Adalat Retard

Uses

Adalat Retard is used for the management of all types of essential & renal hypertension. Also used for the management of hypertension during pregnancy & during coronary by pass surgery.

Adalat Retard is also used for prophylaxis and the treatment of unstable & variant angina, myocardial infarction, and silent myocardial ischaemia. Moreover Adalat Retard is also used in Raynaud's phenomenon & heart failure.

Adalat Retard is also used to associated treatment for these conditions: Achalasia, Anal Fissures, Chronic Stable Angina Pectoris, High Blood Pressure (Hypertension), Hypertensive Emergency, Premature Labour, Proctalgia, Pulmonary Edemas, Pulmonary Hypertension (PH), Raynaud's Phenomenon, Ureteral Calculus, Vasospastic Angina

How Adalat Retard works

Adalat Retard blocks voltage gated L-type calcium channels in vascular smooth muscle and myocardial cells. This blockage prevents the entry of calcium ions into cells during depolarization, reducing peripheral arterial vascular resistance and dilating coronary arteries. These actions reduce blood pressure and increase the supply of oxygen to the heart, alleviating angina.

Dosage

Adalat Retard dosage

Adalat Retard 10 mg:

• Angina: Initially 10 mg 3 times daily with food increased to 20 mg 3 times daily if necessary, in elderly patients, initially 5 mg 3 times daily.
• Raynaud's Phenomenon: 10 mg 3 times daily; maximum 60 mg daily. In urgent cases, the tablet should be dissolved under the tongue like a sublingual tablet. The effect occurs within some minutes.

Adalat Retard 20 mg:

The starting dose for patients, not previously prescribed Adalat Retard products is one tablet once daily. The recommended dose in hypertension and angina prophylaxis is 20 mg twice daily during or after food. Dosage may be adjusted within the range 10 mg twice daily to 40 mg twice daily.

Patients with liver dysfunction should commence therapy with 10 mg twice daily with careful monitoring.

Patients with renal impairment do not require adjustment of dosage.

Side Effects

Headache, flushing, lethargy, gravitational oedema rash, nausea, increased frequency of micturation, eye pain, gum hyperplasia, depression, tremor, photosensitivity and few cases of jaundice have been reported. These reactions may regress on discontinuation of therapy. Its introduction may induce attacks of ischaemic pain in some patients with angina pectoris.

Toxicity

The oral LD₅₀ in rats is 1022mg/kg and in mice is 202mg/kg.

Patients experiencing an overdose may present with hypotension, sinus node dysfunction, atrioventricular node dysfunction, and reflex tachycardia. Overdose may be managed by monitoring cardiovascular and respiratory function; elevating extremities; and administering vasopressors, fluids, and calcium infusions.

Precaution

Tablets should be swallowed whole and should not be bitten, chewed or broken up. It should be used with caution in patient whose cardiac reserve is poor. Should be withdrawn if ischaemic pain occurs or existing pain worsens shortly after initiating treatment. Use in diabetic patients requires adjustment of their control. Since the absorption of the drug could be modified by renal disease, caution should be exercised in treating such patients.

Interaction

• ACE inhibitors: Enhanced hypotensive effect.
• Anti-arrythmics: Plasma concentration of quinidine is reduced.
• Anti-bacterials: Rifampicin possibly increases metabolism of Adalat Retard.
• Anti-epileptics: Plasma concentration of phenytoin increases.
• Antipsychotics: Enhanced hypotensive effect.
• β-blockers: Occasionally severe hypotension and heart failure may occur.
• Cyclosporin: Plasma concentration of Adalat Retard possibly increases.
• Muscle relaxants: Effect of muscle relaxants e.g. tubocurarine increases.
• Ulcer healing drugs: Metabolism of Adalat Retard increases.

Food Interaction

• Avoid excessive or chronic alcohol consumption.
• Avoid grapefruit products. Grapefruit down-regulates post-translational expression of CYP3A4, the major metabolizing enzyme of nifedipine. Grapefruit, in all forms (e.g. whole fruit, juice and rind), can significantly increase serum levels of nifedipine and may cause toxicity. Avoid grapefruit products while on this medication.
• Avoid natural licorice.
• Take with or without food.

[Moderate] GENERALLY AVOID: The consumption of grapefruit juice may be associated with significantly increased plasma concentrations of some calcium channel blockers (CCBs) when they are administered orally.

The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit.

The interaction has been reported with the dihydropyridine CCBs (in roughly decreasing order of magnitude) felodipine, nisoldipine, nifedipine, and nimodipine, often with a high degree of interindividual variability.

Grapefruit juice caused more than twofold increases in felodipine, nifedipine, and nisoldipine AUCs.

MANAGEMENT: The manufacturers of nifedipine and nisoldipine recommend avoiding grapefruit juice.

Patients treated orally with other calcium channel blockers should be advised to avoid consumption of large amounts of grapefruits and grapefruit juice to prevent any undue fluctuations in serum drug levels.

Increased effects on blood pressure may persist for up to 4 days after the consumption of grapefruit juice.

Monitoring for calcium channel blocker adverse effects (e.g., headache, hypotension, syncope, tachycardia, edema) is recommended.

Adalat Retard Hypertension interaction

[Major] For the long-term treatment of hypertension, only the extended-release formulations of nifedipine should be used.

The US National Heart, Lung, and Blood Institute and the FDA Cardiovascular and Renal Drug Advisory Committee have issued warnings against the use of immediate-release nifedipine for this purpose based on review of three epidemiologic studies of patients with hypertension and unstable angina who were treated with calcium channel blockers (CCBs) and at least two meta-analyses of randomized, controlled trials that included patients receiving CCBs.

Two of the case-control studies found an increased risk of myocardial infarction (MI) in patients taking immediate-release nifedipine, although the third did not. The use of immediate-release nifedipine (orally or sublingually) is also contraindicated for acute reduction of blood pressure.

Profound hypotension, acute myocardial infarction, and deaths have been reported when nifedipine was used in this manner.

Adalat Retard multivitamins interaction

[Moderate] Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium.

Calcium chloride has been used to manage acute severe verapamil toxicity.

Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.

Adalat Retard Drug Interaction

Moderate: aspirin, aspirin, apixaban, atorvastatin, metoprolol, metoprololUnknown: rosuvastatin, duloxetine, omega-3 polyunsaturated fatty acids, furosemide, pregabalin, esomeprazole, acetaminophen, clopidogrel, levothyroxine, acetaminophen, cyanocobalamin, ascorbic acid, cholecalciferol, alprazolam

Adalat Retard Disease Interaction

Major: aortic stenosis, cardiogenic shock/hypotension, coronary artery disease, liver disease, hypertension, myocardial infarctionModerate: CHF/AMI, renal dysfunction, GI narrowing

Volume of Distribution

The steady state volume of distribution of nifedipine is 0.62-0.77L/kg and the volume of distribution of the central compartment is 0.25-0.29L/kg.

Elimination Route

Sublingual dosing leads to a C_max of 10ng/mL, with a T_max of 50min, and an AUC of 25ng*h/mL. Oral dosing leads to a C_max of 82ng/mL, with a T_max of 28min, and an AUC of 152ng*h/mL.

Adalat Retard is a Biopharmaceutics Classification System Class II drug, meaning it has low solubility and high intestinal permeability. It is almost completely absorbed in the gastrointestinal tract but has a bioavilability of 45-68%, partly due to first pass metabolism.

Half Life

The terminal elimination half life of nifedipine is approximately 2 hours.

Clearance

The total body clearance of nifedipine is 450-700mL/min.

Elimination Route

Adalat Retard is 60-80% recovered in the urine as inactive water soluble metabolites, and the rest is eliminated in the feces as metabolites.

Pregnancy & Breastfeeding use

There are no adequate and well controlled studies in pregnant women. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Contraindication

Cardiogenic shock, advanced aortic stenosis, nursing mothers, GI obstruction, inflammatory bowel disease, hypotension.

Storage Condition

Protect from strong light, store in a cool place in the original pack

Innovators Monograph

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