非那雄胺
非那雄胺（Finasteride）是一種合成的4-氮雜類固醇化合物，作為5-α還原酶的競爭性特異性抑制劑。 在獸醫學中，它主要用於未絕育雄性犬的**良性前列腺增生（BPH）**的內科治療。對於高價值的種犬而言，它提供了一種極佳的替代外科閹割的方案，因為它能在不顯著影響生育能力或循環睪酮濃度的情況下縮小前列腺體積。 此外，非那雄胺也作為仿單標示外使用（off-label use），用於雪貂**腎上腺疾病**的輔助治療，幫助控制受影響雄性雪貂因雄性激素驅動的臨床症狀（如前列腺腫大和尿道阻塞）。
作用機制: Finasteride specifically and totally inhibits the intracellular enzyme **5-alpha-reductase** (predominantly Type II). * **Pathway**: Testosterone → (via **5-alpha-reductase**) → **Dihydrotestosterone (DHT)** DHT is a highly potent androgen and is the primary hormone responsible for the development and enlargement of the prostate gland. By blocking this conversion, finasteride significantly reduces DHT concentrations in the prostate, liver, and skin. This leads to prostatic involution and a reduction in clinical signs of BPH. Because it does not directly block testosterone or its receptors, normal testosterone-dependent functions (such as spermatogenesis and libido) are largely preserved.
各物種劑量
- Adjunctive treatment of adrenal disease · 5 mg (total dose) · PO · once daily · tablet
- Benign prostatic hyperplasia · 0.1-0.5 mg/kg · PO · once daily · for a 10-50 kg dog, one 5 mg tablet daily
- Benign prostatic hyperplasia · <15 kg: 1.5 mg (approx. 1/3 of a 5 mg tablet); 15-30 kg: 2.5 mg (1/2 tablet); >30 kg: 5 mg (one tablet) · PO · daily
- Benign prostatic hypertrophy · 5 mg per dog · PO · q24h · Extended treatment course (<8 weeks) may be required for full efficacy · Alternative to castration. Use when delmadinone or osaterone are not appropriate.
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。
給藥途徑
禁忌症
- Hypersensitivity to finasteride
- Sexually developing animals
- Females (especially pregnant females)
- Sexually-developing dogs
- Breeding dogs (due to secretion in semen and teratogenic potential)
不良反應
- Decreased libido
- Decreased ejaculate volume
- Impotence (rare/mild)
- Secreted into semen
- Causes fetal anomalies (teratogenic)
藥物相互作用
- Anticholinergic drugs · May precipitate or aggravate urinary retention thereby negating the effects of the drug when used for BPH
監測
- Prostate exam (to evaluate efficacy and reduction in size)
- Prostate size (via palpation or ultrasound)
- Resolution of clinical signs (e.g., tenesmus, dysuria, hematuria)
過量
Limited information is available regarding acute toxicity. Mild **gastrointestinal effects** (such as vomiting or diarrhea) may be noted in the event of an overdose. Supportive care is recommended.
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。