Atechlor

• Hypertension:
• Treatment of essential hypertension to lower blood pressure and reduce risk of cardiovascular events.
• Used in patients requiring combination therapy when monotherapy is insufficient.
• Off-label/Additional uses:
• May be used in managing angina pectoris due to atenolol’s beta-blocking effects.
• Occasionally used in patients with edema associated with hypertension (chlorthalidone component).

• Adults:
• Typical fixed-dose tablet strengths include atenolol 50 mg + chlorthalidone 12.5 mg or atenolol 100 mg + chlorthalidone 25 mg.
• Initial dose usually atenolol 50 mg + chlorthalidone 12.5 mg once daily.
• Dose may be adjusted based on blood pressure response, generally up to atenolol 100 mg + chlorthalidone 25 mg once daily.
• Pediatrics:
• Safety and efficacy not established; use generally not recommended.
• Elderly:
• Initiate at lower doses; monitor renal function and electrolyte levels closely.
• Renal Impairment:
• Caution advised; dose adjustment or alternative therapy may be necessary.
• Hepatic Impairment:
• No specific adjustment for mild/moderate impairment; monitor carefully in severe cases.
• Administration:
• Oral tablets, taken once daily, with or without food.
• Swallow tablets whole; maintain consistent timing daily.

Atenolol is a selective beta-1 adrenergic receptor blocker that decreases heart rate, myocardial contractility, and cardiac output, lowering blood pressure and myocardial oxygen demand. Chlorthalidone is a thiazide-like diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubules of the nephron, promoting diuresis and reducing plasma volume, which decreases peripheral vascular resistance. The combination provides complementary antihypertensive effects via cardiac and vascular mechanisms.

• Atenolol:
• Absorption: Rapid, bioavailability ~50%.
• Distribution: Low lipid solubility; moderate volume of distribution.
• Metabolism: Minimal hepatic metabolism; primarily excreted unchanged by kidneys.
• Half-life: Approximately 6–7 hours.
• Chlorthalidone:
• Absorption: Well absorbed orally with peak plasma levels in 2–6 hours.
• Distribution: High protein binding (~90%).
• Metabolism: Not metabolized; excreted unchanged.
• Half-life: Long elimination half-life (~40–60 hours), supporting once-daily dosing.
• Elimination: Both drugs are mainly eliminated renally.

• Pregnancy:
• Atenolol: Category D (FDA) — risk of fetal growth retardation and bradycardia.
• Chlorthalidone: Category B — limited human data; potential for fetal electrolyte disturbances.
• Combination use during pregnancy is generally not recommended; use only if benefits outweigh risks.
• Lactation:
• Atenolol is excreted in breast milk; potential for infant bradycardia and hypoglycemia.
• Chlorthalidone also excreted in milk; caution advised.
• Breastfeeding not generally recommended during therapy.

• Atenolol: Beta-1 selective beta-blocker (cardioselective)
• Chlorthalidone: Thiazide-like diuretic
• Combination: Antihypertensive agent

• Known hypersensitivity to atenolol, chlorthalidone, or formulation excipients.
• Severe bradycardia (<45 bpm), second- or third-degree heart block without pacemaker.
• Cardiogenic shock, decompensated heart failure.
• Anuria or severe renal impairment without dialysis.
• Hypokalemia or hyponatremia (untreated).
• Gout or history of hypersensitivity to sulfonamide-derived drugs (chlorthalidone).

• Monitor blood pressure, heart rate, and electrolyte levels regularly.
• Use cautiously in patients with diabetes; atenolol may mask hypoglycemia symptoms; chlorthalidone can cause glucose intolerance.
• Risk of electrolyte imbalance (hypokalemia, hyponatremia, hypomagnesemia) with chlorthalidone; monitor serum electrolytes.
• Caution in patients with peripheral vascular disease, hepatic impairment, or history of gout.
• Do not abruptly discontinue atenolol; gradual tapering recommended to prevent rebound hypertension or angina.
• Avoid use in severe renal impairment unless on dialysis.

• Common:
• Dizziness, fatigue, headache (atenolol).
• Increased urination, electrolyte disturbances, hypotension (chlorthalidone).
• Cardiovascular:
• Bradycardia, hypotension, heart block (atenolol).
• Metabolic:
• Hyperuricemia, hyperglycemia, hypokalemia (chlorthalidone).
• Gastrointestinal:
• Nausea, vomiting, abdominal discomfort.
• Rare/Serious:
• Severe bradyarrhythmias, electrolyte imbalance, hypersensitivity reactions.

• Additive hypotensive effects with other antihypertensives, calcium channel blockers, and nitrates.
• Increased risk of bradycardia with digoxin and other negative chronotropes.
• NSAIDs may reduce antihypertensive efficacy and increase risk of renal impairment.
• Chlorthalidone may potentiate the effects of lithium, increasing toxicity risk.
• Atenolol may mask signs of hypoglycemia in diabetic patients on insulin or oral hypoglycemics.

• Combination therapy with beta-blocker and diuretic recognized as effective for hypertension when monotherapy insufficient.
• Recent hypertension guidelines favor individualized treatment; beta-blockers typically second-line except with specific indications (e.g., post-MI).
• Emphasis on monitoring metabolic side effects and electrolyte disturbances during therapy.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture, heat, and light.
• Keep tablets in original packaging tightly closed.
• Keep out of reach of children.