Nifedipine precautions

List of precautions
General Lab tests Carcinogenesis Mutagenesis Impairment of fertility Pregnancy Pediatric use
 * Hypotension
 * Peripheral edema
 * Other
 * Enzyme elevation
 * Allergic hepatitis
 * Serum uric acid/glucose/cholesterol
 * Serum potassium
 * Platelet aggregation
 * Coombs test
 * BUN and serum creatinine

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. Return to top

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. Return to top

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. Return to top

Enzyme elevation
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. This was an isolated finding not associated with clinical symptoms and it rarely resulted in values which fell outside the normal range. Return to top

Allergic hepatitis
Rare instances of allergic hepatitis have been reported. Return to top

Serum uric acid/glucose/cholesterol
In controlled studies, Nifedipine extended-release did not adversely affect serum uric acid, glucose, or cholesterol. Return to top

Serum potassium
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. Return to top

Platelet aggregation
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. Return to top

Coombs test
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. Return to top

BUN and serum creatinine
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. Return to top

Carcinogenesis
Nifedipine was administered orally to rats for two years and was not shown to be carcinogenic. Return to top

Mutagenesis
In vivo mutagenicity studies were negative. Return to top

Impairment of fertility
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. Return to top

Pregnancy
Pregnancy Category C Nifedipine has been shown to produce teratogenic findings in rats and rabbits, including digital anomalies similar to those reported for phenytoin. Digital anomalies have been reported to occur with other members of the dihydropyridine class and are possibly a result of compromised uterine blood flow. Nifedipine administration was associated with a variety of embryotoxic, placentotoxic, and fetotoxic effects, including stunted fetuses (rats, mice, rabbits), rib deformities (mice), cleft palate (mice), small placentas and underdeveloped chorionic villi (monkeys), embryonic and fetal deaths (rats, mice, rabbits), and prolonged pregnancy/decreased neonatal survival (rats; not evaluated in other species). On a mg/kg basis, all of the doses associated with the teratogenic embryotoxic or fetotoxic effects in animals were higher (3.5 to 42 times) than the maximum recommended human dose of 120 mg/day. On a mg/m2 basis, some doses were higher and some were lower than the maximum recommended human dose but all are within an order of magnitude of it. The doses associated with placentotoxic effects in monkeys were equivalent to or lower than the maximum recommended human dose on a mg/m2 basis. There are no adequate and well-controlled studies in pregnant women. Nifedipine extended-release tablets should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Return to top

Pediatric use
Safety and effectiveness in pediatric patients have not been established. Return to top