Nifedipine Information
Nifedipine () Description
Nifedipine () is a drug belonging to a class of pharmacological agents known as the calcium channel blockers. Nifedipine () is 3,5-pyridinedicarboxylic acid, 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-, dimethyl ester, CHNO, and has the structural formula:
Nifedipine () is a yellow crystalline substance, practically insoluble in water but soluble in ethanol. It has a molecular weight of 346.33. Nifedipine () Extended-release Tablet is formulated as a once-a-day extended-release tablet for oral administration designed to deliver 30, 60, or 90 mg of Nifedipine () .
Inert ingredients in the formulations are: black iron oxide; cellulose acetate; colloidal silicon dioxide; hypromellose; lactose monohydrate; magnesium stearate; microcrystalline cellulose; polyethylene glycol; polyethylene oxide; polysorbate; povidone; propylene glycol; red ferric oxide; sodium chloride; titanium dioxide; triacetin.
Nifedipine () Clinical Pharmacology
Nifedipine () is a calcium ion influx inhibitor (slow-channel blocker or calcium ion antagonist) and inhibits the transmembrane influx of calcium ions into cardiac muscle and smooth muscle. The contractile processes of cardiac muscle and vascular smooth 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 cardiac muscle and vascular smooth muscle without altering serum calcium concentrations.
Nifedipine () is completely absorbed after oral administration. Plasma drug concentrations rise at a gradual, controlled rate after a Nifedipine () Extended-release Tablet dose and reach a plateau at approximately six hours after the first dose. For subsequent doses, relatively constant plasma concentrations at this plateau are maintained with minimal fluctuations over the 24-hour dosing interval. About a fourfold higher fluctuation index (ratio of peak to trough plasma concentration) was observed with the conventional immediate-release Nifedipine () capsule at t.i.d. dosing than with once daily Nifedipine () Extended-release Tablet. At steady-state the bioavailability of the Nifedipine () Extended-release Tablet is 86% relative to immediate-release capsules. Administration of the Nifedipine () Extended-release Tablet in the presence of food slightly alters the early rate of drug absorption, but does not influence the extent of drug bioavailability. Markedly reduced GI retention time over prolonged periods (i.e., short bowel syndrome), however, may influence the pharmacokinetic profile of the drug which could potentially result in lower plasma concentrations. Pharmacokinetics of Nifedipine () Extended-release Tablets are linear over the dose range of 30 to 180 mg in that plasma drug concentrations are proportional to dose administered. There was no evidence of dose dumping either in the presence or absence of food for over 150 subjects in pharmacokinetic studies.
Nifedipine () is extensively metabolized to highly water-soluble, inactive metabolites accounting for 60 to 80% of the dose excreted in the urine. The elimination half-life of Nifedipine () is approximately two hours. Only traces (less than 0.1% of the dose) of 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. Thus, the pharmacokinetics of Nifedipine () are not significantly influenced by the degree of renal impairment. Patients in hemodialysis or chronic ambulatory peritoneal dialysis have not reported significantly altered pharmacokinetics of Nifedipine () . Since hepatic biotransformation is the predominant route for the disposition of Nifedipine () , the pharmacokinetics may be altered in patients with chronic liver disease. Patients with hepatic impairment (liver cirrhosis) have a longer disposition half-life and higher bioavailability of Nifedipine () than healthy volunteers. The degree of serum protein binding of Nifedipine () is high (92–98%). Protein binding may be greatly reduced in patients with renal or hepatic impairment.
Nifedipine () Indications And Usage
Nifedipine () Extended-release Tablet is indicated for the management of chronic stable angina (effort-associated angina) without evidence of vasospasm in patients who remain symptomatic despite adequate doses of beta blockers and/or organic nitrates or who cannot tolerate those agents.
In chronic stable angina (effort-associated angina) Nifedipine () has been effective in controlled trials of up to eight weeks duration in reducing angina frequency and increasing exercise tolerance, but confirmation of sustained effectiveness and evaluation of long-term safety in these patients is incomplete.
Controlled studies in small numbers of patients suggest concomitant use of Nifedipine () and beta-blocking agents may be beneficial in patients with chronic stable angina, but available information is not sufficient to predict with confidence the effects of concurrent treatment, especially in patients with compromised left ventricular function or cardiac conduction abnormalities. When introducing such concomitant therapy, care must be taken to monitor blood pressure closely since severe hypotension can occur from the combined effects of the drugs. (See .)
Nifedipine () Contraindications
Known hypersensitivity reaction to Nifedipine () .
Nifedipine () Warnings
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:
There have been rare reports of obstructive symptoms in patients with known strictures in association with the ingestion of Nifedipine () Extended-release Tablets. 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 a 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).
Nifedipine () Precautions
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 jaundice has been reported. A small (5.4%) increase in mean alkaline phosphatase was noted in patients treated with Nifedipine () Extended-release Tablets. 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 Tablets did not adversely affect serum uric acid, glucose, or cholesterol. Serum potassium was unchanged in patients receiving Nifedipine () Extended-release Tablets in the absence of concomitant diuretic therapy, and slightly decreased in patients receiving concomitant diuretics.
Nifedipine () , like other calcium channel blockers, decreases platelet aggregation 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.
Nifedipine () Adverse Reactions
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 Tablets 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:
Of these, only edema and headache were more common in Nifedipine () Extended-release Tablet patients than placebo patients.
The following adverse reactions occurred with an incidence of less than 3.0%. With the exception of leg cramps, the incidence of these side effects was similar to that of placebo alone.
Other adverse reactions were reported sporadically with an incidence of 1.0% or less. These include:
Adverse experiences which occurred in less than 1 in 1000 patients cannot be distinguished from concurrent disease states or medications.
The following adverse experiences, reported in less than 1% of patients, occurred under conditions (e.g., open trials, marketing experience) where a causal relationship is uncertain: gastrointestinal irritation, gastrointestinal bleeding, gynecomastia.
In multiple-dose U.S. and foreign controlled studies with Nifedipine () capsules in which adverse reactions were reported spontaneously, adverse effects were frequent but generally not serious and rarely required discontinuation of therapy or dosage adjustment. Most were expected consequences of the vasodilator effects of Nifedipine () .
There is also a large uncontrolled experience in over 2100 patients in the United States. Most of the patients had vasospastic or resistant angina pectoris, and about half had concomitant treatment with beta-adrenergic blocking agents. The relatively common adverse events were similar in nature to those seen with Nifedipine () Extended-release Tablets.
In addition, more serious adverse events were observed, not readily distinguishable from the natural history of the disease in these patients. It remains possible, however, that some or many of these events were drug related. Myocardial infarction occurred in about 4% of patients and congestive heart failure or pulmonary edema in about 2%. Ventricular arrhythmias or conduction disturbances each occurred in fewer than 0.5% of patients.
In a subgroup of over 1000 patients receiving Nifedipine () with concomitant beta blocker therapy, the pattern and incidence of adverse experiences was not different from that of the entire group of Nifedipine () immediate-release treated patients. (See .)
In a subgroup of approximately 250 patients with a diagnosis of congestive heart failure as well as angina, dizziness or lightheadedness, peripheral edema, headache or flushing each occurred in one in eight patients. Hypotension occurred in about one in 20 patients. Syncope occurred in approximately one patient in 250. Myocardial infarction or symptoms of congestive heart failure each occurred in about one patient in 15. Atrial or ventricular dysrhythmias each occurred in about one patient in 150.
In post-marketing experience, there have been rare reports of exfoliative dermatitis caused by Nifedipine () . There have been rare reports of exfoliative or bullous skin adverse events (such as erythema multiforme, Stevens-Johnson Syndrome, and toxic epidermal necrolysis) and photosensitivity reactions.
Nifedipine () Overdosage
Experience with Nifedipine () overdosage is limited. 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.
There has been one reported case of massive overdosage with Nifedipine () Extended-release Tablets. The main effects of ingestion of approximately 4800 mg of Nifedipine () Extended-release Tablets 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. Electrolyte 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 also 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 () immediate-release 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.
Nifedipine () Dosage And Administration
Dosage must be adjusted according to each patient's needs. Therapy for either hypertension or angina should be initiated with 30 or 60 mg once daily. Nifedipine () Extended-release Tablets should be swallowed whole and should not be bitten or divided. In general, titration should proceed over a 7–14 day period so that the physician can fully assess the response to each dose level and monitor blood pressure before proceeding to higher doses. Since steady-state plasma levels are achieved on the second day of dosing, if symptoms so warrant, titration may proceed more rapidly provided the patient is assessed frequently. Titration to doses above 120 mg are not recommended.
Angina patients controlled on Nifedipine () capsules alone or in combination with other antianginal medications may be safely switched to Nifedipine () Extended-release Tablets at the nearest equivalent total daily dose (e.g., 30 mg t.i.d. of Nifedipine () immediate-release capsules may be changed to 90 mg once daily of Nifedipine () Extended-release Tablets). Subsequent titration to higher or lower doses may be necessary and should be initiated as clinically warranted. Experience with doses greater than 90 mg in patients with angina is limited. Therefore, doses greater than 90 mg should be used with caution and only when clinically warranted.
No "rebound effect" has been observed upon discontinuation of Nifedipine () Extended-release Tablets. However, if discontinuation of Nifedipine () is necessary, sound clinical practice suggests that the dosage should be decreased gradually with close physician supervision.
Care should be taken when dispensing Nifedipine () Extended-release Tablets to assure that the extended release dosage form has been prescribed.
Nifedipine () How Supplied
Nifedipine () Extended-release Tablets 90 mg are round, biconvex, pink coated tablets imprinted with "KU 262 in black ink. They are supplied as follows:
Bottles of 30 Tablets NDC 21695-807-30
Bottles of 90 Tablets NDC 21695-807-90
Dispense in tight, child-resistant containers (USP).
Nifedipine ()
Nifedipine () Principal Display Panel - Mg Bottle Label
