Nifedical XL

Tell your doctor about all prescription, non-prescription, illegal, recreational, herbal, nutritional, or dietary drugs you’re taking, especially:

• Acarbose (Prandase, Precose)
• Anticoagulants (blood thinners) such as warfarin (Coumadin, Jantoven)
• Antifungals such as fluconazole (Diflucan), itraconazole (Sporanox), and ketoconazole (Nizoral)
• Beta blockers such as atenolol (Tenormin), labetalol (Trandate), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), propranolol (Inderal), and timolol (Blocadren)
• Carbamazepine (Carbatrol, Epitol, Tegretol)
• Cimetidine (Tagamet)
• Digoxin (Lanoxin, Lanoxicaps)
• Diltiazem (Cardizem)
• Doxazosin (Cardura)
• Erythromycin (E.E.S., E-Mycin, Erythrocin)
• Fentanyl (Actiq, Duragesic, Fentora, Sublimaze)
• Flecainide (Tambocor)
• HIV protease inhibitors including amprenavir (Agenerase), atazanavir (Reyataz), delavirdine (Rescriptor), fosamprenavir (Lexiva), indinavir (Crixivan), nelfinavir (Viracept), and ritonavir (Norvir, in Kaletra)
• Metformin (Glucophage)
• Nefazodone (Serzone)
• Phenobarbital (Luminal)
• Phenytoin (Dilantin)
• Quinidine (Quinidex)
• Quinupristin and dalfopristin (Synercid)
• Rifampin (Rifadin, Rifamate, Rifater, Rimactane)
• Rifapentine (Priftin)
• St. John’s wort
• Tacrolimus (Prograf)
• Valproic acid (Depakene, Depakote)
• Verapamil (Calan, Covera, Isoptin, Verelan)

Nifedipine and Other Interactions

Nifedipine may cause dizziness.

Don’t drive or operate machinery until you know how this medicine affects you.

Nifedipine and Alcohol

Alcohol may worsen certain side effects of nifedipine.

Talk to your doctor about how much alcohol is safe to consume while taking this medicine.

Nifedipine and Grapefruit

Grapefruit may interact with nifedipine. Don’t drink grapefruit juice or eat grapefruit for three days before starting this medicine or while taking it.

Talk to your doctor about this potential interaction.

Excessive Hypotension

Although in most angina patients the hypotensive effect of nifedipine is modest and well tolerated, occasional patients have had excessive and poorly tolerated hypotension. These responses have usually occurred during initial titration or at the time of subsequent upward dosage adjustment, and may be more likely in patients on concomitant beta-blockers.

Severe hypotension and/or increased fluid volume requirements have been reported in patients receiving nifedipine together with a beta-blocking agent who underwent coronary artery bypass surgery using high-dose fentanyl anesthesia. The interaction with high-dose fentanyl appears to be due to the combination of nifedipine and a beta-blocker, but the possibility that it may occur with nifedipine alone, with low doses of fentanyl, in other surgical procedures, or with other narcotic analgesics cannot be ruled out. In nifedipine-treated patients where surgery using high-dose fentanyl anesthesia is contemplated, the physician should be aware of these potential problems and if the patient's condition permits, sufficient time (at least 36 hours) should be allowed for nifedipine to be washed out of the body prior to surgery.

The following information should be taken into account in those patients who are being treated for hypertension as well as angina:

Increased Angina and/or Myocardial Infarction

Rarely, patients, particularly those who have severe obstructive coronary artery disease, have developed well documented increased frequency, duration and/or severity of angina or acute myocardial infarction on starting nifedipine or at the time of dosage increase. The mechanism of this effect is not established.

Beta-Blocker Withdrawal

It is important to taper beta-blockers if possible, rather than stopping them abruptly before beginning nifedipine. Patients recently withdrawn from beta-blockers may develop a withdrawal syndrome with increased angina, probably related to increased sensitivity to catecholamines. Initiation of nifedipine treatment will not prevent this occurrence and on occasion has been reported to increase it.

Congestive Heart Failure

Rarely, patients, usually receiving a beta blocker, have developed heart failure after beginning nifedipine. Patients with tight aortic stenosis may be at greater risk for such an event, as the unloading effect of nifedipine would be expected to be of less benefit, owing to the fixed impedance to flow across the aortic valve in these patients.

Gastrointestinal Obstruction Requiring Surgery

There have been rare reports of obstructive symptoms in patients with known strictures in association with the ingestion of nifedipine. Bezoars can occur in very rare cases and may require surgical intervention.

Cases of serious gastrointestinal obstruction have been identified in patients with no known gastrointestinal disease, including the need for hospitalization and surgical intervention.

Risk factors for gastrointestinal obstruction identified from post-marketing reports of nifedipine extended-release tablets include alteration in gastrointestinal anatomy (severe gastrointestinal narrowing, colon cancer, small bowel obstruction, bowel resection, gastric bypass, vertical banded gastroplasty, and colostomy), hypomotility disorders (constipation, gastroesophageal reflux disease, ileus, obesity, hypothyroidism, and diabetes) and concomitant medications (H2-histamine blockers, nonsteroidal anti-inflammatory drugs, laxatives, anticholinergic agents, and levothyroxine).