Lec. 8: Medical Therapy 2 (Beta Blockers)

What is the primary location of beta 1 receptors systemically?

Heart

What  is the primary location of beta 2 receptors systemically?

Bronchial muscle, blood vessels, and uterus

What occurs beta1 receptors stimulated systemically?

Stimulation causes increase heart rate, cardiac contractility and atrioventricular conduction

What occurs beta 2 receptors stimulated systemically?

Stimulation causes dilation of bronchi and blood vessels

What occurs beta 1 receptors blocked systemically?

Interferes with normal sympathetic stimulation of heart

What occurs beta 2 receptors blocked systemically?

Pulmonary effects

Beta 3 receptors mediate what?

Lipolysis

If the amount of drug is not limited how much aqueous humor suppression can occur due to beta blockers?

50%

Explain the classic hypothesis of mechanism of action of beta blockers?

1. OBB’s will competitively bind to beta-adrenergic agonists’s receptors and block their activation of a G protein 

2. No activation of g protein will not allow cAMP to increase the aqueous production

Explain the alternate hypothesis of mechanism of action of beta blockers?

Ciliary muscle is always in tonic stage to produce aqueous so beta blockers interfere with the tonic stimulation 

What acts as a second messenger in production of aqueous humor from ciliary process?

cAMP

What are the indications to the use of ocular beta blockers?

ALL

What are the contraindications to the use of no selective ocular beta blockers?

All of the above 

Ocular beta blockers are contraindicated when the pulse rate is below what?

60 beats per minute resting

What selective beta blocker is not contraindicated in patients with pulmonary disease lik bronchial asthma or chronic obstructive pulmonary disease?

Betaxolol

How many times a day should a person use ocular beta blocker timolol if prescribed on label?

Twice a day

Name the beta blockers that does not have an on label used of once daily?

Timolol

What is the more common clinical dosage of off label use of ocular beta blockers like timolol?

Once daily

What percentage of timolol is more commonly utilized in adults?

0.5%

Does the use of timolol lead to corneal anesthesia?

No

Give an example of selective beta blocker?

Betaxolol

What is not the hypothesis for short term escape of IOP lowering with the use of beta blockers?

Timolol has no escape or drift effects

What is the hypothesis for long term drift of IOP lowering with the use of beta blockers?

Over months to years the control of IOP isnt as good as it once was

Clinically what is an acceptable wash out period of a drug?

4 weeks

Which type of formulation increases bioavailability of drug in ophthalmic use?

Gels or ointments

What is a common side effect of ointment or gels to patients vision?

Blurry Vision

Explain how ocular beta blockers can not approach trough serum levels of the usual oral dose?

Through systemic absorption through the olfactory system

What general physiological test is a must before and after prescribing ocular beta blockers?

Always check BP and pulse rate on patients before and after prescribing OBBs

Compared to timolol which beta blocker has less CNS side effects?

Betaxolol

What cautions should be advised to diabetic patients when prescribing ocular beta blockers?

1. It will mask the trembling of hypoglycemic patients which will not allow them to know when theyre low on sugar

2. This is a problem in true insulin dependent patients

What is not a cardiovascular side effects of beta blockers?

• (Blocks beta1 receptors interferes with normal sympathetic stimulation of heart)

Higher heart rate

What are the CNS side effects of beta blockers?

ALL OF THEM