VERELAN- verapamil hydrochloride capsule, delayed release pellets
Lannett Company, Inc.
Verelan® (verapamil hydrochloride capsules) is a calcium ion influx inhibitor (slow channel blocker or calcium ion antagonist). Verelan is available for oral administration as a 360 mg hard gelatin capsule (lavender cap/yellow body), a 240 mg hard gelatin capsule (dark blue cap/yellow body), a 180 mg hard gelatin capsule (light grey cap/yellow body), and a 120 mg hard gelatin capsule (yellow cap/yellow body). These pellet filled capsules provide a sustained-release of the drug in the gastrointestinal tract.
The structural formula of verapamil HCl is given below:
C27 H38 N2 O4 ∙HCl M.W. 491.07
Chemical name: Benzeneacetonitrile, α-[3-[[2-(3,4-dimethoxyphenyl)-ethyl]methylamino]propyl]-3,4-dimethoxy-α-(1-methylethyl), monohydrochloride.
Verapamil HCl is an almost white, crystalline powder, practically free of odor, with a bitter taste. It is soluble in water, chloroform and methanol. Verapamil HCl is not structurally related to other cardioactive drugs.
In addition to verapamil HCl the Verelan capsule contains the following inactive ingredients: fumaric acid, talc, sugar spheres, povidone, shellac, gelatin, FD&C red #40, yellow iron oxide, titanium dioxide, methylparaben, propylparaben, silicon dioxide, and sodium lauryl sulfate. In addition, the Verelan 240 mg and 360 mg capsules contain FD&C blue #1 and D&C red #28; and the Verelan 180 mg capsule contains black iron oxide.
Verelan is a calcium ion influx inhibitor (slow channel blocker or calcium ion antagonist) which exerts its pharmacologic effects by modulating the influx of ionic calcium across the cell membrane of the arterial smooth muscle as well as in conductile and contractile myocardial cells.
Normal sinus rhythm is usually not affected by verapamil HCl. However in patients with sick sinus syndrome, verapamil HCl may interfere with sinus node impulse generation and may induce sinus arrest or sinoatrial block. Atrioventricular block can occur in patients without preexisting conduction defects. (See WARNINGS.) Verapamil HCl does not alter the normal atrial action potential or intraventricular conduction time, but depresses amplitude, velocity of depolarization and conduction in depressed atrial fibers. Verapamil HCl may shorten the antegrade effective refractory period of accessory bypass tracts. Acceleration of ventricular rate and/or ventricular fibrillation has been reported in patients with atrial flutter or atrial fibrillation and a coexisting accessory AV pathway following administration of verapamil. (See WARNINGS.)
Verapamil HCl has a local anesthetic action that is 1.6 times that of procaine on an equimolar basis. It is not known whether this action is important at the doses used in man.
Verapamil HCl exerts antihypertensive effects by decreasing systemic vascular resistance, usually without orthostatic decreases in blood pressure or reflex tachycardia; bradycardia (rate less than 50 beats/minute is uncommon). Verapamil HCl regularly reduces arterial pressure at rest and at a given level of exercise by dilating peripheral arterioles and reducing the total peripheral resistance (afterload) against which the heart works.
With the immediate release formulations, more than 90% of the orally administered dose is absorbed, and peak plasma concentrations of verapamil are observed 1 to 2 hours after dosing. Because of rapid biotransformation of verapamil during its first pass through the portal circulation, the absolute bioavailability ranges from 20% to 35%. Chronic oral administration of the highest recommended dose (120 mg every 6 hours) resulted in plasma verapamil levels ranging from 125 to 400 ng/mL with higher values reported occasionally. A nonlinear correlation between the verapamil HCl dose administered and verapamil plasma levels does exist.
During initial dose titration with verapamil a relationship exists between verapamil plasma concentrations and the prolongation of the PR interval. However, during chronic administration this relationship may disappear. The quantitative relationship between plasma verapamil concentrations and blood pressure reduction has not been fully characterized.
In a multiple dose pharmacokinetic study, peak concentrations for a single daily dose of Verelan 240 mg were approximately 65% of those obtained with an 80 mg t.i.d. dose of the conventional immediate-release tablets, and the 24 hour post-dose concentrations were approximately 30% higher. At a total daily dose of 240 mg, Verelan was shown to have a similar extent of verapamil bioavailability based on the AUC-24 as that obtained with the conventional immediate-release tablets. In this same study Verelan doses of 120 mg, 240 mg and 360 mg once daily were compared after multiple doses. The ratios of the verapamil and norverapamil AUCs for the Verelan 120 mg, 240 mg and 360 mg once daily doses are 1 (565 ng∙hr/mL):3 (1660 ng∙hr/mL):5 (2729 ng∙hr/mL) and 1 (621 ng∙hr/mL):3 (1614 ng∙ hr/mL):4 (2535 ng∙hr/mL) respectively, indicating that the AUC increased non-proportionately with increasing doses.
Food does not affect the extent or rate of the absorption of verapamil from the controlled release Verelan capsule. The Verelan 240 mg capsule when administered with food had a Cmax of 77 ng/mL which occurred 9.0 hours after dosing, and an AUC(O-inf) of 1387 ng∙hr/mL. Verelan 240 mg under fasting conditions had a Cmax of 77 ng/mL which occurred 9.8 hours after dosing, and an AUC(O-inf) of 1541 ng∙hr/mL.
The bioequivalence of Verelan 240 mg, administered as the pellets sprinkled on applesauce and as the intact capsule, was demonstrated in a single-dose, cross-over study in 32 healthy adults. Comparative ratios (sprinkled/intact) of verapamil were 0.95, 1.02, and 1.01 for Cmax , Tmax , and AUC(O-inf) respectively. When the contents of the Verelan® capsule were administered by sprinkling onto one tablespoonful of applesauce, the rate and extent of verapamil absorption were found to be bioequivalent to the same dose when administered as an intact capsule. Similar results were observed with norverapamil.
The time to reach maximum verapamil concentrations (Tmax) with Verelan has been found to be approximately 7-9 hours in each of the single dose (fasting), single dose (fed), the multiple dose (steady state) studies and dose proportionality pharmacokinetic studies. Similarly the apparent half-life (t1/2) has been found to be approximately 12 hours independent of dose. Aging may affect the pharmacokinetics of verapamil. Elimination half-life may be prolonged in the elderly.
In healthy man, orally administered verapamil HCl undergoes extensive metabolism in the liver. Twelve metabolites have been identified in plasma; all except norverapamil are present in trace amounts only. Norverapamil can reach steady-state plasma concentrations approximately equal to those of verapamil itself. The biologic activity of norverapamil appears to be approximately 20% that of verapamil.
Approximately 70% of an administered dose of verapamil HCl is excreted as metabolites in the urine and 16% or more in the feces within 5 days. About 3% to 4% is excreted in the urine as unchanged drug. Approximately 90% is bound to plasma proteins. In patients with hepatic insufficiency, metabolism is delayed and elimination half-life prolonged up to 14 to 16 hours (see PRECAUTIONS), the volume of distribution is increased and plasma clearance reduced to about 30% of normal. Verapamil clearance values suggest that patients with liver dysfunction may attain therapeutic verapamil plasma concentrations with one-third of the oral daily dose required for patients with normal liver function.
After four weeks of oral dosing (120 mg q.i.d.), verapamil and norverapamil levels were noted in the cerebrospinal fluid with estimated partition coefficient of 0.06 for verapamil and 0.04 for norverapamil.
In 10 healthy males, administration of oral verapamil (80 mg every 8 hours for 6 days) and a single oral dose of ethanol (0.8 g/kg), resulted in a 17% increase in mean peak ethanol concentrations (106.45 ± 21.40 to 124.23 ± 24.74 mg/dL) compared with placebo. (See PRECAUTIONS-Drug Interactions.)
The area under the blood ethanol concentration versus time curve (AUC over 12 hours) increased by 30% (365.67 ± 93.52 to 475.07 ± 97.24 mg∙hr/dL). Verapamil AUCs were positively correlated (r = 0.71) to increased ethanol blood AUC values.
The pharmacokinetics of verapamil GITS were studied after 5 consecutive nights of dosing 180 mg in 30 healthy young (19-43 years) versus 30 healthy elderly (65-80years) male and female subjects. Older subjects had significantly higher mean verapamil Cmax , Cmin and AUC (0-24h) compared to younger subjects. Older subjects had mean AUCs that were approximately 1.7-2.0 times higher than those of younger subjects as well as a longer average verapamil t1/2 (approximately 20 hr vs 13 hr).
Hemodynamics and Myocardial Metabolism
Verapamil HCl reduces afterload and myocardial contractility. Improved left ventricular diastolic function in patients with IHSS and those with coronary heart disease has also been observed with verapamil HCl therapy. In most patients, including those with organic cardiac disease, the negative inotropic action of verapamil HCl is countered by reduction of afterload and cardiac index is usually not reduced. In patients with severe left ventricular dysfunction however, (e.g., pulmonary wedge pressure above 20 mm Hg or ejection fraction lower than 30%), or in patients on beta-adrenergic blocking agents or other cardio-depressant drugs, deterioration of ventricular function may occur. (See Drug Interactions.)
Verapamil HCl does not induce broncho-constriction and hence, does not impair ventilatory function.
Verelan (verapamil HCl) is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including this drug.
Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program’s Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC).
Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly.
Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal.
Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy.
Verapamil HCl is contraindicated in:
- Severe left ventricular dysfunction. (See WARNINGS.)
- Hypotension (less than 90 mm Hg systolic pressure) or cardiogenic shock.
- Sick sinus syndrome (except in patients with a functioning artificial ventricular pacemaker).
- Second — or third-degree AV block (except in patients with a functioning artificial ventricular pacemaker).
- Patients with atrial flutter or atrial fibrillation and an accessory bypass tract (e.g., Wolff-Parkinson-White, Lown-Ganong-Levine syndromes). (See WARNINGS.)
- Patients with known hypersensitivity to Verapamil hydrochloride.
Verapamil has a negative inotropic effect which, in most patients, is compensated by its afterload reduction (decreased systemic vascular resistance) properties without a net impairment of ventricular performance. In clinical experience with 4,954 patients, 87 (1.8%) developed congestive heart failure or pulmonary edema. Verapamil should be avoided in patients with severe left ventricular dysfunction (e.g., ejection fraction less than 30% or moderate to severe symptoms of cardiac failure) and in patients with any degree of ventricular dysfunction if they are receiving a beta-adrenergic blocker. (See Drug Interactions.) Patients with milder ventricular dysfunction should, if possible, be controlled with optimum doses of digitalis and/or diuretics before verapamil treatment (note interactions with digoxin under: PRECAUTIONS).
Occasionally, the pharmacologic action of verapamil may produce a decrease in blood pressure below normal levels which may result in dizziness or symptomatic hypotension. The incidence of hypotension observed in 4,954 patients enrolled in clinical trials was 2.5%. In hypertensive patients, decreases in blood pressure below normal are unusual. Tilt table testing (60 degrees) was not able to induce orthostatic hypotension.
Elevations of transaminases with and without concomitant elevations in alkaline phosphatase and bilirubin have been reported. Such elevations have sometimes been transient and may disappear even in the face of continued verapamil treatment. Several cases of hepatocellular injury related to verapamil have been proven by rechallenge; half of these had clinical symptoms (malaise, fever, and/or right upper quadrant pain) in addition to elevations of SGOT, SGPT and alkaline phosphatase. Periodic monitoring of liver function in patients receiving verapamil is therefore prudent.
Some patients with paroxysmal and/or chronic atrial flutter or atrial fibrillation and a coexisting accessory AV pathway have developed increased antegrade conduction across the accessory pathway bypassing the AV node, producing a very rapid ventricular response or ventricular fibrillation after receiving intravenous verapamil (or digitalis). Although a risk of this occurring with oral verapamil has not been established, such patients receiving oral verapamil may be at risk and its use in these patients is contraindicated. (See CONTRAINDICATIONS.)
Treatment is usually DC-cardioversion. Cardioversion has been used safely and effectively after oral verapamil.
The effect of verapamil on AV conduction and the SA node may lead to asymptomatic first-degree AV block and transient bradycardia, sometimes accompanied by nodal escape rhythms. PR interval prolongation is correlated with verapamil plasma concentrations, especially during the early titration phase of therapy. Higher degrees of AV block, however, were infrequently (0.8%) observed.
Marked first-degree block or progressive development to second- or third-degree AV block requires a reduction in dosage or, in rare instances, discontinuation of verapamil HCl and institution of appropriate therapy depending upon the clinical situation.
In 120 patients with hypertrophic cardiomyopathy (most of them refractory or intolerant to propranolol) who received therapy with verapamil at doses up to 720 mg/day, a variety of serious adverse effects were seen. Three patients died in pulmonary edema; all had severe left ventricular outflow obstruction and a past history of left ventricular dysfunction. Eight other patients had pulmonary edema and/or severe hypotension; abnormally high (over 20 mm Hg) capillary wedge pressure and a marked left ventricular outflow obstruction were present in most of these patients. Concomitant administration of quinidine (see Drug Interactions) preceded the severe hypotension in 3 of the 8 patients (2 of whom developed pulmonary edema). Sinus bradycardia occurred in 11% of the patients, second-degree AV block in 4% and sinus arrest in 2%. It must be appreciated that this group of patients had a serious disease with a high mortality rate. Most adverse effects responded well to dose reduction and only rarely did verapamil have to be discontinued.
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