What is the initial dose of amlodipine (calcium channel blocker) and chlorthalidone (thiazide-type diuretic) for a patient with severely elevated blood pressure (hypertension)?

Initial Dosing of Amlodipine and Chlorthalidone for Severely Elevated Blood Pressure (190/110 mmHg)

For a patient with severely elevated blood pressure of 190/110 mmHg, initiate treatment with amlodipine 5 mg once daily and chlorthalidone 25 mg once daily as initial combination therapy. 1, 2, 3

Rationale for Combination Therapy

• For patients with stage 2 hypertension (≥160/100 mmHg), initial pharmacologic treatment with two antihypertensive medications from different classes is recommended to more effectively achieve adequate blood pressure control 1
• A blood pressure of 190/110 mmHg represents severe hypertension requiring prompt intervention with combination therapy rather than monotherapy 1
• For very high average BP (e.g., SBP ≥180 mmHg or DBP ≥110 mmHg), prompt antihypertensive drug treatment with combination therapy is recommended 1

Specific Dosing Recommendations

Amlodipine (Calcium Channel Blocker)

• Initial dose: 5 mg once daily 2
• For elderly, fragile patients, or those with hepatic insufficiency, a lower starting dose of 2.5 mg may be considered 2
• Maximum dose: 10 mg once daily 2

Chlorthalidone (Thiazide-type Diuretic)

• Initial dose: 25 mg once daily 3
• Taken in the morning with food 3
• May be increased to 50 mg daily if response is insufficient after an adequate trial period 3

Special Considerations for African American Patients

• In Black patients, initial antihypertensive treatment should include a thiazide-type diuretic (such as chlorthalidone) or a calcium channel blocker (such as amlodipine) 1
• The ALLHAT trial demonstrated that in Black hypertensive patients, diuretic-based treatment with chlorthalidone resulted in better outcomes compared to ACE inhibitor-based treatment 4
• For Black patients from Sub-Saharan Africa, combination therapy including a CCB combined with either a thiazide diuretic or a RAS blocker should be considered 1

Follow-up and Monitoring

• Evaluate BP control within 1 month after initiating therapy for stage 2 hypertension 1
• Monitor for potential adverse effects:
  • With amlodipine: peripheral edema, headache, and reflex tachycardia 1
  • With chlorthalidone: hyponatremia, hypokalemia, elevated uric acid and calcium levels 1
• Adjust dosage according to blood pressure goals, typically waiting 7 to 14 days between titration steps 2

Treatment Algorithm for Severe Hypertension

1. Initial therapy: Amlodipine 5 mg + Chlorthalidone 25 mg daily 1, 2, 3
2. If BP remains uncontrolled after 1 month: Consider increasing to amlodipine 10 mg and/or chlorthalidone 50 mg 2, 3
3. If still uncontrolled: Add a third agent, typically a RAS blocker (ACE inhibitor or ARB) 1
4. For resistant hypertension: Consider adding spironolactone or other agents 1

Target Blood Pressure

• The recommended target systolic BP for most adults is 120-129 mmHg, provided the treatment is well tolerated 1
• If this target cannot be achieved due to poor tolerance, aim for the lowest reasonably achievable BP (ALARA principle) 1

Clinical Pearls and Pitfalls

• Fixed-dose single-pill combinations improve adherence and are recommended when possible 1
• Avoid combining two RAS blockers (ACE inhibitor and ARB) as this is not recommended 1
• For African American patients, the combination of amlodipine and chlorthalidone is particularly effective 1, 4
• In the ALLHAT trial, only 24-28% of patients achieved BP control on monotherapy, highlighting the importance of combination therapy 5