A adrenergic antagonist

Identify factors that guide selection of a particular a-adrenergic antagonist for an individual patient. 

Compare and contrast a-adrenergic antagonists versus 5a-reductase inhibitors in terms of mechanism of action, treatment outcomes, adverse effects, and interactions when used for management of benign prostatic hyperplasia. 

Among the a-adrenergic antagonists, alfuzosin is considered functionally uroselective because in usual therapeutic doses, it produces relaxation of the bladder neck and prostatic smooth... 

Stromal tissue is the primary locus of aradrenergic receptors in the prostate. It is estimated that 98% of the a-adrenergic receptors in the prostate are found in prostatic stromal tissue. Of the arreceptors found in the prostate, 70% of them are of the a1A-sub-type.5 This explains why a-adrenergic antagonists are effective for managing symptoms of BPH.6... 

For patients with moderate to severe symptoms, the patient is usually offered drug treatment first. a-Adrenergic antagonists are preferred over 5a-reductase inhibitors because the former have a faster onset of action (days to a few weeks) and improve symptoms independent of prostate size. 5a-reductase inhibitors have a delayed onset of action (i.e., peak effect may... 

TABLE 49-4. Comparison of a-Adrenergic Antagonists and 5a-Reductase Inhibitors for Treatment of Benign Prostatic Hyperplasia47... 

In patients with BPH and hypertension, it is not recommended to use an a-adrenergic antagonist alone to treat both disorders. In the ALLHAT study, where doxazosin was compared to other agents for treatment of essential hypertension, doxazosin was associated with a higher incidence of congestive heart failure. Therefore, in patients with hypertension and BPH, it is recommended that an appropriate antihypertensive be added to an a-adrenergic antagonist.11... 

To streamline and reduce the cost of treatment regimens, it has been suggested that the a-adrenergic antagonist maybe discontinued after the first 6 to 12 months of combination therapy. However, long-term treatment is required to determine if such a regimen is as effective as continuous combination therapy.42,43... 

Drug treatment failures may result from a variety of factors. Initial failure to respond to a-adrenergic antagonists occurs in 20% to 70% of treated patients. It is likely in these patients that the static factor may predominate as the cause of symptoms in these patients. Initial failure to respond to 5a-reductase inhibitors occurs in 30% to 70% of treated patients. 

If the patient has no improvement after several weeks of a therapeutic dose of a-adrenergic antagonist or after... 

If the patient is started on an a-adrenergic antagonist, monitor the patient for hypotension, dizziness, or syncope. If present, assess the severity of each symptom. Reduce the drug dose or discontinue the drug, as necessary. If the patient has malaise or rhinitis, reassure the patient that these are usual, but bothersome, adverse effect, that often improve with continued therapy. 

Initial therapy with an a-adrenergic antagonist provides faster onset of symptom relief. A 5a-reductase inhibitor is preferred as initial therapy in... 

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