Virtual Medical Centre

Drugs

Prazosin-BC

Generic Name: Prazosin hydrochloride
Product Name: Prazosin-BC

• Indication of Prazosin-BC
• Action of Prazosin-BC
• Dose Advice of Prazosin-BC
• Schedule of Prazosin-BC
• Common side effects of Prazosin-BC
• Uncommon side effects of Prazosin-BC

Indication of Prazosin-BC:

Minipress is used in the treatment of:
- hypertension (of all causes and grades)
- severe refractory congestive cardiac failure, as part of the therapeutic regime
- Raynaud’s phenomenon and Raynaud’s disease
- benign prostatic hyperplasia (BPH)

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Action of Prazosin-BC:

Prazosin is an alpha-adrenergic antagonist. This means that it blocks alpha receptors, which are mainly found in the smooth muscle that lines blood vessels. The blockade of these receptors causes dilation of vessels (vasodilation), reducing resistance and resulting in a decrease in blood pressure. Unlike other alpha-adrenergic antagonists, Prazosin is selective and therefore does not cause a reflex increase in heart rate or cardiac output.
The smooth muscle in the prostate also has alpha receptors, the blockade of which is useful in the treatment of benign prostatic hyperplasia (enlargement). Prazosin causes an increase in urine flow and a reduction in residual bladder volume.
The vasodilatory action also allows Prazosin to be useful in the treatment of Raynaud’s phenomenon, which is caused by constriction of peripheral blood vessels.

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Dose Advice of Prazosin-BC:

Patient tolerance of Minipress is best when starting dose is small and therapy is adjusted slowly. Dose should be adjusted according to response (ie: blood pressure) and results should be seen within 2 weeks.
Hypertension
- initial dose range: 0.5mg twice daily, increasing to 1mg 2-3 times daily
- maintenance range: 3-20mg daily in divided doses
Patients receiving no antihypertensive therapy
- 0.5mg twice daily for three days
- 1mg 2-3 times daily for next three days
- 2mg 2-3 times daily thereafter
- daily dose can then be increased gradually, depending on response, to 20mg
- optimal results may take 6 weeks
- a diuretic may be added to increase efficacy, and this should take place when the Minipress dose is 2mg 2-3 times daily
Patients receiving diuretic therapy who need blood pressure control
- the other agent should be reduced and Minipress initiated at 0.5mg twice daily
- further dose increases must be made depending on patient response
- combination with other agents may cause a large change in blood pressure, therefore a low initial dose is strongly recommended
Moderate-severe renal impairment
- Minipress does not further compromise renal function
- patients in this category regularly respond to small doses, so treatment should always be initiated at 0.5mg daily
Congestive heart failure
- initial dose: 0.5mg daily
- increase to 4mg daily in divided doses
- maintenance range: 4-20mg daily in divided doses
- dose should be started at 0.5mg 3-4 times daily in recumbent patients
- dose titration can be performed as often as every 2-3 days under close medical supervision
- rapid dose titration may be required in severely ill, decompensated patients
Raynaud’s phenomenon/disease
- initial dose: 0.5mg twice daily for 3-7 days
- maintenance dose: 1-2mg twice daily, adjusted according to patient response
Benign prostatic hyperplasia
- initial dose: 0.5mg twice daily for 3-7 days
- adjust according to patient response
- usual maintenance dose is 2mg twice daily

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