Tamsulosin
Tamsulosin is an **alpha-1 adrenergic antagonist** with high selectivity for the urinary tract. It works by relaxing the smooth muscle in the prostate, urethra, and bladder neck, thereby aiding urine flow. It has a longer duration of action compared to other alpha-blockers like prazosin or phenoxybenzamine. **Clinical Pearl:** In veterinary medicine, tamsulosin is frequently used off-label to manage functional urinary retention, benign prostatic hyperplasia (BPH) in intact male dogs, and to facilitate the medical expulsive therapy of ureteroliths or uroliths.
กลไกการออกฤทธิ์: 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.
วิธีการให้ยา
ข้อห้ามใช้
- Hypersensitivity to tamsulosin
- Severe hepatic impairment
- History of orthostatic hypotension
อาการไม่พึงประสงค์
- Hypotension
- Lethargy
- Weakness
- Gastrointestinal upset (vomiting, diarrhea)
- Dizziness
อันตรกิริยาระหว่างยา
- 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
การติดตาม
- Urine output and ease of urination
- Blood pressure
- Renal function
การได้รับยาเกินขนาด
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.
ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต