睪酮 / 睪丸酮
**睪酮 (Testosterone)** 是一種內源性雄性激素，在獸醫學中主要用於治療已絕育雄性犬貓的**激素反應性尿失禁**。 - **小動物**：主要用於治療絕育雄性犬貓的尿失禁，偶爾用於治療特定的雙側性脫毛（皮膚炎）。 - **大動物**：在牛隻醫學中，被用來製造「試情牛」(teaser animals) 以偵測發情。 - **臨床提示**：其用於提高家畜性慾或治療不孕症的效果通常不佳。 - **法規**：睪酮產品屬於**第三級管制藥品 (C-III)**。
作用機制: Testosterone is highly lipophilic and diffuses across target cell membranes. In many tissues, it is converted by **5-alpha-reductase** → **dihydrotestosterone (DHT)**. Both testosterone and DHT bind to intracellular **androgen receptors** → the receptor complex translocates to the nucleus → binds to DNA hormone response elements → modulates gene transcription. - **Urethral Tone**: Helps maintain normal urethral muscle tone and mucosal integrity in neutered males. - **Anabolic Effects**: Increases protein anabolism and decreases catabolism → retention of nitrogen, sodium, potassium, and phosphorus. - **Erythropoiesis**: Stimulates **erythropoietic stimulating factor (erythropoietin)** → increases red blood cell production. - **Endocrine Feedback**: Large exogenous doses exert negative feedback on the pituitary gland → inhibits **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)** → inhibits spermatogenesis.
各物種劑量
- Infertility or reduced libido · 0.1-1 mg every other day or every third day for 3-5 injections IM or SC. Not indicated for testis descent. · IM/SC · every other day or every third day · 3-5 injections · Using either testosterone cypionate or propionate
- Testosterone-responsive urinary incontinence (may be used with phenylpropanolamine) in males · Testosterone propionate 5-10 mg IM as needed. · IM · as needed
- To produce an estrus-detector (teaser) animal (cull cows, heifers, steers) · Testosterone propionate 200 mg IM on day 1 and on days 4-9. On day 10, give 1 gram IM and attach a chinball marker and put with the breeding herd. To maintain the teaser give 1 gram booster every 10-14 days. · IM · varies
- To produce an estrus-detector (teaser) animal (cull cows, heifers, steers) · Alternatively, initially give testosterone enanthate 0.5 gram IM and 1.5 gram SC (divided in two separate locations). After 4 days attach chinball marker and put in with breeding herd. To maintain, give 0.5-0.75 gram SC every 10-14 days. · IM/SC · varies
- Testosterone-responsive urinary incontinence (may be used with phenylpropanolamine) in males · Testosterone propionate: approximately 2 mg/kg IM or SC 3 times per week. Testosterone cypionate: 200 mg IM once per month · IM/SC · 3 times per week / once per month
- Testosterone-responsive urinary incontinence · Testosterone propionate: 2.2 mg/kg IM q2-3 days. Testosterone cypionate: 2.2 mg/kg IM once per month · IM · q2-3 days / once per month
給藥途徑
禁忌症
- Known hypersensitivity to the drug
- Prostate carcinoma
- Pregnancy (FDA Category X / Papich Class D)
不良反應
- Perianal adenomas
- Perineal hernias
- Prostatic disorders (enlargement)
- Behavior changes (aggression)
- Polycythemia (at high doses)
- Oligospermia or infertility (in intact males with chronic use)
藥物相互作用
- Corticosteroids · May enhance the edema associated with ACTH or adrenal steroid therapy
- Insulin / Oral Antidiabetic Agents · Testosterone may decrease serum glucose levels
- Propranolol · Testosterone cypionate may increase propranolol clearance
- Warfarin · Testosterone may increase anticoagulant effects
監測
- Clinical efficacy (resolution of incontinence, estrus detection behavior)
- Adverse effects (prostatic enlargement, aggression, perineal hernias)
- Hematocrit/PCV (for polycythemia with chronic use)
過量
No specific acute toxicity information is available. - **Chronic Overdose**: High dosages or chronic usage may result in oligospermia or infertility in intact males due to negative feedback on LH/FSH. - **Other Effects**: Polycythemia (excessive red blood cells) has been reported in humans receiving high dosages. - **Treatment**: Discontinue therapy and provide supportive care. Monitor hematocrit and prostatic size.
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