去氨加壓素
**去氨加壓素 (DDAVP)** 是一種天然腦下垂體抗利尿激素（精氨酸血管加壓素）的合成類似物。其結構經過修飾，顯著增強了抗利尿特性，同時幾乎消除了血管加壓（升高血壓）的作用。 在獸醫學中，它主要用於兩個不同的臨床目的： * **中樞性尿崩症 (CDI)：** 它是診斷（透過試驗治療）和長期管理犬貓 CDI 的黃金標準，能有效解決嚴重的多尿和多渴症狀。 * **溫韋伯氏疾病 (vWD)：** 用於圍手術期，短暫提升特定亞型 vWD 患畜的凝血因子，但其作用時間短且容易快速產生抗藥性（快速耐受），限制了其長期效用。 **臨床要點：** 由於動物口服的生物利用度極差，人類用的鼻腔噴霧劑在獸醫臨床上最常被**局部滴入患畜的結膜囊（眼睛）**中，提供了一種可靠且非侵入性的吸收途徑。
作用機制: Desmopressin exerts its effects through two primary mechanisms based on its high affinity for specific receptors: * **Antidiuretic Action (Kidneys):** Desmopressin selectively binds to **V2 receptors** on the basolateral membrane of cells in the renal distal tubules and collecting ducts. This binding activates adenylate cyclase → increases intracellular cAMP → triggers the translocation and insertion of **aquaporin-2 (AQP2)** water channels into the apical membrane. This dramatically increases water permeability, allowing water to be reabsorbed passively back into the bloodstream, thereby concentrating the urine and reducing urine volume. * **Hemostatic Action (Endothelium):** Desmopressin binds to **V2 receptors** on vascular endothelial cells → stimulates the rapid exocytosis of Weibel-Palade bodies → releases stored **von Willebrand factor (vWF)** and **Factor VIII** into the plasma. It also increases plasminogen factor levels.
各物種劑量
- Differentiate central diabetes insipidus from nephrogenic form · 1 drop into the conjunctival sac · topical · twice daily · 2-3 days · Dramatic reduction in water intake or >=50% increase in urine concentration gives strong evidence for ADH deficit.
- Central diabetes insipidus · 1-2 drops into the conjunctival sac · topical · once or twice a day · Duration of activity is 8-24 hours.
- Central diabetes insipidus · 1- 4 drops of the intranasal solution in the conjunctival sac · topical · once to twice daily
- Central diabetes insipidus · 2-5 micrograms · SC · once to twice daily · Using intranasal solution parenterally.
- Central diabetes insipidus (oral alternative) · 25-50 micrograms (total dose; 1/4th to 1/2 of a 100 microgram tablet) · PO · q12h · Dose and response may be variable.
- Diagnosis of diabetes insipidus · 20 micrograms · IV · Once
- Diagnosis of diabetes insipidus · 0.05 micrograms/kg · IV · Once · Dilute the nasal spray formulation (0.1 mg/ml) in sterile water. Measure USG every 2 hours. Increase to >=1.025 within 2-7 hours is consistent with central DI.
- Central diabetes insipidus · One drop placed in the conjunctival sac · topical · twice daily (or three times a day) · Using one drop three times a day usually returns urine production to normal.
給藥途徑
禁忌症
- Hypersensitivity to desmopressin
- Type IIB or platelet-type (pseudo) Von Willebrand's disease (may cause platelet aggregation and thrombocytopenia; notably seen in German Shorthair Pointers)
- Hyponatraemia (specifically for modified water deprivation test)
- Renal disease (specifically for modified water deprivation test)
- Dehydration (specifically for modified water deprivation test)
- Hypercalcaemia (specifically for modified water deprivation test)
不良反應
- Eye irritation (following conjunctival administration)
- Hypersensitivity reactions
- Fluid retention (with overdosage)
- Hyponatremia (with overdosage)
- Headache (reported in humans)
藥物相互作用
- Chlorpropamide · May enhance the antidiuretic effects of desmopressin
- Fludrocortisone · May enhance the antidiuretic effects of desmopressin
- Urea · May enhance the antidiuretic effects of desmopressin
監測
- Serum electrolytes (especially sodium)
- Urine osmolality and/or urine volume
- Bleeding times (when used for Von Willebrand's disease)
- Adrenocortical function (prior to water deprivation test)
- Serum sodium (Clinical Pearl)
- Urine specific gravity (Clinical Pearl)
- Bleeding times/vWF levels if used for bleeding disorders (Clinical Pearl)
過量
Chronic oral doses of 0.2 mg/kg/day have been given to dogs for 6 months without significant toxicity. However, acute or severe overdosage may lead to **fluid retention** and **hyponatremia** (water intoxication). > **Treatment:** Employ dosage reduction and strict fluid restriction. Monitor serum electrolytes (especially sodium) closely to prevent neurological complications associated with hyponatremia.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。