Usage
Atenolol + Losartan is prescribed for the treatment of hypertension (high blood pressure). It is also used to reduce the risk of cardiovascular events such as heart attack and stroke, and to protect kidneys from damage, especially in patients with diabetes. This combination belongs to the pharmacological class of antihypertensives. The mechanism of action involves two components: Atenolol, a beta-blocker, reduces heart rate and cardiac output; Losartan, an angiotensin II receptor blocker (ARB), blocks the vasoconstricting effects of angiotensin II, leading to vasodilation.
Alternate Names
No internationally recognized alternate names exist for this specific combination. However, the individual components are known by their generic names: Atenolol and Losartan potassium. Brand names vary depending on the manufacturer and region.
How It Works
Pharmacodynamics: Atenolol, a beta-1 selective adrenergic receptor blocker, decreases heart rate, myocardial contractility, and cardiac output, thereby lowering blood pressure. Losartan, an ARB, blocks the binding of angiotensin II to its receptor, preventing vasoconstriction and the release of aldosterone. This leads to vasodilation and decreased sodium and water retention, further contributing to blood pressure reduction.
Pharmacokinetics:
- Atenolol: Well absorbed orally, but bioavailability is approximately 50% due to first-pass metabolism. Not extensively metabolized by the liver. Primarily excreted unchanged in the urine. Half-life is 6-9 hours.
- Losartan: Orally absorbed, but undergoes first-pass metabolism to its active metabolite, EXP3174, which is more potent than losartan. Highly bound to plasma proteins. Metabolized by CYP2C9 and CYP3A4. Eliminated primarily in the urine and feces as metabolites. Half-life is 2 hours, while EXP3174 has a half-life of 6-9 hours.
Mode of Action:
- Atenolol: Binds to beta-1 adrenergic receptors in the heart, blocking the effects of catecholamines like norepinephrine and epinephrine.
- Losartan: Competitively binds to angiotensin II type 1 (AT1) receptors, preventing angiotensin II from binding and exerting its effects.
Elimination Pathways: Atenolol is primarily excreted unchanged by the kidneys. Losartan is metabolized by CYP2C9 and CYP3A4 and eliminated as metabolites in urine and feces.
Dosage
Standard Dosage
Adults:
Initially, 50 mg of Losartan and 50 mg of Atenolol are administered orally once a day. The dosage may be increased to 100 mg of each drug once a day, depending on blood pressure response.
Children:
Not recommended for children under 6 years of age. Limited data are available, and dosage should be determined by a doctor based on the child’s weight and condition.
Special Cases:
- Elderly Patients: Initial dose of 25mg of Atenolol is usually recommended, and may be increased according to blood pressure control and tolerability. No dosage adjustment is usually necessary for Losartan.
- Patients with Renal Impairment: Dose adjustment may be necessary for both Atenolol and Losartan in patients with renal dysfunction depending upon creatinine clearance.
- Patients with Hepatic Dysfunction: Caution should be exercised when administering Atenolol and Losartan to patients with hepatic impairment, especially in severe cases.
- Patients with Comorbid Conditions: Dosage adjustments may be required based on coexisting medical conditions like diabetes, heart failure, and other cardiovascular diseases.
Clinical Use Cases
Dosage adjustments for procedures like intubation, surgical procedures, mechanical ventilation, and ICU use should be made on a case-by-case basis considering hemodynamic status and individual patient factors. In emergency situations such as acute hypertensive crisis, intravenous antihypertensives are typically preferred for rapid blood pressure control.
Dosage Adjustments
Dose modifications are necessary based on patient-specific factors such as renal and hepatic function, other medications, and response to therapy.
Side Effects
Common Side Effects
Dizziness, lightheadedness, fatigue, headache, nausea, diarrhea, cold extremities, slow heart rate, and low blood pressure.
Rare but Serious Side Effects
Severe allergic reactions (angioedema), worsening heart failure, bradycardia, bronchospasm, and liver dysfunction.
Long-Term Effects
Electrolyte imbalances, particularly hyperkalemia.
Adverse Drug Reactions (ADR)
Severe hypotension, bradycardia requiring intervention, angioedema, and acute renal failure.
Contraindications
Second or third-degree heart block, severe bradycardia, cardiogenic shock, decompensated heart failure, severe hypotension, and hypersensitivity to either Atenolol or Losartan.
Drug Interactions
Atenolol can interact with other antihypertensive medications, calcium channel blockers, and digoxin. Losartan can interact with potassium supplements, potassium-sparing diuretics, NSAIDs, and lithium. Both drugs can interact with other drugs metabolized by CYP2C9 and CYP3A4.
Pregnancy and Breastfeeding
Atenolol + Losartan is contraindicated during pregnancy, particularly in the second and third trimesters, due to the risk of fetal harm. Atenolol and Losartan are excreted in breast milk. Use during breastfeeding is not recommended.
Drug Profile Summary
- Mechanism of Action: Atenolol: Beta-blocker; Losartan: ARB.
- Side Effects: Dizziness, fatigue, headache, hypotension, bradycardia.
- Contraindications: Heart block, bradycardia, heart failure, pregnancy.
- Drug Interactions: Other antihypertensives, digoxin, potassium supplements, NSAIDs.
- Pregnancy & Breastfeeding: Contraindicated.
- Dosage: 50-100 mg each, once daily; adjust based on patient factors.
- Monitoring Parameters: Blood pressure, heart rate, renal function, potassium levels.
Popular Combinations
Atenolol + Losartan is itself a combination. Adding hydrochlorothiazide (a thiazide diuretic) is a common practice to enhance blood pressure control.
Precautions
Monitor renal function, electrolyte levels (potassium), and blood glucose in diabetic patients. Use caution in patients with asthma or COPD, peripheral artery disease, or Raynaud’s phenomenon. Monitor patients for signs of heart failure.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Atenolol + Losartan?
A: The initial dose is 50 mg of each component once daily. This may be increased to 100 mg of each, once daily, depending on blood pressure control and tolerability.
Q2: Can Atenolol + Losartan be used in patients with asthma?
A: Atenolol should be used with caution in asthmatic patients as it may trigger bronchospasm. Losartan is generally safe in asthmatics.
Q3: How does this combination affect potassium levels?
A: Both atenolol and losartan can increase potassium levels. Monitor potassium levels, especially in patients with renal impairment or taking other drugs affecting potassium levels.
Q4: Can this medication be abruptly stopped?
A: Abrupt discontinuation, especially of atenolol, may lead to rebound hypertension or angina. Taper down the dose gradually under medical supervision.
Q5: Is this combination safe in pregnancy?
A: No. It is contraindicated in pregnancy, especially during the second and third trimesters, due to the risk of fetal harm.
Q6: Are there any dietary restrictions with this medication?
A: Patients should maintain a healthy diet low in sodium. Monitor potassium intake, especially if also taking potassium supplements or potassium-sparing diuretics.
Q7: Can I take this medication if I have diabetes?
A: Yes, it can be used in patients with diabetes. However, monitor blood glucose levels as atenolol can mask the symptoms of hypoglycemia.
Q8: What should I do if I miss a dose?
A: Take the missed dose as soon as you remember, unless it is almost time for your next dose. Do not take two doses at the same time.
Q9: How long does it take for this medication to work?
A: It may take several weeks to achieve maximum blood pressure lowering effects.
Q10: What are the signs of an allergic reaction to this medication?
A: Swelling of the face, lips, tongue, or throat; difficulty breathing; hives; and rash. Seek immediate medical attention if these occur.
