Antiadrenergics drugs : By Dr Rahul R Kunkulol

1,505 views

Published on

Published in: Health & Medicine
0 Comments
9 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,505
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
52
Comments
0
Likes
9
Embeds 0
No embeds

No notes for slide

Antiadrenergics drugs : By Dr Rahul R Kunkulol

  1. 1. DR. RAHUL Antiadrenegics
  2. 2. Antiadrenegics These are the drugs which antagonize the actions of adrenaline and related drugs. They are both competitive antagonist of alpha or beta or both.
  3. 3. ALHA 1 receptors • Radial fibers – contraction – mydriasisEye • Contraction – can increase peripheral resistance Arterioles and veins –. • Contraction – urinary retention Bladder trigone and sphincter – • Glycogenolysis.Liver • Ejaculation.Vas deferens
  4. 4. ALPHA 2 • Aggregation Platelets • Decrease release of transmitter (NE) Presynaptic receptors • Decrease insulin release (predominant)Pancrease -
  5. 5. Alpha adrenergic blockers • Ergot alkaloids : Ergotoxine, Ergotamine • Hydrogenated ergot alkaloids: Dihydroergotoxine • Imidazolines : Phentolamine, Tolazoline Reversible type • Prazosin, Terazosin, Doxazosin, Tamsulosin Alpha1 selective- Alpha2 selective- Yohimbine
  6. 6. Pharmacological Effects Cardiovascular system: Fall in BP (alpha1 & 2 blockade) Postural hypotension Reflex tachycardia Vasomotor reversal of Dale Hypovolemia accentuates hypotension • Na & water retention • renin release BP Hypotension-g.f.r reduced
  7. 7. Pharmacological Effects Nasal stuffiness Eye – miosis • decreased tone in sphincter and prostate (alpha1a blockade) Urinary bladder Metabolic effects – increased insulin secretion Reproductive system Inhibition of contraction of Vas defrence and related organs is blocked by alpha1 blockade…..inhibition of ejaculation…impotence
  8. 8. Phenoxybenzamine Alpha blockade develops gradually and lasts for 3-4 days. Fall in BP by Phenoxy. is mainly due to venodilatation…postural hypotension. Shifts blood from pulmonary to systemic circulation, extra vascular to vascular compartments. Lipid soluble drug can penetrate CNS may cause nausea & vomiting on rapid iv administration Management of pheochromocytoma. Pheripheral vascular diseases.
  9. 9. Imidazoline derivatives - Phentolamine Congener of Tolazoline Rapidly acting alpha blocker with short DOA Many other effects including: • Parasympathomimetic • Increased gastric acid secretion Cardiac stimulation Increased secretion from exocrine glands, such as salivary, sweat, lacrimal, pancreatic Coronary artery disease and peptic ulcer relative contraindication to it.
  10. 10. Phentolamine : uses Diagnostic and intraoperative management of pheochromocytoma For control of hypertension due to clonidine withdrawal. Cheese reaction. To counteract vasoconstriction due to extravasation of noradrenaline / Dopamine given IV.
  11. 11. Ergot alkaloids Ergotoxine, Ergotamine are partial agonist and antagonist at adrenergic alpha, serotonergic and dopaminergic receptors. Ergotoxine, dihydroergotoxine are more potent alpha blocker and less potent vasoconstrictor than ergotamine. USE: Migraine
  12. 12. Alpha-1 selective blockers Prazosin Highly selective Alpha1 blocker, selectivity ratio 1000: 1 Less cardiac stimulation since it preserves alpha2 mediated negative feedback + other mechanisms Fall in BP with no/ minimal tachycardia. Used in hypertension but tolerance develops with time, maybe due to fluid retention. Adverse effects: First dose phenomenon i.e postural hypotension with initial doses. Favorable effect on plasma lipids: increase HDL/LDL ratio
  13. 13. ADR (µg/Kg) 1 10 100 5000.1 1 10 100 500 +PRAZOSIN BP HR Effect of Adrenaline (ADR) on Blood Pressure and Heart Rate Before and After Prazosin
  14. 14. Prazosin : uses Antihypertensive DOC: Benign prostatic hyperplagia ( BPH) • Blocks alpha 1 in bladder trigone & prostate • Decreases tone • Improves urine flow • Decreases residual urine Dose :1-4 mg BD/ TDS Terazosin : longer t1/2 , OD dosing
  15. 15. Tamsulosin Dizziness and retrograde ejaculation are the only AE. No effect on BP and heart rate. Alpha Ia are predominant in bladder base and prostate. 30 times high affinity for alpha1a. As effective as Terazosin in BPH Uroselective alpha 1a/ alpha 1d blocker.
  16. 16. Alpha-2 selective blockers Yohimbine Cardiovascular effects – peripheral and central effects Blocks other receptors also – serotonin, dopamine Increases ADH release Enhances sexual activity – aphrodisiac Potential uses: depression, obesity, NIDDM
  17. 17. Alpha Blockade—Adverse Effects Orthostatic hypotension • Reduces blood flow to brain causing dizziness, lightheadedness and fainting • Due to vasodilation of veins lowering blood flow to brain Reflex tachycardia • Increase heart rate by stimulating baroreceptor reflex which causes and increased heart rate to compensate Nasal Congestion • Dilates vessels of nasal mucosa Inhibition of ejaculation • Alpha1, sympathetic reaction needed Sodium retention • Decreased blood pressure decreases filtering by kidneys and causes retention of water and salt MenuB F
  18. 18. Alpha Blockade—Uses • Essential hypertension • Benign prostatic hyperplasia • Pheochromocytoma • Overdose of alpha1 agonist Therapeutic Applications
  19. 19. Therapeutic Uses of Alpha-Adrenergic Blockers Hypertension - alpha-1 selective Conditions associated with increased sympathetic activity – e.g. pheochromocytoma Hemodynamic shock Peripheral vascular disease – Raynaud’s Congestive heart failure Benign prostatic hyperplasia-prazosin Pulmonary hypertension – tolazoline Yohimbine or intracavernous Phentolamine+ papaverine for impotence
  20. 20. BETA BLOCKERS DR. RAHUL
  21. 21. Beta blockers  These drugs inhibit adrenergic responses mediated through beta receptors.  All beta blockers are competitive antagonists.  History: Dichloroisoproterenol- 1958 Propranolol-1963
  22. 22. Classification  NONSELECTIVE: (BETA 1 & 2) A) Without intrinsic symphathomimetic activity  Propranolol  Sotalol : Class III antiarrhythmic  Timolol : topical use in eye B) With intrinsic symphathomimetic activity  Pindolol C) With alpha blockade activity (alpha + beta blockade)  Labetalol  carvedilol
  23. 23. CARDIOSELECTIVE (BETA 1 )  Metoprolol  Atenolol  Bisoprolol  Esmolol  Acebutolol (intrinsic symphathomimetic and membrane stabilizing activity)  Celiprolol (Beta 1 blocker + beta 2 agonism)  Nebivolol
  24. 24. Pharmacological actions : CVS:  Heart:  Propranolol decreases heart rate, force of contraction, COP. Decreases cardiac work and oxygen consumption.  Blood vessels: Fall in BP both diastolic and systolic after continuous treatment.  Decrease in COP  Initial increase followed by decrease in TPR  Decrease renin release from kidney  Central action decreasing symphathetic outflow
  25. 25. OTHER SYSTEMS  Respiratory system : Bronchoconstriction  CNS: Decreases anxiety, tremors, other actions.  Metabolic :  Increases LDL, triglycerides, decreases HDL by inhibiting lipolysis.  Adversely effects recovery from insulin induced hypoglycemia.  Skeletal muscles : Pnl inhibits adrenegically evoked tremors.  Eye : synthesis and releases of aqueous humour … iop
  26. 26. Contraindication  CHF  Bradycardia  COPD  Bronchial asthma  Diabetis mellitus  Hypertriglygeridemia
  27. 27. Adverse effects  Adverse Effects of beta1 blockade  Bradycardia  Reduced cardiac output  Heart failure  AV block  COPD, Bronchial asthma  Tiredness , reduced exercise capacity.  Rebound hypertension on abrupt withdrawl.  Cold hands and feets  Hypoglycemia  Others: gi upset, lack of drive, lightheadedness, forgetfulness, nightmares, rarely hallucinations
  28. 28. CARDIOSELECTIVE (BETA 1 )  Metoprolol  Atenolol  Acebutolol  Bisoprolol  Esmolol  No effect on bronchus, carbohydrate metabolism, lipids.  Lower incidences of Cold hands and feets.  Less liable to impair essential tremors.
  29. 29. CARDIOSELECTIVE (BETA 1 ) DRUG FEATURES USE Metoprolol Preferred in diabetics on insulin or oral hypoglycemics. AMI without bradycardia Atenolol Low lipid solubility. Longer duration action. (OD) Hypertention Angina Acebutolol Cardioselective with intrinsic symphathomimetic and membrane stabilizing activity Preferred in severe bradycardia and low cardiac reserve Esmolol Ultra short acting cardioselective beta blocker. DOA 15-20mins after iv infusion To terminate supraventricular tachycardia Atrial fibrillation or flutter Early treatment of AMI Celiprolol Nebivolol Beta 1 blocker + beta 2 agonism Acts as NO donor (vasodilatation) Hypertension CHF
  30. 30. Without intrinsic symphathomimetic activity  Sotalol : Class III antiarrhythmic  Timolol : topical use in eye
  31. 31. Uses of Beta blockers  Hypertension  Angina pectoris  Cardiac arryhythmias  AMI  Secondary prophylaxis of AMI  Myocardial salvage  CHF  Pheochromocytoma  Thyrotoxicosis  Migraine  Essential tremors.  Glaucoma  Anxiety
  32. 32. Carvedilol  β 1 + β2+ α1 blocker, calcium channel blocker.  Antioxidant property.  Use:  Hypertension  CHF  Angina.
  33. 33. With alpha blockade activity (alpha + beta blockade)  Labetalol  β 1 + β2+ α1 blocking aswellas β2 agonism.  5 times more potent β blocker than α.  Effects at low dose resembles propranolol while at high dose ppn + prazosin  Fall in BP is due to decrease in COP and TPR  Uses : pheochromocytoma, clonidine withdrawl, essential hypertention.  A/E: postural hypotension, impotence.

×