醋甲唑胺
Methazolamide
N-(4-methyl-2-sulfamoyl-Δ2-1,3,4-thiadiazolin-5-ylidene)acetamide
別名: Neptazane · GlaucTabs · Glaumetax · MZM · Methazolamidum
由 VetSheet 獸醫團隊審訂更新於 2026年4月5日本內容以實證獸醫文獻為本
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Medical treatment of glaucoma | 2.5-5 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 NA |
| Medical treatment of glaucoma | 2-4 mg/kg PO two to three times a day | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 3-5 mg/kg divided q12h PO | PO | q12h | — | 🌎 NA |
| Medical treatment of glaucoma | 2-5 mg/kg PO two to three times a day | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 2.2-4.4 mg/kg PO two to three times a day. | PO | two to three times a day | — | 🌎 NA |
| Medical treatment of glaucoma | 2-10 mg/kg PO two to three times a day. | PO | two to three times a day | — | 🌎 NA |
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Medical treatment of glaucoma | 3-4 mg/kg PO twice a day. | PO | twice a day | — | 🌎 NA |
| Medical treatment of glaucoma | 1-2 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 NA |
- Medical treatment of glaucoma: Cats may not tolerate oral carbonic anhydrase inhibitors (CAIs) as well as dogs. Reported side effects include lethargy, inappetence, vomiting. Topical CAIs may be better tolerated.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
概覽
醋甲唑胺 (Methazolamide) 是一種口服的碳酸酐酶抑制劑 (CAI)，在獸醫學中主要用於開角型青光眼的內科治療。
在過去，全身性 CAI 是降低眼內壓 (IOP) 的主要藥物，但目前已大多被局部點眼劑（如 dorzolamide、brinzolamide）所取代。局部用藥能提供相當的降眼壓效果，且全身性副作用的發生率大幅降低。
臨床重點：
- 全身性影響： 由於是口服給藥，醋甲唑胺會抑制全身的碳酸酐酶，可能導致代謝性酸中毒和電解質不平衡（尤其是低血鉀）。
- 臨床應用： 通常保留用於對局部治療反應不佳的頑固性青光眼病例，或無法進行局部給藥時。
- 物種敏感性： 貓對口服 CAI 的副作用特別敏感，可能會表現出嚴重的嗜睡和厭食。
作用機制
Methazolamide acts via noncompetitive, reversible inhibition of the enzyme carbonic anhydrase (CA), specifically the CA-II isoenzyme.
- In the Eye (Ciliary Body): Inhibition of CA → reduces the formation of hydrogen (H+) and bicarbonate (HCO3-) ions from carbon dioxide and water → decreases the availability of these ions for active transport into the posterior chamber → decreased aqueous humor production → reduced intraocular pressure (IOP).
- In the Kidneys (Proximal Tubule): Inhibition of CA → increased renal tubular secretion of sodium (Na+), potassium (K+), and bicarbonate (HCO3-) → increased urine alkalinity and volume, often resulting in a mild hyperchloremic metabolic acidosis.
- In the CNS: Exhibits anticonvulsant activity independent of its diuretic effects, potentially due to localized CA inhibition in the brain or secondary to systemic metabolic acidosis.
安全性與警告
禁忌症
- Significant hepatic disease (may precipitate hepatic coma)
- Renal or adrenocortical insufficiency
- Hyponatremia or hypokalemia
- Hyperchloremic acidosis or severe electrolyte imbalance
- Severe pulmonary obstruction (inability to increase alveolar ventilation to compensate for metabolic acidosis)
- Hypersensitivity to carbonic anhydrase inhibitors or sulfonamides
- Chronic, noncongestive, angle-closure glaucoma (long-term use may mask the condition by lowering IOP while angle closure progresses)
不良反應
- GI disturbances (vomiting, diarrhea, inappetence)
- Metabolic acidosis (often manifesting as heavy panting in dogs)
- CNS effects (sedation, depression, disorientation, excitement)
- Hematologic effects (bone marrow depression, thrombocytopenia)
- Renal effects (crystalluria, dysuria, renal colic, polyuria, polydipsia)
- Hypokalemia
- Hyperglycemia
- Hyponatremia
- Hyperuricemia
- Hepatic insufficiency
- Dermatologic effects (rash)
- Hypersensitivity reactions
- Weakness or cardiac arrhythmias (secondary to electrolyte imbalances)
注意事項
Laboratory Interferences: By alkalinizing the urine, carbonic anhydrase inhibitors may cause false-positive results in determining urine protein using bromphenol blue reagent, sulfosalicylic acid, nitric acid ring test, or heat and acetic acid test methods. They may also decrease iodine uptake by the thyroid gland in hyperthyroid or euthyroid patients.
- Use with caution in pregnant animals (FDA Category C in humans; animal studies show adverse fetal effects).
- Combining oral methazolamide with topical dorzolamide does not yield additive reductions in IOP and may increase adverse effects.
- Monitor closely for signs of hypokalemia and metabolic acidosis, especially in cats.
藥物相互作用
Alkaline urine caused by methazolamide may decrease excretion of tricyclic antidepressants.
Increased risk of methazolamide accumulation and toxicity; increased risk for metabolic acidosis; methazolamide increases salicylate excretion.
Methazolamide may cause hypokalemia, leading to an increased risk for digoxin toxicity.
Rarely, carbonic anhydrase inhibitors may interfere with the hypoglycemic effects of insulin.
Methazolamide alkalinizes urine, which may negate the urinary antiseptic effects of methenamine.
Concomitant use may exacerbate potassium depletion and hypokalemia.
Increased urinary excretion due to alkaline urine, which may reduce phenobarbital serum levels.
May result in decreased primidone concentrations.
Alkaline urine caused by methazolamide may decrease quinidine excretion.
監測
- Intraocular pressure (IOP) / tonometry
- Serum electrolytes (especially potassium and sodium)
- Blood pH / acid-base status
- Baseline CBC with differential, and periodic retests if using chronically
- Clinical signs of adverse effects (lethargy, GI upset, heavy panting)
藥物動力學
吸收
Absorbed from the GI tract, albeit more slowly than acetazolamide.
分佈
Distributed throughout the body, including the cerebrospinal fluid (CSF) and aqueous humor.
代謝
At least partially metabolized in the liver.
排除
Excreted primarily via the kidneys, leading to increased urine alkalinity.
過量
Information regarding acute overdosage of methazolamide in veterinary species is limited.
Clinical Signs: Expected signs of toxicity include severe electrolyte imbalances (hypokalemia, hyponatremia), profound metabolic acidosis, CNS depression or disorientation, and dehydration secondary to diuresis.
Management:
- Monitor serum electrolytes, blood gases (for acidosis), volume status, and CNS status.
- Treat symptomatically and supportively.
- Administer intravenous fluids to correct dehydration and electrolyte deficits (especially potassium supplementation if indicated).
- Correct severe metabolic acidosis with sodium bicarbonate if necessary, based on blood gas analysis.
可用產品
劑型
- Tablets
人用標示
- Methazolamide Tablets: 25 mg & 50 mg (generic, Rx)
各地核准狀態
暫無法規資料: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Methazolamide tablets should be stored at room temperature in well-closed containers. Tablets typically have an expiration date of 5 years after manufacture.
飼主須知
了解藥物： 醋甲唑胺用於降低寵物因青光眼引起的眼內壓。它的作用原理是減少眼睛內部液體的生成。
給藥方式：
- 與食物同服： 如果此藥物引起腸胃不適（嘔吐或食慾不振），與食物一起餵食可以幫助緩解。
- 請勿壓碎或咀嚼，除非獸醫師另有指示。
注意事項：
- 嚴重喘氣： 此藥物可能會引起血液酸鹼度輕微改變（代謝性酸中毒），狗通常會透過大量喘氣來試圖代償。如果喘氣過度，請聯繫您的獸醫師。
- 嗜睡和躲藏： 貓對此藥物特別敏感，可能會變得非常疲倦或停止進食。
- 排尿和飲水增加： 您可能會注意到寵物比平時喝更多的水和排尿。
- 立即就醫： 如果您發現寵物有異常出血或瘀傷、嚴重虛弱、肌肉顫抖或起皮疹，請立即尋求獸醫協助。
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