Initial Dosing of Angiotensin Receptor Blockers (ARBs)
ARBs should be initiated at low doses and gradually titrated upward, with candesartan starting at 4-8 mg once daily, valsartan at 40 mg twice daily, and other ARBs at their respective low starting doses to minimize the risk of first-dose hypotension, renal dysfunction, and hyperkalemia. 1, 2
Starting Doses for Common ARBs
ARBs should be initiated at the following starting doses:
| ARB | Initial Dose | Target/Maximum Dose |
|---|---|---|
| Candesartan | 4-8 mg once daily | 32 mg once daily |
| Valsartan | 40 mg twice daily | 160 mg twice daily |
| Losartan | 50 mg once daily | 100 mg once daily |
| Irbesartan | 150 mg once daily | 300 mg once daily |
| Telmisartan | 40 mg once daily | 80 mg once daily |
| Olmesartan | 20 mg once daily | 40 mg once daily |
| Azilsartan | 40 mg once daily | 80 mg once daily |
Special Considerations for Initiation
Patient Monitoring
- Assess blood pressure (including postural changes), renal function, and serum potassium within 1-2 weeks after initiation 1
- Follow closely after any dose changes
- Monitor more frequently in high-risk patients
High-Risk Patients Requiring Extra Caution
- Patients with systolic blood pressure below 80 mmHg
- Low serum sodium
- Diabetes mellitus
- Impaired renal function
- Elderly patients
- Patients on diuretics (potential volume depletion)
Hepatic Impairment
- For patients with moderate hepatic insufficiency, start with lower doses (e.g., candesartan 8 mg) 2
- No specific dosing recommendations available for severe hepatic impairment
Dose Titration Protocol
- Start with the initial dose as recommended above
- Reassess blood pressure, renal function, and potassium after 1-2 weeks
- If well tolerated with inadequate blood pressure response, double the dose every 2-4 weeks 1
- Aim for target doses shown to reduce cardiovascular events in clinical trials
- If maximum doses are not tolerated, maintain at highest tolerated dose
Clinical Pearls and Pitfalls
Advantages of ARBs
- Similar efficacy to ACE inhibitors in reducing morbidity and mortality in heart failure with reduced ejection fraction 1
- Lower incidence of cough and angioedema compared to ACE inhibitors 1
- Excellent alternative for patients intolerant to ACE inhibitors 1
Common Pitfalls to Avoid
- Starting with too high a dose, especially in volume-depleted patients
- Failure to monitor renal function and potassium after initiation
- Combining ARBs with ACE inhibitors (increased risk of adverse effects without additional benefit) 1
- Combining ARBs with aliskiren in diabetic patients (contraindicated) 2
- Inadequate dose titration (many patients remain on suboptimal doses)
Specific Situations
- For heart failure: Start with lower doses (e.g., candesartan 4 mg once daily) and double the dose at approximately 2-week intervals to target dose of 32 mg once daily 2
- For hypertension with diabetes and albuminuria: ARBs are recommended first-line therapy 1
- For stable patients: Consider adding beta-blockers before reaching full target doses of ARBs 1
By following these dosing guidelines and monitoring protocols, clinicians can safely initiate ARB therapy while minimizing the risk of adverse effects and optimizing cardiovascular outcomes.