる短時間作用型のテトラサイクリン系抗生物質です。歴史的には広域スペクトル抗菌薬として使用されてきましたが、細菌の耐性増加によりその臨床的役割は変化しています。
現代の獣医療において：
- 小動物臨床：感染症に対しては、組織移行性が良く投与頻度が少ないドキシサイクリンが一般的に好まれます。しかし、テトラサイクリンはナイアシンアミドと併用され、その免疫調節作用を利用して免疫介在性皮膚疾患（円板状エリテマトーデス、天疱瘡など）の治療に頻繁に使用されます。
- 大動物臨床：通常、オキシテトラサイクリンが好まれます。
臨床のポイント：
- マイコプラズマ、リケッチア、スピロヘータ（ライム病など）、クラミジアなどの非定型病原体に対しては依然として有効です。
- 顕著な抗炎症および免疫調節作用を持ち、獣医皮膚科において価値があります。
作用機序
Tetracycline is a time-dependent, bacteriostatic antibiotic.
- Antimicrobial Action: Reversibly binds to the 30S ribosomal subunit of susceptible organisms → prevents binding of aminoacyl transfer-RNA to the ribosome → inhibits bacterial protein synthesis. It may also bind to the 50S subunit and alter cytoplasmic membrane permeability.
- Immunomodulatory/Anti-inflammatory Action: Suppresses antibody production and neutrophil chemotaxis. Inhibits key inflammatory mediators including lipases, collagenases, prostaglandin synthesis, and the activation of complement component 3.
安全性・警告
禁忌
- Hypersensitivity to tetracyclines
- Pregnancy (last half) - retards fetal skeletal development and discolors teeth
- Young, growing animals (unless benefits outweigh risks)
有害事象
- Gastrointestinal distress (nausea, vomiting, anorexia, diarrhea)
- Discoloration of developing teeth and bones (yellow/brown/gray)
- Delayed bone growth and healing in young animals
- Superinfections (bacterial or fungal overgrowth)
- Photosensitivity
- Urolith formation (with long-term use in dogs)
- Hepatotoxicity and blood dyscrasias (rare)
- Cats: Colic, fever, hair loss, depression (poorly tolerated)
- Horses: Severe diarrhea (especially if stressed)
- Ruminants: Ruminal microflora depression and stasis (high oral doses)
- Injection site reactions (IM): Local necrosis and yellow staining
注意事項
Extreme Caution: Pregnancy (Category D). Can cause congenital malformations, embryotoxicity, and discoloration of deciduous teeth.
- Renal/Hepatic Impairment: Use cautiously. Lower dosages and enhanced monitoring are recommended. Avoid concurrent nephrotoxic or hepatotoxic drugs.
- Cats: Do not tolerate oral tetracycline well; monitor closely for adverse effects.
- IV Administration: Rapid IV injection can cause transient collapse and cardiac arrhythmias due to calcium chelation. Administer slowly or pre-treat with IV calcium gluconate if rapid injection is necessary.
医薬品相互作用
Tetracyclines may decrease atovaquone levels.
Theoretical antagonism of bactericidal activity, though clinical significance is doubtful.
May increase bioavailability of digoxin, potentially causing toxicity that persists for months.
Chelation occurs, significantly decreasing the absorption of tetracycline. Separate doses by at least 1-2 hours.
Concomitant use can cause fatal nephrotoxicity.
May impair oral absorption of tetracycline; separate dosing by at least 2 hours.
May depress plasma prothrombin activity; anticoagulant dosage adjustment may be needed.
監視
- Adverse effects (GI signs, injection site reactions)
- Clinical efficacy
- Periodic renal, hepatic, and hematologic evaluations (with long-term use or in susceptible patients)
薬物動態
半減期
吸収
Readily absorbed after oral administration in fasting animals (bioavailability ~60-80%). Food or dairy products can significantly reduce absorption by 50% or more. Erratically and poorly absorbed after IM administration.
分布
Widely distributed to heart, kidney, lungs, muscle, pleural fluid, bronchial secretions, bile, saliva, urine, synovial fluid, and aqueous/vitreous humor. Poor penetration into CSF. Crosses the placenta and distributes into milk. Volume of distribution is ~1.2-1.3 L/kg in small animals and 1-2.5 L/kg in cattle.
代謝
Apparently not metabolized.
消失
Eliminated unchanged primarily via glomerular filtration. Excreted into the GI tract via biliary and nonbiliary routes (may become inactive after chelation with fecal materials). Patients with impaired renal function can accumulate the drug.
過剰投与
Tetracyclines are generally well tolerated after acute overdoses.
- Oral Overdose: Most likely associated with GI disturbances (vomiting, anorexia, diarrhea). Monitor fluids and electrolytes if severe emesis/diarrhea occurs.
- Chronic Overdose: May lead to drug accumulation and nephrotoxicity.
- Ruminants: High oral doses can cause ruminal microflora depression and ruminoreticular stasis.
- IV Overdose/Rapid Injection: Rapid IV injection can induce transient collapse and cardiac arrhythmias, presumably due to chelation with intravascular calcium ions. If rapid IV administration is necessary, pre-treatment with intravenous calcium gluconate is recommended by some clinicians.
製品
製剤
- Capsules
- Oral Suspension
- Soluble Powder (water additive)
- Injection (rarely used in small animals)
動物用医薬品
- Tetracycline HCl Soluble Powder (water additive): 25 grams/lb or 324 grams/lb
- Delta Albaplex (Combination product containing tetracycline, novobiocin, and prednisone)
ヒト用医薬品
- Tetracycline HCl Capsules: 250 mg & 500 mg (Sumycin, generic)
- Tetracycline HCl Oral Suspension: 25 mg/mL (Sumycin Syrup)
規制ステータス
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保管・安定性
Store oral tablets and capsules in tight, light-resistant containers at room temperature (15-30°C). Store oral suspension and powder for injection at room temperature; avoid freezing the oral suspension.
飼主向け情報
- 投与方法：可能であれば空腹時にこの薬を投与してください。食事や牛乳・乳製品を与える前後1〜2時間以内の投与は避けてください。薬の吸収が著しく低下する可能性があります。
- 胃腸の不調：ペットが嘔吐したり吐き気をもよおしたりする場合は、少量の非乳製品の食事と一緒に薬を与えると改善する場合がありますが、薬の効果がわずかに低下する可能性があります。
- 日光：この薬により、ペットの皮膚が日光に対して敏感になる（光線過敏症）可能性があります。長時間の直射日光は避けてください。
- 変色：成長期の若い動物では、この薬が歯に永久的な黄色や茶色の着色を引き起こす可能性があることに注意してください。
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