Benign Prostatic Hyperplasia (BPH)

Pathophysiologic characteristics of BPH

  • Body usually produces ~ 1 mL urine/min
  • BPH is he progressive narrowing of the urethra secondary to hyperplastic prostatic tissue growth
  • Common disease of men over 50

Clinical symptoms associated with BPH

  • Obstructive symptoms:  weak stream, dribbling, hesitancy, straining, intermittency, incomplete voiding
    • Be sure to differentiate these symptoms from other disease states such as prostate cancer, a poorly contracting bladder, urethral stricture, urethral valves, bladder neck contracture that can also cause these symptoms
    • Drugs that can cause urinary hesitation/outflow obstruction:  beta blockers, alpha agonists, other drugs w/ anticholinergic activity
  • Irritative symptoms:  frequency, nocturia, urgency, incontinence
    • Be sure to differentiate these symptoms from other disease states such as UTIs, prostatitis, bladder cancer, bladder calculi, nospecific cystitis, uninhibited bladder contractions that can also cause these symptoms
  • Complications of BPH:  refractory urinary retention, renal impairment, UTIs, gross hematuria, bladder stones

Agents used for BPH

  • The AUA symptom index is a self test used to help diagnose the extent of the BPH:  mild (0-7), moderate (8-19), severe (20-35)
    • Usually do treatment for anything over 7
  • Alpha adrenergic blockers
    • Terazosin (hytrin), doxazosin (cardura), tamsulosin (flomax), alfuzosin (uroxatral), silodosin (rapaflo)
    • Cause smooth muscle relaxation of the bladder neck, prostate capsule & prostatic urethra
      • Doesn’t affect prostate size
    • Indicated for mild-moderate BPH
    • Maximum increase in urine flow will occur within 2 weeks; 50-70 % of pts demonstrate symptom improvement with a 30-50% reduction in symptom score
    • Start doses low & at bedtime to minimize the potential for orthostatic hypotension changes
    • Adverse effects:  ED, decreased ejaculate, orthostatic hypotension, lightheadedness, dizziness, fatigue
    • Tamsulosin is the only apha-blocker that isn’t contraindicated with phosphodiesterase inhibitors (viagra, etc)
    • Contraindicaions:  hypotension, other potent 3A4 inhibitors, severe hepatic dysfunction, CrCl < 30, prolonged QT interval
  • 5-alpha reductase inhibitors
    • Finasteride (proscar), dutasteride (avodart)
      • Finasteride has been shown to decrease half of the symptoms in half of men.  Long term use decreases the need for surgery
        • Symptom improvement may not be seen for 3-6 months.
        • Dose = 5 mg/day
        • SE:  breast tenderness, gynecomastia, hair growth, rash, impotence/decreased libido, decreases PSA levels
        • Contraindications:  kids, women, prego category X
      • Dutasteride inhibits both isoforms of 5-alpha reductase
        • Metabolized by 3A4
        • Dose:  0.5 mg soft gel capsule/day
        • SE are similar to finasteride
    • Decrease the concentration of dihydrotestosterone (DHT)
    • Produce an androgen deficiency in the prostatic tissue (decreases prostate size)
    • Increase testosterone concentrations
  • Combo therapy of a 5-alpha reductase drug (finasteride) + an alpha adrenergic blocker (doxazosin)  helps reduce the risk of surgery
  • Antimuscarinics
    • May be beneficial in men w/ overactive bladder (obstructive symptoms) & moderate-severe symptoms
    • Use tolteridone in combo with an alpha blocker
    • SE:  urinary retention, dry mouth, etc
  • Saw Palmetto
    • Inhibits 5-alpha reductase
    • Inhibits DHT binding to androgenic receptor & antiestrogenic activity
    • NO PROVEN benefit
    • Dose:  160 mg BID
    • SE:  GI disturbances
  • Pygeum Africanum (from the African plum tree)
    • Twice as effective as placebo (increases peak urinary flow by 23%)
    • Don’t recommend herbals w/o a previous doctors assessment
  • Surgical & other nonpharmacological treatments:  TURP (resection), TUNA (needle ablation), thermal ablation (TUMT)

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