Betaxolol is a racemic mixture and selective beta-1 adrenergic receptor antagonist with antihypertensive and anti-glaucoma activities and devoid of intrinsic sympathomimetic activity. Betaxolol selectively and competitively binds to and blocks beta-1 adrenergic receptors in the heart, thereby decreasing cardiac contractility and rate. This leads to a reduction in cardiac output and lowers blood pressure. When applied topically in the eye, this agent reduces aqueous humor secretion and lowers the intraocular pressure (IOP). In addition, betaxolol prevents the release of renin, a hormone secreted by the kidneys that causes constriction of blood vessels.
Betaxolol also shows greater affininty for beta1 receptors than metoprolol. It works by blocking the action of certain natural chemicals in your bodies such as epinephrine that affects the heart and blood vessels.
Mechanism of action of Betaxolol
Betaxolol selectively blocks catecholamine stimulation of beta(1)-adrenergic receptors in the heart and vascular smooth muscle. This results in a reduction of heart rate, cardiac output, systolic and diastolic blood pressure, and possibly reflex orthostatic hypotension. Betaxolol can also competitively block beta(2)-adrenergic responses in the bronchial and vascular smooth muscles, causing bronchospasm.Betaxolol is a competitive, beta(1)-selective (cardioselective) adrenergic antagonist . Activation of beta(1)-receptors (located mainly in the heart) by epinephrine increases the heart rate and the blood pressure, and the heart consumes more oxygen. Drugs such as betaxolol that block these receptors, therefore, have the reverse effect: they lower the heart rate and blood pressure and hence are used in conditions when the heart itself is deprived of oxygen. They are routinely prescribed in patients with ischemic heart disease. In addition, beta(1)-selective blockers prevent the release of renin, which is a hormone produced by the kidneys which lead to constriction of blood vessels. Betaxolol is lipophilic and exhibits no intrinsic sympathomimetic activity (ISA) or membrane stabilizing activity.
Indications of Betaxolol
- Angina pectoris prophylaxis
- To treatment of hypertension,
- Arrhythmias,
- Coronary heart disease,
- Glaucoma,
- To reduce non-fatal cardiac events in patients with heart failure.
- Ophthalmic: for the management of glaucoma
- the drug seems to have an effect of neuroprotection in glaucoma treatment
- Reduction of elevated intraocular pressure in conditions such as ocular hypertension
- Chronic open-angle glaucoma.
Contra-Indications of Betaxolol
- Patients with sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure
- Sinus bradycardia, sick sinus syndrome, sino-atrial block
- Cardiogenic shock;
- Overt cardiac failure;
- Pheochromocytoma
- Diabetes
- Depression
- Complete heart block
- Second-degree atrioventricular heart block
- Sinus bradycardia
- Suddenly serious symptoms of heart failure
- Occasional Numbness
- Prickling
- Tingling of fingers and toes
- Asthma
- Asthma attack
- Liver problems
- kidney disease with the reduction in kidney function
- Severe renal impairment
- Psoriasis
- Blood circulation failure due to the serious heart condition
- Pregnancy
- Anaphylactic shock due to Allergy Shots
- Second or third degree AV block not controlled with pace-maker.;
- Hypersensitivity to the active substance (betaxolol),
- Reactive airway disease including severe bronchial asthma or a history of severe bronchial asthma, severe chronic obstructive pulmonary disease.
Dosage of Betaxolol
Intraocular Hypertension
- 0.25% suspension: One drop in the affected eye(s) twice a day
- 0.5% solution: One to two drops in the affected eye(s) twice a day
Glaucoma (Open Angle)
- 0.25% suspension: One drop in the affected eye(s) twice a day
- 0.5% solution: One to two drops in the affected eye(s) twice a day
Pediatric Dose for Intraocular Hypertension
- 0.25% suspension: One drop in the affected eye(s) twice a day
Side Effects of Betaxolol
The most common
- Heart failure, chest pain, a slow heart rate, heart block, heart disease, or any other heart problems
- Breathing disorders, such as bronchitis, asthma, sleep apnea, or chronic obstructive pulmonary disease (COPD)
- A dry cough
- Dizziness and light-headedness due to low blood pressure
- Fatigue, especially in the early stages
- Mouth dryness in the early stages
- The most common (a burning feeling in the chest, behind the breastbone or gullet)
- Abdominal or stomach pain
- Constipation
- High blood pressure
- Nausea, vomiting,
- painful or swollen gums
- numbness or heavy feeling in the jaw
- dull, aching pain in the hip, groin, or thigh
- stomach pain,
- a headache,
- reversible hair loss or thinning, and
- fever.
Common
- chills or fever
- a headache, severe and throbbing
- joint or back pain
- muscle aching or cramping
- muscle pains or stiffness
- chest pressure or squeezing pain in the chest
- excessive sweating
- sudden drowsiness or need to sleep
- coughing up blood
- liver problems–nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes)
- decreased amount of urine
Rare
- Anxiety
- change in vision
- chest pain or tightness
- confusion
- a cough
- Agitation
- arm, back, or jaw pain
- blurred vision
- chest pain or discomfort
- convulsions
- extra heartbeats
- hallucinations
- a headache
- irritability
- lightheadedness
- cold and clammy skin
- fast and shallow breathing
- swelling of your feet, legs, or hands purple spot on your skin caused by internal bleeding
- fast or abnormal heart rate or palpitations
- loss of appetite
- lower back, side, or stomach pain
- mental depression
- muscle pain or cramps
Drugs interactions of Betaxolol
Betaxolol may interact with following drugs, supplements, & may change the efficacy of drugs
- antidiabetes medications (e.g., insulin, metformin, gliclazide)
- beta-2 agonists (e.g., formoterol, salmeterol, salbutamol)
- bosutinib
- Beta-blocker eye drops, betaxolol, carteolol, levobunolol , metipranolol,
- Calcium channel blockers, such as Cardizem, diltiazem; nifedipine; and verapamil
- Diabetes medication
- bupropion
- calcium channel blocking agents (e.g., diltiazem, verapamil)
- cimetidine
- cyclosporine
- fluoxetine
- MAO inhibitors (e.g., phenelzine, tranylcypromine)
- medications that affect heart rhythm
- medications that lower blood pressure
- nitroglycerin
- paroxetine
- rituximab
- tricyclic antidepressants (e.g., amitriptyline, nortriptyline)
Pregnancy & Lactation
Pregnancy
There are no adequate data for the use of betaxolol in pregnant women. Betaxolol should not be used during pregnancy unless clearly necessary.
Epidemiological studies have not revealed malformative effects but show a risk for intra uterine growth retardation when beta-blockers are administered by the oral route. In addition, signs and symptoms of beta-blockade (e.g. bradycardia, hypotension, respiratory distress, and hypoglycemia) have been observed in the neonate when beta-blockers have been administered until delivery. If Betaxolol Eye Drops is administered until delivery, the neonate should be carefully monitored during the first days of life.
Lactation
Beta-blockers are excreted in breast milk, having the potential to cause serious undesirable effects in the infant of the nursing mother. However, at therapeutic doses of betaxolol in eye drops, it is not likely that sufficient amounts would be present in breast milk to produce clinical symptoms of beta-blockade in the infant.
References
- https://www.webmd.com/drugs/2/drug-6861/betaxolol-oral/details/list-contraindications
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