To assess the effect of food on the bioavailability of 3 mg cytisinicline following single-dose administration, and to evaluate the PK profile of 3 mg cytisinicline TID following multiple days of administration during Days 5-8.

Inclusion Criteria:

1. Free written informed consent prior to any procedure required by the study.

2. Willingness to accept and comply with all study procedures and restrictions.

3. Male or female subject ≥ 18 years, at the date of signing the informed consent.

4. Regular moderate combustible cigarette smokers (self-reported average of at least 10 cigarettes per day).

5. Body mass index (BMI) of 18.0 to 30.0 kg/m^2, inclusive.

6. Healthy subject, based on medical history, physical examination, vital signs, ECG and clinical laboratory tests.

7. Negative test results for anti-human immunodeficiency virus 1 and 2 antibodies (anti-HIV-1Ab and anti-HIV-2Ab), Hepatitis B surface antigen (HBsAg) and anti-hepatitis C virus antibodies (anti-HCVAb).

8. A female subject is eligible if she also meets one of the following criteria:

   1. is of non-childbearing potential (underwent a permanent sterilization method [eg, hysterectomy, bilateral salpingectomy or bilateral oophorectomy], is clinically diagnosed infertile, or is in a post-menopausal state); or
   2. is of childbearing potential and agrees to use an accepted contraceptive method from at least 4 weeks prior to admission and until at least 4 weeks after the last dose administration (Day 8).

Exclusion Criteria:

AT SCREENING

1. Known hypersensitivity/allergic reaction to cytisinicline or any of the excipients.

2. Known severe hypersensitivity reaction to any other drug.

3. Any medical condition (eg, gastrointestinal, renal or hepatic, including peptic ulcer, inflammatory bowel disease or pancreatitis) or surgical condition (eg, cholecystectomy, gastrectomy) that may affect drug pharmacokinetics (absorption, distribution, metabolism or excretion) or subject safety.

4. Stroke or acute myocardial infarction within the previous 3 months.

5. History of hyperthyroidism.

6. History of psychosis or of a psychotic event.

7. Estimated renal creatinine clearance (CLCr) below the lower limit of the normal range (ie, 90-120 mL/min/1.73 m^2 for males and 80-110 mL/min/1.73 m^2 for females), based on creatinine clearance calculation by the Cockcroft-Gault formula and normalized to an average body surface area of 1.73 m^2.

8. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) above the upper limit of the normal (ULN) range.

9. Positive result in urine drugs-of-abuse or ethanol tests at Screening.

10. Excessive caffeine consumption, defined as ≥ 800 mg per day.

11. Veins unsuitable for intravenous puncture on either arm (eg, veins that are difficult to locate, access or puncture; veins with a tendency to rupture during or after puncture).

12. Participation in any clinical trial within the previous 2 months.

13. Use of any smoking cessation medications such as cytisinicline, bupropion, varenicline, nortriptyline, or any nicotine replacement therapy (NRT; eg, nicotine patch, nicotine chewing gum, or electronic cigarettes) in the previous 8 weeks.

14. Participation in more than 2 clinical trials within the previous 12 months.

15. Blood donation or significant blood loss (≥ 450 mL) due to any reason or had plasmapheresis within the previous 2 months.

16. Female subjects who are lactating or pregnant by serum pregnancy test.

17. Any other condition that the investigator considers the subject to be unsuitable for the study.

    AT ADMISSION

18. Any recent disease or condition or treatment that, according to the investigator, would put the subject at undue risk due to study participation or occurred at a time frame in which may interfere with the pharmacokinetics of study drug.

19. Use of any medicinal products, prescription and non-prescription (including vitamins, food supplements, herbal supplements [including St John's Wort]), in the previous 2 weeks, unless in the investigator's opinion the medication does not interfere with the pharmacokinetics of study drug or compromise subject safety.

    NOTE: The use of topical products without systemic absorption, acetaminophen (paracetamol) at doses of ≤ 2 grams/day, and hormonal contraceptives are acceptable.

20. Use of any smoking cessation medications (eg, cytisinicline, bupropion, varenicline, nortriptyline, or any NRT eg, nicotine patch, nicotine chewing gum, or electronic cigarettes) since Screening.

21. Positive result in drugs-of-abuse or ethanol tests.

22. If female, positive pregnancy test in urine.

23. Any other condition that the investigator considers to render the subject unsuitable for the study.