You have received some good discussions about this question. Here is another angle to consider.

A blood pressure of 124/79 is basically normal, and this number alone is not a reason to skip your next dose of 120 mg diltiazem. In most cases, you should take it as prescribed unless your doctor told you to hold doses for certain blood pressure limit.

1. Diltiazem is prescribed for:

Heart rhythm control (AFib, SVT).

Blood pressure control.

Chest pain (angina):

Because of this, doctors usually want the dose taken regularly, even when BP looks normal.

2. When doctors usually tell patients to hold diltiazem:

Sometimes a prescriber will say:

“Hold if systolic < 100”

“Hold if heart rate < 55–60”.
But this must be specifically ordered.

A blood pressure of 124/79 does not meet the typical “hold” criteria.

3. What does matter is your heart rate.

Diltiazem can slow the heart.
If your HR is below 50–55, you should double-check before taking it.

4. When to contact your doctor:

Call your prescriber if:

You’re feeling dizzy, faint, weak, or unusually tired.

Your systolic BP is consistently below ~100.

Your HR is consistently below 55.

Bottom line:

Based on a BP of 124/79, most doctors would say to take the next 120 mg diltiazem dose as scheduled, unless you were specifically instructed otherwise.

Diltiazem is supplied in several oral formulations and strengths:

Immediate-release tablets: 30 mg, 60 mg, 90 mg, and 120 mg.

Extended-release capsules (once-daily or twice-daily dosing, various brand names like Cardizem CD, Cartia XT, Tiazac): 60 mg, 90 mg, 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, and 420 mg.

Extended-release tablets (once-daily dosing, e.g., Cardizem LA, Matzim LA): 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, and 420 mg.

The above information is based on an authentic study with diltiazem 120 mgs.