Terazon

Approved Indications:

• Benign Prostatic Hyperplasia (BPH):
  For the treatment of signs and symptoms of BPH, including urinary frequency, urgency, nocturia, weak stream, and incomplete bladder emptying. Effective in both mild and moderate to severe BPH.
• Hypertension (Essential):
  As monotherapy or adjunct therapy in the management of mild to moderate hypertension to lower blood pressure, reducing the risk of cardiovascular morbidity.

Clinically Accepted Off-Label Uses:

• Bladder outlet obstruction due to neurogenic bladder
• Ureteral stone expulsion therapy: Used in medical expulsive therapy for distal ureteral calculi.
• Raynaud’s phenomenon (vasospastic disorder)
• Female voiding dysfunction or urinary retention due to bladder outlet resistance

Route of Administration: Oral (tablets)

For Benign Prostatic Hyperplasia:

• Initial Dose: 1 mg at bedtime
• Titration: Increase to 2 mg, 5 mg, or up to 10 mg once daily at bedtime, depending on patient response and tolerance.
• Maintenance Dose: 5–10 mg once daily is typical.

For Hypertension:

• Initial Dose: 1 mg at bedtime to minimize risk of orthostatic hypotension
• Titration: Increase gradually to 2 mg, 5 mg, or up to 20 mg daily in one or two divided doses.
• Maximum Dose: 20 mg per day

Elderly Patients:

• Start at 1 mg once daily. Titrate slowly with close monitoring due to increased risk of hypotension.

Renal Impairment:

• No specific dose adjustment required, but caution is advised; monitor closely.

Hepatic Impairment:

• Use with caution; initiate at lowest dose and monitor closely.

Administration Advice:

• First dose should be taken at bedtime to reduce the risk of first-dose syncope.
• Tablets should be swallowed whole with water.

Terazosin Hydrochloride is a selective alpha-1 adrenergic receptor blocker. It relaxes smooth muscle in the bladder neck and prostate by blocking alpha-1 receptors, improving urinary flow and reducing symptoms of BPH. In blood vessels, alpha-1 receptor blockade leads to vasodilation, which lowers peripheral vascular resistance and blood pressure. The reduction in smooth muscle tone reduces urethral resistance, facilitating urination in BPH and improving blood flow in hypertensive patients.

• Absorption: Rapidly absorbed after oral administration with peak plasma concentrations achieved within ~1 hour.
• Bioavailability: Approximately 90–100%.
• Distribution: Widely distributed; about 90–94% protein-bound in plasma.
• Metabolism: Extensively metabolized in the liver via oxidative pathways (not significantly dependent on CYP450 isoenzymes).
• Half-life: Terminal half-life ranges from 8 to 13 hours, allowing once-daily dosing.
• Excretion: Primarily via feces (60%) and urine (40%) as metabolites; only a small percentage of the unchanged drug is excreted renally.
• Steady-state: Reached within 4–6 days of repeated dosing.

• Pregnancy: FDA Pregnancy Category C
  Animal studies have shown adverse effects on the fetus, but there are no adequate human studies. Use only if the potential benefit justifies the potential risk.
• Lactation:
  It is unknown if terazosin is excreted in human breast milk. Caution should be exercised if administered to nursing mothers. Alternative treatments may be preferred during breastfeeding, especially in neonates or preterm infants.

• Primary Class: Alpha-1 Adrenergic Receptor Antagonist (Alpha Blocker)
• Subclass: Quinazoline derivative alpha-blocker
• Generation: Second-generation selective alpha-1 blocker

• Known hypersensitivity to terazosin or any component of the formulation
• History of orthostatic hypotension
• Concomitant use with other alpha-blockers due to risk of severe hypotension
• Severe hepatic impairment (use with extreme caution)

• First-dose syncope: May occur within 30 to 90 minutes; start at bedtime under observation.
• Orthostatic hypotension: Caution in elderly and volume-depleted patients; monitor blood pressure.
• Intraoperative Floppy Iris Syndrome (IFIS): Observed during cataract surgery; inform ophthalmologist prior to procedure.
• Priapism: Rare but serious; requires immediate medical attention.
• Hepatic impairment: Use cautiously; monitor liver function if used long-term.
• Driving and machinery use: May impair alertness during dose titration.

Common (≥1%):

• Cardiovascular: Dizziness, postural hypotension, palpitations, syncope
• CNS: Headache, drowsiness, fatigue
• GI: Nausea, constipation
• Genitourinary: Ejaculatory dysfunction, nasal congestion

Less Common:

• Edema, dyspnea, blurred vision, vertigo

Serious/Rare:

• Severe hypotension
• Angioedema
• Priapism
• Intraoperative floppy iris syndrome (during cataract surgery)

Onset: Typically within days of initiation, especially with the first dose
Dose-Dependent: Yes, especially with hypotension and dizziness

• PDE5 inhibitors (e.g., sildenafil, tadalafil): Additive hypotensive effects; space doses or monitor closely.
• Other antihypertensives (e.g., beta-blockers, diuretics): Increased risk of hypotension.
• Alcohol: May potentiate hypotensive effects.
• NSAIDs: May reduce antihypertensive efficacy.
• CYP interactions: Minimal involvement with CYP450 isoenzymes; low risk of metabolic drug interactions.

• No recent changes in approved indications or black box warnings as of 2025.
• Guideline note (AUA 2023): Terazosin remains a recommended option for BPH management, particularly in patients with both BPH and hypertension.
• Surgical risk reminder: Continuing emphasis on the association with IFIS; ophthalmologists advised to inquire about alpha-blocker use before cataract surgery.

• Temperature: Store below 30°C (86°F)
• Humidity: Protect from moisture; keep in a dry place
• Light: Store in original container to protect from light
• Handling: Do not split or crush tablets
• Refrigeration: Not required