Atenolol/ Chlorthalidone

Registered South African indications:

• Hypertension

Contraindications

• Hypersensitivity to the active ingredient or any of the excipients in this combination product
• Pregnancy
• Breastfeeding 
• Severe renal impairment
• Second or third degree heart block
• Sick-sinus syndrome
• Bradycardia
• Uncontrolled heart failure
• Cardiogenic shock
• Intermittent claudication 
• Hypotension
• Severe peripheral arterial circulatory disturbances
• Metabolic acidosis
• Untreated phaeochromocytoma

Cautions  

• Mild to moderate renal impairment 
• Hepatic impairment 
• Poor cardiac reserve 
• Ischaemic heart disease 
• Peripheral arterial disease 
• Prinzmetal angina 
• First degree heart block 
• Thyrotoxicosis 
• Hypoglycaemia
• Abrupt withdrawal 
• History of anaphylaxis
• Bronchospastic disease 
• Diabetes mellitus 
• Gout
• Predisposition to uricaemia
• Patients at risk for hypokalaemia 

Forms avail. in SA and covered in this monograph: tab 

Hypertension

Atenolol/ Chlorthalidone
100/25 (mg)
50/12.5 (mg)

• Oral (tab): 1 tab, daily

---

Patients can be transferred to combination from other antihypertensive agents 

Not recommended for use in children below 18 years

Pregnancy

• Contraindicated
• Atenolol/ chlorthalidone tablets must not be given during pregnancy

Breastfeeding

• Contraindicated
• Atenolol/ chlorthalidone tablets must not be given during breastfeeding

Renal Impairment

• eGFR ≥30- 89 mL/min/1.73 m²: No dose adjustment is recommended
• eGFR ≥11- 29 mL/min/1.73 m²: Dose adjustment is recommended
• Limit maximum daily dose to 50mg/12.5mg, once daily
• eGFR ≤10 mL/min/1.73 m²: Contraindicated

Hepatic Impairment

• Caution; no dose adjustment recommended

Elderly

• Caution; no dose adjustment recommended 

Porphyria Information

• Not yet classified (NC)

Drugs in Sport

• Prohibited - At all times

Central Nervous System Disorders

• Dizziness
• Headache 
• Paraesthesia
• Sleep disturbance 
• Mood changes
• Nightmares
• Confusion 
• Psychosis 
• Hallucinations 
• Syncope 

Cardiovascular Disorders

• Bradycardia
• Heartblock
• Heart failure 
• Fatigue 
• Postural hypotension
• Intermittent claudication 

Respiratory Disorders

• Bronchospasm 

Gastrointestinal Disorders

• Nausea 
• Dry mouth
• Constipation 

Hepatobiliary Disorders

• Intrahepatic cholestasis
• Pancreatitis 

Genitourinary Disorders

• Impotence 

Endocrine and Metabolic Disorders

• Hyperuricaemia
• Hyponatraemia
• Hypokalaemia
• Impaired glucose tolerance
• Elevations of transaminase levels
• Increased in antinuclear antibodies (ANA)

Musculoskeletal Disorders

• Lupus-like syndrome  

Skin and Subcutaneous Tissue Disorders

• Alopecia
• Psoriasiform skin reaction
• Exacerbation of psoriasis
• Skin rashes

Immune, Blood and Lymphatic System Disorders

• Purpura
• Thrombocytopenia
• Neutropenia 
• Leucopenia

Sensory Disorders

• Dry eyes 
• Visual disturbances

• Dihydropyridines 
• Baclofen 
• Aminoglycoside 
• Indomethacin
• Anaesthetic agents
• Lithium 
• Immunosuppressants 
• Oral hypoglycaemic agents 
• Sympathomimetic agents
• Clonidine 
• Digoxin
• Class I antiarrhythmic agents
• Calcium channel blockers
• Ergotamine 
• Calcium hydroxide
• Aluminum hydroxide

• ECG
• Heart rate 
• Serum electrolytes 

Specific cases may require

• Renal function
• Hepatic function
• Glycaemic monitoring 

Atenolol
Atenolol is a beta-blocker, which acts preferentially on beta1-adrenergic receptors in the heart. It has negative inotropic effects resulting in reduction in heart rate, myocardial contractility, impulse conduction rate and adrenergic-induced renin release. As with other beta-blockers, the mode of action of atenolol in the treatment of hypertension is unclear.

Chlorthalidone
Chlorthalidone has a long acting diuretic with anti-hypertensive effect. It blocks the sodium-chloride co-transporter thereby preventing sodium and chloride reabsorption from the distal convoluted tubule of the nephron. This results in decreased extracellular fluid volume, cardiac output, total exchangeable sodium, glomerular filtration rate and renal plasma flow. Chlorthalidone has also been reported to act at the cortical diluting segment of the ascending limb of the loop of Henle. It increases renal prostacyclin, decreases renal vascular resistance and decreases responsiveness of the vasculature to noradrenaline and angiotensin II.

COMBINATION PREPARATIONS

Atenolol/ Chlorthalidone

Tablet 50mg/12.5mg

• Sandoz Co-Tenidone (Sandoz)
• Tenchlor HS (Pharmacare)
• Tenoret (AstraZeneca) originator

Tablet 100mg/25mg

• Sandoz Co-Tenidone (Sandoz)
• Tenchlor (Pharmacare)
• Tenoretic (AstraZeneca) originator