Verapamil Hcl Information
Verapamil hcl () Description
Verapamil hcl () is a calcium antagonist or slow channel inhibitor. Verapamil Hydrochloride is available in 5 mg/2 mL single dose vials (for intravenous administration). Each mL contains Verapamil HCI 2.5 mg, Sodium Chloride 8.5 mg and Water for Injection q.s. pH adjusted with Hydrochloric Acid and/or Sodium Hydroxide. The pH of the solution is between 4 and 6.5. Protect contents from light. Sterile, nonpyrogenic.
The structural formula of Verapamil HCI is given below:
Verapamil HCI is an almost white, crystalline powder, practically free of odor, with a bitter taste. It is soluble in water, chloroform and methanol. Verapamil HCI is not chemically related to other antiarrhythmic drugs.
Verapamil hcl () Clinical Pharmacology
Mechanism of Action:
In the isolated rabbit heart, concentrations of verapamil that markedly affect SA nodal fibers or fibers in the upper and middle regions of the AV node, have very little effect on fibers in the lower AV node (NH region) and no effect on atrial action potentials or His bundle fibers.
Electrical activity in the SA and AV nodes depends, to a large degree, upon calcium influx through the slow channel. By inhibiting this influx, verapamil slows AV conduction and prolongs the effective refractory period within the AV node in a rate-related manner. This effect results in a reduction of the ventricular rate in patients with atrial flutter and/or atrial fibrillation and a rapid ventricular response.
By interrupting reentry at the AV node, verapamil can restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardias (PSVT), including PSVT associated with Wolff-Parkinson-White syndrome.
Verapamil does not induce peripheral arterial spasm.
Verapamil 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 does not alter total serum calcium levels.
Hemodynamics:
Pharmacokinetics:
Aging may affect the pharmacokinetics of verapamil given to hypertensive patients. Elimination half-life may be prolonged in the elderly.
Verapamil hcl () Indications And Usage
Intravenous Verapamil HCI is indicated for the following:
In controlled studies in the United States, about 60% of patients with supraventricular tachycardia converted to normal sinus rhythm within 10 minutes after intravenous verapamil. Uncontrolled studies reported in the world literature describe a conversion rate of about 80%. About 70% of patients with atrial flutter and/or fibrillation with a fast ventricular rate respond with a decrease in ventricular rate of at least 20%. Conversion of atrial flutter or fibrillation to sinus rhythm is uncommon (about 10%) after verapamil and may reflect the spontaneous conversion rate, since the conversion rate after placebo was similar. Slowing of the ventricular rate in patients with atrial fibrillation/flutter lasts 30 to 60 minutes after a single injection.
Cardioversion has been used safely and effectively after intravenous verapamil.
Verapamil hcl () Contraindications
Intravenous Verapamil HCI is contraindicated in:
Verapamil hcl () Warnings
VERAPAMIL HYDROCHLORIDE SHOULD BE GIVEN AS A SLOW INTRAVENOUS INJECTION OVER AT LEAST A TWO MINUTE PERIOD OF TIME. (See )
Hypotension:
Extreme Bradycardia/Asystole:
Heart Failure:
Heart Block:
Hepatic and Renal Failure:
Premature Ventricular Contractions:
Duchenne's Muscular Dystrophy:
Increased Intracranial Pressure:
Verapamil hcl () Precautions
Drug Interactions:
intravenous
Pregnancy:
Labor and Delivery:
Nursing Mothers:
The most commonly used single doses in patients up to 12 months of age have ranged from 0.1 to 0.2 mg/kg of body weight, while in patients aged 1 to 15 years, the most commonly used single doses ranged from 0.1 to 0.3 mg/kg of body weight. Most of the patients received the lower dose of 0.1 mg/kg once but, in some cases, the dose was repeated once or twice every 10 to 30 minutes.
Verapamil hcl () Adverse Reactions
The following reactions were reported with intravenous Verapamil HCI used in controlled U.S. clinical trials involving 324 patients.
Cardiovascular:
Central Nervous System Effects:
Gastrointestinal:
In rare cases of hypersensitive patients, broncho/laryngeal spasm accompanied by itch and urticaria have been reported.
The following reactions have been reported at low frequency: emotional depression, rotary nystagmus, sleepiness, vertigo, muscle fatigue, diaphoresis, and respiratory failure.
Verapamil hcl () Overdosage:
Treatment of overdosage should be supportive and individualized. Beta-adrenergic stimulation and/or parenteral administration of calcium solutions may increase calcium ion flux across the slow channel, and have been effectively used in treatment of deliberate overdosage with oral Verapamil HCI. Verapamil cannot be removed by hemodialysis. Clinically significant hypotensive reactions or high degree AV block should be treated with vasopressor agents or cardiac pacing, respectively. Asystole should be handled by the usual measures including isoproterenol hydrochloride, other vasopressor agents or cardiopulmonary resuscitation (see )
Verapamil hcl ()
Verapamil hcl ()
