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Nifedipine

February 10, 2011 by staff 

Nifedipine, Nifedipine (brand names Adalat, Nifediac, Nifedical, and Procardia) is a dihydropyridine calcium channel inhibitor. Its main uses are as an antianginal (especially in Prinzmetal’s angina) and antihypertensive, although many other indications have recently been found for this agent, such as Raynaud’s phenomenon, premature labor, and painful spasms of the esophagus in patients with cancer and teta**s. It is also commonly used for the small subset of patients with pulmonary hypertension whose symptoms respond to calcium channel blockers.
Nifedipine rapidly lowers blood pressure, and patients are often warned, they may feel dizzy or faint after taking the first doses. Tachycardia (rapid heartbeat) may occur a reaction. These problems are much less frequent in preparations with sustained release nifedipine (Adalat OROS like). A newer version is GITS (gastrointestinal therapeutic system), which – according to Bayer – provides 24 hours continuous release through a push system osmotic. Recent trials with GITS include INSIGHT (for blood pressure) and action (for angina pectoris).

Release formulations of nifedipine should be taken on an empty stomach, and patients are advised not to consume anything containing grapefruit juice or grapefruit, because they increase blood levels of nifedipine. There are several possible mechanisms, including lowering the activity of CYP3A4.

Approved uses of nifedipine are the long-term treatment of hypertension (high blood pressure) and angina pectoris. In hypertension, recent clinical guidelines are generally supportive of diuretics and ACE inhibitors, although calcium channel blockers and thiazide diuretics are still in favor as the primary treatment for over 55 years and black patients.

Sublingual nifedipine has been used in hypertensive emergencies. This proved to be dangerous, and was abandoned. Sublingual nifedipine causes anti-hypertension by peripheral vasodilation. It can cause a decrease in blood pressure control, reflex tachycardia, and a flight phenomenon in certain vascular beds. There have been several reports in the medical literature of serious adverse effects with sublingual nifedipine, including cerebral and myocardial ischemia, myocardial infarction, complete heart block, and death. Following this, the FDA has reviewed all data on the safety and efficacy of sublingual nifedipine for hypertensive emergencies in 1995, and concluded that the practice should be abandoned because it was neither safe nor effective.

Nifedipine has often been used as tocolytic (agent that delays preterm delivery). A Cochrane review concluded that it is comparable to magnesium sulfate and beta-agonists (eg ritodrine) with fewer side effects. Its role vis-à-vis atosiban is not established.

Raynaud’s phenomenon is often treated with nifedipine. In 2005, a meta-analysis showed modest gains (33% reduction in the severity of attack, from 2.8 to 5 reduction in the absolute number of attacks per week), it does conclude that most studies included used low doses of nifedipine.

Topical nifedipine has been shown to be as effective as the topical nitrates foranl fissures.

Nifedipine is also used in high altitude medicine for treating high altitude pulmonary edema.

Oral nifedipine was also found to cause a loss of iron in the urine of small animals. An NIH study is currently NIDDK see whether the drug can increase the elimination of iron in the urine in humans as well, becoming a potential treatment for iron overload.

A number of people have developed a toxicity due to acute overdosage with nifedipine, accidentally or intentionally, and oral or parenteral. Adverse effects include lethargy, bradycardia, marked hypotension and loss of consciousness. The drug can be quantified in blood or plasma to confirm a diagnosis of poisoning in hospital patients or to assist in a forensic investigation of death. Theanlytical methods generally involve concentrations of gas and liquid chromatography and sample are generally in the 100-1000? G / L.

[via online sources and wikipedia]

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