nifedipine
Adalat, Adalat CC, Adalat XL†, Adalat PA†, Adipine MR§, Apo-Nifed†, Cardilate MR§, Coracten§, Hypolar Retard 20§, Nifedotard 20 MR§, Nifelease§, Nifensar XL§, Novo-Nifedin†, Nu-Nifed†, Procardia, Procardia XL, Tensipine MR§, Unipine XL§
Pregnancy Risk Category C
How supplied
Tablets (extended-release): 30 mg, 60 mg, 90 mg
Capsules: 10 mg, 20 mg
Action
Unknown. Thought to inhibit calcium ion influx across cardiac and smooth-muscle cells, decreasing contractility and oxygen demand. Also may dilate coronary arteries and arterioles.
Indications & dosage
Vasospastic angina (Prinzmetal's or variant angina), classic chronic stable angina pectoris--
Adults: initially 10 mg P.O. t.i.d. Usual effective dosage range is 10 to 20 mg t.i.d. Some patients may require up to 30 mg q.i.d. Maximum daily dose is 180 mg.
Hypertension--
Adults: 30 or 60 mg P.O. (extended-release form) once daily. Adjusted over 7 to 14 days. Doses larger than 90 mg (for Adalat CC) and 120 mg (for Procardia XL) aren't recommended.
Adverse reactions
CNS: dizziness, light-headedness, headache, weakness, syncope, nervousness.
CV: peripheral edema, hypotension, palpitations, heart failure, MI, pulmonary edema, flushing.
EENT: nasal congestion.
GI: nausea, diarrhea, constipation, abdominal discomfort.
Hepatic: increased serum levels of alkaline phosphate, LD, AST, and ALT.
Metabolic: hypokalemia.
Musculoskeletal: muscle cramps.
Respiratory: dyspnea, cough.
Skin: rash, pruritus.
Interactions
Drug-drug. Cimetidine, ranitidine: decreased nifedipine metabolism. Dosage may be adjusted.
Digoxin: may cause elevated digoxin levels. Monitor closely.
Fentanyl: severe hypotension may occur. Monitor closely.
Propranolol, other beta blockers,: may cause hypotension and heart failure. Use together cautiously.
Phenytoin: may reduce phenytoin metabolism. Monitor closely.
Drug-food. Grapefruit juice: increased bioavailability of nifedipine. Avoid concomitant use. Monitor patient closely if given together.
Effects on diagnostic tests
None reported.
Contraindications
Contraindicated in patients with hypersensitivity to drug.
Nursing considerations
- Use cautiously in patients with heart failure or hypotension and in elderly patients. Use extended-release tablets cautiously in patients with severe GI narrowing.
- When a rapid response to drug is desired, have patient bite and swallow the capsule. If he can't chew capsules, the liquid can be withdrawn by puncturing the capsule with a needle and squeezing the contents into the mouth. When these methods are used, continuous blood pressure and ECG monitoring is recommended. These methods aren't recommended for the treatment of hypertension.
- Despite widespread S.L. use of nifedipine capsules, this route of administration should be avoided. Peak serum levels are lower and take longer to occur than when capsules are bitten and swallowed.
- Monitor blood pressure regularly, especially in patients who are taking beta blockers or antihypertensives.
- Although rebound effect hasn't been observed when drug is stopped, dosage should be reduced slowly under doctor's supervision.
- Alert:
Don't confuse nifedipine with nimodipine or nicardipine.
Patient teaching
- If patient is kept on nitrate therapy while nifedipine dosage is being adjusted, urge continued compliance. S.L. nitroglycerin especially may be taken as needed when angina symptoms are acute.
- Tell patient he may briefly develop angina exacerbation when beginning drug therapy or when dosage is increased.
- Instruct patient to swallow extended-release tablets without breaking, crushing, or chewing.
- Instruct patient to avoid taking drug with grapefruit juice.
- Reassure patient who is taking the extended-release form that a wax-matrix "ghost" from the tablet may be passed in the stools. Drug is completely absorbed before this occurs.
- Warn patient not to switch brands. Procardia XL and Adalat CC aren't therapeutically equivalent because of major differences in their pharmacokinetics.
- Tell patient to protect capsules from direct light and moisture and to store at room temperature.
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING