Adult: As conventional cap: Initially, 5 mg 8 hourly, may titrate to 20 mg 8 hourly according to response. As conventional tab: 10 mg tid, may titrate dose up to Max of 60 mg daily if needed. Dosage recommendations may vary between individual products (refer to specific product guidelines). Elderly: Dose reduction may be necessary.
Oral Hypertension
Adult: As monotherapy or in combination with other antihypertensive agents: As extended-release tab or cap: 10-40 mg bid or 20-90 mg once daily. Dose must be adjusted according to patient response or needs. Dosage recommendations may vary between individual products (refer to specific product guidelines). Elderly: Dose reduction may be necessary.
Oral Chronic stable angina, Prinzmetal's angina
Adult: As extended-release tab or cap: 10-40 mg bid or 30-90 mg once daily. Dose must be adjusted according to patient response or needs. Dosage recommendations may vary between individual products (refer to specific product guidelines). Elderly: Dose reduction may be necessary.
Hepatic Impairment
Dose reduction may be necessary.
Administration
immediate-release: May be taken with or without food. Avoid grapefruit juice. extended-release: Should be taken on an empty stomach. Swallow whole, do not crush/split/chew. Avoid grapefruit juice.
Contraindications
Cardiogenic shock, clinically significant aortic stenosis, unstable angina; during or within 4 weeks of acute MI; acute anginal attacks, secondary prevention of MI. Concomitant use with rifampicin. Contraindications may vary between individual products (refer to specific product labelling for detailed information).
Special Precautions
Patient with poor cardiac reserve, severe hypotension (systolic blood pressure <90 mmHg), heart failure, significantly impaired left ventricular function, hypertrophic cardiomyopathy with outflow tract obstruction, diabetes mellitus. Extended-release form: Patient with risk factors for gastrointestinal obstruction (e.g. severe gastrointestinal narrowing, bowel resection, colon cancer, gastric bypass, vertical banded gastroplasty, hypomotility disorder). Patient undergoing major surgery. Use of conventional (immediate-release) preparation to manage angina or hypertension is not recommended. Avoid abrupt withdrawal. Hepatic impairment. Elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Peripheral oedema, deterioration of heart failure; symptomatic hypotension with or without syncope (conventional form). Rarely, exacerbation of angina and/or acute MI (during treatment initiation or dose increase of conventional form); bezoar formation (use of extended-release form, particularly in patients with gastrointestinal strictures); elevated alkaline phosphatase, ALT, AST, LDH and creatine phosphokinase. Cardiac disorders: Palpitations. Gastrointestinal disorders: Constipation, abdominal pain, dyspepsia, diarrhoea, flatulence, dry mouth, nausea, heartburn. General disorders and administration site conditions: Malaise, fatigue. Musculoskeletal and connective tissue disorders: Muscle cramps. Nervous system disorders: Headache, dizziness, tremor. Psychiatric disorders: Nervousness, mood changes. Respiratory, thoracic and mediastinal disorders: Nasal congestion, cough, wheezing, sore throat, dyspnoea. Skin and subcutaneous tissue disorders: Dermatitis, rash, pruritus, urticaria, diaphoresis. Vascular disorders: Vasodilation, flushing.
PO: C, Z (Use for tocolysis is associated with pulmonary oedema and cardiovascular complications (hypotension, cardiogenic shock, myocardial infarction, atrial fibrilation).)
Monitoring Parameters
Monitor blood pressure (regularly), heart rate, heart rhythm, ECG changes; signs or symptoms of heart failure and peripheral oedema.
Overdosage
Symptoms: Severe hypotension, flushing, tachycardia, bradycardia, hyperglycaemia, metabolic acidosis, hypokalaemia, hyperkalaemia, hypoxia, cardiogenic shock with pulmonary oedema, heart block, heart rhythm disturbances, loss of consciousness and coma. Management: Symptomatic and supportive treatment. Administer activated charcoal if ingestion of a potentially toxic amount is within 1 hour. Alternatively, gastric lavage may be considered. Observe asymptomatic patients for at least 4 hours following ingestion of conventional preparation and for 12 hours if an extended-release preparation is taken. Monitor blood pressure, ECG, pulmonary wedge pressure, central arterial pressure, urea and electrolytes. In case of hypotension due to cardiogenic shock and arterial vasodilatation, treatment may be done by placing the patient in a supine position with feet raised and administering plasma expanders. If ineffective, hypotension may be treated with 10-20 mL of Ca gluconate 10% solution administered via IV over 5-10 minutes. May continue treatment with ECG monitoring if the effects are inadequate. If the increase in blood pressure is insufficient with Ca, vasoconstricting sympathomimetics (e.g. dopamine, norepinephrine) may be administered. For the treatment of symptomatic bradycardia, atropine, β-sympathomimetics, or a temporary cardiac pacemaker may be used as required.
Drug Interactions
May enhance the hypotensive effect of other antihypertensive agents. Concomitant use with β-blockers (e.g. propranolol, timolol) may increase the risk of heart failure, severe hypotension and exacerbation of angina. Increased exposure with CYP3A4 inhibitors (e.g. erythromycin, ritonavir, ketoconazole, fluoxetine, nefazodone, cimetidine, diltiazem, quinupristin/dalfopristin). Decreased exposure with CYP3A4 inducers (e.g. phenytoin, carbamazepine, phenobarbital). May increase plasma levels of digoxin, tacrolimus, phenytoin and theophylline. May decrease plasma levels of quinidine. Increased risk of excessive hypotensive effect with IV magnesium sulfate. Potentially Fatal: Decreased bioavailability and efficacy with rifampicin.
Food Interaction
Increased plasma levels and prolonged action with grapefruit juice. May reduce serum levels with St. John's wort. May decrease the rate but not the extent of absorption with food (conventional form).
Lab Interference
May give false elevations of spectrophotometric values of urinary vanillylmandelic acid. May result in false-negative aldosterone/renin ratio (ARR).
Action
Description: Mechanism of Action: Nifedipine is a dihydropyridine Ca channel blocker that inhibits the transmembrane influx of extracellular Ca ions across the membranes of the vascular smooth muscle cells and myocardial cells. This results in coronary vascular smooth muscle relaxation and coronary vasodilation. Additionally, it reduces peripheral and coronary vascular resistance, leading to an increased coronary blood flow, cardiac output and stroke volume while lowering the afterload. Onset: Conventional form: Approx 20 minutes. Pharmacokinetics: Absorption: Almost completely absorbed from the gastrointestinal tract; rapidly absorbed (conventional form). Food may reduce the rate but not the extent of absorption (conventional form). Bioavailability: 40-77% (conventional form); 65-89% (extended-release; relative to conventional form). Time to peak plasma concentration: 30-60 minutes (conventional form). Distribution: Crosses the placenta and enters breast milk. Plasma protein binding: Approx 92-98%. Metabolism: Extensively oxidised in the liver by CYP3A4 isoenzyme into inactive metabolites. Undergoes extensive hepatic first-pass metabolism. Excretion: Via urine (approx 60-80% as inactive metabolites); faeces. Elimination half-life: 2-5 hours.
Chemical Structure
Nifedipine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 4485, Nifedipine. https://pubchem.ncbi.nlm.nih.gov/compound/Nifedipine. Accessed Mar. 22, 2024.
Storage
Conventional cap or tab: Store between 15-25°C. Protect from light and moisture. Extended-release cap or tab: Store below 30°C. Protect from light and moisture.
C08CA05 - nifedipine ; Belongs to the class of dihydropyridine derivative selective calcium-channel blockers with mainly vascular effects. Used in the treatment of cardiovascular diseases.
References
Adipine XL 30 mg, 60 mg Tablets (Chiesi Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/06/2024.Anon. Nifedipine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 03/06/2024.Brayfield A, Cadart C (eds). Nifedipine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/06/2024.Coracten SR Capsules 10 mg (Teofarma S.r.l.). MHRA. https://products.mhra.gov.uk. Accessed 05/06/2024.Cordipin Retard Tablet 20 mg (Pahang Pharmacy Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/06/2024.Fenamon 10 mg Tablets (Komedic Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/06/2024.Fortipine LA 40 mg Modified-release Tablets (Mercury Pharmaceuticals Ltd.). MHRA. https://products.mhra.gov.uk. Accessed 03/06/2024.Joint Formulary Committee. Nifedipine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/06/2024.Nifedipine Capsule (Greenstone LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/06/2024.Nifedipine Capsules 5 mg (Ennogen Pharma Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/06/2024.Nifedipine. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 03/06/2024.Procardia XL Tablet, Film Coated, Extended Release (Pfizer Laboratories Div Pfizer Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/06/2024.
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