Why use nonselective beta blockers over cardioselective?

[lacrosse87]

I understand the benefits of a cardioselective beta-blocker over a nonselective beta-blocker in pt's with asthma, diabetes and peripheral vascular disease, but what the heck are the benefits of using a nonselective over cardioselective? Why use nonselective beta blockers like propanolol and timolol over others? Are they more efficacious or something? Cheaper for patients?

In the case of timolol for decreasing aqueous production, a quick pubmed search led some abstracts to pop up that mentioned that Betaxolol, which is cardioselective, is able to decrease IOP almost as much as Timolol, may actually result in greater visual field preservation despite the slightly smaller decrease in IOP-reduction that you'd see in Timolol (probably through some other neuroprotective mechanisms), has less systemic circulation compared to Timolol, and is devoid of the bronchopulmonary/cardiac effects you'd see with a nonselective drug like Timolol.

Soooo, why choose drugs like Timolol and Propanolol??

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[loveoforganic2]

I was under the impression timolol was given as eye drops (along with most medication given to decrease IOP).

Some nonselective beta blockers have additional effects that are desirable (e.g. alpha 1 antagonism with carvedilol). Others, e.g. pindolol, may have demonstrate ISA (i.e. some partial agonist activity). Of course, this is true for some selective agents as well (acebutolol). Just as another example, carvedilol and metoprolol also have beta arrestin activity that causes increased ejection fraction.

Basically, anything that seems to have an obvious reason for or against use probably has a complicated reason negating that rationale. Look up the binding profile of pretty much any psychopharmaceutical for a more poignant example - they have activity described at like 30 receptors

Beyond receptor affinity, there are different routes of metabolism, half lives, affordability, individual response to each drug, etc. etc.

 

[lacrosse87]

Yup, timolol is given as drops. The systemic effects I mentioned would result after drainage at the medial canthus into the nasolacrimal duct.

Thanks for the response. Still pretty new to pharm, need to learn more! Didn't think to look up binding profiles. And yeahh, half lives, another factor I forgot about. Good call

 

[Oreoomar]

I believe the non-selectives were discovered much earlier than cardioselective, which would probably make them much cheaper. In areas where drug availability may not be widespread and money is more of an issue, it probably plays a much bigger role than we might expect.

 

[loveoforganic2]

Yup, timolol is given as drops. The systemic effects I mentioned would result after drainage at the medial canthus into the nasolacrimal duct.

Thanks for the response. Still pretty new to pharm, need to learn more! Didn't think to look up binding profiles. And yeahh, half lives, another factor I forgot about. Good call

Do you know for sure that drainage into the nasolacrimal duct is the means of systemic absorption? It's covered in mucosal tissue, but it doesn't have much surface area, and it just drains out the nose. There are certainly systemic effects with eye drops, but they're much less pronounced than w/PO administration.

Also, one more thing specific to IOP - beta 2 stimulates aqueous humor production, and we don't have any beta 2 selective medications on the market that I'm aware of

 

[lacrosse87]

Do you know for sure that drainage into the nasolacrimal duct is the means of systemic absorption? It's covered in mucosal tissue, but it doesn't have much surface area, and it just drains out the nose. There are certainly systemic effects with eye drops, but they're much less pronounced than w/PO administration.

Also, one more thing specific to IOP - beta 2 stimulates aqueous humor production, and we don't have any beta 2 selective medications on the market that I'm aware of

Don't know for sure tbh. Mostly going from experience when I worked as an ophthalmic tech. Was told one of the strategies for counseling pt's c/o of the side effects from their glaucoma drops was to instruct them to occlude their medial canthus with a tissue when they instill their drops to minimize the systemic effects. Whether that's actually correct/factual, I'm not sure. Good question.

And ah, I don't know why I forgot beta-2 stim increases aqueous production too, not just beta-1. Guess the timolol example wasn't good for me to use. I'm going to have to specifically see if there are any indications for choosing to use nonselective anti-hypertensives with no ISA like propanolol or nadolol over cardioselective anti-hypertensive meds next.

 

[Choo]

I think I read somewhere that propranolol is the most lipophilic and build up in the brain (amygdala, I think) making it useful for treatment of PTSD. Also, it is the most effective migraine prophylactic.

 

[nowanmd]

nonselective beta blockers are used as prophylaxis against bleeding of esophageal varicosities esp with liver dz

 

[lacrosse87]

Thanks a ton everyone!