What is the dosing regimen for Nifedipine (calcium channel blocker) 10 mg orally for hypertension management?

Nifedipine 10 mg Oral Dosing

For immediate-release nifedipine 10 mg capsules, administer one capsule (10 mg) orally, which can be repeated every 20-30 minutes if needed, up to a maximum of 30 mg total for acute severe hypertension, though this formulation should generally be avoided in favor of extended-release preparations. 1

Critical Safety Warning

Immediate-release nifedipine capsules should NOT be used for routine hypertension management and are contraindicated without concomitant beta-blockade due to risk of adverse cardiovascular events. 2, 3 The capsule formulation has been associated with uncontrolled hypotension, particularly when combined with magnesium sulfate, resulting in fetal compromise. 1

Acute Severe Hypertension (Obstetric Emergency Context)

If you are treating severe hypertension in pregnancy (BP ≥160/110 mmHg):

• Administer 10 mg nifedipine orally (immediate-release, NOT extended-release) 1
• Repeat dose: Can give additional 10 mg every 20 minutes if BP remains ≥160/110 mmHg 1
• Maximum total dose: 30 mg within the first hour 1
• Goal: Reduce mean BP by 15-25%, targeting SBP 140-150 mmHg and DBP 90-100 mmHg 1
• Treatment must be initiated within 60 minutes of first severe BP reading 1

Important Caveats for Acute Use

• Avoid combining with magnesium sulfate due to risk of severe hypotension 1
• Close monitoring of maternal BP and fetal wellbeing is mandatory 1
• If immediate-release nifedipine is unavailable, consider 200 mg labetalol orally or 1.0-1.5 g methyldopa orally instead 1
• Intravenous labetalol or hydralazine are preferred alternatives when IV access is available 1

Chronic Hypertension Management

For chronic hypertension, do NOT use the 10 mg immediate-release formulation. 2, 3 Instead:

• Use extended-release nifedipine starting at 30 mg once daily 4
• Titrate over 7-14 days based on response 4
• Usual maintenance dose: 30-60 mg once daily 4
• Maximum dose: 90 mg daily (extended-release formulation can go up to 180 mg daily) 3, 4
• Administer on an empty stomach, swallow whole—do not bite or divide 4

Why the 10 mg Capsule Is Problematic

The immediate-release 10 mg capsule formulation causes:

• Unpredictable and excessive hypotension 1, 5
• Reflex tachycardia (heart rate increases from ~79 to 95 bpm) 6
• Poor adherence due to multiple daily dosing requirements 2
• Increased risk of adverse cardiovascular events without beta-blockade 2, 3

The British Hypertension Society explicitly states that "nifedipine in capsule form should no longer be prescribed." 1

Alternative Approach

If you have only 10 mg immediate-release capsules available for chronic use:

• This is suboptimal and should be avoided 1, 2
• If absolutely necessary in resource-limited settings, dosing would be 10-20 mg three times daily 5, 6
• Strongly recommend switching to extended-release formulation (30-90 mg once daily) as soon as possible 2, 4

Avoid Grapefruit Juice

Co-administration with grapefruit juice must be avoided as it significantly affects nifedipine metabolism. 4