Timolol can be given in all, except –
Correct Answer: Bronchial asthma
Description: Ans. is 'b' i.e., Bronchial asthma Contraindications of 13-blockers 1. Bronchial Asthma (b-blocker can cause bronchoconstriction by blocking b2 mediated bronchodilatation. 2. Variant angina o Variant angina occurs due to coronary vasospasm. b-blockers exacerbates coronary vasconstriction by unopposed alpha-mediated action. 3. Paial and complete hea block o b1-receptors increase conduction in AV node. b-blockers decrease conduction by reducing sympathetic drive on b1-receptors --> Worsening of block. 4. Bradycardia o P-blockers reduce hea rate by reducing sympathetic tone on b1 receptors --> worsening of bradycardia (Cardiac arrest may occur). 5. Hypoglycemia b2 receptors increase blood glucose by enhancing glycogenolysis and gluconeogenosis. o b blocker cause worsening of hypoglycemia by blocking normal sympathetic-mediated homeostatic mechanism for maintaining the blood glucose b2 receptors. 6. Decompensated hea failure o First let me clear, what is decompensated hea failure. o Acute hea failure (acute left ventricular failure) is called decompensated hea failure. o The two primary hemodynamic derangement in acute HF are elevated left ventricular filling pressure and decreased cardiac output. o Because these derangement are not compensated by compensatory mechanism in acute LF it is called decompensated HF. o Sympathetic system provide critical suppo to hea for compensation. o b-blockers are contraindicated in this condition because they will fuher depress the hea. About option 'd' o Congesitive hea failure (CHF) is chronic or compensated hea failure. o In CHF the primary pathological changes are due to overactivity of sympathetic system and RAA system. o Overactivity of cardiac b-receptors in CHF accelerate myocyte apoptosis and promotes functionallly unourable remodeling. o So, in CHF ft-blocker can be used, but they should be staed at lowest possible dose with gradual increment. o b-blockers are one of the group of drugs which decrease diseae progression and moality in CHF (Other drugs are ACE inhibitors, AT, antagonists, Spironolactone). Remember o b-blockers are contraindicated in decompensated or acute HF. o b-blockers can be used in congestive, chronic or compensated HF. 7. Hypotensive states (Systolic BP < 100) o In hypotension, body tries to compensate by increasing sympathetic activity and by increasing renin release. o b-blockers abolish these effects and may cause worsening of hypotension.
Category:
Pharmacology
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