Alpha-Blocker (2/5): Doxazosin
Review Literatur: (Chapple, 2004).
General Pharmacology of Doxazosin
Please see section general pharmacology of alpha-blocker.
Mechanism of Action of Doxazosin
Doxazosin is a non-selective alpha1-blocker with a long elimination half-life.
Indications for Doxazosin
- Treatment of lower urinary tract symptoms due to benign prostatic hyperplasia
- Treatment of arterial hypertension
Pharmacokinetics of Doxazosin
- Elimination half-life 22 h
Doxazosin: Mechanism of Action
Postsynaptic alpha1-blockade leads to:
- Arterial and venous vasodilation, hypotension
- Smooth muscle relaxation of the prostate, bladder neck and the urethra. Alpha-blocker improve the dynamic component of subvesical obstruction due to benign prostatic hyperplasia (BPH).
- Positive effect on the lipid metabolism by lowering cholesterol and triglycerides
Side Effects of Doxazosin
- Hypotension, orthostatic syncope, reflex tachycardia
- Stuffy nose
- Retrograde ejaculation
- Tachyphylaxis in the treatment of hypertension due to volume retention and peripheral edema.
- Dizziness, weakness
- Overall rate of side effects is between 10–30%
Contraindications of Doxazosin
Conservative treatment of BPH is not indicated, if surgical treatment is imperative: chronic urinary retention with renal failure, recurrent hematuria due to prostatic enlargement, recurrent infections and bladder stones.
Hypotension, mechanical heart failure (valvular, pulmonary embolism, pericarditis), congestive heart failure.
Doxazosin should be paused perioperatively for cataract surgery to prevent an intraoperative floppy iris syndrome.
Dosage of Doxazosin
The treatment of doxazosin should be started with a low dosage, such as 1 mg 1-0-0. The dosage can be increased each week to 2–4–8 mg 1-0-0, depending on treatment effect, side effects and blood pressure.
Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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Chapple 2004 CHAPPLE, C. R.:
- Pharmacological therapy of benign prostatic hyperplasia/lower urinary
tract symptoms: an overview for the practising clinician.
In: BJU Int
94 (2004), Nr. 5, S. 738–44