lecture presentation

1. Anti Adrenergic
Drugs
For BSc Nursing 1st Year
Dr. Pravin Prasad
2nd Year Resident, MD Clinical Pharmacology
Maharajgunj Medical Campus
26th March, 2017 (Chaitra 13, 2073), Sunday

2. Introduction
• Antagonise the receptor action of adrenaline and
related drugs
• Classified on the basis of receptors they block
primarily
• Alpha, Beta, Both
• Each has their own sub types
• Anti-adrenergics vs Adrenergic neurone blockers

3. Alpha adrenergic blocking Drugs
• Non-equilibrium type (Non competitive):
• Beta-haloalkylamines: Phenoxybenzamines
• Equilibrium type (Competitive)
• Non-selective
• Ergot alkaloids: Ergotamine, Ergotoxin
• Hydrogenated ergot alkaloids: Dihydroergotamine (DHE),
Dihydroergotoxin
• Imidazoline: Phentolamine
• Miscellaneous: Chlorpromazine (Neuroleptics)
• Alpha1 selective: Prazosin, Terazosin, Doxazosin, Alfuzosin,
Tamsulosin
• Alpha2 selective: Yohimbine

4. General effects of alpha blockers
• Fall in BP
• Postural reflex interfered: marked hypotension  dizziness,
syncope
• Vasomotor reversal of Dale
• Reflex tachycardia
• Na+ retention and expansion of blood volume

5. General effects of alpha blockers
• Nasal stuffiness and miosis
• Increased intestinal motility
• Reduced tone of bladder trigone, sphincter and prostate
• Inhibits ejaculation (relaxation of vas deferens and related)

6. Alpha adrenergic blocking Drugs
• Uses:
• Pheochromocytoma
• Hypertension (phenoxybenzamine/phentolamine)
• HTN d/t clonidine withdrawal, cheese reaction
• Benign hypertrophy of prostate
• Secondary shock
• Peripheral vascular disease (Raynaud’s, acrocyanosis)
• Congestive heart failure

7. Alpha adrenergic blocking Drugs
• Side effects:
• Phenoxybenzamine: Postural hypotension, palpitation,
nasal blockade, miosis, inhibition of ejaculation
• Ergot alkaloids: peripheral vascular insufficiency and
gangrene of toes and fingers (ergotism)
• Prazosin and alike : postural hypotension

8. Beta adrenergic blocking drugs
• Nonselective (beta-1 and beta -2)
• Without intrinsic sympathomimetic activity: propranolol,
sotalol, timolol
• With intrinsic sympathomimetic activity: pindolol
• With additional alpha blocking property: labetolol,
carvedilol
• Cardioselective (beta- 1)
• Metoprolol, Atenolol, Acebutolol, Bisoprolol, Esmolol,
Betaxolol, Celiprolol, Nebivolol

9. Beta adrenergic blocking drugs
First Generation
(Older,
nonselective)
Second
Generation (β1
selective)
Third Generation (with additional
alpha blocking and/or vasodilator
property)
Propanolol Metoprolol Labetalol
Timolol Atenolol Carvedilol
Sotalol Acebutolol Celiprolol
Pindolol Bisoprolol Nebivolol
Esmolol Betaxolol

10. General Effects of beta blockers
•Heart:
•Decreases heart rate, force of contraction (high dose)
and cardiac output
•Reduced cardiac work and oxygen consumption
•Blood supply to sub-endocardial region not impaired:
improved oxygen supply/demand status in angina
patients

11. General Effects of beta blockers
• Blood vessels:
• Blocks fall in BP evoked by Isoprenaline; Enhanced rise in BP
by Adr
• Re-reversal of vasomotor reversal of Dale
• Gradual fall in BP on prolonged administration in
hypertensives
• Adaptation of resistance vessels to reduced C.O.  fall in total
peripheral resistance

12. General Effects of beta blockers
System Effects
Respiratory Increase bronchial resistance (β2 blockade)
CNS Subtle behaviour changes, forgetfulness, increased dreaming and
nightmares
Anti-anxiety effect (peripheral action of propranolol)
Metabolic Blocks adrenergically mediated lipolysis
Inhibits glygenolysis in heart, skeletal muscles, liver
May reduce carbohydrate tolerance (decreased insulin release)
Skeletal
muscle
Inhibits adrenergically provoked tremor (β2 blockade)
Attenuate exercise capacity
Eye Reduced secretion of aqueous humour and intra ocular tension
Uterus Relaxant activity of β agonists blocked

13. Cardio-selective beta blockers
Metoprolol, Atenolol, Acebutolol, Bisoprolol, Nebivolol
• More potent β1 blocking action (lost at high doses)
• Low propensity to cause bronchoconstriction
• Less interference with carbohydrate metabolism
• Lower incidence of colder hands and feet
• Less effect on lipid profile
• Less liable to impair exercise capacity

14. Partial agonistic beta blockers
Pindolol, Celiprolol, Acebutolol
• Activates β1 and/or β2 receptors sub-maximally
• Bradycardia and depression of contractility:
• Not prominent at rest
• Exercise tachycardia blocked
• Prevents development of super-sensitivity
• No/less effect on plasma lipid profile
• Not suitable for prophylaxis in MI, migraine

15. Beta blockers: Additional Properties
Membrane stabilizing activity of beta
blockers
Propanolol, Oxprenolol,
acebutolol
• Contributes to the anti
arrhythmic action
• Significant only at high doses
Lipid insoluble beta blockers
Atenolol, Celiprolol, Bisoprolol,
Sotalol
• Less likely to produce sleep
disturbances and nightmares
• Incomplete absorption, no first
pass metabolism, excreted
unchanged in urine
• Longer acting (6-20 hrs)
• Effective in narrow dose range

16. Beta adrenergic blocking drugs: Uses
• Hypertension
• Stable Angina
• Cardiac arrhythmias
• Myocardial infarction
• Congestive heart failure
• Hypertrophic obstructive
cardiomyopathy
• Dissecting aortic aneurysm
• Pheochromocytoma
• Thyrotoxicosis
• Migraine
• Anxiety
• Essential tremor
• Glaucoma

17. Beta blockers: Adverse effects
• Can accentuate myocardial insufficiency and precipitate CHF/edema
• Bradycardia
• Exacerbates variant angina
• Impaired Carbohydrate tolerance
• Altered plasma lipid profile
• Tiredness and reduced exercise capacity
• Cold hands and feet
• Others: G.I. upset, lack of drive, nightmares, forgetfulness,
hallucinations, sexual distress in male

18. Beta blockers: Warnings and
Contraindications
• Sudden withdrawal : rebound hypertension, worsening of
angina, sudden death
• Worsens COPD; can produce acute Bronchial asthma:
Contraindicated
• Partial or complete heart block: Contraindicated

19. α + β adrenergic blockers
Labetalol, Carvedilol
• β1+ β2 + α1 blocking property; weak β2 agonistic activity
• 5 times more potent in blocking β receptors
• Fall in BP
• Uses:
• Pheochromocytoma
• Clonidine withdrawal
• Essential Hypertension
• Side effects:
• Postural Hypotension
• Rashes, liver damage

20. That would be all for this topic.
Thank you!!!
Any queries?