ドキシサイクリン
Doxycycline
Doxycycline calcium, Doxycycline hyclate, Doxycycline monohydrate
別名: Vibramycin · Doxirobe · Periostat · Doryx · Oracea · Monodox · Adoxa · Atridox · Doxybactin · Ronaxan · Doxycycline hydrochloride · Doxycycline monohydrate · Doxycyclinum · GS-3065 · Doxycycline hyclate
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Borreliosis (ie, Borrelia burgdorferi [Lyme disease]) (extra-label)
- q12-24h
NA
必ず考慮する臨床コンテキスト (2)
- ■ Do not give multivitamins, calcium supplements, antacids, or laxatives 2 hours before or after giving doxycycline as these products can reduce effectiveness of the medicine.
- Doxycycline hyclate tablets and capsules should be stored in tight, light-resistant containers below 30°C (86°F), preferably at controlled room temperature (15°C to 30°C [59°F-86°F]). After being reconstituted with water, the monohydrate oral suspension is stable for 14 days when stored at room temperature.
Susceptible bacterial infections (extra-label)
- q12-24h
NA
必ず考慮する臨床コンテキスト (2)
- ■ Do not give multivitamins, calcium supplements, antacids, or laxatives 2 hours before or after giving doxycycline as these products can reduce effectiveness of the medicine.
- Doxycycline hyclate tablets and capsules should be stored in tight, light-resistant containers below 30°C (86°F), preferably at controlled room temperature (15°C to 30°C [59°F-86°F]). After being reconstituted with water, the monohydrate oral suspension is stable for 14 days when stored at room temperature.
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
ドキシサイクリンは、オキシテトラサイクリンから誘導された広域スペクトルの半合成テトラサイクリン系抗生物質です。古いテトラサイクリン系と比較して良好な薬物動態プロファイルを持つため、獣医療で広く使用されています。
主な臨床的利点：
- 高脂溶性： 中枢神経系（CSF）、前立腺、眼などの組織への移行性が非常に優れています。
- 腎臓への安全性： 他のテトラサイクリン系とは異なり、主に不活性なキレートとして糞便中に排泄されます。腎機能障害のある患者でも蓄積しないため、高窒素血症の患者に対する第一選択のテトラサイクリン系薬となります。
- 犬糸状虫（フィラリア）の補助治療： 現代の犬糸状虫治療プロトコルにおいて重要な役割を果たします。糸状虫の生存と繁殖に不可欠な内部共生細菌であるWolbachiaを排除し、成虫を弱体化させ、成虫駆除後の肺の病理学的変化を軽減します。
ボレリア（ライム病）、レプトスピラ、リケッチア、クラミジア、マイコプラズマ、バルトネラ、ボルデテラなどの非定型病原体に対して高い有効性を示します。
作用機序
Doxycycline is a bacteriostatic antibiotic.
- Primary Mechanism: It reversibly binds to the 30S ribosomal subunit of susceptible organisms → prevents the binding of aminoacyl transfer-RNA to the mRNA-ribosome complex → inhibits bacterial protein synthesis.
- Secondary Mechanisms: It may also reversibly bind to 50S ribosomes and alter cytoplasmic membrane permeability.
- Anti-inflammatory/Immunomodulatory Effects: Beyond its antimicrobial properties, doxycycline inhibits matrix metalloproteinases (MMPs) and scavenges reactive oxygen species, which contributes to its efficacy in treating chronic inflammatory conditions (e.g., idiopathic rhinitis, arthritis).
安全性・警告
禁忌
- Hypersensitivity to tetracyclines
- Intravenous administration in horses (associated with fatal cardiac arrhythmias)
- First half of pregnancy (can retard fetal skeletal development and discolor deciduous teeth, though less likely than other tetracyclines)
- Pregnant animals
- Animals with evidence of oesophagitis or dysphagia
有害事象
- Vomiting
- Diarrhea
- Anorexia
- Elevated liver enzymes (ALT, ALP)
- Esophageal strictures (especially in cats if dry-pilled)
- Superinfections (non-susceptible bacteria or fungi)
- Photosensitivity (reported in humans)
- Cardiac arrhythmias, collapse, and death (if given IV to horses)
- Nausea
- Diarrhoea
- Oesophagitis
- Oesophageal ulceration/stricture (especially in cats)
- Tooth discoloration (if given during tooth development, though risk is lower than other tetracyclines)
注意事項
WARNING: Do not administer IV to horses due to risk of fatal cardiac arrhythmias. Do not give IM or SC to any species.
- Esophageal Strictures: Highly associated with "dry pilling" in cats. Always follow oral solid doses with at least 6 mL of water or liquid.
- Hepatotoxicity: Use with caution in animals with significant liver dysfunction, as increases in hepatic enzymes have been documented.
- Pregnancy/Pediatric: Use with caution in pregnant and young animals due to potential for bone and teeth abnormalities, though doxycycline is safer than older tetracyclines.
- MDR1 Mutants: Safe to use; no dose alterations recommended for dogs with MDR1 mutations.
医薬品相互作用
Chelates with divalent/trivalent cations, significantly decreasing doxycycline absorption. Give at least 1-2 hours apart.
May reduce gastrointestinal absorption of doxycycline.
Decreases tetracycline absorption. Give iron 3 hours before or 2 hours after doxycycline.
Bacteriostatic drugs (doxycycline) may theoretically interfere with the bactericidal activity of these antibiotics.
May decrease doxycycline half-life and reduce serum levels.
Tetracyclines may depress plasma prothrombin activity; anticoagulant dosage may need adjustment.
Reduced absorption of doxycycline
Reduced absorption of doxycycline
Reduced absorption of doxycycline
Reduced absorption of doxycycline
May increase doxycycline metabolism, decreasing plasma levels
Reduced absorption of doxycycline (though less marked than with water-soluble tetracyclines)
監視
- Clinical efficacy
- Adverse effects (GI upset)
- Liver enzymes (ALT, ALP) with prolonged use
- Clinical response to therapy
- Signs of dysphagia, regurgitation, or oesophagitis (especially in cats)
- Gastrointestinal upset
薬物動態
半減期
吸収
Well absorbed after oral administration (90-100% bioavailability in humans/monogastrics). Unlike other tetracyclines, absorption is only minimally reduced (by ~20%) by food or dairy products. However, in horses, feeding can reduce bioavailability to <5% due to high fiber content.
分布
Highly lipid-soluble. Widely distributed to heart, kidney, lungs, muscle, pleural fluid, bronchial secretions, bile, saliva, synovial fluid, and aqueous/vitreous humor. Penetrates CSF, prostate, and eye better than other tetracyclines. Volume of distribution (Vd) in dogs is ~1.5 L/kg. Protein binding: 75-86% (dogs), 82% (horses), 93% (cattle/pigs/cats).
代謝
Partially inactivated in the intestine by chelate formation.
消失
Primarily excreted into the feces via non-biliary routes in an inactive form (chelate). Renal excretion accounts for only ~25% in dogs, and biliary excretion <5%. Does not accumulate in patients with renal dysfunction.
過剰投与
Doxycycline is generally quite safe in mild overdose situations (except for IV administration in horses).
- Oral Overdose: Most likely associated with gastrointestinal disturbances (vomiting, anorexia, diarrhea).
- Treatment: Oral administration of divalent or trivalent cation antacids (e.g., calcium, magnesium, aluminum) can bind the drug in the gut and reduce GI distress. Monitor and replace fluids/electrolytes if severe emesis or diarrhea occurs.
- IV Overdose: Rapid intravenous injection has induced transient collapse and cardiac arrhythmias in several species, presumably due to chelation with intravascular calcium ions.
製品
製剤
- Delayed-Release Tablets and Capsules
- Powder for Oral Suspension
- Oral Syrup
- Injection (Lyophilized powder)
- Periodontal Gel (8.5%)
- 20 mg tablet
- 50 mg tablet
- 100 mg tablet
- 200 mg tablet
- 400 mg tablet
- Oral paste (named patient basis)
動物用医薬品
- Doxirobe® (Pfizer): Doxycycline gel 8.5% activity once mixed (for periodontal disease in dogs)
- Doxybactin 20 mg, 50 mg, 200 mg, 400 mg tablets
- Ronaxan 20 mg, 100 mg tablets
- Oral paste (named patient basis)
ヒト用医薬品
- Periostat®, Alodox Convenience Kit®, Vibramycin®, Vibra-Tabs®, Oraxyl®, generic: Tablets & Capsules (20 mg, 50 mg, 100 mg)
- Doryx®, Oracea®: Delayed-Release Tablets & Capsules (40 mg, 75 mg, 100 mg, 150 mg)
- Monodox®, Adoxa®, generic: Tablets and Capsules (as monohydrate) (50 mg, 75 mg, 100 mg, 150 mg)
- Vibramycin®, Doxycycline (Teva): Powder for Oral Suspension (5 mg/mL after reconstitution)
- Vibramycin®: Oral Syrup (as calcium salt) (10 mg/mL)
- Atridox®: Injection (42.5 mg in vials)
- Doxy®-100 & -200, generic: Lyophilized Powder for Injection (100 mg, 200 mg)
規制ステータス
POM-V
POM-V
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Tablets and capsules should be stored in tight, light-resistant containers at <30°C (preferably 15-30°C). Reconstituted monohydrate oral suspension is stable for 14 days at room temperature. Compounded oral suspensions degrade rapidly between 7-14 days even if refrigerated. Tablets mixed with water/food lose >10% potency after 24 hours. Reconstituted hyclate injection (0.1-1 mg/mL) is stable for 72 hours refrigerated.
飼主向け情報
- 猫に関する重要な警告： 絶対に「ドライピリング（水なしでの投薬）」を行わないでください。ドキシサイクリンのカプセルや錠剤が食道に引っかかり、重度で永久的な損傷（食道狭窄）を引き起こす可能性があります。錠剤を飲ませた後は、必ず少なくとも6 mL（小さじ1杯強）の水または液体を飲ませてください。投薬後に唇にバターを塗ると、唾液の分泌が促され、薬が飲み込みやすくなります。
- 食事と乳製品： ドキシサイクリンは食事の有無にかかわらず投与できます。食事と一緒に与えることで、胃腸の不調を防ぐことができます。古いテトラサイクリン系とは異なり、牛乳や乳製品がドキシサイクリンの吸収を著しく妨げることはありません。
- 日光： まれに、この薬によって皮膚が日光に対して過敏になることがあります。
VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。