Nifedipine; Indications/Uses, Dosage, Side effects, Interaction ,Pregnancy

Nifedipine








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Nifedipine is a dihydropyridine calcium channel blocking agent. Nifedipine inhibits the transmembrane influx of extracellular calcium ions into myocardial and vascular smooth muscle cells, causing dilatation of the main coronary and systemic arteries and decreasing myocardial contractility. This agent also inhibits the drug efflux pump P-glycoprotein which is overexpressed in some multi-drug resistant tumors and may improve the efficacy of some antineoplastic agents.

It works by relaxing the muscles of your heart and blood vessels. It is a medication used to manage angina, high blood pressure, Raynaud’s phenomenon, and premature labor. It is one of the treatments of choice for Prinzmetal angina. It may be used to treat severe high blood pressure in pregnancy. Its use in preterm labor may allow more time for steroids to improve the baby’s lungs and time to transfer the mother to a well qualified medical facility before delivery. Nifedipine has been formulated as both a long- and short-acting 1,4-dihydropyridine calcium channel blocker. It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, nifedipine prevents calcium-dependent myocyte contraction and vasoconstriction.

Mechanism of Action of Nifedipine

Nifedipine decreases arterial smooth muscle contractility and subsequent vasoconstriction by inhibiting the influx of calcium ions through L-type calcium channels. Calcium ions entering the cell through these channels bind to calmodulin. Calcium-bound calmodulin then binds to and activates myosin light chain kinase (MLCK). Activated MLCK catalyzes the phosphorylation of the regulatory light chain subunit of myosin, a key step in muscle contraction. Signal amplification is achieved by calcium-induced calcium release from the sarcoplasmic reticulum through ryanodine receptors. Inhibition of the initial influx of calcium inhibits the contractile processes of smooth muscle cells, causing dilation of the coronary and systemic arteries, increased oxygen delivery to the myocardial tissue, decreased total peripheral resistance, decreased systemic blood pressure, and decreased afterload. The vasodilatory effects of nifedipine result in an overall decrease in blood pressure.

or

The principal physiologic action of nifedipine is to inhibit the transmembrane influx of extracellular calcium ions across the membranes of myocardial cells and vascular smooth muscle cells, without changing serum calcium concentrations. Calcium plays important roles in the excitation-contraction coupling processes of the heart and vascular smooth muscle cells and in the electrical discharge of the specialized conduction cells of the heart. The membranes of these cells contain numerous channels that carry a slow inward current and that are selective for calcium. Activation of these slow calcium channels contributes to the plateau phase (phase 2) of the action potential of cardiac and vascular smooth muscle cells. The exact mechanism whereby nifedipine inhibits calcium ion influx across the slow calcium channels is not known, but the drug is thought to inhibit ion-control gating mechanisms of the channel, deform the slow channel, and/or interfere with release of calcium from the sarcoplasmic reticulum. By inhibiting calcium influx, nifedipine inhibits the contractile processes of cardiac and vascular smooth muscle, thereby dilating the main coronary and systemic arteries.

Indications of Nifedipine

Contra-Indications of Nifedipine

  • Porphyria
  • Acute syndrome of the heart
  • Severe narrowing of the aortic heart valve
  • Severe heart failure
  • Abnormally low blood pressure
  • Kidney disease with reduction in kidney function
  • Fluid Retention in the Legs ,arms or hands
  • Blood Circulation Failure due to Serious Heart Condition
  • Chronic idiopathic constipation
  • Stomach or intestine blockage
  • Narrowing of the intestines
  • Decreased motility function of stomach or intestines
  • Heart attack
  • Allergies to Calcium Channel Blockers
  • Calcium Channel Blocking Agents-Dihydropyridines

Dosage of Nifedipine

Strengths: 10 mg; 20 mg; 30 mg; 60 mg; 90 mg

Hypertension

Extended-release tablets

  • Initial dose: 30 to 60 mg orally once a day
  • Maintenance dose: 30 to 90 mg orally once a day
  • Maximum dose: Up to 120 mg/day

Angina Pectoris Prophylaxis

Immediate-release capsules

  • difficulty with moving
  • Initial dose: 10 mg orally 3 times a day
  • Maintenance dose: 10 to 30 mg orally 3 to 4 times a day
  • Maximum dose: 180 mg/day

Extended-release tablets

  • Initial dose: 30 to 60 mg orally once a day
  • Maintenance dose: 30 to 90 mg orally once a day
  • Maximum dose: Up to 120 mg/day

Angina Pectoris

Immediate-release capsules

  • Initial dose: 10 mg orally 3 times a day
  • Maintenance dose: 10 to 30 mg orally 3 to 4 times a day
  • Maximum dose: 180 mg/day

Extended-release tablets

  • Initial dose: 30 to 60 mg orally once a day
  • Maintenance dose: 30 to 90 mg orally once a day
  • Maximum dose: Up to 120 mg/day

Side Effects of Nifedipine

The most common 

More common

Rare

Drug Interactions of Nifedipine

Nifedipine  may interact with following drug, supplements, & may change the efficacy of the drug

Pregnancy Category of Nifedipine

FDA Pregnancy Category C

Pregnancy

This medication should not be taken by women who are or may become pregnant, as nifedipine may cause harm to the developing baby if it is taken by the mother during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

This medication should not be taken by women who are breastfeeding. The safety and effectiveness of using this medication have not been established for children.

References

 

Nifedipine

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