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Penbutolol; Indications/Uses, Dosage, Side Effects, Drug Interaction ,Pregnancy

Penbutolol is a lipophilic, nonselective beta-adrenergic receptor antagonist with anti-anginal and antihypertensive activities. Penbutolol 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. In addition, penbutolol prevents the release of renin, a hormone secreted by the kidneys that causes constriction of blood vessels.

Penbutolol is a medication in the class of beta blockers, used in the treatment of high blood pressure. Penbutolol is able to bind to both beta-1 adrenergic receptors and beta-2 adrenergic receptors (the two subtypes), thus making it a non-selective β blocker. Penbutolol is a sympathomimetic drug with properties allowing it to act as a partial agonist at β adrenergic receptors. Penbutolol binds both beta-1 and beta-2 adrenergic receptors, rendering it a non-selective beta-blocker. Penbutolol can act as a partial agonist at beta-adrenergic receptors since it is a sympathomimetic drug. Penbutolol also demonstrates the high binding affinity to the 5-hydroxytryptamine receptor 1A with antagonistic effects.

Mechanism of Action of Penbutolol

Penbutolol acts on the β1 adrenergic receptors in both the heart and the kidney. When β1 receptors are activated by catecholamines, they stimulate a coupled G protein that leads to the conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). The increase in cAMP leads to activation of protein kinase A (PKA), which alters the movement of calcium ions in the heart muscle and increases the heart rate. Penbutolol blocks the catecholamine activation of β1 adrenergic receptors and decreases heart rate, which lowers blood pressure.

Indications of Penbutolol

Angina Pectoris Prophylaxis
High Blood Pressure
Angina pectoris
Gastroesophageal variceal hemorrhage prophylaxis
High blood pressure (Hypertension)
Used in cardiovascular disease to treat arrhythmias,
Nonvalvular atrial fibrillation
Penbutolol is also indicated in the treatment of mild to moderate arterial hypertension. It may be used alone or in combination with other antihypertensive agents, especially thiazide-type diuretics. Penbutolol is contraindicated in patients with cardiogenic shock, sinus bradycardia, second and third-degree atrioventricular conduction block, bronchial asthma, and those with known hypersensitivity.

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Contra-Indications of Penbutolol

Diabetes
Depression
Myasthenia Gravis
Complete Heart Block
Partial Heart Block
Sinus Bradycardia
Suddenly serious symptoms of heart failure
Occasional Numbness
Tingling of Fingers and Toes
Emphysema
Asthma
Severe Chronic Obstructed Lung Disease
Liver problems
Blood Circulation Failure due to Serious Heart Condition
Anaphylactic Shock due to Allergy Shots
Right-sided Heart Failure
kidney disease with likely reduction in kidney function
Allergies to beta-Blockers (Beta-Adrenergic Blocking Agents)

Dosage of Penbutolol

Strength: 20 mg

Hypertension

Initial dose: 20 mg orally once a day.
Maintenance dose: 20 to 40 mg orally once a day.

Angina Pectoris

Initial dose: 20 mg orally once a day.
Maintenance dose: 20 to 40 mg orally once a day.

Side Effects of Penbutolol

The most common

Chest pain or discomfort
a headache
Blurred vision or other vision problems
Fever, chills, or a sore throat
Shortness of breath
Slow or irregular heartbeat
Dry mouth / a cough
muscle trembling, jerking, or stiffness
anxiety
changes in vision, including blurred vision
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
stomach pain or cramping
diarrhea
stomach pain;
back pain, joint or muscle pain.
problems with your vision (including color vision);
sudden chest pain or trouble breathing;
pain or swelling in one or both legs;
a migraine headache;
pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating; or

More common

Abdominal or stomach pain, discomfort, or tenderness
chills or fever
difficulty with moving
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
discomfort in arms, shoulders, neck or upper back
excessive sweating
feeling of heaviness, pain, warmth and/or swelling in a leg or in the pelvis
sudden tingling or coldness in an arm or leg
sudden slow or difficult speech
sudden drowsiness or need to sleep
fast breathing
sharp pain when taking a deep breath
fast or slow heartbeat
coughing up blood
rust colored urine
decreased amount of urine

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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
fainting
hallucinations
a headache
irritability
lightheadedness
mood or mental changes
muscle pain or cramps
muscle spasm or jerking of all extremities
nervousness

Drug Interactions of Penbutolol

Penbutolol may interact with the following drug, supplements, & may change the efficacy of the drug

alpha-1 blockers (e.g., doxazosin, prazosin, tamsulosin)
alpha-2 blockers (e.g., clonidine, dexmedetomidine, methyldopa)
angiotensin-converting enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
angiotensin II receptor blockers (i.e., irbesartan, losartan, valsartan)
antipsychotics (e.g., clozapine, olanzapine, quetiapine, risperidone)
atorvastatin
azole antifungals (e.g., itraconazole, ketoconazole, posaconazole)
barbiturates (e.g., phenobarbital)
benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
beta-agonists (e.g., formoterol, salbutamol, salmeterol)
calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
carbamazepine
cyclosporine
dexamethasone
diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
duloxetine
lapatinib
levodopa
lidocaine
MAO inhibitors (e.g., phenelzine, moclobemide, selegiline)
macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
nilotinib
nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, naproxen)
other beta-blockers (e.g., atenolol, metoprolol, propranolol)
pentoxifylline
phosphodiesterase-5-inhibitors (e.g., sildenafil, tadalafil)
sulfonylureas (e.g., gliclazide, glyburide, tolbutamide)
sunitinib
theophyllines (e.g., aminophylline, oxtriphylline, theophylline)

Pregnancy Catagory of Penbutolol

FDA Pregnancy Category C

Pregnancy

There are no reports of the use of penbutolol during pregnancy. As with other beta-blockers, it is recommended that newborns of mothers who were exposed to penbutolol near term or delivery be monitored for signs or symptoms of beta-blockade (bradycardia, hypotension, hypoglycemia) for at least 48 hours.

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Lactation

Based on its physicochemical properties, penbutolol appears to present a low-risk to the breastfed infant. Because there is no published experience with penbutolol during breastfeeding, other agents may be preferred, especially while nursing a newborn or preterm infant.