Products
Nifedipine is commercially available in the form of sustained-release tablets (generics). It was first approved in the mid-1970s. Sales of the original Adalat were discontinued in many countries in 2019.
Structure and properties
Nifedipine (C17H18N2O6, Mr = 346.3 g/mol) is a dihydropyridine. It exists as a yellow crystalline powder that is practically insoluble in water. Nifedipine is highly photosensitive.
Effects
Nifedipine (ATC C08CA05) has antihypertensive and vasodilator properties and relaxes smooth muscle. Its effects are due to blockade of calcium influx into vascular smooth muscle cells by inhibition of L-type voltage-gated calcium channels. Calcium is the trigger for smooth muscle cell contraction.
Indications
- Chronic stable angina pectoris
- Vasospastic angina pectoris
- High blood pressure (essential hypertension)
- Acute hypertensive crisis (parenteral).
Off-label, nifedipine is also commonly used as a labor inhibitor. In the form of nifedipine cream, it is used to treat anal fissures. Another potential use is for chilblains.
Dosage
According to the SmPC. The sustained-release tablets are usually taken once or twice daily. They should not be administered with grapefruit juice.
Contraindications
- Hypersensitivity
- First 20 weeks of pregnancy
- Breastfeeding
- Cardiovascular shock
- Unstable angina pectoris
- Acute myocardial infarction
- Kock pouch
- Nifedipine must not be combined with rifampicin.
Full details of precautions and interactions can be found in the drug label.
Interactions
Nifedipine is metabolized in the intestine and liver by CYP3A4 and undergoes high first-pass metabolism. Therefore, drug-drug interactions occur with CYP inhibitors (eg, grapefruit juice) and CYP inducers (eg, rifampicin). Other interactions are possible (see SmPC).
Adverse effects
The most common possible adverse effects include weakness, malaise, headache, constipation, vasodilatation, and edema.
