Verapamil 40mg Tablets

Verapamil is a non-dihydropyridine calcium channel blocker. It inhibits the transmembrane influx of extracellular calcium ions across the membranes of myocardial and vascular smooth muscle cells. This leads to: 1) Dilation of coronary and peripheral arteries, reducing afterload and improving myocardial oxygen supply. 2) Reduction in myocardial contractility. 3) Slowing of AV nodal conduction, prolonging the PR interval and decreasing ventricular rate in supraventricular tachyarrhythmias.

Urgent Side Effects: Seek Medical Attention Immediately

Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Slow heartbeat
Abnormal heartbeat that is new or worsening
Severe dizziness or fainting
Shortness of breath, significant weight gain, or swelling in the arms or legs

Other Possible Side Effects

Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor:

Dizziness or headache
Constipation

Reporting Side Effects

This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
Certain health conditions, such as:
+ Heart failure (a weakened heart)
+ Specific types of abnormal heart rhythms, including heart block, Lown-Ganong-Levine syndrome, sick sinus syndrome, or Wolff-Parkinson-White syndrome
+ Low blood pressure
+ A slow heartbeat
Medications you are currently taking, including:
+ Dofetilide, ivabradine, or quinidine
+ Beta blockers like atenolol, metoprolol, or propranolol
If you have taken disopyramide or flibanserin within the last 48 hours
* If you are breastfeeding, as you should not breastfeed while taking this medication

This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health problems with your doctor and pharmacist. They will help determine if it is safe to take this medication with your existing health conditions and medications. Never start, stop, or change the dose of any medication without consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.

When starting this medication, avoid driving and other activities that require alertness until you understand how it affects you. To minimize the risk of dizziness or fainting, get up slowly from a sitting or lying position, and be cautious when climbing stairs.

Follow your doctor's instructions for monitoring your blood pressure and heart rate, and undergo blood tests as recommended. Discuss any concerns or questions with your doctor.

If you have high blood pressure, consult your doctor before taking any over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and certain natural products or supplements.

Before consuming alcohol, discuss it with your doctor. Additionally, if you regularly drink grapefruit juice or eat grapefruit, talk to your doctor about potential interactions.

If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.

If you are pregnant or planning to become pregnant, inform your doctor to discuss the benefits and risks of using this medication during pregnancy.

• Intravenous beta-blockers (risk of severe bradycardia, asystole, AV block, heart failure)
• Disopyramide (do not administer within 48 hours before or 24 hours after verapamil due to additive negative inotropic effects)
• Dantrolene (risk of hyperkalemia and myocardial depression)
• Ivabradine (additive bradycardia)

• Digoxin (verapamil increases digoxin serum levels by 50-75%, requiring dose reduction of digoxin)
• Amiodarone (additive bradycardia, AV block, hypotension)
• Statins (e.g., simvastatin, lovastatin, atorvastatin - verapamil inhibits CYP3A4, increasing statin levels and risk of myopathy/rhabdomyolysis)
• Fentanyl (severe hypotension)
• Quinidine (hypotension, pulmonary edema)
• Cyclosporine, Tacrolimus, Sirolimus, Everolimus (verapamil increases levels of these immunosuppressants)
• Carbamazepine (verapamil increases carbamazepine levels, leading to toxicity)
• Phenobarbital, Rifampin (inducers of CYP3A4, may decrease verapamil levels)
• Clonidine (additive bradycardia/AV block)
• P-glycoprotein inhibitors/inducers (affect verapamil transport)

• Beta-blockers (oral - additive bradycardia, AV block, hypotension; monitor closely)
• Alpha-blockers (e.g., prazosin - additive hypotensive effects)
• Other antihypertensives (additive hypotensive effects)
• Grapefruit juice (increases verapamil bioavailability, avoid or limit intake)
• Theophylline (verapamil may increase theophylline levels)
• Buspirone (verapamil may increase buspirone levels)
• Midazolam, Triazolam (verapamil may increase levels of these benzodiazepines)
• Colchicine (increased colchicine toxicity)

• Aspirin (may increase bleeding risk with some CCBs, but less significant with verapamil)
• Cimetidine (may increase verapamil levels slightly)

• Dizziness
• Lightheadedness
• Fatigue
• Headache
• Constipation
• Peripheral edema (swelling of ankles/feet)
• Shortness of breath
• Chest pain (worsening or new)
• Palpitations
• Signs of liver dysfunction (e.g., jaundice, dark urine, persistent nausea/vomiting)

Verapamil is classified as Pregnancy Category C. Studies in animals have shown an adverse effect on the fetus, but there are no adequate and well-controlled studies in pregnant women. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Verapamil is excreted in human breast milk. While the amount is generally small, the American Academy of Pediatrics considers it compatible with breastfeeding. However, monitor the infant for potential adverse effects such as bradycardia, hypotension, or sedation.

Safety and efficacy of oral verapamil in pediatric patients have not been established for routine use. Its use is generally limited to specific indications like supraventricular tachycardia, often via intravenous administration, and under close supervision due to potential for severe adverse effects (e.g., profound hypotension, bradycardia, asystole), especially in infants.

Elderly patients may be more sensitive to the hypotensive and bradycardic effects of verapamil due to age-related decreases in hepatic and renal function, and increased sensitivity of the cardiovascular system. Initiate therapy with lower doses and titrate slowly, monitoring closely for adverse effects.

• Verapamil is a non-dihydropyridine CCB, meaning it has significant effects on cardiac conduction and contractility, unlike dihydropyridines (e.g., amlodipine) which primarily affect vascular smooth muscle.
• Constipation is a very common and often dose-limiting side effect of verapamil. Advise patients on dietary fiber, fluid intake, and potential need for stool softeners.
• Avoid concomitant use with IV beta-blockers due to the risk of severe bradycardia, AV block, and asystole. If a patient is on oral verapamil and requires a beta-blocker, use extreme caution and close monitoring.
• Grapefruit juice significantly increases verapamil levels; patients should be advised to avoid or limit its consumption.
• Verapamil is a potent inhibitor of CYP3A4 and P-glycoprotein, leading to numerous significant drug interactions, especially with statins (simvastatin, lovastatin), digoxin, and immunosuppressants. Always review concomitant medications.
• Immediate-release verapamil requires multiple daily dosing (TID or QID) due to its relatively short half-life. Ensure patients understand the dosing schedule to maintain therapeutic levels.

• Other non-dihydropyridine calcium channel blockers (e.g., Diltiazem)
• Dihydropyridine calcium channel blockers (e.g., Amlodipine, Nifedipine, Felodipine) for hypertension/angina
• Beta-blockers (e.g., Metoprolol, Atenolol, Propranolol) for hypertension, angina, arrhythmias
• ACE inhibitors (e.g., Lisinopril, Enalapril) for hypertension
• Angiotensin Receptor Blockers (ARBs) (e.g., Valsartan, Losartan) for hypertension
• Diuretics (e.g., Hydrochlorothiazide, Furosemide) for hypertension
• Antiarrhythmics (e.g., Digoxin, Amiodarone, Adenosine) for specific arrhythmias

If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it occurred.