Nifedipine, tablets 10 mg 50 pcs

Nifedipine is a selective “slow calcium channel blocker” derivative of 1,4-dihydropyridine. It has antianginal and antihypertensive effects. It reduces the flow of extracellular calcium ions inside cardiomyocytes and smooth muscle cells of coronary and peripheral arteries.

Limits spasm and dilates coronary and peripheral (mainly arterial) vessels, reduces blood pressure, total peripheral vascular resistance, reduces postload and myocardial oxygen demand.

Enhances coronary blood flow. Negative chrono-, dromo- and inotropic effects are overridden by reflex activation of the sympathoadrenal system in response to peripheral vasodilatation. It enhances renal blood flow, causes moderate natriuresis. Time of onset of clinical effect is 20 min, duration of clinical effect is 4-6 h.

Pharmacokinetics

Nifedipine is rapidly and almost completely (more than 90%) absorbed from the gastrointestinal tract. After oral administration its bioavailability is 40-60%. Food intake increases the bioavailability. It has a “first pass” effect through the liver.

The maximum concentration in plasma is observed after 1-3 hours and is 65 ng/ml. It penetrates through the blood-brain barrier and the placental barrier, is excreted with breast milk. Binding with blood plasma proteins is 90%. It is completely metabolized in liver. It is excreted by kidneys as inactive metabolites (70-80% of the dose taken).

The elimination half-life is 2-4 hours. There is no cumulative effect. Chronic renal failure, hemodialysis and peritoneal dialysis do not affect pharmacokinetics. Tolerance to the action of the drug develops with prolonged use (for 2-3 months).

Indications

Active ingredient

How to take, the dosage

Individual. For oral administration the initial dose is 10 mg 3-4 times a day. If necessary, the dose is gradually increased to 20 mg 3-4 times per day. In special cases (variant angina pectoris, severe arterial hypertension) the dose may be briefly increased to 30 mg 3-4 times per day. To relieve a hypertensive crisis, as well as an attack of angina pectoris, sublingually 10-20 mg (rarely 30 mg) may be used.

In/v to stop an attack of angina or hypertensive crisis, 5 mg for 4-8 hours.

Intracoronary for relief of acute coronary artery spasms is administered in a bolus of 100-200 mcg. In stenosis of large coronary vessels, the initial dose is 50-100 mcg.

The maximum daily doses are 120 mg when administered orally and 30 mg when administered intravenously.

Interaction

In concomitant use with antihypertensive drugs, diuretics, phenothiazine derivatives the antihypertensive effect of nifedipine is increased.

Concomitant use with anticholinergic agents may cause memory and attention disorders in elderly patients.

Concomitant use with beta-adrenoblockers may lead to severe arterial hypotension; in some cases, development of heart failure.

Concomitant use with nitrates increases the antianginal effect of nifedipine.

Concomitant use with calcium preparations decreases efficacy of nifedipine due to antagonistic interaction caused by increased concentration of calcium ions in extracellular fluid.

Cases of muscular weakness have been reported with concomitant use of magnesium salts.

Concomitant use with digoxin may slow down excretion of digoxin from the body and, consequently, increase its plasma concentrations.

Concomitant use with diltiazem increases the antihypertensive effect.

Concomitant use with theophylline may cause changes in plasma concentrations of theophylline.

Rifampicin induces liver enzyme activity, accelerating the metabolism of nifedipine, which leads to a decrease in its effectiveness.

Concomitant use with phenobarbital, phenytoin, carbamazepine decreases the plasma concentration of nifedipine.

There have been reports of increased plasma concentrations of nifedipine and an increase in its AUC when used concomitantly with fluconazole, itraconazole.

Concomitant use with fluoxetine may increase nifedipine side effects.

In some cases concomitant use with quinidine may decrease plasma quinidine concentration, and when nifedipine is withdrawn there may be a significant increase in quinidine concentration accompanied by prolongation of QT interval on ECG.

Cimetidine and, to a lesser extent, ranitidine increase the plasma concentration of nifedipine and, thus, enhance its antihypertensive effect.

Ethanol may increase the effects of nifedipine (excessive arterial hypotension), which causes dizziness and other adverse reactions.

Special Instructions

Nifedipine should be used only in the clinical setting under strict medical supervision in acute myocardial infarction, severe cerebral circulation disorders, diabetes mellitus, hepatic and renal dysfunction, malignant arterial hypertension and hypovolemia as well as in patients on hemodialysis. High doses of nifedipine should be avoided in patients with hepatic and/or renal dysfunction. In elderly patients it is more likely to decrease cerebral blood flow due to acute peripheral vasodilation.

In oral administration, nifedipine may be chewed to speed up the effect.

Nifedipine should be stopped if pain in the chest occurs during treatment. Nifedipine should be withdrawn gradually, as abrupt withdrawal (especially after long-term treatment) may cause withdrawal syndrome.

In intracoronary administration with two vessels stenosis, nifedipine should not be injected into a third open vessel because of the risk of significant negative inotropic effects.

At the time of treatment, alcohol should be avoided because of the risk of excessive lowering of BP.

Impact on driving and operating machinery

In the beginning of treatment, driving and other potentially dangerous activities requiring rapid psychomotor reactions should be avoided. During further treatment, the degree of restriction is determined depending on the individual tolerability of nifedipine.

Synopsis

Contraindications

To use with caution in patients:
with chronic heart failure, marked liver and/or renal dysfunction; severe cerebral circulation disorders, diabetes mellitus, malignant arterial hypertension, patients on hemodialysis (because of the risk of arterial hypotension).

Side effects

Cardiovascular system: skin hyperemia, feeling of heat, tachycardia, arterial hypotension, peripheral edema; rarely – bradycardia, ventricular tachycardia, asystole, increased angina attacks.

Digestive system disorders: nausea, heartburn, diarrhea; rarely – deterioration of liver function; in single cases – gum hyperplasia. Prolonged use in high doses may cause dyspeptic symptoms, increased liver transaminase activity, and intrahepatic cholestasis.

CNS and peripheral nervous system disorders: headache. Paresthesias, muscle pain, tremor, slight visual disturbances, sleep disorders are possible with prolonged use in high doses.

With the hematopoietic system: in single cases – leukopenia, thrombocytopenia.

Urinary system disorders: increase in daily diuresis. In prolonged use in high doses renal function disorders are possible.

Endocrine system disorders: in single cases – gynecomastia.

Allergic reactions: skin rash.

Local reactions: when injected intravenously, burning at the injection site is possible.

In 1 min after intracoronary injection, nifedipine negative inotropic effect, increased HR, arterial hypotension may occur; these symptoms gradually disappear after 5-15 min.

Overdose

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