Alpha-adrenergic receptor antagonists such as tamsulosin are first-line treatment for BPH, and they work by decreasing the sympathetic action at the bladder outlet allowing for easier excretion of urine. Note that certain alpha-antagonists such as terazosin, prazosin and doxazosin appear on the 2015 Beers Criteria for medications which should be used with caution in older patients due to the risk of orthostatic hypotension.5 However, this refers to their use as antihypertensives. When starting alpha-1 adrenergic antagonists, it is important to begin with the lowest possible dose and titrate up as needed. Note that Prazosin is not recommended for the treatment of BPH related symptoms due to the high incidence of side effects.2 Note that alpha-adrenergic antagonists must not be initiated prior to planned cataracts surgery due to the association of their use with intraoperative floppy iris syndrome noted during cataracts surgery; of all alpha-1 adrenergic antagonist, tamsulosin is the most frequently implicated. If a patient is already on tamsulosin, there is no clear evidence that stopping the medication before cataract surgery will prevent the occurrence of intraoperative floppy iris syndrome.2,4
5-alpha reductase inhibitors work by decreasing prostatic volume which ultimately alleviates symptoms of BPH although they work much slower than alpha-adrenergic antagonists. Occasionally, both drug classes will be used in a combination regimen. 5-alpha reductase inhibitors work by delaying the progression of disease in patients with BPH. They are particularly useful in preventing episodes of acute urinary retention and eventually alleviating the need for surgery. 5-alpha reductase inhibitors are more efficient in patients with a significantly enlarged prostate as determined on physical examination. Drugs in this class are less effective at alleviating lower urinary tract symptoms compared to alpha-adrenergic inhibitors. Examples of medications in this drug class include dutasteride and finasteride. Note that dutasteride is associated with longer side effects due to its long half-life of approximately 5 weeks. Side effects of dutasteride include decreased libido, impotence, breast tenderness and enlargement.2,3,4 Finasteride can only be administered in patients who are able to swallow whole pills because it cannot be crushed.
Combination therapy using 5-alpha reductase inhibitors and alpha-adrenergic inhibitors work more effectively than either drug classes by itself. Currently, finasteride and doxazosin are used in combination while dutasteride and tamsulosin are used in combination.2,3,4
Phosphodiesterase inhibitors are currently used in the treatment of erectile dysfunction but also have been shown to improve the symptoms of BPH. There are 4 phosphodiesterase inhibitors presently used in the United States, and they all appear to work effectively in reducing the symptoms of BPH; namely, sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis) and avanafil (Stendra). A common side effect of phosphodiesterase inhibitors is hypotension which is also a side effect of alpha-adrenergic antagonists; therefore, patients must be warned about the potentiation of hypotension, and drug dosing should be carefully monitored.1,2
There are several alternative medicine options and over the counter medications which are used to treat symptoms of BPH. Examples include saw palmetto and stinging nettle. There is little evidence documenting their efficacy.
It is not usual for symptoms of BPH to occur concurrently with symptoms of overactive bladder. The most common medication class used to treat overactive bladder is anticholinergics such as Oxybutynin (Ditropan XL, Oxytrol) and Tolterodine (Detrol).2