オメプラゾール
Omeprazole
5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole
別名: Gastrogard · Prilosec · Ulcergard · Zegerid · H-168/68 · omeprazolum
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
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。
動物種別用量
🌎 NA — North America🌍 EU — Europe
犬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| GI ulcer management/prevention | 0.5-1 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of uremic gastropathy | 0.5-1 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
| Prevent exercise-induced gastritis in racing Alaskan sled dogs | approx. 0.85 mg/kg (one 20 mg tablet) once daily approximately 30 minutes before being fed | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of esophagitis or gastric ulcers | 0.5-1 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
| Gastrinomas or severe esophagitis | 0.7-1.5 mg/kg PO q24h, but if severe esophagitis or gastrinomas may use up to 2 mg/kg PO q12h | PO | q12h-q24h | — | 🌎 NA |
| General GI therapeutics | 0.7 mg/kg PO q24h (20 mg/dog) | PO | q24h | — | 🌎 NA |
| Esophagitis | 0.7 mg/kg PO twice daily | PO | q12h | — | 🌎 NA |
| Adjunctive treatment of uremic vomiting | 0.7 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Helicobacter infection/gastritis | Omeprazole 0.7 mg/kg PO once daily (or an H2 blocker), amoxicillin 15 mg/kg PO twice daily, metronidazole 10 mg/kg PO twice daily, and Pepto Bismol ¼-2 tablets PO twice daily | PO | q24h | 2 weeks | 🌎 NA |
- Adjunctive treatment of uremic gastropathy: Dosage may need to be modified in moderate or severe renal failure.
- Prevent exercise-induced gastritis in racing Alaskan sled dogs: Dosing began approximately 48 hours before exercise.
- Helicobacter infection/gastritis: Other suggestions include omeprazole with either azithromycin 10-20 mg/kg PO once daily or clarithromycin 7.5 mg/kg PO twice daily.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Adjunctive treatment of esophagitis or gastric ulcers | 0.5-1 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
| GI ulcer management/prevention | 0.7-1.5 mg/kg PO q12-24h | PO | q12h-q24h | — | 🌎 NA |
| Adjunctive treatment of uremic gastropathy | 0.7 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
- Adjunctive treatment of uremic gastropathy: Dosage may need to be modified in moderate or severe renal failure.
フェレット
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Short-term treatment of gastroenteritis | 0.7 mg/kg PO q24h | PO | q24h | Short-term | 🌎 NA |
馬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Treatment of gastric ulcers | 4 mg/kg PO once daily for 4 weeks; to prevent recurrence treat for at least another 4 weeks at 2 mg/kg PO once daily | PO | q24h | 8 weeks total | 🌎 NA |
| Foals: Preventative dose | 1 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
| Foals: Treatment dose | 4 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
| Treatment or prophylaxis of gastric ulcers in foals | 4 mg/kg PO once daily for treatment, 1-2 mg/kg PO once daily for prophylaxis | PO | q24h | — | 🌎 NA |
| Foals: Gastric ulcers | 4 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
- Treatment of gastric ulcers: ARCI UCGFS Class 5 Drug
- Foals: Preventative dose: There has been a recent shift to not administering prophylactic antiulcer medication routinely to sick foals.
- Foals: Treatment dose: Will reduce gastric pH in a few hours.
- Foals: Gastric ulcers: Commonly foals will be started on ranitidine (1.5 mg/kg IV q8h; 6.6 mg/kg PO q8h) and omeprazole together.
豚
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Ulcer management | 40 mg of PO daily for two days; fasted for 48 hours | PO | q24h | 2 days | 🌎 NA |
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
オメプラゾールは、獣医療において胃十二指腸潰瘍やびらんの治療および予防に広く使用されている非常に効果的なプロトンポンプ阻害薬（PPI）です。
- 優れた有効性： 胃内pHの上昇や、アラスカン・スレッド・ドッグでの運動誘発性胃炎の予防において、H2受容体拮抗薬（ファモチジンなど）よりも優れていると一般に考えられています。
- 馬への応用： 経口ペースト製剤は、馬の胃潰瘍（EGUS）の治療および予防に特化して認可されており、高い効果を示します。
- 幅広い適用： 犬、猫、フェレット、豚など複数の動物種で使用され、尿毒症性胃症、食道炎、ヘリコバクター感染症、NSAID/コルチコステロイド誘発性潰瘍などの管理に役立ちます。
臨床上のポイント： オメプラゾールは活性化に酸性環境を必要としますが、吸収される前に胃酸によって分解されるため、人間用の経口製剤は腸溶性コーティングが施されています。薬の生体利用効率を損なうため、絶対に砕いたり噛んだりしてはいけません。
作用機序
Omeprazole is a prodrug that acts as a substituted benzimidazole gastric acid pump inhibitor.
- Absorption & Distribution: After absorption, it diffuses from the blood into the highly acidic secretory canaliculi of the gastric parietal cells.
- Activation: In this acidic environment (pH < 3), it is protonated and rearranged into its active form, a sulphenamide derivative.
- Irreversible Binding: The active sulphenamide binds irreversibly via disulfide bonds to the H⁺/K⁺ ATPase enzyme (the proton pump) at the secretory surface.
- Acid Suppression: This blocks the final common pathway of gastric acid secretion, inhibiting the transport of hydrogen ions into the stomach lumen during both basal and stimulated conditions.
Pharmacological Note: Because the binding is irreversible, acid secretion only resumes when new H⁺/K⁺ ATPase enzymes are synthesized. This explains why its duration of action (24-72 hours) far outlasts its short plasma half-life (~1 hour). Omeprazole also inhibits the hepatic cytochrome P-450 mixed-function oxidase system, which can lead to drug interactions.
安全性・警告
禁忌
- Known hypersensitivity to omeprazole
有害事象
- GI distress (anorexia, colic, nausea, vomiting, flatulence, diarrhea)
- Hematologic abnormalities (rare)
- Urinary tract infections
- Proteinuria
- CNS disturbances
- Urticaria (rare in horses)
注意事項
Use with caution in patients with severe hepatic or renal disease, as the drug's half-life may be prolonged and dosage adjustment may be necessary. Safety during pregnancy is not fully established (FDA Category C); high doses in lab animals showed embryo-lethality. Nursing is discouraged due to potential adverse effects in infants and tumorigenicity seen in rat studies. Chronic very high doses in rats caused enterochromaffin-like cell hyperplasia and gastric carcinoid tumors, though the clinical significance for standard veterinary use (e.g., 4 weeks in dogs, 90 days in horses) is believed to be low.
医薬品相互作用
Omeprazole may potentially alter benzodiazepine metabolism and prolong CNS effects
Increased levels of omeprazole, clarithromycin and 14-hydroxyclarithromycin are possible
Omeprazole may decrease oral absorption
Omeprazole may reduce cyclosporine metabolism
Omeprazole increases gastric pH, which may decrease the absorption of these drugs that require an acidic environment
Omeprazole may increase anticoagulant effect
監視
- Clinical efficacy (resolution of clinical signs of ulcers/esophagitis)
- Adverse effects (GI distress)
- Liver enzymes (may increase)
- Serum gastrin levels (will increase early in therapy)
薬物動態
半減期
吸収
Rapidly absorbed from the gut. The human commercial product is in an enteric-coated granule form as the drug is rapidly degraded by stomach acid. The equine paste is not enteric coated. In humans, peak serum levels occur within 0.5-3.5 hours and onset of action within 1 hour.
分布
Distributed widely, but primarily concentrates in gastric parietal cells. In humans, approximately 95% is bound to albumin and alpha1-acid glycoprotein. It is unknown whether omeprazole enters maternal milk.
代謝
Extensively metabolized in the liver via the cytochrome P-450 mixed function oxidase system to at least six different metabolites. Significant hepatic dysfunction will reduce the first pass effect of the drug.
消失
Metabolites are excreted principally in the urine, but also via the bile into feces.
過剰投与
The LD50 in rats after oral administration is reportedly >4 grams/kg. Humans have tolerated oral dosages of 360 mg/day without significant toxicity.
Should a massive overdose occur, treat symptomatically and supportively. Due to its wide safety margin, acute toxicity from accidental ingestion is generally mild.
製品
製剤
- Oral paste
- Delayed-release capsules (enteric-coated)
- Delayed-release tablets (enteric-coated)
- Powder for oral suspension (with sodium bicarbonate)
- Immediate-release capsules (with sodium bicarbonate)
動物用医薬品
- Omeprazole Oral Paste, 2.28 g per syringe; Gastrogard® (Merial), (Rx)
- Omeprazole Oral Paste, 2.28 g per syringe; Ulcergard® (Merial), (OTC)
ヒト用医薬品
- Omeprazole Oral Delayed-Release Capsules: 10 mg, 20 mg & 40 mg; Prilosec®
- Omeprazole Oral Delayed-Release Tablets: 20 mg; Prilosec® OTC
- Omeprazole/Sodium Bicarbonate Oral Capsules (Immediate Release): 20 mg or 40 mg omeprazole with 1,100 mg sodium bicarbonate; Zegerid®
- Omeprazole/Sodium Bicarbonate Powder for Oral Suspension: 20 mg or 40 mg omeprazole with 1,680 mg sodium bicarbonate; Zegerid®
規制ステータス
規制データなし: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Omeprazole oral paste should be stored below 86°F (30°C). Transient exposure to temperatures up to 104°F is permitted. Omeprazole tablets/capsules should be stored at room temperature in light-resistant, tight containers. Omeprazole pellets found in the capsules are fragile and should not be crushed.
飼主向け情報
- タイミングが重要です： この薬は空腹時、できれば朝の食事の30〜60分前に与えてください。薬が効果を発揮するには活性化したプロトンポンプが必要であり、食事によってこれが刺激されます。
- 砕いたり噛んだりしないでください： 人間用のカプセルや錠剤を使用する場合、胃酸に耐えるための特殊なコーティングが施されています。砕いたり噛んだりすると、吸収される前に薬が破壊されてしまいます。
- カプセルを開けて中の顆粒を与える必要がある場合は、少量のフルーツジュース（水、牛乳、生理食塩水は不可）と優しく混ぜ、顆粒を砕かずにすぐに与えてください。
- ペットに持続的な嘔吐、下痢、または食欲不振が見られる場合は、獣医師にご相談ください。
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。