Uroxatral
Uroxatral
Generic Name
Uroxatral
Mechanism
- Selective α1A‑adrenergic receptor blockade in the prostate and bladder neck.
- ↓ Intramural smooth‑muscle tone → relaxation of the prostatic urethra.
- ↓ Lumen resistance → increased urinary flow, decreased post‑void residual volume.
- Minimal activity at α1B/α1D receptors → reduced systemic vascular effects and fewer sexual side‑effects compared with non‑selective α1‑blockers.
---
Pharmacokinetics
| Parameter | Details |
| Route | Oral, fast‑acting formulation |
| Absorption | Peak plasma concentration (Tmax) ~ 1–2 h after dosing |
| Bioavailability | ~ 70 % (unchanged with food) |
| Protein Binding | ~ 85 % to plasma proteins |
| Metabolism | Primarily hepatic via CYP3A4; minor CYP1A2 involvement |
| Elimination | Renal (≈ 60 %) and biliary excretion |
| Half‑life | ~ 7 h (steady‑state trough ~ 4–6 h) |
| Duration of Action | 24 h, supporting once‑daily dosing |
--
•
Indications
- Benign Prostatic Hyperplasia (BPH) presenting with lower urinary tract symptoms (LUTS): urinary urgency, weak stream, incomplete bladder emptying, nocturia.
---
Contraindications
| Contraindication | Reason |
| Hypersensitivity to Uroxatral or any excipients | Severe allergic reaction |
| Severe hepatic impairment (Child‑Pugh C) | Risk of elevated plasma levels |
| Recent or concurrent use of strong CYP3A4 inhibitors (ketoconazole, ritonavir) | ↑ risk of bradycardia, hypotension |
| Severe cardiovascular disease (e.g., uncontrolled hypertension, angina) | Potential exacerbation |
| Recent ingestion of nitrates or PDE5 inhibitors | Heightened risk of profound orthostatic hypotension |
Warnings
• Orthostatic hypotension: evaluate postural blood pressure before first dose and after any dose increase.
• Drug-drug interaction: caution with antihypertensives, diuretics, anticholinergics.
--
•
Dosing
- Initial dose – 0.40 mg once daily (typically in the evening).
- Maintenance – May increase to 0.80 mg daily if adequate improvement not achieved and tolerated.
- Administration – Take with or without food; avoid lying down immediately after ingestion to reduce dizziness.
- Missed dose – Omit; do not take a double dose the next day.
---
Adverse Effects
| Symptom | Frequency (Common) |
| Dizziness / vertigo | 10–20 % |
| Headache | ~15 % |
| Postural hypotension | 5–10 % |
| Somnolence | 5 % |
| Flushing | <5 % |
| Gastrointestinal upset | <5 % |
| Sexual dysfunction | Rare (<1 %)—infertility, ejaculate depression minimal |
Serious
• Orthostatic syncope (rare) → hospitalization.
• Severe hypotension in susceptible patients.
--
•
Monitoring
1. Blood pressure & heart rate – check supine and standing daily for first week, then quarterly.
2. Serum creatinine & eGFR – assess renal function after 3 months if chronic therapy.
3. Liver function tests (AST, ALT, bilirubin) – baseline, then annually, or sooner if symptoms.
4. Prostate-specific antigen (PSA) – baseline and follow‑up per urologist guidance.
5. Urine flow (Qmax) – baseline, 6–12 weeks, then annually to gauge efficacy.
---
Clinical Pearls
- Ultra‑selectivity for α1A → *Uroxatral* provides a superior safety profile regarding sexual side‑effects compared with non‑selective α1 blockers like tamsulosin or alfuzosin.
- Give in the evening to mitigate nocturia while minimizing daytime dizziness.
- CYP3A4 inhibitors drastically elevate exposure; in patients on such drugs, consider an alternative BPH agent or reduce dose by 50 %.
- Postural hypotension is dose‑dependent; a gradual titration from 0.40 mg to 0.80 mg eases tolerance.
- Patients with substantial bladder outlet obstruction may require surgical evaluation after 3–6 months of optimal medical therapy.
- Use the 24‑h urinary flow measurement not only to assess efficacy but also to rule out conditions like bladder outlet obstruction secondary to prostate surgery or post‑prostatectomy.
--
• Key Takeaway: *Uroxatral* offers a highly selective, once‑daily α1A antagonist that alleviates LUTS in BPH while minimizing systemic side‑effects and sexual dysfunction, making it a valuable first‑line agent for many patients.