Effective dosage: Usual Dosage for Adults: The recommended and maximum dose is 300 mg/day, given as 150 mg twice daily. Dosing should begin at 150 mg once daily for the first 3 days, followed by a dose increase to the recommended usual dose of 300 mg/day as necessary. There should be an interval of at least 8 hours between successive doses. Doses above 300 mg/day should not be used.

Effective dosage: It is taken orally. For the first three days, the dosage is 0.5 mg once daily. For days four to seven, the dosage is 0.5 mg twice a day. From day eight until the end of the treatment, the dose is 1 mg twice a day. You should set a date to quit smoking, and start taking the drug one week before this date.