Prazosin

Prazosin is a piperazinyl quinazoline derivative, is a selective competitive a1 receptor blocking similar to the other alpha I -antagonists doxazosin and terazosin, both of which are longer acting than it. Prazosin is given orally for the management of hypertension. It also has been used in the treatment of heart failure; however, due to the development of tolerance, Prazosin is seldom used for this condition today. It was approved by the FDA in 1976.


Adult Dose
Dose: 0.5 mg
Single Dose: 0.5 (0.5)
Frequency: 12 hourly
Route: PO
Instructions: Gradually increase after 3-7 days.
Neonatal
Dose: 0.05 to 0.2 mg/kg
Single Dose: 0.12 (0.125)
Frequency: 12 hourly
Route: Oral
Instructions: -
Paedriatic
Dose: 0.05 to 0.2 mg/kg
Single Dose: 0.12 (0.125)
Frequency: 12 hourly
Route: Oral
Instructions: -
Characteristics
Prazosin also known as Furazosin. Prazosin HCI is the derivative of Prazosin. It is of Synthetic origin and belongs to Pyridine. It belongs to Alpha-1 adrenergic antagonist pharmacological group on the basis of mechanism of action and also classified in Antihypertensive Agents pharmacological group.The Molecular Weight of Prazosin is 419.90. Its pKa is 6.5.
Contraindications
Prazosin
Effects
The severe or irreversible adverse effects of Prazosin, which give rise to further complications include Palpitation, Dizziness, Loss of consciousness.Prazosin produces potentially life-threatening effects which include Hypotension. which are responsible for the discontinuation of Prazosin therapy.The signs and symptoms that are produced after the acute overdosage of Prazosin include Drowsiness, Depression.The symptomatic adverse reactions produced by Prazosin are more or less tolerable and if they become severe, they can be treated symptomatically, these include Dizziness, Orthostatic hypotension.
Indications
'Prazosin is primarily indicated in conditions like Congestive heart failure, Dissolution of gallstones, Hypertension, Infertility or irregular cycles, Raynaud''s phenomenon, and can also be given in adjunctive therapy as an alternative drug of choice in Raynaud`s syndrome.'
Interactions
Prazosin is known to interact with other drugs, the details of drug interactions is as follows:DrugDetailsSeverityOnsetManagementAlcoholAldesleukinEnhanced hypotensive effect when aldesleukin given with Alpha-blockers (e.g prazosin).AlprostadilEnhanced hypotensive effects when alprostadil given with Alpha-blockers (e.g Prazosin)AtenololEnhanced hypotensive effects when alpha-blockers (e.g Prazosin) given with beta-blockers (e.g Atenolol), also increased risk of first-dose hypotension. MajorDexamphetamine (Sulphate)DiazoxideEnhanced hypotensive effect when Diazoxide given with Prazosin.DigoxinPrazosin increases plasma concentration of digoxin.Dobutamine (HCl)PerindoprilInfrequent reports of Perindopril Erbumine increasing the HYPOTENSIVE effect of PRAZOSIN.MajorSildenafilWhen sildenafil is given with Alpha blockers (e.g.Prazosin) the hypotensive effect is enhanced These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Interfrence
Test for Phaeochromocytoma
Risks
Drug should not be given to Paediatrics, Pregnant Mothers, Geriatrics, and Neonates.If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.
Storage
Tab Store in a well closed container, Below 40°C. Protect from Sunlight.
Warnings
To avoid first dose effect i.e. marked postural hypotension and syncope, initial dose of prazocin should be reduced and to be taken at the bedtime.
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