59. DRUG INTERACTIONS
Calcium channel blockers (verapamil)
Cardiac arrest, CHF
NSAIDS Attenuate antihypertensive effect
Cold remedies ( phenylephrine) increases BP
Anti diabetic drugs Delay in recovery from
hypoglycemia
60.
61. THERAPEUTIC USES
CARDIO VASCULAR USES
Angina pectoris
Hypertension
Arrhythmias
Myocardial infarction (cardio protective effects)
Early use
Delayed use
Fallot’s tetrology
Hypertrophic obstructive cardiomyopathy
Dissecting aneurysm
Portal hypertension
62.
63.
64.
65. Hypertension:
• Past- recommended as first-line therapy
• Present status - benefits have been
overshadowed by their side-effect profile
•sexual dysfunction
•fatigue
• depression
• metabolic abnormalities
66. Consider Beta blocker if:
intolerance or contraindication
to ACE inhibitors/angiotensin II
receptor antagonists
With increased sympathetic drive-
HTN with tachycardia
Tense young patient
Post MI
67.
68.
69.
70. ENDOCRINE USES
Hyperthyroidism ( decreases adrenergic activity,
peripheral conversion of T4 TO T3)
Pheochromocytoma (given along with alpha
blockers)
71.
72. Hyperthyroidism
• Thyroxine
Up regulation of β-1 receptors in myocardium
Tachycardia, palpitations
• T 4 T 3
73. Pheochromocytoma:
• Adrenal gland tumour
Excess catecholamines
hypertension, tachycardia
• First alpha blocker is given then Beta blocker
otherwise dangerous rise in BP can occur
74.
75. CNS USES
Anxiety , palpitation before examination , stage
appearance
Migraine prophylaxis (nonselective better)
Essential tremor
Alcohol withdrawal state
Opioid withdrawal state
Eyes Glaucoma (timolol)
80. Advantages of topical β- blockers
over Miotics in glaucoma
No
change in pupil size
myopia
headache
fluctuations in i.o.t
convenient OD / BD dosing
87. ADVANTAGES
Safer in diabetes
Safer in Bronchial asthma (better)
Does not Alter lipid profile
Does not cause Peripheral vascular diseases
No impairment of exercise capacity
88. ATENOLOL
Low lipid solubility – incomplete absorption, no CNS
effects
Low Ist pass effect
long acting
Narrow range
Preferred in hypertension, angina
91. TIMOLOL
Topical –as eye drops indicated in Glaucoma
Oral – like atenolol
used in MI,
angina,
hypertension
92.
93. PINDOLOL
Beta blocker with intrinsic sympathomimetic
activity
Advantageous in bradycardia
Less incidence of rebound hypertension on
withdrawal
94.
95. ACEBUTOLOL
Has intrinsic sympathomimetic activity
Membrane stabilizer (useful in arrhythmias)
Longer t1/2 single daily dose
Less effect on resting heart rate
96.
97. BISOPROLOL
Cardio selective beta-blocker without intrinsic
sympathomimetic activity
Used in angina, hypertension once daily
98. ESMOLOL
Ultra short acting beta-blocker
T½ < 10 min
Has membrane stabilizing activity
Used to terminate SVT, AF, A.FIB
Early treatment of M.I
during & after cardiac surgery decrease BP,
HR
102. NEBIVOLOL
Highly selective B1 blocker
Also acts as NO donor
Improve endothelial function and delay
atherosclerosis
Rapid onset of hypotensive effect
103. LABETALOL
Alpha & and β blocker
Low dose – actions like propranolol given
alone
High dose – like propranolol + phenoxy
benzamine
Orally effective
Used in pheochromocytoma
ADR postural hypotension, failure of
ejaculation
104. CARVEDILOL
Βeta-1, Βeta-2 & alpha-1 blocker
Vasodilator
Antioxidant
Cardio protective in Congestive heart failure
Also used in hypertension
105.
106. Beta blocker Overdose
• Glucagon
- specific antidote
-positive inotropic action on the heart
• Cardiac pacing
• If bronchospasm occurs- Ipratopium
• Other antidotes –Salbutamol
and Isoprenaline
107. New β blockers:
• Nipradilol (nonselective β-receptor and
selective α1-receptor blocking properties,
glaucoma)
• Dilevalol ( stereoisomer of Labetalol)- HTN
• Bopindolol
109. Summary
• Therapeutically important class of drugs
To summarise:
• Heart failure- Carvedilol
• Hypertension- Atenolol
• Emergency - Esmolol
• Migraine - Propranolol
• Glaucoma - Timolol
Editor's Notes
Mechanism of action of -blockers
Binding of -blockers to -receptors does not in itself evoke a cellular response. Instead, most -blockers counter the effect of the adrenergic neutrotransmitter, noradrenaline, and the hormone, adrenaline, by preventing them from binding to their receptors.
Please refer to the next slides for -blockers with ISA and the physiology of noradrenaline and adrenaline.