initial dose:

5

mg

Orally 

once a day

Maintenance dose: 10 mg orally once a day after 2 to 4 weeks of the initial dose

Chronic:

500

mg

Tablet

Oral

twice a day

increase to 1000 mg tablet twice a day only if needed

(Off-label)
indicated for Chronic Stable Angina:

15 - 40

mg/day

Orally 

dose divided every 4 hours

Indicated for Angina

Immediate release-80 mg orally three times a day initially, usual dose range 80-120 mg orally three times a day. It should not exceed 480 mg daily.
Extended-release(Covera-HS)- 180 mg every day orally at bedtime as an initial dose.
Maintenance dose-180-540 mg every day orally at bedtime.

Paroxysmal Supraventricular Tachycardia and Chronic Atrial Fibrillation

Immediate release-240-480 mg every day orally in divided doses three-four times a day.
Atrial Fibrillation or Flutter and Supraventricular Arrhythmia
2.5-5 mg intravenously over 2 min; after 15-30 min, 5-10 mg dose may be repeated.
Or

0.075-0.15mg/kg (should not exceed 10 mg) intravenously over 2 min; after 30 min, the dose may be repeated.
Tardive Dyskinesia
40 mg orally three times a day may enhance the dose up to 120 mg three times a day.
Migraine as off-label
As prophylaxis 160-320 mg orally three-four times a day.
Hypertension
Immediate release
Initial dose:80 mg orally three times a day.
Maintenance dose: 80-320 mg orally two times a day.
Extended-release
Isoptin SR, Calan-180 mg every day orally in the morning (if the patient is elderly,120 mg every day); for desired therapeutic response, the dose may enhance to 240 mg every day and then 360 mg every day (i.e., 180 mg two times a day or 240 mg at morning time and 120 mg at evening time)
Verelan-180 mg every day orally in the morning (if the patient is elderly,120 mg every day); for desired therapeutic response, the dose may enhance to 240 mg every day and then 120 mg every day at weekly intervals, should not exceed 480 mg every day.
Covera-HS-180 mg every day orally at bedtime (if the patient is elderly,120 mg every day); for desired therapeutic response, the dose may enhance to 240 mg every day and then 120 mg every day at weekly intervals, should not exceed 480 mg every day.
Verelan PM-200 mg every day orally at bedtime (if the patient is elderly,100 mg every day); the dose may be enhanced by 100 mg every day at weekly intervals, and should not exceed 400 mg every day.

Take 20 to 40 mg orally every 8 hours
Start at 20 mg, and allow three days between dose raise to achieve steady-state plasma drug concentration
General daily dose range be 60 to 120 mg
Dosing Modifications
Renal impairment
Take a dose of 20 mg as immediate release orally every 8 hour initially and titrated in every three days
Take a dose of 30 mg as extended release orally every 12 hours initially and titrated in every three days
Use cautiously as intravenously
Hepatic impairment
Take a dose of 20 mg as immediate release orally every 12 hour initially and titrated in every three days
Daily immediate-release dose, may be not equivalent to daily extended-release dose
Use cautiously as intravenously
Pitt-Hopkins Syndrome (Orphan)
Orphan designation for treatment of Pitt-Hopkins Syndrome

Indicated for chronic stable angina
100 mg orally every day
Depending on the plasma levels, adjust the dosage at two to four weeks intervals
The Maximum dosage is 300 mg to 400 mg in a day in divided doses

Indicated for Angina

Immediate release-80 mg orally three times a day initially, usual dose range 80-120 mg orally three times a day. It should not exceed 480 mg daily.
Extended-release (Covera-HS)- 180 mg every day orally at bedtime as an initial dose.
Maintenance dose-180-540 mg every day orally at bedtime.
Hypertension
Immediate release
Initial dose:80 mg orally three times a day.
Maintenance dose: 80-320 mg orally two times a day.
Extended-release
Verelan PM-100 mg every day orally at bed time.
Covera-HS-180 mg every day orally at bed time.
Isoptin SR, Calan SR, Verelan-120 mg every day orally in the morning.
Note:
Generally, low doses are warranted, and based on clinical response dose may be adjusted.