PRAZOSIN (Minipress): What is used for?

What is Prazosin?

Prazosin is an active ingredient used for the treatment of HBP (High Blood Pressure), Raynaud’s Disease and Benign Prostatic Hyperplasia.
The product ingredient is Prazosin hydrochloride (hcl).

The brand name of Prazosin in United States is Minipress.

Prazosin Mechanism of Action (MOA)

Reduces peripheral vascular resistance.
The antihypertensive action of prazosin, unlike non-selective alpha-adrenergic receptor antagonists, is usually not accompanied by reflex compensatory tachycardia.

Therapeutic indications, uses, benefits of Prazosin

  • High blood pressure.
  • Raynaud’s disease or phenomenon.
  • Benign prostatic hyperplasia

Dosage of Prazosin

Oral. Adjust dose according to individual tolerance during the first week.

– High blood pressure (HBP):
Monotherapy: initial: 0.5 mg/2 times daily (first dose with dinner) for 4 days, increase to 1 mg/2 times daily. The next 4 days, monitor blood pressure and adjust dose. Maintenance: 3-20 mg/day (divided into 2 intakes with meals).

With diuretic treatment and inadequate blood pressure control: reduce diuretic dose, administer 0.5 mg/2 times daily and gradually increase to desired effect.

With other antihypertensives and inadequate blood pressure control: reduce dose and add prazosin 0.5 mg/2 times/day, then increase according to response.
Renal insufficiency: initial 0.5 mg/day.

– Raynaud’s disease/phenomenon:
Initial 0.5 mg at bedtime, then 0.5 mg (morning) and 0.5 mg (afternoon) during the first week. Maintenance: 4-6 mg/2 times daily.

– Benign prostatic hyperplasia:
Initial 0.5 mg/2 times daily for 3-7 days. Maintenance: 2 mg/2 times daily.

Method of administration

Oral use. Administer with meals.


  • 1 mg/1
  • 2 mg/1
  • 5 mg/1

Contraindications of Prazosin

Hypersensitivity to this active ingredient.

Warnings and Precautions of Prazosin

  • Kidney failure.
  • Risk of orthostatic (postural) hypertension.
  • Blood pressure monitoring.
  • Risk of intraoperative flaccid iris syndrome during cataract surgery.
  • Not recommended in children < 12 years.

Renal insufficiency

Caution in kidney failure.
Start at 0.5 mg/day.

Interactions with Prazosin

Although no studies with this active ingredient have been performed, concomitant administration of alpha-adrenergic receptor antagonists with phosphodiesterase type 5 inhibitors may cause symptomatic hypotension.
The addition of a diuretic or other antihypertensive agent to prazosin treatment may cause an additive antihypertensive effect, readjusting the dose according to the patient’s clinical response.

Pregnancy and Prazosin

Although no teratogenic effects have been observed in experimental animals, there are no adequate and well-controlled clinical studies establishing safety during pregnancy in humans.
Administer when the potential benefits outweigh the potential risks.


This active ingredient is excreted in small amounts through breast milk and should not be given to women during breastfeeding.

Effects on driving ability

Dizziness, weakness and even loss of consciousness may occur, especially at the onset treatment, so caution is advised when driving vehicles and operating dangerous or precision machinery until the assessment of the initial response to treatment.

Adverse reactions and side effects of Prazosin

Depression, nervousness; dizziness, drowsiness, headache, syncope, loss of consciousness; blurred vision; vertigo; palpitations; dyspnea, nasal congestion; constipation, diarrhea, nausea, vomiting, dry mouth; rashes; urinary frequency; edema, asthenia, weakness, lack of energy.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 4893
NCI Thesaurus: C767

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