坦索羅辛
坦索羅辛是一種**α-1腎上腺素受體拮抗劑**，對泌尿道具有選擇性。它透過放鬆前列腺、尿道和膀胱頸的平滑肌來幫助尿液排出。其作用時間比哌唑嗪 (prazosin) 或酚苄明 (phenoxybenzamine) 更長。 **臨床提示：** 在獸醫學中常以仿單標示外使用 (off-label) 於治療功能性尿瀦留、未絕育雄犬的良性前列腺增生 (BPH)，或協助排出輸尿管結石/尿石。
作用機制: Tamsulosin selectively binds to and blocks **alpha-1A and alpha-1D adrenergic receptors** located predominantly in the smooth muscle of the prostate, prostatic capsule, prostatic urethra, and bladder neck. Blockade of these receptors → relaxation of smooth muscle → decreased urethral resistance → improved urine flow and relief of functional urinary obstruction.
給藥途徑
禁忌症
- Hypersensitivity to tamsulosin
- Severe hepatic impairment
- History of orthostatic hypotension
不良反應
- Hypotension
- Lethargy
- Weakness
- Gastrointestinal upset (vomiting, diarrhea)
- Dizziness
藥物相互作用
- Other alpha-1 blockers (e.g., prazosin, phenoxybenzamine) · Additive hypotensive effects · major
- Calcium channel blockers (e.g., amlodipine) · Increased risk of hypotension · moderate
- Cimetidine · Decreased clearance of tamsulosin, potentially increasing plasma concentrations · minor
監測
- Urine output and ease of urination
- Blood pressure
- Renal function
過量
Overdosage may lead to severe **hypotension**. Treatment is primarily supportive, including intravenous fluid therapy and potentially vasopressors if hypotension is refractory. Emesis or gastric lavage may be considered if ingestion is recent.
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