Nifedipine

Nifedipine
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alonso Alvarado, M.D. [2]

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Overview

Nifedipine is a calcium channel blocker, dihydropirydine calcium channel blocker that is FDA approved for the treatment of hypertension. Common adverse reactions include hypotension, palpitations, peripheral edema, flushing, nausea, dizziness, headache, feeling nervous, cough, dyspnea.

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

Condition 1

• Dosing Information

• 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. Afeditab® CR is an extended release dosage form and tablets should be swallowed whole, not bitten or divided. In general, titration should proceed over a 7 to 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 Afeditab® CR 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.

Care should be taken when dispensing Afeditab® CR to assure that the extended-release dosage form has been prescribed.

Condition 2

• Dosing Information

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Off-Label Use and Dosage (Adult)

Guideline-Supported Use

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• Strength of Evidence: (Category A/B/C) (Link)

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Condition 2

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Non–Guideline-Supported Use

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Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

Condition 1

• Dosing Information

• (Dosage)

Condition 2

• Dosing Information

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Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

Condition 1

• Developed by: (Organisation)

• Class of Recommendation: (Class) (Link)

• Strength of Evidence: (Category A/B/C) (Link)

• Dosing Information/Recommendation

• (Dosage)

Condition 2

• Developed by: (Organisation)

• Class of Recommendation: (Class) (Link)

• Strength of Evidence: (Category A/B/C) (Link)

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Non–Guideline-Supported Use

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Condition 3

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Contraindications

• Hypersensitivity to nifedipine

Warnings

Excessive Hypotension

Although, in most 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. Although patients have rarely experienced excessive hypotension on nifedipine alone, this may be more common in patients on concomitant beta blocker therapy. Although not approved for this purpose, nifedipine capsules have been used (orally and sublingually) for acute reduction of blood pressure. Several well-documented reports describe cases of profound hypotension, myocardial infarction, and death when immediate-release nifedipine was used in this way. Nifedipine capsules should not be used for the acute reduction of blood pressure.

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.

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.

Several well-controlled, randomized trials studied the use of immediate-release nifedipine in patients who had just sustained myocardial infarctions. In none of these trials did immediate-release nifedipine appear to provide any benefit. In some of the trials, patients who received immediate-release nifedipine had significantly worse outcomes than patients who received placebo. Nifedipine capsules should not be administered within the first week or two after myocardial infarction, and they should also be avoided in the setting of acute coronary syndrome (when infarction may be imminent).

Use in Essential Hypertension

Nifedipine and other immediate-release nifedipine capsules have also been used for the long-term control of essential hypertension, although nifedipine capsules have not been approved for this purpose and no properly controlled studies have been conducted to define an appropriate dose or dose interval for such treatment. Nifedipine capsules should not be used for the control of essential hypertension.

Beta Blocker Withdrawal

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 might be expected to exacerbate it by provoking reflex catecholamine release. There have been occasional reports of increased angina in a setting of beta blocker withdrawal and nifedipine initiation. It is important to taper beta blockers if possible, rather than stopping them abruptly before beginning nifedipine.

Congestive Heart Failure

Rarely, patients, usually those 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 to these patients, owing to their fixed impedance to flow across the aortic valve.

Precausions

Hypotension

Because nifedipine decreases peripheral vascular resistance, careful monitoring of blood pressure during the initial administration and titration of nifedipine is suggested. Close observation is especially recommended for patients already taking medications that are known to lower blood pressure.

Peripheral Edema

Mild to moderate peripheral edema occurs in a dose dependent manner with an incidence ranging from approximately 10% to about 30% at the highest dose studied (180 mg). It is a localized phenomenon thought to be associated with vasodilation of dependent arterioles and small blood vessels and not due to left ventricular dysfunction or generalized fluid retention. With patients whose angina or hypertension is complicated by congestive heart failure, care should be taken to differentiate this peripheral edema from the effects of increasing left ventricular dysfunction.

Other

As with any other non-deformable material, caution should be used when administering nifedipine extended-release in patients with preexisting severe gastrointestinal narrowing (pathologic or iatrogenic). There have been rare reports of obstructive symptoms in patients with known strictures in association with the ingestion of nifedipine extended-release.

Laboratory Tests

Rare, usually transient, but occasionally significant elevations of enzymes such as alkaline phosphatase, CPK, LDH, SGOT and SGPT have been noted. The relationship to nifedipine therapy is uncertain in most cases, but probable in some. These laboratory abnormalities have rarely been associated with clinical symptoms; however, cholestasis with or without jaundicehas been reported. A small (5.4%) increase in mean alkaline phosphatase was noted in patients treated with nifedipine extended-release. This was an isolated finding not associated with clinical symptoms and it rarely resulted in values which fell outside the normal range. Rare instances of allergic hepatitis have been reported. In controlled studies, nifedipine extended-release did not adversely affect serum uric acid, glucose, or cholesterol. Serum potassium was unchanged in patients receiving nifedipine extended-release in the absence of concomitant diuretic therapy, and slightly decreased in patients receiving concomitant diuretics.

Nifedipine, like other calcium channel blockers, decreases platelet aggregation in vitro. Limited clinical studies have demonstrated a moderate but statistically significant decrease in platelet aggregation and an increase in bleeding time in some nifedipine patients. This is thought to be a function of inhibition of calcium transport across the platelet membrane. No clinical significance for these findings has been demonstrated.

Positive direct Coombs test with/without hemolytic anemia has been reported but a causal relationship between nifedipine administration and positivity of this laboratory test, including hemolysis, could not be determined.

Although nifedipine has been used safely in patients with renal dysfunction and has been reported to exert a beneficial effect, in certain cases, rare, reversible elevations in BUN and serum creatinine have been reported in patients with pre-existing chronic renal insufficiency. The relationship to nifedipine therapy is uncertain in most cases but probable in some.

Adverse Reactions

Clinical Trials Experience

Over 1000 patients from both controlled and open trials with nifedipine extended-release tablets in hypertension and angina were included in the evaluation of adverse experiences. All side effects reported during nifedipine extended-release tablet therapy were tabulated independent of their causal relation to medication. The most common side effect reported with nifedipine extended-release was edema which was dose related and ranged in frequency from approximately 10% to about 30% at the highest dose studied (180 mg). Other common adverse experiences reported in placebo-controlled trials include:

This image is provided by the National Library of Medicine.

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.

Postmarketing Experience

There is limited information regarding Nifedipine Postmarketing Experience in the drug label.

Drug Interactions

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Use in Specific Populations

Pregnancy

Pregnancy Category (FDA): C In rodents, rabbits and monkeys, nifedipine has been shown to have a variety of embryotoxic, placentotoxic and fetotoxic effects, including stunted fetuses (rats, mice and rabbits), digital anomalies (rats and rabbits), rib deformities (mice), cleft palate (mice), small placentas and underdeveloped chorionic villi (monkeys), embryonic and fetal deaths (rats, mice and rabbits), prolonged pregnancy (rats; not evaluated in other species), and decreased neonatal survival (rats; not evaluated in other species). On a mg/kg or mg/m2 basis, some of the doses associated with these various effects are higher than the maximum recommended human dose and some are lower, but all are within an order of magnitude of it.

The digital anomalies seen in nifedipine-exposed rabbit pups are strikingly similar to those seen in pups exposed to phenytoin, and these are in turn similar to the phalangeal deformities that are the most common malformation seen in human children with in utero exposure to phenytoin.

There are no adequate and well-controlled studies in pregnant women. Nifedipine should generally be avoided during pregnancy and used only if the potential benefit justifies the potential risk to the fetus.
Pregnancy Category (AUS): There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Nifedipine in women who are pregnant.

Labor and Delivery

There is no FDA guidance on use of Nifedipine during labor and delivery.

Nursing Mothers

Nifedipine is excreted in human milk. Therefore, a decision should be made to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

There is no FDA guidance on the use of Nifedipine in pediatric settings.

Geriatic Use

Although small pharmacokinetic studies have identified an increased half-life and increased Cmax and AUC, clinical studies of nifedipine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Gender

There is no FDA guidance on the use of Nifedipine with respect to specific gender populations.

Race

There is no FDA guidance on the use of Nifedipine with respect to specific racial populations.

Renal Impairment

No studies have been performed with nifedipine extended release tablets in patients with renal failure; however, significant alterations in the pharmacokinetics of nifedipine immediate release capsules have not been reported in patients undergoing hemodialysis or chronic ambulatory peritoneal dialysis. Since the absorption of nifedipine could be modified by renal disease, caution should be exercised in treating such patients.

Hepatic Impairment

Because hepatic biotransformation is the predominant route for the disposition of nifedipine, its pharmacokinetics may be altered in patients with chronic liver disease. Nifedipine extended-release tablets have not been studied in patients with hepatic disease; however, in patients with hepatic impairment (liver cirrhosis) nifedipine has a longer elimination half-life and higher bioavailability than in healthy volunteers.

Females of Reproductive Potential and Males

There is no FDA guidance on the use of Nifedipine in women of reproductive potentials and males.

Immunocompromised Patients

There is no FDA guidance one the use of Nifedipine in patients who are immunocompromised.

Administration and Monitoring

Administration

Oral

Monitoring

Hypotension

Because nifedipine decreases peripheral vascular resistance, careful monitoring of blood pressure during the initial administration and titration of nifedipine is suggested. Close observation is especially recommended for patients already taking medications that are known to lower blood pressure.

IV Compatibility

There is limited information regarding the compatibility of Nifedipine and IV administrations.

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.

Pharmacology

Nifedipine
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Mechanism of Action

The mechanism by which nifedipine reduces arterial blood pressure involves peripheral arterial vasodilatation and, consequently, a reduction in peripheral vascular resistance. The increased peripheral vascular resistance that is an underlying cause of hypertension results from an increase in active tension in the vascular smooth muscle. Studies have demonstrated that the increase in active tension reflects an increase in cytosolic free calcium.

Nifedipine is a peripheral arterial vasodilator which acts directly on vascular smooth muscle. The binding of nifedipine to voltage-dependent and possibly receptor-operated channels in vascular smooth muscle results in an inhibition of calcium influx through these channels. Stores of intracellular calcium in vascular smooth muscle are limited and thus dependent upon the influx of extracellular calcium for contraction to occur. The reduction in calcium influx by nifedipine causes arterial vasodilation and decreased peripheral vascular resistance which results in reduced arterial blood pressure.

Structure

Nifedipine is 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:

This image is provided by the National Library of Medicine.

Nifedipine is a yellow crystalline substance, practically insoluble in water but soluble in ethanol. It has a molecular weight of 346.3.

Nifedipine tablets contain either 30 mg or 60 mg of nifedipine for once-a-day oral administration.

Each tablet also contains the following inactive ingredients: colloidal silicon dioxide, hypromellose, lactose monohydrate (60 mg), magnesium stearate, and microcrystalline cellulose (30 mg). The inert ingredients in the film coating are: hypromellose, iron oxide, polyethylene glycol, and titanium dioxide. The ingredients of the printing ink are: ammonium hydroxide, iron oxide black, isopropyl alcohol, n-butyl alcohol, propylene glycol and shellac.

Pharmacodynamics

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.

Pharmacokinetics

Nifedipine is completely absorbed after oral administration. The bioavailability of nifedipine as extended release relative to immediate release nifedipine is in the range of 84%-89%. After ingestion of nifedipine tablets under fasting conditions, plasma concentrations peak at about 2.5-5 hours with a second small peak or shoulder evident at approximately 6-12 hours post dose. The elimination half-life of nifedipine administered as nifedipine is approximately 7 hours in contrast to the known 2 hour elimination half-life of nifedipine administered as an immediate release capsule.

When nifedipine is administered as multiples of 30 mg tablets over a dose range of 30 mg to 90 mg, the area under the curve (AUC) is dose proportional: however, the peak plasma concentration for the 90 mg dose given as 3 x 30 mg is 29% greater than predicted from the 30 mg and 60 mg doses.

Two 30 mg nifedipine tablets may be interchanged with a 60 mg nifedipine CR tablet. Three 30 mg nifedipine tablets, however, result in substantially higher Cmax values than those after a single 90 mg nifedipine tablet. Three 30 mg tablets should, therefore, not be considered interchangeable with a 90 mg tablet.

Once daily dosing of nifedipine extended-release tablets under fasting conditions results in decreased fluctuations in the plasma concentration of nifedipine when compared to t.i.d. dosing with immediate-release nifedipine capsules. The mean peak plasma concentration of nifedipine following a 90 mg nifedipine extended-release tablets, administered under fasting conditions, is approximately 115 ng/mL. When nifedipine extended-release tablets is given immediately after a high fat meal in healthy volunteers, there is an average increase of 60% in the peak plasma nifedipine concentration, a prolongation in the time to peak concentration, but no significant change in the AUC. Plasma concentrations of nifedipine when nifedipine extended-release tablets is taken after a fatty meal result in slightly lower peaks compared to the same daily dose of the immediate release formulation administered in three divided doses. This may be, in part, because nifedipine extended-release tablets are less bioavailable than the immediate release formulation.

Nifedipine is extensively metabolized to highly water soluble, inactive metabolites accounting for 60% to 80% of the dose excreted in the urine. Only traces (less than 0.1% of the dose) of the unchanged form can be detected in the urine. The remainder is excreted in the feces in metabolized form, most likely as a result of biliary excretion.

No studies have been performed with nifedipine extended release tablets in patients with renal failure; however, significant alterations in the pharmacokinetics of nifedipine immediate release capsules have not been reported in patients undergoing hemodialysis or chronic ambulatory peritoneal dialysis. Since the absorption of nifedipine from nifedipine could be modified by renal disease, caution should be exercised in treating such patients.

Because hepatic biotransformation is the predominant route for the disposition of nifedipine, its pharmacokinetics may be altered in patients with chronic liver disease. Nifedipine extended-release tablets have not been studied in patients with hepatic disease; however, in patients with hepatic impairment (liver cirrhosis) nifedipine has a longer elimination half-life and higher bioavailability than in healthy volunteers. The degree of protein binding of nifedipine is high (92%- 98%). Protein binding may be greatly reduced in patients with renal or hepatic impairment.

After administration of nifedipine extended-release tablets to healthy elderly men and women (age > 60 years), the mean Cmax is 36% higher and the average plasma concentration is 70% greater than in younger patients.

In healthy subjects, the elimination half-life of a different sustained release nifedipine formulation was longer in elderly subjects (6.7 h) compared to young subjects (3.8 h) following oral administration. A decreased clearance was also observed in the elderly (348 mL/min) compared to young subjects (519 mL/min) following intravenous administration. Co-administration of nifedipine with grapefruit juice results in up to a 2-fold increase in AUC and Cmax, due to inhibition of CYP3A4 related first-pass metabolism.

Nonclinical Toxicology

Nifedipine was administered orally to rats for two years and was not shown to be carcinogenic. When given to rats prior to mating, nifedipine caused reduced fertility at a dose approximately 30 times the maximum recommended human dose. There is a literature report of reversible reduction in the ability of human sperm obtained from a limited number of infertile men taking recommended doses of nifedipine to bind to and fertilize an ovum in vitro. In vivo mutagenicity studies were negative.

Clinical Studies

Condition 1

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Storage

There is limited information regarding Nifedipine Storage in the drug label.

Images

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Patient Counseling Information

(Patient Counseling Information)

Precautions with Alcohol

Alcohol-Nifedipine interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

There is limited information regarding Nifedipine Brand Names in the drug label.

Look-Alike Drug Names

• (Paired Confused Name 1a) — (Paired Confused Name 1b)
• (Paired Confused Name 2a) — (Paired Confused Name 2b)
• (Paired Confused Name 3a) — (Paired Confused Name 3b)

Drug Shortage Status

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References

The contents of this FDA label are provided by the National Library of Medicine.