Drug Comparisons

Alpha blockers are commonly used to treat hypertension (high blood pressure) or benign prostatic hyperplasia (BPH). This class of drugs is generally not preferred as a first-line treatment to lower blood pressure, but is most frequently used in combination with other medications when blood pressure is difficult to control.

Alpha blockers may be a good choice of drug therapy in men who have both hypertension and BPH, a common disorder in older men that involves enlargement of the prostate and can cause urinary problems such as difficulty urinating and increased frequency of urination.

Drugs in this Class
Doxazosin Tablets (Cardura Tablets)
Prazosin (Minipress)
Terazosin (Hytrin)

Summarizing the Evidence

• There have only been a few studies directly comparing these drugs with one another for the treatment of high blood pressure. Based on those studies, all three drugs lowered blood pressure similarly and there does not seem to be a major advantage of one alpha blocker over another in terms of blood pressure lowering.

• Based on the results of a large study known as the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), alpha blockers should generally not be used as first-line therapy for the treatment of hypertension, unless they are being used to treat both hypertension and BPH.

• Alpha blockers are generally well tolerated with mild side effects such as drowsiness, dizziness, lightheadedness, heart palpitation, and fainting. There may be more dizziness associated with alpha blockers especially after the first few doses, as compared to other classes of drugs used to lower blood pressure. These side effects can sometimes be minimized or avoided by taking the alpha blocker at bedtime and starting at low doses and gradually working up to higher doses if needed. No major differences in the frequency of side effects among the alpha blockers are apparent.

Dosing and Administration

• Doxazosin and terazosin are typically taken once daily. However, prazosin is typically taken three times a day because it has a shorter duration of action (meaning, the effects do not last long).

Generic Availability

• Doxazosin (Cardura), prazosin (Minipress) and terazosin (Hytrin) are all available in generic formulations.

Drug Interactions

Some interactions between medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how the drugs interact and the severity of the interaction, please use our Drug Interactions Checker.

Side Effects

To view specific side effect information, please use our Side Effect Checker.

Additional Information

References

1. Cardura [package insert]. New York, NY: Pfizer, Inc; April 2002.
2. Hytrin [package insert]. North Chicago, IL: Abbott Laboratories; February 2001.
3. Gutherie R. Terazosin in the treatment of hypertension and symptomatic benign prostatic hyperplasia: a primary care trial. J Fam Pract. 1994;39:129-133.
4. Gutherie RM, Siegel RL for the Hypertension and BPH Intervention Trial (HABIT) Multicenter Study Group. A multicenter, community-based study of doxazosin in the treatment of concomitant hypertension and symptomatic benign prostatic hyperplasia: the hypertension and BPH intervention trial (HABIT). Clin Ther. 1999;21:1732-1748.
5. Fawzy A, Hendry A, Cook E, et al. Long-term (4 year) efficacy and tolerability of doxazosin for the treatment of concurrent benign prostatic hyperplasia and hypertension. Int J Urol. 1999;6:346-354.
6. The ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major cardiovascular events in hypertensive patients randomized to doxazosin vs chlorthalidone. The Antihypertensive and Lipid-Lowering Treatment to Prevention Heart Attack Trial (ALLHAT). JAMA. 2000;283:1967-1975.
7. Messerli H. Implications of discontinuation of doxazosin arm of ALLHAT. Lancet. 2000;355(9207):863-864.
8. Drugdex Database. In: Gelman CJ, Rumack BH, editors. Denver: Micromedex Inc. 2007.
9. Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA. 2003; 285:2560-2572.

Last Updated: April 2008
This content was created by members of the DrugDigest team of experts and is solely under DrugDigest's editorial control.

Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It should not be construed to indicate that the use of the product is safe, appropriate, or effective for you. Consult your healthcare professional before taking any medication.