This three-group randomized double-blind placebo-controlled trial (N=180) will evaluate the impact of combination zonisamide and bupropion on the process of switching from combustible cigarettes (CCs) to an e-cigarette. There will be a data collection period of at least five days to obtain baseline information on the use of combustible cigarettes. All participants enrolled in the study will receive a JUUL e-cigarette at Visit 2 for ad libitum use. After the first week of e-cigarette use (at Visit 3), participants will be given bupropion (150 mg each morning for days 1-3, then 300 mg daily) with either zonisamide (100 mg daily) or placebo (group 1 and group 2 respectively), or placebo for both medications (group 3) in addition to continued use of the e-cigarette. At each visit, participants will receive enough study drugs (or placebos) and e-cigarettes to last until their next study visit. The combination of zonisamide and bupropion use will continue until Visit 6 (7 weeks of treatment), and e-cigarette use will continue until the end of treatment (Visit 7).

Inclusion Criteria:

1. Has signed the ICF and is able to read and understand the information provided in the ICF.
2. Is 21 to 65 years of age (inclusive) at screening.
3. Smokes at least 10 commercially available cigarettes per day (no brand restrictions), for the last 12 months.
4. Has an expired air CO reading of at least 10 ppm at screening.
5. Is interested in switching to an electronic cigarette.
6. Is willing and able to comply with the requirements of the study.
7. Owns a smartphone with text message and data capabilities compatible with necessary surveys.

Exclusion Criteria:

1. Is unhealthy or cannot participate in the study for any reason (e.g., medical, psychiatric, and/or social reason) as judged by the Investigator or designated medical staff based on all available assessments from the screening period (e.g., safety laboratory, vital signs, physical examination, ECG, concomitant medications and medical history).

2. Has a PHQ-9 score greater than 9, or a score greater than 0 on item #9 ("Thoughts that you would be better off dead, or of hurting yourself in some way") at screening.

3. Has plans to use an FDA-approved smoking cessation product during the study.

4. Has high blood pressure (systolic > 150 mmHg or diastolic >95 mmHg) at screening.

5. Has body mass index (BMI) less than 15.0 kg/m2 or greater than 40.0 kg/m2.

6. Has coronary heart disease, structural cardiac disease (including, but not limited to valvular heart disease or cardiac murmurs), cardiac dysrhythmias, syncope, cardiac chest pain, or history of heart attack or heart failure.

7. Has received psychotherapy or behavioral treatments potentially impacting symptoms of depression, anxiety, or nicotine withdrawal within 30 days of screening, or during the study.

8. Is taking antidepressants, psychoactive medications (e.g. antipsychotics, benzodiazepines, hypnotics) or medications that prolong QTc.

9. Has used any of these products in the past 30 days:

   1. Illegal drugs (or if the urine drug screen is positive for cocaine, THC, amphetamines, methamphetamines, or opiates);
   2. Experimental (investigational) drugs that are unknown to participant;
   3. Chronic opiate use.

10. Has used smokeless tobacco (chewing tobacco, snuff), cigars (except for "Black & Mild" cigars or Cigarillos), pipes, hookah, e-cigarettes, nicotine replacement therapy or other smoking cessation treatments within 14 days of screening.

11. Has a plan to use an FDA-approved quit-smoking treatment in the next 30 days.

12. Is pregnant or nursing (by self-report) or has a positive pregnancy test.

13. Enrollment requirements met.