Prazosin is an α1-adrenergic receptor antagonist primarily used to treat hypertension (high blood pressure) and to alleviate symptoms of post-traumatic stress disorder (PTSD). This medication relaxes vascular smooth muscle, reduces peripheral vascular resistance, thereby lowering blood pressure. Recent studies also indicate its effectiveness in relieving nightmares, flashbacks, and other symptoms in PTSD patients.
The mechanism of action involves blocking α1 receptors, which reduces norepinephrine-induced vasoconstriction responses. Unlike other antihypertensive agents, Prazosin also has a beneficial effect on urinary obstruction caused by benign prostatic hyperplasia (BPH), but this use should be evaluated and prescribed by a physician.
The main brand name is Praxin®, with the generic name Prazosin Hydrochloride. Other brand names may exist in different countries or regions, but the active ingredient remains the same. Available formulations include tablets and orally disintegrating tablets for convenience.
Generic drugs have the same efficacy and safety profile as brand-name drugs but are usually more affordable. Patients should verify that the active ingredient on the packaging is Prazosin Hydrochloride and avoid switching manufacturers without medical approval.
It belongs to the class of α1-adrenergic receptor antagonists, categorized under antihypertensive agents. This class directly acts on the vascular system and can be used synergistically with other antihypertensive drugs such as diuretics and calcium channel blockers.
Pharmacologically, Prazosin also exhibits peripheral α1 receptor blockade, which provides unique advantages in treating certain neuropsychiatric symptoms like PTSD, but interactions with other drug classes should be monitored.
The primary indication is primary hypertension (systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg), used alone or in combination with other antihypertensive medications. Second-line indications include symptom relief in PTSD, especially sleep disturbances and re-experiencing symptoms.
In some countries, this medication is also approved for urinary difficulties caused by BPH, but caution is advised as it may increase the risk of hypotension. Physicians may prescribe this off-label based on personalized medical considerations.
Mild side effects include dizziness, headache, fatigue, and lower limb edema. About 15-20% of patients may experience orthostatic hypotension during initial treatment, with dizziness upon standing. It is recommended to rise slowly to prevent falls.
Contraindications: Patients allergic to Prazosin, those with severe heart failure, or those who have experienced shock reactions to this drug should avoid use. During pregnancy, use only if necessary, and breastfeeding women should discontinue nursing.
Black box warning includes: initial use may cause orthostatic hypotension; it is recommended to administer at bedtime. When combined with other antihypertensives, dose reduction is necessary to prevent excessive blood pressure lowering.
Combining with ACE inhibitors or β-blockers can enhance antihypertensive effects, increasing the risk of syncope. Co-administration with SSRIs (e.g., fluoxetine) may increase the risk of blood pressure lowering, requiring dose adjustments.
The initial dose is typically 1 mg once daily, with gradual increases every 3-7 days to the target dose (usually 2-5 mg daily). Patients with severe hepatic impairment should halve the dose. Do not crush or chew extended-release formulations.
It is recommended to take after breakfast to reduce gastrointestinal discomfort, but orally disintegrating tablets can be taken directly. Avoid eating within 30 minutes of dosing to optimize absorption. Take at a consistent time daily to maintain stable blood drug levels.
If a dose is missed and more than 4 hours remain before the next dose, take it as soon as remembered and adjust the schedule accordingly. If close to the next dose, skip the missed dose and resume the normal schedule the following day. Do not double doses to make up for missed doses.
If doses are missed for more than 2 days, contact a healthcare professional before resuming medication. If symptoms like dizziness worsen after missing a dose, rest and measure blood pressure before deciding whether to take the missed dose.
Acute overdose can cause severe hypotension, shock, or renal impairment. If overdose is suspected, seek immediate medical attention. Do not induce vomiting or administer other antidotes without medical supervision.
Emergency treatment includes IV fluids, vasopressors, and renal function monitoring. Store medication in a locked cabinet out of reach of children and unauthorized persons.
If combined with other antihypertensives such as calcium channel blockers or diuretics, blood pressure may decrease more significantly. Regular blood pressure monitoring and dose adjustments by a healthcare provider are necessary. If dizziness or fainting occurs, seek medical evaluation promptly to assess whether medication adjustments are needed.
How should I manage bradycardia during Praxin® therapy?If bradycardia (heart rate below 60 bpm) or related symptoms occur, stop the medication for the day and check your pulse. If low blood pressure or dizziness persists, consult a healthcare provider for dose adjustment. Regularly measure your pulse at the same time each day and record any abnormalities for medical review.
What precautions should be taken for patients with liver impairment using Praxin®?Patients with liver dysfunction may have slower drug metabolism, increasing the risk of toxicity. Dose adjustments based on liver enzyme levels are recommended, with periodic liver function tests. Symptoms such as jaundice, dark urine, or right upper quadrant pain require immediate medical attention and discontinuation of the drug.
What are the risks of sudden discontinuation of Praxin® after long-term use?Sudden cessation may cause rebound phenomena such as elevated blood pressure or increased heart rate. Tapering off gradually under medical supervision over several weeks is advised. If chest pain or headaches occur during tapering, seek medical evaluation immediately.
Are there dietary or fluid intake restrictions while taking Praxin®?Generally, there is no need to restrict total fluid intake, but avoid rapid large-volume hydration to prevent excessive blood pressure drops. A low-sodium diet may enhance drug efficacy; maintaining regular meal times can help stabilize blood sugar and reduce hypoglycemia risks associated with medication.
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