Norvasc 5 mg Tablets

Brand Name

This medication is marketed under the trade name Norvasc, widely recognized among healthcare practitioners for its role in managing cardiovascular conditions.

International Nonproprietary Name (INN)

The active ingredient is universally identified as amlodipine, ensuring its consistent recognition across global medical standards.

Form of Release

The drug is available as tablets, designed for oral administration and offered in various strengths to accommodate diverse patient needs. These tablets are crafted for ease of use and maintain stability under typical storage conditions.

Composition

Amlodipine besylate serves as the primary active component, formulated to influence vascular function and blood pressure regulation. Accompanying this are auxiliary substances such as microcrystalline cellulose, calcium phosphate, sodium starch glycolate, and magnesium stearate, which provide structural integrity and facilitate tablet disintegration upon ingestion. Some formulations may include minor additives to enhance appearance or stability. Each element is purposefully integrated to support the therapeutic action of amlodipine while ensuring its reliability and consistency.

Pharmacologic Properties

Pharmacodynamics

This medication functions as a dihydropyridine calcium channel blocker, targeting L-type calcium channels in vascular smooth muscle and cardiac tissue to exert its effects. By inhibiting calcium influx, it prevents vasoconstriction, leading to relaxation of arterial smooth muscle, reduced peripheral resistance, and lowered blood pressure. It also dilates coronary arteries, improving myocardial oxygen supply, which benefits conditions involving reduced blood flow. Its selective action on vascular tissue over cardiac muscle minimizes negative inotropic effects, preserving heart contractility. Effects typically begin within six to twelve hours, with peak activity sustained over 24 hours due to its long duration, supporting once-daily dosing. This mechanism enhances its utility in maintaining cardiovascular stability.

Pharmacokinetics

Following oral intake, the drug absorbs slowly and completely from the gastrointestinal tract, achieving a bioavailability of 60% to 80%, unaffected by food. Peak plasma concentrations occur within six to twelve hours. Amlodipine binds extensively to plasma proteins, approximately 93% to 98%, and distributes widely, with a large volume of distribution reflecting its tissue affinity. It undergoes extensive hepatic metabolism via cytochrome P450 3A4, producing inactive metabolites. Elimination occurs primarily through urine, with about 60% excreted as metabolites and 10% unchanged, and a half-life ranging from 30 to 50 hours, prolonged in hepatic impairment or elderly patients. Renal function has minimal impact on clearance, allowing consistent dosing across varied kidney states.

Indications for Use

This medication is prescribed for conditions requiring vascular relaxation or improved blood flow. It is primarily indicated for hypertension, effectively reducing elevated blood pressure to lower cardiovascular risk, suitable for mild to severe cases. It also manages chronic stable angina by enhancing coronary perfusion and reducing myocardial oxygen demand, improving exercise tolerance. In vasospastic angina, it prevents coronary artery spasms, alleviating chest pain episodes. Its versatility supports use in both monotherapy and combination regimens, addressing a spectrum of cardiovascular challenges and contributing to long-term heart health strategies.

Contraindications

Specific conditions limit the use of this drug to protect patient well-being. Hypersensitivity to amlodipine or dihydropyridine derivatives prohibits its administration, as reactions could range from skin irritation to severe allergic episodes. Severe hypotension or cardiogenic shock contraindicates it due to its potent pressure-lowering effects, which could exacerbate circulatory compromise. It is avoided in advanced aortic stenosis, where reduced afterload might impair cardiac output. Significant liver failure with impaired metabolism warrants caution to prevent accumulation, though not an absolute barrier. Unstable angina or acute myocardial infarction within the first month also restricts its use until stabilized, ensuring safety in acute settings.

Method of Administration and Dosage

How to Take

Tablets are taken orally, with or without food, offering flexibility in timing, though consistency each day supports stable blood levels. Swallowing them whole with water ensures effective delivery to the digestive system. Taking them at a regular time enhances therapeutic reliability.

Dosage for Adults and Children

For adults with hypertension or angina, treatment typically starts at 5 mg once daily, adjustable to 10 mg daily based on response with a maximum of 10 mg. Pediatric use for hypertension in children aged 6 and older begins at 2.5 mg once daily, increasing to 5 mg if needed, tailored under specialist guidance. Elderly patients may also start at 2.5 mg daily, with adjustments based on tolerance and efficacy. Regular monitoring ensures dosing balances benefits and safety across age groups.

Dose Adjustment in Specific Conditions

Renal impairment requires no adjustment, as excretion is primarily hepatic, though monitoring for fluid status is wise. Hepatic dysfunction suggests starting at 2.5 mg daily, with slow increases due to prolonged half-life and potential accumulation risks. Older adults or those with reduced metabolic capacity may also initiate at 2.5 mg daily to minimize side effects like edema or dizziness. Frequent evaluations confirm that dosing suits each patient’s physiological state, particularly in compromised conditions.

Side Effects

This medication may elicit various unintended responses, though most are mild and transient. Swelling in the ankles or feet, linked to vasodilation, is common, often resolving with time or position changes. Dizziness or lightheadedness might occur, typically tied to blood pressure reductions, especially early in use. Fatigue, flushing, or headache can affect some individuals, usually diminishing with continued therapy. Gastrointestinal discomfort, such as nausea or abdominal pain, is less frequent but reported. Rarely, severe reactions like significant hypotension, palpitations, or allergic responses such as rash emerge, necessitating immediate medical attention. Patient feedback and periodic checks help manage these effects effectively.

Overdose

Symptoms of Overdose

Excessive intake can lead to marked hypotension, resulting in dizziness, fainting, or circulatory collapse due to excessive vessel relaxation. Reflex tachycardia may develop as the body compensates, though severe cases could progress to shock. Weakness, confusion, or lethargy might accompany these effects, reflecting profound pressure drops. Symptoms typically appear within hours and intensify without intervention, highlighting the drug’s strong vascular influence.

First Aid Measures

In an overdose scenario, discontinue administration immediately and seek urgent medical assistance. If ingestion is recent, activated charcoal may reduce absorption, applied under professional supervision. Intravenous fluids or vasopressors like dopamine address hypotension, while continuous monitoring stabilizes heart rate and pressure. Positioning the patient flat with legs elevated may assist initially until medical support arrives. Focus is on restoring circulatory function swiftly.

Drug Interactions

Effects on Other Medications

This drug can influence the effects of other medications when used concurrently. It may amplify the pressure-lowering action of other antihypertensives, requiring dose recalibration to avoid excessive drops. Combining it with strong CYP3A4 inhibitors like ketoconazole increases its levels, heightening effect risks, needing careful monitoring. Beta-blockers could enhance its hypotensive effects, necessitating gradual introduction. It might alter the metabolism of simvastatin, increasing myopathy risks, requiring dose limits. Adjustments and oversight minimize these interaction concerns.

Compatibility with Alcohol and Food

Alcohol consumption may intensify hypotension or dizziness, particularly due to additive vasodilatory effects, so moderation is advised. Food does not affect absorption, allowing flexible timing, with no specific dietary restrictions beyond avoiding excessive grapefruit juice, which could enhance its effects. A balanced diet supports overall efficacy.

Special Precautions

Use During Pregnancy and Breastfeeding

This medication is generally avoided during pregnancy unless benefits outweigh risks, as animal data suggest potential fetal harm, though human evidence is limited. It may pass into breast milk in small amounts, with unclear effects on infants, so nursing mothers should consult their physician, possibly opting for alternatives to reduce exposure.

Impact on Driving and Machinery Operation

Dizziness or fatigue, especially at initiation or dose changes, may impair driving or machinery operation. Patients should assess their tolerance before such activities, ensuring safety for themselves and others.

Considerations for Elderly and Pediatric Populations

Older adults may require lower initial doses due to slower metabolism, with monitoring for edema or pressure drops. In children aged 6 and up, its use is tailored for hypertension, with doses adjusted cautiously under specialist guidance to avoid developmental impact. Personalized care optimizes safety and efficacy across these groups.