Nifedipine

Nifedipine (brand name Adalat and Procardia) is a dihydropyridine calcium channel blocker. Its main uses are in angina pectoris (especially Prinzmetal's angina) and hypertension, although a large number of other uses have recently been found for this agent, such as Raynaud's phenomenon, premature labour, and painful spasms of the oesophagus in cancer patients.

Nifedipine lowers the blood pressure rapidly, and patients are commonly warned they may feel dizzy or faint after taking the first few doses. Tachycardia (fast heart rate) may occur as a reaction. These problems are much less frequent in the sustained-release preparations of nifedipine (such as Adalat OROS).

Nifedipine should be taken on an empty stomach, and patients are warned not to consume anything containing grapefruit or grapefruit juice, as it lowers CYP3A4 activity (the enzyme that digests nifedipine) and may lead to increased levels of nifedipine or other medications that are metabolised by CYP3A4 in the blood.

Incorrect use of Nifedipine

While Nifedipine is safe for use in sustained-release form, some doctors continue to use it for hypertensive crises (emergency situations where bringing down the blood pressure is of critical importance to avoid organ damage). When used in this way, the doctor asks for the patient to bite open the capsule, and keep it under their tongue as the contents is absorbed sublingually. This sublingual use of Nifedipine has not been approved by the FDA, and there are documented cases indicating that the incorrect use of this drug has caused:

  • death
  • stroke
  • acute myocardial infarction (tissue death of the heart muscle mass)
  • cerebrovascular ischaemia (Lack of blood flow to the brain, causing lack of oxygen and vital nutrients)
  • severe hypotension (very low blood pressure)
  • conduction disturbances
  • foetal distress

    For a detailed review of management of hypertensive crises, with reference to Nifedipine, see "Clinical review: The management of hypertensive crises" by Joseph Varon (Associate Professor of Medicine, Pulmonary and Critical Care Section, Baylor College of Medicine, Clinical Associate Professor, The University of Texas Health Science Center, Houston, Texas, USA) and Paul E Marik (Professor of Critical Care and Medicine, Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA).

    • © Medic8 ® All Rights Reserved.