FDA Label for Nifedipine

Description

Nifedipine extended-release tablets are an extended release tablet dosage form of the calcium channel blocker nifedipine. Nifedipine is 3,5-pyridinedicarboxylic acid, 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-dimethyl ester, C₁₇H₁₈N₂O₆, and has the structural formula:

Molecular Structure - nifedipine er tab 01

Nifedipine is a yellow crystalline substance, practically insoluble in water but soluble in ethanol. It has a molecular weight of 346.3. Nifedipine extended-release tablets contain either 30 or 60 mg of nifedipine for once-a-day oral administration.

Inert ingredients in the formulation are: colloidial silicon dioxide, hypromellose, lactose monohydrate, magnesium stearate. The inert ingredients in the film coating are: hypromellose, polydextrose, polyethylene glycol, triacetin, yellow iron oxide, and titanium dioxide.

Dissolution test is pending.

Clinical Pharmacology

Nifedipine is a calcium ion influx inhibitor (slow-channel blocker or calcium ion antagonist) which inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. The contractile processes of vascular smooth muscle and cardiac muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Nifedipine selectively inhibits calcium ion influx across the cell membrane of vascular smooth muscle and cardiac muscle without altering serum calcium concentrations.

Indications And Usage

Nifedipine extended-release tablets is indicated for the treatment of hypertension. It may be used alone or in combination with other antihypertensive agents.

Contraindications

Known hypersensitivity to nifedipine.

Beta-Adrenergic Blocking Agents

(See WARNINGS.)

Nifedipine is mainly eliminated by metabolism and is a substrate of CYP3A. Inhibitors and inducers of CYP3A4 can impact the exposure to nifedipine and consequently its desirable and undesirable effects. In vitro and in vivo data indicate that nifedipine can inhibit the metabolism of drugs that are substrates of CYP3A, thereby increasing the exposure to other drugs. Nifedipine is a vasodilator, and co-administration of other drugs affecting blood pressure may result in pharmacodynamic interactions.

Beta-Blockers

Nifedipine extended-release tablets was well tolerated when administered in combination with beta-blockers in 187 hypertensive patients in a placebo-controlled clinical trial. However, there have been occasional literature reports suggesting that the combination of nifedipine and beta-adrenergic blocking drugs may increase the likelihood of congestive heart failure, severe hypotension or exacerbation of angina in patients with cardiovascular disease. Clinical monitoring is recommended and a dose adjustment of nifedipine should be considered.

Antifungal Drugs

Ketoconazole, itraconazole and fluconazole are CYP3A inhibitors and can inhibit the metabolism of nifedipine and increase the exposure to nifedipine during concomitant therapy. Blood pressure should be monitored and a dose reduction of nifedipine considered.

Antiviral Drugs

Amprenavir, atanazavir, delavirine, fosamprinavir, indinavir, nelfinavir and ritonavir, as CYP3A inhibitors, can inhibit the metabolism of nifedipine and increase the exposure to nifedipine. Caution is warranted and clinical monitoring of patients recommended.

Cns Drugs

Nefazodone, a CYP3A inhibitor, can inhibit the metabolism of nifedipine and increase the exposure to nifedipine during concomitant therapy. Blood pressure should be monitored and a reduction of the dose of nifedipine considered.

Valproic acid may increase the exposure to nifedipine during concomitant therapy. Blood pressure should be monitored and a dose reduction of nifedipine considered.

Adverse Reactions

The incidence of adverse events during treatment with nifedipine extended-release tablets in doses up to 90 mg daily were derived from multi-center placebo-controlled clinical trials in 370 hypertensive patients. Atenolol 50 mg once daily was used concomitantly in 187 of the 370 patients on Nifedipine extended-release tablets and in 64 of the 126 patients on placebo. All adverse events reported during Nifedipine extended-release tablets therapy were tabulated independently of their causal relationship to medication.

The most common adverse event reported with Nifedipine extended-release tablets was peripheral edema. This was dose related and the frequency was 18% on Nifedipine extended-release tablets 30 mg daily and 22% on Nifedipine extended-release tablets 60 mg daily versus 10% on placebo.

Other common adverse events reported in the above placebo-controlled trials include:

Where the frequency of adverse events with Nifedipine extended-release tablets and placebo is similar, causal relationship cannot be established.

The following adverse events were reported with an incidence of 3% or less in daily doses up to 90 mg:

Body as a Whole/Systemic: chest pain, leg pain
Central Nervous System: paresthesia, vertigo
Dermatologic: rash
Gastrointestinal: constipation
Musculoskeletal: leg cramps
Respiratory: epistaxis, rhinitis
Urogenital: impotence, urinary frequency
Other adverse events reported with an incidence of less than 1.0% were:

Body as a Whole/Systemic: allergic reaction, asthenia, cellulitis, substernal chest pain, chills, facial edema, lab test abnormal, malaise, neck pain, pelvic pain, pain, photosensitivity reaction
Cardiovascular: atrial fibrillation, bradycardia, cardiac arrest, extrasystole, hypotension, migraine, palpitations, phlebitis, postural hypotension, tachycardia, cutaneous angiectases
Central Nervous System: anxiety, confusion, decreased libido, depression, hypertonia, hypesthesia, insomnia, somnolence
Dermatologic: angioedema, petechial rash, pruritus, sweating
Gastrointestinal: abdominal pain, diarrhea, dry mouth, dysphagia, dyspepsia, eructation, esophagitis, flatulence, gastrointestinal disorder, gastrointestinal hemorrhage, GGT increased, gum disorder, gum hemorrhage, vomiting
Hematologic: eosinophilia, lymphadenopathy
Metabolic: gout, weight loss
Musculoskeletal: arthralgia, arthritis, joint disorder, myalgia, myasthenia
Respiratory: dyspnea, increased cough, rales, pharyngitis, stridor
Special Senses: abnormal vision, amblyopia, conjunctivitis, diplopia, eye disorder, eye hemorrhage, tinnitus
Urogenital/Reproductive: dysuria, kidney calculus, nocturia, breast engorgement, polyuria, urogenital disorder The following adverse events have been reported rarely in patients given nifedipine in coat core or other formulations: allergenic hepatitis, alopecia, anaphylactic reaction, anemia, arthritis with ANA (+), depression, erythromelalgia, exfoliative dermatitis, fever, gingival hyperplasia, gynecomastia, hyperglycemia, jaundice, leukopenia, mood changes, muscle cramps, nervousness, paranoid syndrome, purpura, shakiness, sleep disturbances, Stevens-Johnson syndrome, syncope, taste perversion, thrombocytopenia, toxic epidermal necrolysis, transient blindness at the peak of plasma level, tremor and urticaria.

Overdosage

Experience with nifedipine overdosage is limited. Symptoms associated with severe nifedipine overdosage include loss of consciousness, drop in blood pressure, heart rhythm disturbances, metabolic acidosis, hypoxia, cardiogenic shock with pulmonary edema. Generally, overdosage with nifedipine leading to pronounced hypotension calls for active cardiovascular support including monitoring of cardiovascular and respiratory function, elevation of extremities, judicious use of calcium infusion, pressor agents and fluids. Clearance of nifedipine would be expected to be prolonged in patients with impaired liver function. Since nifedipine is highly protein bound, dialysis is not likely to be of any benefit; however, plasmapheresis may be beneficial.

There has been one reported case of massive overdosage with tablets of another extended release formulation of nifedipine. The main effects of ingestion of approximately 4800 mg of nifedipine in a young man attempting suicide as a result of cocaine-induced depression was initial dizziness, palpitations, flushing, and nervousness. Within several hours of ingestion, nausea, vomiting, and generalized edema developed. No significant hypotension was apparent at presentation, 18 hours post ingestion. Blood chemistry abnormalities consisted of a mild, transient elevation of serum creatinine, and modest elevations of LDH and CPK, but normal SGOT. Vital signs remained stable, no electrocardiographic abnormalities were noted and renal function returned to normal within 24 to 48 hours with routine supportive measures alone. No prolonged sequelae were observed.

The effect of a single 900 mg ingestion of nifedipine capsules in a depressed anginal patient on tricyclic antidepressants was loss of consciousness within 30 minutes of ingestion, and profound hypotension, which responded to calcium infusion, pressor agents, and fluid replacement. A variety of ECG abnormalities were seen in this patient with a history of bundle branch block, including sinus bradycardia and varying degrees of AV block. These dictated the prophylactic placement of a temporary ventricular pacemaker, but otherwise resolved spontaneously. Significant hyperglycemia was seen initially in this patient, but plasma glucose levels rapidly normalized without further treatment.

A young hypertensive patient with advanced renal failure ingested 280 mg of nifedipine capsules at one time, with resulting marked hypotension responding to calcium infusion and fluids. No AV conduction abnormalities, arrhythmias, or pronounced changes in heart rate were noted, nor was there any further deterioration in renal function.

Dosage And Administration

Dosage should be adjusted according to each patient's needs. It is recommended that nifedipine extended-release tablets be administered orally once daily on an empty stomach. Nifedipine extended-release tablets are an extended release dosage form and tablets should be swallowed whole, not bitten or divided. In general, titration should proceed over a 7-14 day period starting with 30 mg once daily. Upward titration should be based on therapeutic efficacy and safety. The usual maintenance dose is 30 mg to 60 mg once daily. Titration to doses above 90 mg daily is not recommended.

If discontinuation of nifedipine extended-release tablets is necessary, sound clinical practice suggests that the dosage should be decreased gradually with close physician supervision.

Co-administration of nifedipine with grapefruit juice is to be avoided (See CLINICAL PHARMACOLOGY and PRECAUTIONS).

Care should be taken when dispensing nifedipine extended-release tablets to assure that the extended release dosage form has been prescribed.

How Supplied

Nifedipine extended-release tablets are supplied as 30 mg and 60 mg round, biconvex, film-coated tablets which are 11 mm in diameter and 6 mm in height.

They are supplied by State of Florida DOH Central Pharmacy as follows:

The tablets should be protected from light and moisture and stored at 20° - 25°C (68° - 77°F) [See USP Controlled Room Temperature]. Dispense in tight, light--resistant containers.

Manufactured by:
Eurand, Inc.
Vandalia, OH 45377

Distributed by:
Actavis South Atlantic LLC
Sunrise, FL 33325

This Product was Repackaged By:

State of Florida DOH Central Pharmacy
104-2 Hamilton Park Drive
Tallahassee, FL 32304
United States

RX Only