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Alpha blockers
- 1. – ReceptorAntagonists / – Blockers Dr.S.P.Dhanya Assistant Professor Dept of Pharmacology
- 2. Adrenoceptor antagonists -α &β blockers Drugs affecting the synthesis storage & release of NE. Antiadrenergic drugs
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- 4. Reversible (Competitive , shortacting) Phentolamine Tolazoline Ergotamine, Ergotoxine Dihydro ergotamine Dihydro ergotoxine Irreversible (Noncompetitive, long acting) Phenoxy benzamine Dibenamine Non selective
- 5. i) 1 Blockers •PRAZOSIN DOXAZOSIN • ALFUZOSIN TERAZOSIN • TAMSULOSIN ii) 2 Blockers • YOHIMBINE • RAUWOLSCINE Selective
- 6. • Labetalol ,Carvedilol B. Mixed and β Blockers • Chlorpromazine • Haloperidol • Trazodone • Ketanserin C. Other drugs with - blockade as adverse effect
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- 8. PHARMACOLOGICAL ACTIONS ofAlpha Blockers Alpha Blocker
- 9. Vasomotor reversal phenomenonof Dale Reversal in the effect of large doses of epinephrine on blood pressure from a pressor response to a depressor response (mediated by β2 receptors) by prior administration of α blocker.
- 11. Decreased resistance tourinary out flow Blockade of α1A &α1D receptors in prostate
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- 16. Phentolamine Non selective, Quickand Short acting 1. Diagnostic and intraoperative Pheochromocytoma 2.Hypertension-clonidine withdrawal, cheese reaction 3.Extravasation of NA/D dermal necrosis 4.PIPE therapy
- 18. Prazosin •Selective 1blocker(1000:1) •Competitive blocker •Phosphodiesteraseenzyme inhibitor •Orally effective •Highly bound to plasma proteins •t ½ =2-3h,duration 7-10 hrs
- 19. FIRST DOSE HYPOTENSION Fallin BP-postural hypotension
- 20. Uses 1. Antihypertensive startwith 1mg then titrate 2. Raynaud’s disease 3. BHP 4. CCF
- 21. Terazosin High oral BA-90% Long plasma t½ =12 h, duration =18h Induction of apoptosis- quinazoline Single daily use-2-10mg OD
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- 23. TAMSULOSIN Uroselective 1A &1D t ½=5-10hrs NoCVS side effects Dizziness and retrograde ejaculation Modified release -0.4 mg/day
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- 25. Uses of blockers •Pheochromocytoma •Hypertension •Secondary shock decrease vasoconstriction shift pulmnary to systemic return fluid from extravascular to vascular •Peripheral diseases-prazosin •Congestive heart failure-prazosin •BHP- 1ablocker, 5- reductase inhibitor- finasteride •PIPE therapy