How Do Alpha1 Blockers Work?

Alpha1 blockers are medications prescribed to treat bladder outlet obstruction due to prostate enlargement (benign prostatic hyperplasia) in men. Alpha1 blockers relax the smooth muscles in the bladder neck and prostate, which improves urine flow and reduces urinary symptoms associated with prostate enlargement.

Alpha1 blockers relax the prostate and bladder muscles by selectively blocking alpha1A and alpha1D adrenoreceptors. Alpha1A and alpha1D adrenoreceptors are protein molecules on the smooth muscle cells of the prostate, bladder, and urethra, which stimulate muscle contraction when activated by the hormones, epinephrine, and norepinephrine.

Alpha1 blockers are administered as oral capsules for the treatment of the following conditions:

FDA-approved:

• Signs and symptoms of benign prostatic hyperplasia (BPH)

Off-label:

• Bladder outlet obstruction
• Ureteral stones, to facilitate kidney stone expulsion

Side effects of alpha1 blockers may include the following:

• Headache
• Orthostatic hypotension (drop in blood pressure when standing up from sitting or lying down)
• Syncope (fainting)
• Rhinitis (inflammation of the nasal passage)
• Abnormal ejaculation
• Dizziness
• Arthralgia (joint pain)
• Infection
• Asthenia (weakness)
• Back pain
• Myalgia (muscle pain)
• Hypersensitivity reactions such as:
  • Skin rash
  • Urticaria (hives)
  • Pruritus (itching)
  • Erythema multiforme (round lesions like a bullseye)
  • Exfoliative dermatitis (skin inflammation with redness and peeling of the skin)
  • Stevens-Johnson syndrome (a rare medical emergency with flu-like symptoms and a painful rash)
  • Angioedema (swelling in the tissue under the skin or mucous membranes)
  • Respiratory symptoms
• Pharyngitis (inflammation of the throat)
• Sinusitis (inflammation of the sinuses)
• Chest pain
• Cough
• Somnolence (drowsiness)
• Diarrhea
• Nausea
• Vomiting
• Abdominal discomfort
• Constipation
• Bitter taste
• Dry mouth
• Epistaxis (nasal bleeding)
• Decreased libido
• Priapism (prolonged erection), rare
• Insomnia
• Visual impairment
• Intraoperative floppy iris syndrome (IFIS), a condition in which the pupils do not dilate normally, after cataract and glaucoma surgery in people on alpha1 blocker therapy
• Dyspnea (shortness of breath)
• Hypotension (low blood pressure)
• Palpitations
• Atrial fibrillation
• Arrhythmia (irregular heart rhythm)
• Tachycardia (rapid heartbeat)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of alpha1 blocker drugs include:

• Flomax
• tamsulosin