Question

Sadie was prescribed betaxolol ophthalmic drops by her ophthalmologist to treat her glaucoma. oral beta blockers should be avoided in patients who use ophthalmic beta blockers because:

Answer 1

I believe the correct answer is that ophthalmic beta receptors are addictive and have drastic effects on the cardiac cells.

Explanation:

Both ophthalmic beta blockers and oral beta blockers target the beta receptors that can be found in the heart. They do not act antagonistic to one another and use of ophthalmic beta blockers concurrently with the oral beta blockers will multiply the effect of the drugs and the person will experience heart failure.

Further Explanation:

The human central nervous system is divided into the Central Nervous System which involves the brain and spinal cord and the Peripheral Nervous System that involves the rest of the body. The Peripheral Nervous System is further divided into the Somatic Nervous System and the Autonomous Nervous System (ANS). The ANS is controlled involuntarily by the brain and involves functions such as respiration and the cardiac rhythm including contraction and relaxation of blood vessels. The ANS has specific receptors that the CNS uses to produce the response and they include the α (alpha), β (beta) and D receptors. The beta receptors are usually divided into the beta 1 and 2. Beta 1 receptors are found exclusively on the heart and Beta 2 receptors are found on blood vessels and the bronchioles. Beta blockers bind to the two β1 and β2 blockers to produce an effect such as Betaxolol which is a cardioselective β1 blocker that lowers blood pressure by acting on the heart and slows the cardiac rhythm. Oral beta blockers will bind antagonistically to both β1 and β2 and binds to both heart receptors, blood vessels and the bronchioles. Using both oral and ophthalmic beta blockers will result in excessive antagonism and the heart will slow until it stops and the blood pressure will go down excessively and the lungs will also not function properly leading to hypoxia. The results will then prove to be fatal.

Level: College

Subject: Pharmacology

Topic: The Autonomous Nervous System

Answer 2

Betaxolol belongs to the drug class of beta blockers wherein these drugs block the action of the beta adrenergic receptors in different organs, including the heart and the bronchial tissues. Oral beta blockers (i.e. Propranolol) must be avoided because there can be additive effects of the ophthalmic drops and the oral drug and may cause severe bradycardia (and/or asthma exacerbation, if the patient has asthma).