Adult: Initially, 80 mg once daily. Dosage is individualised and may be increased to 160 mg once daily according to clinical response. Max: 320 mg once daily. Child: 6-18 years <35 kg: 20 mg once daily. Max dose: 40 mg daily; >35 kg: 40 mg once daily. Max dose: 80 mg daily. Individualised dosing according to clinical response.
Oral Post-myocardial infarction
Adult: May start as early as 12 hours after MI in clinically stable patients: Initially, 20 mg bid. Dose may be doubled at intervals over few weeks up to 160 mg twice daily based on clinical response. Max: 160 mg bid.
Oral Heart failure
Adult: Initially, 40 mg bid, may increase to 80 mg bid may further titrate to 160 mg bid according to clinical response. Dosage is individualised and may be increased at least 2 weeks interval. Max: 320 mg daily in divided doses.
Hepatic Impairment
Mild to moderate: Max: 80 mg once daily. Severe: Contraindicated.
Administration
May be taken with or without food.
Contraindications
Biliary cirrhosis, cholestasis. Concomitant use with aliskiren in patient with diabetes mellitus or renal impairment (GFR<60 mL/min/1.73 m2). Severe hepatic impairment. Pregnancy.
Special Precautions
Patients with aortic or mitral stenosis, severe CHF, hypertrophic obstructive cardiomyopathy, post-MI, heart failure, ascites due to cirrhosis, refractory ascites, unstented unilateral or bilateral renal artery stenosis, Na- and/or volume-depletion, primary hyperaldosteronism, diabetes mellitus, idiopathic or hereditary angioedema. Patients undergoing major surgery or during anaesthesia. Renal and mild to moderate hepatic impairment. Children. Lactation.
Adverse Reactions
Significant: Hypotension, hyperkalaemia, orthostatic hypotension. Rarely, hepatitis. Blood and lymphatic system disorders: Neutropenia, thrombocytopenia. Cardiac disorders: Dyspnoea, palpitation. Gastrointestinal disorders: Diarrhoea, abdominal pain, nausea, dyspepsia, flatulence. General disorders and admin site conditions: Fatigue, asthenia. Infections and infestations: Viral infection. Musculoskeletal and connective tissue disorders: Back pain, myalgia, arthralgia. Nervous system disorders: Dizziness, headache, vertigo, postural dizziness, paraesthesia. Psychiatric disorders: Insomnia, anxiety. Reproductive system and breast disorders: Impotence. Respiratory, thoracic and mediastinal disorders: Cough. Skin and subcutaneous tissue disorders: Rash, pruritus. Vascular disorders: Syncope, vasculitis. Potentially Fatal: Renal function deterioration characterised by oliguria, progressive azotaemia, and acute renal failure; hepatic injury, cardiac failure. Rarely, angioedema.
This drug may cause dizziness or weariness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor blood pressure, electrolytes levels (e.g. serum K levels), urinalysis and renal function prior to treatment initiation, during therapy, and periodically thereafter. Assess for signs of angioedema.
Overdosage
Symptoms: Marked hypotension, tachycardia or bradycardia, depressed level of consciousness, circulatory collapse and/or shock. Management: Symptomatic and supportive treatment. Administration of activated charcoal following ingestion. If hypotension occurs, place the patient in supine position then administer normal saline IV infusion to facilitate blood volume correction.
Drug Interactions
Increased risk of hyperkalaemia with K-sparing diuretics (e.g. spironolactone, triamterene, amiloride), K supplements or K-containing salt substitutes (e.g. heparin). May increase serum lithium concentration and toxicity. May antagonise hypotensive effect and deteriorate renal function with aspirin, NSAIDs including selective COX-2 inhibitors. Increased systemic exposure with rifampicin, ciclosporin, and ritonavir. Potentially Fatal: Increased risk of hypotension, hyperkalaemia and reduced renal function including acute renal failure with aliskiren in patients with diabetes mellitus. Increased risk of angioedema with ACE inhibitors.
Food Interaction
May reduce bioavailability with food.
Lab Interference
May result to false-negative aldosterone/renin ratio (ARR).
Action
Description: Valsartan is an angiotensin II receptor antagonist producing its BP lowering effects by selectively blocking the binding of angiotensin II to AT1 receptors, thereby antagonising angiotensin I-induced vasoconstriction, aldosterone release, catecholamine release, arginine vasopressin release, water intake, and hypertrophic responses. Onset: Approx 2 hours. Duration: 24 hours. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Reduced rate and extent of absorption with food. Bioavailability: Approx 23% (tab); approx 39% (oral solution). Time to peak plasma concentration: 2-4 hours (tab); 1-2 hours (oral solution). Distribution: Volume of distribution: 17 L. Plasma protein binding: 95% mainly to serum albumin. Metabolism: Metabolised minimally in the liver by CYP2C9 to inactive valeryl 4-hydroxy valsartan metabolite. Excretion: Mainly via faeces (approx 83%); urine (approx 13% as unchanged drug). Elimination half-life: Approx 6 hours.
Chemical Structure
Valsartan Source: National Center for Biotechnology Information. PubChem Database. Valsartan, CID=60846, https://pubchem.ncbi.nlm.nih.gov/compound/Valsartan (accessed on Jan. 20, 2020)
C09CA03 - valsartan ; Belongs to the class of angiotensin II receptor blockers (ARBs). Used in the treatment of cardiovascular disease.
References
Anon. Valsartan. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 04/04/2019.Anon. Valsartan. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/04/2019.Buckingham R (ed). Valsartan. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/04/2019.Joint Formulary Committee. Valsartan. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/04/2019.Prexxartan Solution (Medicure International Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 04/04/2019.Valsartan 80 mg Hard Capsules (Milpharm Limited). MHRA. https://products.mhra.gov.uk/. Accessed 04/04/2019.
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