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Drug Information
Pharmacokinetics
| Indication
& Dosage | Action
| Interacations |
Adverse
Effects & Precautions |
Brands available in Market
It shows first pass metabolism in liver and it is highly bound to plasma protein.
Indication
& Dosage
Oral
HYPERTENSION ALL GRADES: Start with 0.5mg b.i.d increasing as required
to 1mg t.i.d. Some patients may need upto 20mg daily in divided doses.
Oral Ext. Rel. (GITS)
HYPERTENSION ALL GRADES: 2.5-5mg o.d., preferably at bedtime. Increase
to 10mg o.d. if reqd Max: 20mg o.d.
Action
Blocks the postsynaptic alpha-1 adrenoceptors causing vasodilatation
and reductionin blood pressure. The effect is seen in resistant vessels.
There is no reflex tachycardia. Diastolic pressure reduced to a greater
extent.
Clonidine: Antihypertensive effect of clonidine may
be decreased.
Beta-adrenergic blocking agents: May enhance ‘first dose’ acute postural
hypotension of prazosin.
Indomethacin: Antihypertensive effect of prazosin decreased.
Verapamil & Nifedipine: Acute hyypotensive effect when
coadministered with prazosin.
Lab Tests: False positive results may occur in screening tests for
phaeochromocytoma in patients receiving prazosin.
Adverse Effect & Precautions
Postural hypotension, dizziness, faint-ness tachycardia, palpitation,
headache, weight gain, dry mouth, nausea, diarrhoea, constipation, nasal
stuffiness, priapism, skin rash.
Precaution: Pheochromocytoma, hepatic dysfunction, children below 12
years abrupt withdrawal.
Pregnancy: Use with caution. Reduce initial dose.
Breast Feeding: Use with caution. Reduce initial dose.
Man: May be used with caution. Reduce initial dose.
