Atenolol + Chlortalidone


Concise Prescribing Info
Indications/Uses
HTN.
Dosage/Direction for Use
Adult : Per tab contains Atenolol (mg)/Chlorthalidone (mg): 50/25 or 100/25. Initially one tab of 50/12.5 once daily; may increase to one tab of 100/25 based on response.
Dosage Details
Oral
Hypertension
Adult: Per tab contains Atenolol (mg)/Chorthalidone (mg): 50/25 or 100/25. Initially one tab of 50/25 once daily; may increase to one tab of 100/25 once daily according to response.
Renal Impairment
CrClDosage
<15Max dose of Atenolol component: 50 mg every other day.
15-35Max dose of Atenolol component: 50 mg/day
Contraindications
Sinus bradycardia, 2nd or 3rd degree heart block, cardiogenic shock, anuria, hypersentivity to either product or sulphonamide derivatives.
Special Precautions
Bronchospastic disease, renal or hepatic impairment, elderly. May aggravate peripheral arterial circulatory disorder. Beta-blocker can depress myocardial contractility; continued use in patients without history of cardiac failure may in some cases, lead to cardiac failure. Caution in patients receiving anaesthetic agents that may depress myocardium. In patients with coronary artery disease, abrupt withdrawal may cause angina pectoris exacerbation, MI. Atenolol may mask signs (tachycardia) of hypoglycaemia and thyrotoxicosis. Latent DM may manifest with Chlorthalidone therapy. Chlorthalidone can cause hyperuricaemia and precipitate gout. Monitor renal functions, potassium levels, and signs of fluid and electrolytes imbalance. Discontinue if progressive renal impairment is evident. Not recommended in pregnancy and lactation. Safety and efficacy in paediatric patients have not been established.
Adverse Reactions
Atenolol: Dyspnoea, wheeziness, bradycardia, hypotension, cold extremities, fatigue, dizziness, insomnia, lethargy, confusion, headache, depression, nightmares, nausea, diarrhoea, constipation, impotence, paraesthesia, rash, Raynaud's phenomenon. Chlorthalidone: Orthostatic hypotension, GI disturbances, jaundice, pancreatitis, vertigo, lethargy, paraesthesia, photosensitivity, rash, muscle cramps, hypokalaemia, hyponatraemia, hyperglycaemia, hyperuricaemia or gout, leucopenia, agranulocytosis, aplastic anaemia, thrombocytopenia.
Potentially Fatal: Atenolol: Heart failure, 2nd or 3rd degree AV block. Chlorthalidone: Hypersensitivity reaction including toxic epidermal necrolysis.
Overdosage
Symptoms of Atenolol overdose: Lethargy, bradycardia, respiratory disorder, wheezing, sinus pause, heart block, congestive heart failure, hypotension, bronchospasm. Symptoms of Chlorthalidone overdose: Nausea, weakness, dizziness, electrolyte imbalance. Provide supportive and symptomatic treatment; unabsorbed drug may be removed by induced emesis, admin of activated charcoal. May remove Atenolol from general circulation by haemodialysis.
Drug Interactions
Potentiate effects of other antihypertensives. Atenolol: Reduced hypotensive effect with pseudoephedrine, xylometazoline or NSAIDs. Additive effect with calcium antagonist and catecholamine-depleting drugs e.g. reserpine. Increase risk of bradycardia with amisulpride, flecainide, digitalis glycosides. Increase risk of hypotension with alprostadil, baclofen. Withdrawal of clonidine in patients receiving β-blockers may result in rebound hypertension. Chlorthalidone: May alter insulin and dosage of oral hypoglycaemic agents required in diabetics. May reduce renal clearance of lithium and increases risk of lithium toxicity. May cause hypokalaemia therefore increase risk of digitalis toxicity. Risk of hypercalcaemia with paricalcitol. Increased risk of hypokalaemia with ritodrine, amphotericin B. Increased responsiveness to tubocurarine.
Potentially Fatal: Atenolol: Bradycardia, heart block may occur when used with verapamil or diltiazem. Severe bradycardia, asystole and heart failure have been reported when used with disopyramide. High degree of cardiac depression may occur with methoxyflurane. Chlorthalidone: Risk of cardiac arrhythmias with ketanserin.
Action
Description: Atenolol is a β-blocker that acts preferentially on the β1 adrenergic receptors in the heart. Chlorthalidone is a thiazide-like diuretic that reduces BP possibly by inhibiting sodium reabsorption at the beginning of the distal convulated tubule. Combination of the two drugs results in additive antihypertensive action.
Onset: Chlorthalidone: Diuresis occurs within 2 hr.
Duration: Chlorthalidone: 48-72 hr.
Pharmacokinetics:
Absorption: Atenolol: About 50% of an oral dose is absorbed from GI tract; Tmax: 2-4 hr after oral admin.
Distribution: Atenolol: 6-16% is bound to proteins. Chlorthalidone: About 75% is bound to plasma protein.
Metabolism: Atenolol: No significant hepatic metabolism.
Excretion: Atenolol: Elimination half-life: 6-7 hr. Absorbed portion from GI tract is excreted in the urine; remainder is excreted unchanged in faeces. Chlorthalidone: Mainly excreted unchanged via urine.
Storage
Store at 20-25°C.
MIMS Class
Disclaimer: This information is independently developed by MIMS based on Atenolol + Chlortalidone from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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