Beta-blocker systemic effects

Drugs that block beta-1 receptors on the myocardium are one of the mainstays in arrhythmia treatment. Beta blockers are effective because they decrease the excitatory effects of the sympathetic nervous system and related catecholamines (norepinephrine and epinephrine) on the heart.5,28 This effect typically decreases cardiac automaticity and prolongs the effective refractory period, thus slowing heart rate.5 Beta blockers also slow down conduction through the myocardium, and are especially useful in controlling function of the atrioventricular node.21 Hence, these drugs are most effective in treating atrial tachycardias such as atrial fibrillation.23 Some ventricular arrhythmias may also respond to treatment with beta blockers. 

Brismar, K., Hylander, B., Eliasson, K., Rossner, S. Wetterberg, L. (1988). Melatonin secretion related to side-effects of beta-blockers from the central nervous system. Acta Med. Scand. 223, 525-30. 

Geriatric Considerations - Summary Systemic absorption of ophthalmic drugs may occur and cause adverse effects in older adults. Since betaxolol is beta-selective, cardiovascular, respiratory and CNS adverse effects occur less frequently than with beta-nonselective topical opthalmics. These effects may still occur therefore close monitoring for systemic side effects is warranted. Betaxolol maybe less effective than the nonselective topical beta-blockers with an average lOP reduction of 18%-26%. Tachyphylaxis may occur after long-term therapy. 

Geriatric Considerations - Summary Carteolol decreases lOP on average 20%-32%. Systemic absorption of ophthalmic drugs may occur and cause adverse effects in older adults. Since carteolol is a nonselective beta-blocker, older adults maybe more... 

Drug interactions Proleukin may affect central nervous system function. Therefore interactions could occur following concomitant administration of psychotropic drugs. Concurrent administration of drugs possessing nephrotoxic, myelotoxic, cardiotoxic, or hepatotoxic effects with Proleukin may increase toxicity in these organ systems. Reduced kidney and liver function secondary to Proleukin treatment may delay elimination of concomitant medications and increase the risk of adverse events from those drugs. Beta-blockers and other antihypertensives may potentiate the hypotension seen with Proleukin. 

Propranolol inhibits the stimulation of renin production by catecholamines (mediated by receptors). It is likely that propranolol s effect is due in part to depression of the renin-angiotensin-aldosterone system. Although most effective in patients with high plasma renin activity, propranolol also reduces blood pressure in hypertensive patients with normal or even low renin activity. Beta blockers might also act on peripheral presynaptic adrenoceptors to reduce sympathetic vasoconstrictor nerve activity. 

With some drugs that are delivered via eye drops, some systemic absorption can occur which in turn can cause systemic side-effects. For example, timolol (a beta-blocker) can worsen or precipitate bronchospasm in asthmatic and COPD patients. 

NICE (2006) also recommends that beta-blockers are not used as an initial therapy for hypertension since they have been shown to be less effective at reducing the risk of a major cardiovascular system event, in particular stroke. 

BETA-BLOCKERS OPIOIDS 1. Risk of t plasma concentrations and effects of labetalol, metoprolol and propranolol t systemic effects of timolol eye drops 2. t plasma concentrations of esmolol when morphine is added 3. t plasma concentrations of metoprolol and propranolol when dextro-propoxyphene is added 1. Methadone inhibits CYP2D6, which metabolizes these beta-blockers 2. Unknown 3. i hepatic clearance of metoprolol and propanolol 1. Monitor BP at least weekly until stable 2. Monitor BP closely 3. Monitor BP at least weekly until stable. Warn patients to report symptoms of hypotension (lightheadedness, dizziness on standing, etc.)... 

BETA-BLOCKERS QUININE Risk oft plasma concentrations and effects of labetalol, metoprolol and propranolol t systemic effects of timolol eye drops Quinine inhibits CYP2D6, which metabolizes these beta-blockers Monitor BP at least weekly until stable... 

Systemic Effects. Because levobunolol is a potent and effective Pi and P2 blocker, it shares with timolol the same potential for systemic beta-blockade. Mean resting heart rate may decrease 3 to 10 bpm during use of levobunolol, and some reduction in blood pressure may occur.Topical ocular dosing with levobunolol results in plasma levels of approximately 1 ng/ml. As with timolol, 0.5% levobunolol reduces maximal exercise-induced heart rate by approximately 9 bpm. 

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