Use the PharmacoPhoto video ‘flash-card’ series to reinforce your knowledge of drug classes and specific medications.
Hello thanks for joining me as we talk about the non-selective adrenergic blocking agents labetalol and carvedilol are the non-selective edge energic blocking agents what do we mean by non-selective adrenergic blocking agents we mean that it’s going to block the adrenaline receptors but it does it in a non selective way so we don’t just block for instance the alpha
One receptors or the beta 1 or the beta 2 receptors we block all of those receptors these are essentially beta blockers but they have some alpha blocking properties which i’m going to explain in just a minute the most common use for the non selective adrenergic blocking agents is in the treatment of essential hypertension and that can be alone or in combination
With diuretics however because they are non selective they have quite a few adverse effects labetalol and carvedilol are alpha 1 beta 1 and beta 2 adrenergic receptor blockers meaning that they block the actions of adrenaline or in the united states epinephrine at all those receptors in order to understand the actions and side-effects of labetalol and carvedilol
We just need to know what adrenaline does at each one of those receptors and think logically what would happen if we blocked that so for instance in the alpha 1 receptor and they’re not just on the blood vessels so in the blood vessels they actually can strict the blood vessels and a blocking of that constriction would result in dilation and therefore it would
Result in a decrease in blood pressure but they’re also the alpha-1 receptor is also on the iris it’s on the gut it’s in the urinary bladder and if you think about each one of those what happens at the pupils of the eye in a sympathetic nervous system stimulation there is going to be a dilation so we’re blocking that and therefore there’s a constriction so with
That effect there could be i pain there could be decreased night vision or blurred vision in the gi t it will block the decrease in peristalsis so in other words it’s actually going to increase the gut motility possibly leading to diarrhea nausea vomiting and possibly anorexia and flatulence as well in the urinary bladder it will block the constrictions possibly
Leading to urinary incontinence also the beta receptors are not just on the heart there are beta 2 receptors on the bronchi and blocking the dilation of the bronchi is going to result basically in a constriction and therefore they’ll be contraindicated in asthma so as you can see by blocking the alpha one receptors on the blood vessels and by blocking the beta
1 receptors on the heart it seems like a perfect drug for essential hypertension but these drugs aren’t well tolerated as a matter of fact even with the intended action of decreasing the blood pressure we can go a little bit too much and actually result in hypotension or orthostatic hypotension dizziness as matter-of-fact dizziness 11 percent of people who are on
These medications actually complain of dizziness due to that non-selective nature of labetalol and carvedilol other alternatives are often safer and now you know thanks for joining me
Transcribed from video
Labetalol and Carvedilol: alpha and beta blockers (non-selective) By PharmacoPhoto