ヒドロクロロチアジド
Hydrochlorothiazide
6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide
別名: HydroDIURIL · Microzide · Aldactazide · Hydro-Par · Ezide · Co-amilozide · Moduretic · HCTZ · hidroclorotiazida · hydrochlorothiazidum
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 |
|---|---|---|---|---|---|
| Treatment of nephrogenic diabetes insipidus | 2 mg/kg PO twice daily with a low sodium diet | PO | twice daily | — | 🌎 NA |
| Treatment of nephrogenic diabetes insipidus | 2.5-5 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
| Treatment of systemic hypertension | 1 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria | 2 mg/kg q12h PO | PO | q12h | — | 🌎 NA |
| Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria | 2.2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria | 2-4 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Diuretic for heart failure (refractory to furosemide alone) | 2-4 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Adjunctive treatment of heart failure | 2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Ascites secondary to right-sided heart failure | 2 mg/kg initially on an every other day bases | PO | every other day | — | 🌎 NA |
| Ascites in patients with liver disease | 0.5-1 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
| As a diuretic (general) | 1-4 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Refractory congestive heart failure / Calcium oxalate urolithiasis prevention / Hypertension | 0.5-4 mg/kg | PO | q12-24h | Long-term | 🌍 EU |
- Treatment of nephrogenic diabetes insipidus: Based on a case report
- Treatment of systemic hypertension: As a second choice agent; may combine with spironolactone (1-2 mg/kg PO q12 hours) to reduce potassium loss
- Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria: Usually added when dietary therapy does not adequately control calcium oxalate crystalluria
- Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria: Repeat urinalysis q2-4 weeks and monitor serum electrolytes within several weeks of initial dose and within 2 weeks of dosage adjustment
- Diuretic for heart failure (refractory to furosemide alone): In combination with furosemide
- Adjunctive treatment of heart failure: When a dog requires 4-5 mg/kg PO q8h of furosemide and continues to exhibit clinical signs of congestion, reduce the furosemide dose by 50% and add hydrochlorothiazide
- Ascites secondary to right-sided heart failure: In addition to furosemide, spironolactone, ACE inhibitors, dietary sodium restriction; monitor electrolytes and renal function
- Ascites in patients with liver disease: Using the fixed-dose combination with spironolactone (Aldactazide); dosed empirically based on the spironolactone content
- Refractory congestive heart failure / Calcium oxalate urolithiasis prevention / Hypertension: Start at low dose and titrate upwards every 5-10 days, to effect. Monitor urea, creatinine, electrolytes and blood pressure before increasing dose.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Treatment of systemic hypertension | 1 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Treatment of systemic hypertension | 2-4 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Diuretic for heart failure | 1-2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Ascites in patients with liver disease | 0.5-1 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
| To reduce calcium oxalate saturation in urine | 1 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Refractory congestive heart failure / Calcium oxalate urolithiasis prevention / Hypertension | 1-2 mg/kg | PO | q12-24h | Long-term | 🌍 EU |
- Treatment of systemic hypertension: As a second choice agent; may combine with spironolactone (1-2 mg/kg PO q12 hours) to reduce potassium loss
- Treatment of systemic hypertension: Not effective as a single agent in cats, and may be contraindicated (e.g., chronic renal failure). Possibly helpful acutely with retinal detachment.
- Diuretic for heart failure: In combination with furosemide in patients who have become refractory to furosemide alone
- Ascites in patients with liver disease: Using the fixed-dose combination with spironolactone (Aldactazide); dosed empirically based on the spironolactone content
- To reduce calcium oxalate saturation in urine: Study done in normal cats, unknown what effect HCTZ will have in cats with spontaneously occurring calcium oxalate urolithiasis
- Refractory congestive heart failure / Calcium oxalate urolithiasis prevention / Hypertension: Start at low dose and titrate upwards cautiously. Monitor urea, creatinine, electrolytes and blood pressure.
馬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Adjunctive therapy of hyperkalemic periodic paralysis (HyPP) | 0.5-1 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
- Adjunctive therapy of hyperkalemic periodic paralysis (HyPP): When diet adjustment does not control episodes. Note: ARCI UCGFS Class 4 Drug
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
ヒドロクロロチアジド (HCTZ) は中等度の効力を持つチアジド系利尿薬です。獣医学における一般的な浮腫治療ではループ利尿薬（フロセミドなど）に取って代わられつつありますが、特定の適応症においては依然として非常に有用です。
主な臨床用途：
- シュウ酸カルシウム尿石症：尿中カルシウム排泄を減少させる独自の作用（低カルシウム尿効果）により、犬（および潜在的に猫）の再発予防に使用されます。
- 全身性高血圧：補助的または二次選択の降圧薬として頻繁に使用されます。
- 腎性尿崩症 (DI)：尿崩症患者において逆説的に尿量を減少させ、腎性尿崩症の主要な薬物療法となります。
- 難治性心不全：利尿薬抵抗性を克服するため、ループ利尿薬と組み合わせて使用されます（逐次ネフロン遮断）。
- 高カリウム性周期性四肢麻痺 (HyPP)：食事療法だけではコントロールできない馬において、アセタゾラミドの代替薬として使用されます。
臨床のポイント：処方ハイライトには「低血糖」と記載されていますが、チアジド系薬剤はインスリン分泌と末梢でのグルコース利用を低下させるため、実際には高血糖を引き起こす、または悪化させることが知られています。高インスリン性低血糖（インスリノーマなど）の管理に時折使用されますが、ジアゾキシドの方が一般的です。
作用機序
Hydrochlorothiazide acts primarily on the distal convoluted tubule (DCT) (cortical diluting segment) of the nephron.
- Diuretic Effect: It competitively antagonizes the Na⁺/Cl⁻ cotransporter (NCC) → inhibits sodium and chloride reabsorption → enhances excretion of Na⁺, Cl⁻, and water.
- Electrolyte Alterations: Increased distal delivery of Na⁺ stimulates the renin-angiotensin-aldosterone system (RAAS) → increased aldosterone → enhanced secretion of K⁺ and H⁺ (leading to hypokalemia and metabolic alkalosis). It also increases excretion of magnesium, phosphate, iodide, and bromide.
- Calcium Sparing: Unlike loop diuretics, thiazides decrease calcium excretion. By depleting intracellular Na⁺ in the DCT, they enhance the activity of the basolateral Na⁺/Ca²⁺ exchanger → increased calcium reabsorption into the blood.
- Paradoxical Effect in Diabetes Insipidus: Mild volume depletion induced by the diuretic → compensatory increase in proximal tubule reabsorption of Na⁺ and water → decreased delivery of water to the distal nephron → overall reduction in polyuria.
安全性・警告
禁忌
- Hypersensitivity to thiazides or sulfonamides
- Anuria
- Pregnancy (relative contraindication in otherwise healthy patients with mild edema)
- Dogs with absorptive (intestinal) hypercalciuria (may result in hypercalcemia)
- Renal impairment (due to reduction in GFR)
- Severe electrolyte imbalances (e.g., severe hypokalaemia or hyponatraemia)
有害事象
- Hypokalemia (most common)
- Hypochloremic alkalosis
- Dilutional hyponatremia
- Hypomagnesemia
- Hypercalcemia (hyperparathyroid-like effects)
- Hypophosphatemia
- Hyperuricemia
- Gastrointestinal reactions (vomiting, diarrhea)
- Polyuria
- Hyperglycemia
- Hyperlipidemias
- Orthostatic hypotension
- Hypersensitivity/dermatologic reactions
- Hypokalaemia
- Hyponatraemia
- Hypochloraemia
- Hyperglycaemia
- Volume contraction (dehydration)
- Activation of the renin-angiotensin-aldosterone system (RAAS)
注意事項
Extreme Caution/Avoid: Severe renal disease, preexisting electrolyte (including hypercalcemia) or water balance abnormalities, impaired hepatic function (may precipitate hepatic coma), hyperuricemia, systemic lupus erythematosus (SLE), or diabetes mellitus.
Monitoring: Patients with conditions that may lead to electrolyte or water balance abnormalities (e.g., vomiting, diarrhea) should be monitored carefully. Chronic therapy requires monitoring of serum potassium.
Laboratory Test Interferences: May increase serum amylase, decrease renal excretion of cortisol, falsely decrease total urinary estrogen, cause false-negative histamine tests for pheochromocytoma, elevate serum calcium (discontinue prior to parathyroid testing), compete for PSP secretion, cause false-negative phentolamine tests, decrease protein-bound iodine, slightly reduce T3 resin uptake, and cause false-negative tyramine tests.
医薬品相互作用
Increased risk for severe hypokalemia
Increased risk for severe hypokalemia
Increased risk for hyperglycemia, hyperuricemia, and hypotension
Thiazide-induced hypokalemia, hypomagnesemia, and/or hypercalcemia may increase the likelihood of digitalis toxicity
Thiazides may increase insulin requirements
Thiazides can increase serum lithium concentrations
Thiazides can alkalinize urine and reduce methenamine effectiveness
Thiazides may increase risk for renal toxicity and NSAIDs may reduce diuretic actions of thiazides
Tubocurarine or other nondepolarizing neuromuscular blocking agents response or duration of effect may be increased
Blocks thiazide-induced uric acid retention (used to therapeutic advantage)
Half-life may be prolonged by thiazides (thiazides can alkalinize the urine)
Hypercalcemia may be exacerbated if thiazides are concurrently administered
Increased risk of developing hypokalaemia.
Synergistic diuresis (sequential nephron blockade) but significantly increased risk of hypokalaemia and dehydration.
Concurrent administration may exacerbate hypercalcaemia.
Concurrent administration may exacerbate hypercalcaemia.
監視
- Serum electrolytes (especially potassium, sodium, chloride, calcium, magnesium)
- Renal function (BUN, Creatinine)
- Hydration status and body weight
- Blood pressure (if treating hypertension)
- Urine output and clinical signs of congestion (if treating heart failure)
- Blood Urea Nitrogen (BUN)
- Serum Creatinine
- Serum Electrolytes (Potassium, Sodium, Chloride, Calcium)
薬物動態
半減期
吸収
In humans, hydrochlorothiazide is about 65-75% absorbed after oral administration. Onset of diuretic activity occurs in 2 hours; peaks at 4-6 hours.
分布
Not specifically described in domestic animals.
代謝
The drug is apparently not metabolized.
消失
Excreted unchanged into the urine. In humans, the serum half-life is approximately 5.6-14.8 hours and duration of activity is 6-12 hours.
過剰投与
Acute overdosage may cause:
- Electrolyte and water balance problems (hypokalemia, hyponatremia, dehydration)
- CNS effects (ranging from lethargy to coma and seizures)
- GI effects (hypermotility, GI distress)
- Transient increases in BUN
Treatment:
- Empty the gut after recent oral ingestion using standard protocols.
- Avoid concomitant cathartics as they may exacerbate fluid and electrolyte imbalances.
- Monitor and treat electrolyte and water balance abnormalities supportively.
- Monitor respiratory, CNS, and cardiovascular status; treat supportively and symptomatically if required.
製品
製剤
- Oral Tablets
- Oral Capsules
- Oral Suspension (Compounded)
- 25 mg hydrochlorothiazide / 2.5 mg amiloride tablets
- 50 mg hydrochlorothiazide / 5 mg amiloride tablets
動物用医薬品
- None (ARCI Class 4 substance)
ヒト用医薬品
- Hydrochlorothiazide Oral Tablets: 25 mg, 50 mg, & 100 mg (HydroDIURIL, Hydro-Par, Ezide, generic)
- Hydrochlorothiazide Oral Capsules: 12.5 mg (Microzide, generic)
- Spironolactone/Hydrochlorothiazide Oral Tablets: 25 mg/25 mg & 50 mg/50 mg (Aldactazide, generic)
- Co-amilozide tablets (25 mg hydrochlorothiazide / 2.5 mg amiloride)
- Co-amilozide tablets (50 mg hydrochlorothiazide / 5 mg amiloride)
- Moduretic
規制ステータス
Available as human generic (Co-amilozide) or branded products. Used under the cascade.
POM (Prescription Only Medicine). Used under the prescribing cascade.
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Capsules and tablets should be stored at room temperature in well-closed containers. Compounded liquid preparations should be protected from light. A compounded suspension with spironolactone in Ora-Plus/Ora-Sweet retains >90% potency for 60 days at 5°C and 25°C.
飼主向け情報
ヒドロクロロチアジド (HCTZ) は、体液貯留、高血圧、特定の種類の腎結石（シュウ酸カルシウム）、および尿崩症と呼ばれる水分バランスの障害を治療するために使用される「水薬」（利尿薬）です。
- 排尿の増加：ペットの排尿回数と量が増える可能性が高いです。獣医師から特別な制限がない限り、常に新鮮で清潔な飲み水を利用できるようにしてください。
- トイレの回数：犬の場合は、室内での粗相を防ぐために、より頻繁に外に出す必要があります。猫の場合は、トイレを清潔に保つようにしてください。
- バランスの崩れに注意：この薬は体から水分と塩分を排出するため、脱水症状や低カリウム血症の兆候に注意してください。以下の症状に気づいた場合は、すぐに獣医師に連絡してください：
- 過度の喉の渇き、または極度の無気力/脱力感
- 落ち着きのなさ、または混乱
- 嘔吐または下痢（水分の喪失を悪化させる可能性があります）
- 排尿の急激な減少
- 食事と一緒に与える：薬によってペットの胃の調子が悪くなる場合は、少量の食事やおやつと一緒に与えてみてください。
- 急に中止しない：心不全や高血圧の治療を行っている場合、獣医師に相談せずにこの薬の投与を中止しないでください。症状が急速に再発する可能性があります。
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。