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Urology/Why can the Alpha-1 blockers not help the bladder distension due to the BPH but Anticholinergic drugs can?


I am 50s and was diagnosed with mildly enlarged prostate by the CT scan. The Cystoscopy found my bladder outlet obstruction. But, my post-void residual urine test is only 26 ml. I only feel a little difficult urination in the morning, the first urination of the day. My main symptom is bladder distension, like pressure in my bladder. The Alpha-1 blocker medications such as Flomax and Rapaflo have no help in the relief of my bladder distension. The Anticholinergic drugs such as Oxybutynin, however, can relieve my bladder distension. I do not know why The Alpha-1 blockers cannot relieve my bladder distension but Anticholinergic drugs can. Can you explain it? In addition, the drug instructions indicate the Anticholinergic drugs can cause the urine retention that is not good for the patient with the existing BPH. Should I take both of the Alpha-1 blockers such as Flomax and Anticholinergic drug Oxybutynin? Will it have potential problems to take both of the medications? Thank you for your answer.

Ray, I think the main issue is trying to understand which underlying condition is causing your symptom. Your only symptoms are a feeling of pressure in the bladder area and some mild morning "difficulty" by which I assume you mean some trouble initiating the stream or the stream is a bit slow.  

Benign enlargement of the prostate gland (benign prostatic hyperplasia or BPH) occurs to varying degrees in all men as they age.  The prostate surrounds the urinary canal (urethra) just after its connection to the urinary bladder.  Inward growth of the prostate either into the bladder neck (opening) or into the urethra itself can cause difficulty with urinating.  The prostate is checked by digital examination through the rectum.  This gives the doctor an idea as to the size and benignity of the gland.  However, it does not always correlate to symptoms as a small gland may have significant inward growth and a large glands enlargement may be entirely peripheral.   

The ability to urinate involves the urinary bladder muscle actually becoming stronger as it works against increasing resistance from the prostate.  This delicate balance can be upset by any factor that decreases the bladder muscles ability to contract with sufficient force to open the prostate (such as medications, anesthesia, too much alcohol, ignoring the desire to urinate, etc.) or those factors that might cause the prostate to suddenly swell (ie acute prostatitis, sitting  for extended periods of time, biking, horseback riding, etc.).  It is not unusual for men with BPH to have problems initiating the stream in the morning as their bladder is a little over-distended from accumulation during sleep.

The typical symptoms that occur with BPH (most of which you do not have) include diurnal frequency (daytime), nocturia (night-time frequency), urgency, hesitancy, slow stream and dribbling after voiding.  This complex of symptoms is termed “prostatism”.  If the obstruction to flow progressively worsens, the bladder eventually may not be able to empty completely.  This leads to the accumulation of “residual urine” which may predispose to urinary infections and  kidney damage from back pressure.

However, relatively asymptomatic men with BPH do NOT necessarily require therapy.  Treatment is indicated to relieve symptoms and prevent complications.  In many cases medications can be used.  Alpha - blockers (ie Hytrin, Cardura, Flomax, Uroxatral etc.) work by relaxing the bladder neck and urethra so the pressure generated by a bladder contraction has less resistance to work against. Think of these drugs as allowing the prostatic urethra to spring open.   Natural herbal products such a saw palmetto and pygeum often provide symptomatic relief but the exact mechanism of action has not yet been defined.  The prescription drugs Proscar and Avodart actually shrink the prostate.  They work best in the larger glands and improvement may not be noted for up to 6 months.   In cases refractory to medication, interventional measures are indicated.  The “gold standard” for treatment is the time honored transurethral resection (TUR) of the prostate.  For huge glands, open surgery may be necessary.  In the past decade a number of other less invasive interventional therapies have been developed to reduce the obstructing prostate tissue utilizing various forms of energy.   These include laser prostatectomy, microwave (TUMP or transurethral microwave of the prostate), and radiofrequency (TUNA or transurethral needle ablation of the prostate).  TUMP is actually a minimally invasive, out-patient treatment that can be tried initially if the patient's gland size is appropriate.  

I suspect you have mild, early BPH perhaps accounting for the AM problem.  Not everyone responds to alpha blockers (approximately 80%) and, in your case, I would expect mainly the morning problem to be helped.  The is also a common syndrome called LUTS (lower urinary tract symptoms)  that responds very favorably to anticholinergics.  This can be caused by many conditions including BPH, inflammation of the prostate gland (prostatitis), bladder muscle instability, nerve disorders, etc.  Anticholinergics work by relaxing the bladder muscle to allow the bladder to hold more before one gets the desire to urinate.  Apparently you are tolerating your present dose well but if your BPH increases the outlet resistance or you require a higher dose of anticholinergics to control your symptoms, urinary retention is a possibliity.

For now, since you did not seem to be helped by the alpha blockers, I suggest just trying to see how you do on the anticholinergics alone.  If necessary to control symptoms, the dose of this could be increased or as an option, the alpha blockers could then be added.  However, most individuals with LUTS (which is probably the main source of your problem) can be controlled with just anticholinergics.  Hope I haven't confused you too much.  good luck.


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Arthur Goldstein, M.D.


Problems or questions related to the field of urology; ie urinary stone disease, urinary cancers (kidney, bladder, prostate, testis, etc.), urinary infections, etc. I no longer answer questions related to erection problems or male sexual dysfunction.


I am retired from the active practice of urology. My 34 years was totally in the clinical field and involved the entire gamut of genitourinary problems, with special interest in endourology.

American Medical Association, American Urological Association, American College of Surgeons

College degree - BS Medical degree - MD Master of Science - MS

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