Alphapress XR

Approved Indications:

• Hypertension (mild to moderate):
  Used alone or as adjunctive therapy with other antihypertensives to lower blood pressure and reduce the risk of stroke, myocardial infarction, and kidney complications.
• Benign Prostatic Hyperplasia (BPH):
  Symptomatic treatment to relieve urinary outflow obstruction by relaxing smooth muscle in the bladder neck and prostate.

Clinically Accepted Off-label Uses:

• Post-Traumatic Stress Disorder (PTSD):
  Used to reduce trauma-related nightmares, hyperarousal, and sleep disturbances.
• Raynaud’s phenomenon:
  May reduce frequency and severity of vasospastic episodes.
• Congestive Heart Failure (CHF):
  Occasionally used as adjunct therapy to reduce afterload (less commonly used now due to availability of better alternatives).

Adults:

• Hypertension:
• Initial: 1 mg orally 2–3 times daily.
• Maintenance: 6–15 mg/day in divided doses.
• Maximum: Up to 20 mg/day in resistant cases.
• BPH:
• Initial: 1 mg at bedtime.
• Maintenance: 2–5 mg twice daily.
• Maximum: Up to 20 mg/day in divided doses.
• PTSD (off-label):
• Initial: 1 mg at bedtime.
• Titrate by 1–2 mg every few days.
• Common effective dose: 3–15 mg/day at bedtime.

Pediatrics:

• Safety and efficacy not well established. Off-label use in pediatric PTSD or hypertension may occur with specialist supervision.

Elderly:

• Increased sensitivity to hypotension. Start with 1 mg once daily at bedtime. Titrate cautiously.

Renal Impairment:

• Use with caution. Start at lowest dose. Monitor closely.

Hepatic Impairment:

• Caution advised due to hepatic metabolism. No specific dose adjustment provided, but careful monitoring is required.

Administration:

• Oral tablets.
• Administer with or without food.
• First dose and dose increases should be taken at bedtime to minimize risk of first-dose hypotension.

Prazosin hydrochloride is a selective, competitive alpha-1 adrenergic receptor antagonist. It binds to postsynaptic alpha-1 receptors in vascular smooth muscle, inhibiting catecholamine-induced vasoconstriction. This leads to peripheral arterial and venous vasodilation, reducing systemic vascular resistance and blood pressure. In the lower urinary tract, alpha-1 blockade reduces smooth muscle tone in the bladder neck and prostate, improving urine flow. In PTSD, the central alpha-1 blockade may dampen sympathetic outflow, reducing hyperarousal and nightmares.

• Absorption: Rapid and nearly complete after oral administration.
• Bioavailability: Approximately 60%.
• Distribution: Widely distributed; ~97% bound to plasma proteins.
• Metabolism: Extensively metabolized in the liver.
• Elimination: Primarily via bile and feces; ~6–10% excreted in urine.
• Half-life: Approximately 2–4 hours.
• Peak plasma concentration: Achieved in 1–3 hours.
• Duration of effect: 6–10 hours (may vary with repeated dosing).

• Pregnancy: Category C. Animal studies have shown adverse fetal effects. Use only if the potential benefit justifies the potential risk to the fetus.
• Lactation: Unknown if prazosin is excreted in human milk. Caution is advised; monitor infants for hypotension or sedation.

• Primary: Alpha-1 adrenergic blocker
• Subclass: Selective alpha-1 receptor antagonist
• Functional class: Antihypertensive; urologic agent; PTSD symptom modulator (off-label)

• Hypersensitivity to prazosin or any component of the formulation
• History of orthostatic hypotension or syncope related to alpha-blockers
• Severe hepatic impairment (use extreme caution)

• First-dose effect: Marked hypotension and syncope may occur, especially with first dose or dose escalation. Start at bedtime.
• Hypotension and dizziness: May impair the ability to operate machinery or drive.
• Use in CHF: May cause fluid retention; use with a diuretic if needed.
• Priapism: Rare, but prolonged erections require emergency treatment.
• Surgical precautions: Intraoperative Floppy Iris Syndrome (IFIS) has occurred in patients undergoing cataract surgery. Inform ophthalmologist if patient uses or has used prazosin.
• Monitor: Blood pressure, signs of hypotension, and urinary symptoms.

Very Common:

• Dizziness
• Postural hypotension
• Headache

Common:

• Palpitations
• Fatigue
• Nausea
• Drowsiness
• Nasal congestion

Uncommon to Rare:

• Syncope (especially with first dose)
• Peripheral edema
• Depression
• Blurred vision
• Priapism (rare, serious)

Timing: Most side effects occur early in therapy and often subside with continued use or slower titration.

• Antihypertensives: Additive hypotensive effect with beta-blockers, diuretics, ACE inhibitors.
• Phosphodiesterase inhibitors (e.g., sildenafil, tadalafil): Risk of symptomatic hypotension—space doses by several hours.
• NSAIDs: May reduce antihypertensive effect.
• CNS depressants (alcohol, sedatives): Enhanced sedation or dizziness.
• No significant CYP450 interactions reported.

• PTSD Guidelines (VA/DoD): Prazosin recommended as a first-line agent for PTSD-associated nightmares and sleep disturbances.
• Hypertension Guidelines: Less commonly used as monotherapy but may be added for resistant hypertension.
• Ophthalmology Alerts: Patients undergoing cataract surgery should inform their surgeon if they have taken or are taking prazosin due to IFIS risk.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep in a tightly closed container.
• Do not freeze.
• Keep out of reach of children.