Alfuzosin

Alfuzosin is a prescription drug used for the treatment of benign prostatic hyperplasia (BPH). BPH is a noncancerous enlargement of the prostate gland. Symptoms include frequent urination and urinary retention. The Food and Drug Administration approved alfuzosin on June 12, 2003.

Diagram of location of prostate gland. In benign prostatic hyperplasia, the prostate gland grows and places pressure on the surrounding tissues. Alfuzosin acts on muscles in this regin to releave symptoms. Source: Wikimedia Commons

Other Names

Alfuzosin is marketed in the U.S. by Sanofi-Aventis under the brand name Uroxatral. Outside of the United States, Alfuzosin is marketed as Xatral.

Uses

Alfuzosin is used to relieve the symptoms of BPH.

How Alfuzosin is Taken

Alfuzosin is available in 10 mg tablets. The recommended dose is one tablet daily taken immediately after the same meal each day.

How Alfuzosin Works

The symptoms of BPH, such as increased urination, urination throughout the night, weak urine stream, hesitancy and incomplete emptying of bladder, are attributed to both anatomical and functional causes. The anatomical cause is related to the size of the prostate. The functional cause is related to muscle tone in the prostate, the bladder, and the urethra, which is the vessel through which urine exits the body (see diagram above). Alpha adrenergic receptors control the tone of this muscle. Stimulation of these receptors increases muscle tone and causes many of the symptoms of BPH. Alfuzosin blocks these receptors. This results in relaxation of the muscles in the bladder and prostate, improves urine flow, and relieves the symptoms of BPH.

How the Body Affects Alfuzosin

Alfuzosin reaches a maximum concentration in the blood approximately eight hours after dosing. Food increases absorption of alfuzosin by 50% compared to the fasting state. Thus, alfuzosin is more effective when taken with a meal.

Alfuzosin undergoes extensive metabolism by the liver, with only 11% of the administered dose excreted unchanged in the urine. CYP3A4 is the primary liver enzyme involved in this metabolism. Alfuzosin is metabolized through three different pathways that produce compounds with no physiological activity.

After metabolism, 69% of the original dose is excreted in the feces and 24% is excreted in the urine.

Side Effects

The following side effects were reported by between 1% and 2% of patients receiving alfuzosin in clinical trials:

Gastrointestinal

• abdominal pain
• acid reflux
• constipation
• nausea

Reproductive

• impotence

Respiratory

• bronchitis
• inflammationin the sinuses or pharynx

Risks and Precautions

• Low blood pressure, with or without symptoms (e.g., dizziness or fainting), may develop within a few hours after taking alfuzosin.

• Intraoperative floppy iris syndrome has been reported in some people receiving alpha blockers and undergoing cataract removal. This syndrome occurs when the fluid in the eye causes the iris to billow and shift during removal of a cataract. It usually resolves after the surgery without complication.

• Levels of alfuzosin in the blood are increased in people with moderate to severe liver damage. This limits the use of alfuzosin in these individuals.

Drug Interactions

Alfuzosin is not used in combination with other drugs that block alpha adrenergic receptors. In addition, because of metabolism by the enzyme CYP3A4, alfuzosin is not generally used in combination with drugs that inhibit this enzyme:

• ketoconazole(Nizoral)
• itraconazole(Sporanox)
• ritonavir(Norvir)

Research

An analysis of three clinical trials of the use of alfuzosin (10 mg) in BPH was performed on over 900 patients.^[1] Effectiveness was measured in two ways:

• The International Prostate Symptom Score (IPSS) consisting of seven questions that assess the severity of both irritative (frequency, urgency, urination at night) and obstructive (incomplete emptying, stopping and starting, weak stream, and pushing or straining) symptoms, with possible scores ranging from 0 to 35
• Peak urinary flow rate

In the studies, IPSS score was reduced by six points in alfuzosin-treated patients and four points in placebo-treated patients. This improvement in scores suggests that the severity of symptoms was reduced by alfuzosin. Alfuzosin also increased peak urinary flow rate and improved quality of life relative to that seen in the placebo-treated patients.

References

1. ↑ Roehrborn CG, Van Kerrebroeck P, Nordling J. Safety and efficacy of alfuzosin 10 mg once-daily in the treatment of lower urinary tract symptoms and clinical benign prostatic hyperplasia: a pooled analysis of three double-blind, placebo-controlled studies. BJU Int. 2003 Aug;92(3):257-61. Abstract

External Links

FDA: Uroxatral Consumer Information