Nurses Compass
Drug Guide
Prazosin Hydrochloride
Classification
Therapeutic: Antihypertensive, Alpha-1 Adrenergic Blocker
Pharmacological: Alpha-1 Adrenergic Antagonist
FDA Approved Indications
- Hypertension
- Benign Prostatic Hyperplasia (BPH)
Mechanism of Action
Prazosin selectively blocks alpha-1 adrenergic receptors in vascular smooth muscle, resulting in vasodilation and decreased blood pressure. It also relaxes smooth muscle in the prostate and bladder neck, improving urinary flow in BPH.
Dosage and Administration
Adult: Starting dose is typically 1 mg two or three times daily, titrated up as needed to control blood pressure, not exceeding 20 mg per day.
Pediatric: Not typically used in pediatric patients.
Geriatric: Start at lower doses due to increased sensitivity; titrate carefully.
Renal Impairment: Use caution; dosage adjustment may be necessary depending on severity.
Hepatic Impairment: Use with caution; no specific dosage adjustment established.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Significantly bound to plasma proteins.
Metabolism: Partially metabolized in the liver.
Excretion: Excreted mainly in the urine.
Half Life: 2 to 3 hours.
Contraindications
- Hypersensitivity to prazosin or other quinazoline derivatives.
Precautions
- Caution in patients with a history of syncope, hepatic impairment, or orthostatic hypotension.
Adverse Reactions - Common
- Dizziness (Common)
- Drowsiness (Less common)
- Headache (Less common)
- NV (nausea and vomiting) (Less common)
Adverse Reactions - Serious
- Syncope (fainting) (Less common)
- Priapism (Rare)
- Dyspnea (Rare)
- Laryngeal edema (Rare)
Drug-Drug Interactions
- Other antihypertensives (additive hypotension)
- Phosphodiesterase inhibitors (risk of hypotension)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure regularly, especially during dose titration and for orthostatic hypotension.
Diagnoses:
- Risk for Falls related to hypotension and dizziness.
- Ineffective tissue perfusion related to vasodilation.
Implementation: Administer initially at bedtime to decrease episodic dizziness. Titrate dose gradually. Educate patient to rise slowly from sitting or lying position.
Evaluation: Evaluate blood pressure response, symptom improvement, and adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Rise slowly from seated or lying positions to avoid dizziness and falls.
- Notify healthcare provider if experiencing dizziness, fainting, or other concerning symptoms.
- Avoid sudden changes in position.
Special Considerations
Black Box Warnings:
- None currently
Genetic Factors: None established.
Lab Test Interference: May cause false-positive results in certain lab tests for catecholamines.
Overdose Management
Signs/Symptoms: Severe hypotension, dizziness, tachycardia or bradycardia, syncope.
Treatment: Place patient in supine position, monitor vital signs, administer IV fluids as needed, use vasopressors if necessary; activated charcoal if ingestion is recent.
Storage and Handling
Storage: Store at room temperature, away from moisture and heat.
Stability: Stable under recommended storage conditions.