Adult: Initially, 5 mg once daily. Dosage is individualised and may be increased after at least 1-2 weeks. Max: 10 mg once daily. Child: 6-17 years Initially, 2.5 mg once daily, may increase to 5 mg once daily after 4 weeks intervals according to clinical response. Elderly: Initially, 2.5 mg once daily.
Hepatic Impairment
Severe: Initially, 2.5 mg once daily, may be titrated according to clinical response.
Administration
May be taken with or without food.
Contraindications
Severe hypotension, cardiogenic shock, left ventricular outflow tract obstruction (e.g. high-grade aortic stenosis), heart failure after acute MI.
Special Precautions
Patients with aortic stenosis, congestive heart failure, hypertrophic cardiomyopathy, outflow tract obstruction, severe obstructive coronary disease. Hepatic impairment. Elderly and children. Pregnancy and lactation.
Adverse Reactions
Significant: Peripheral oedema, hypotension, angina/MI. Blood and lymphatic system disorders: Leucopenia, thrombocytopenia. Cardiac disorders: Bradycardia, ventricular tachycardia, chest pain, palpitation. Ear and labyrinth disorders: Tinnitus. Eye disorders: Visual disturbance, diplopia, conjunctivitis. Gastrointestinal disorders: Nausea, dyspepsia, diarrhoea, constipation, abdominal pain. General disorders and admin site conditions: Fatigue, asthenia. Investigations: Weight gain, elevated hepatic enzymes. Musculoskeletal and connective tissue disorders: Muscle cramps, arthralgia, back pain. Nervous system disorders: Headache, somnolence, dizziness, extrapyramidal symptoms. Psychiatric disorders: Insomnia, anxiety, depression. Renal and urinary disorders: Micturition disorder, nocturia. Reproductive system and breast disorders: Sexual dysfunction, gynaecomastia. Respiratory, thoracic and mediastinal disorders: Pulmonary oedema, dyspnoea, cough, rhinitis. Skin and subcutaneous tissue disorders: Rash, skin discolouration, pruritus. Vascular disorders: Flushing.
This drug may cause dizziness, headache, fatigue or nausea, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor BP, heart rate, pulse, frequency and intensity of angina, weight, and peripheral oedema.
Overdosage
Symptoms: Bradycardia, dysrhythmia, marked hypotension, excessive peripheral vasodilation, reflex tachycardia, shock. Management: Perform gastric lavage and administration of charcoal up to 2 hours after ingestion. Initiate active cardiovascular support, monitor cardiac and respiratory function, elevation of extremities and attention of circulation fluid volume and urine output. For restoring vascular tone and blood pressure, may give a vasoconstrictor and IV Ca gluconate to reverse the effects of Ca channel blocker.
Drug Interactions
Increased systemic plasma concentration with immunosuppressants (e.g. ciclosporin, tacrolimus). Increased serum concentration of simvastatin. Increased exposure with CYP3A4 enzyme inhibitors (e.g. protease inhibitors, azole antifungals, erythromycin, diltiazem). Decreased plasma concentration with CYP3A4 inducers (e.g. rifampicin).
Food Interaction
Increased plasma concentration with grapefruit or grapefruit juice. Decreased plasma concentrations with St. John’s wort.
Lab Interference
May result to false-positive aldosterone/renin ratio (ARR).
Action
Description: Amlodipine, a dihydropyridine Ca-channel blocker, reduces peripheral vascular resistance and BP by relaxing coronary vascular smooth muscle and coronary vasodilation through inhibition of Ca ion transmembrane influx into cardiac and vascular smooth muscles. Onset: 24-48 hours. Duration: 24 hours. Pharmacokinetics: Absorption: Well absorbed from the gastrointestinal tract. Bioavailability: Approx 60-65%. Time to peak plasma concentration: 6-12 hours. Distribution: Crosses placenta and enters breast milk. Volume of distribution: 21 L/kg. Plasma protein binding: Approx 98%. Metabolism: Extensively metabolised in the liver to inactive metabolites. Excretion: Via urine (60% as metabolites, 10% as unchanged drug). Terminal elimination half-life: 35-50 hours.
Chemical Structure
Amlodipine Source: National Center for Biotechnology Information. PubChem Database. Amlodipine, CID=2162, https://pubchem.ncbi.nlm.nih.gov/compound/Amlodipine (accessed on Jan. 20, 2020)
C08CA01 - amlodipine ; Belongs to the class of dihydropyridine derivative selective calcium-channel blockers with mainly vascular effects. Used in the treatment of cardiovascular diseases.
References
Amlodipine Besylate Tablet (Teva Pharmaceuticals USA, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 05/03/2019.Anon. Amlodipine Besylate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 05/03/2019.Anon. Amlodipine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/03/2019.Buckingham R (ed). Amlodipine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/03/2019.Joint Formulary Committee. Amlodipine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/03/2019.
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