This research study is looking into the effects of clavulanic on smoking behavior in adult cigarette smokers. The primary study hypothesis is that, compared to placebo, clavulanic acid will reduce smoking over the course of the study.

Entry criteria:

Inclusion Criteria all subjects:

1. Age 18-65 years
2. English fluency
3. Functional vision (with corrective lenses as needed) to complete assigned assessments and tasks
4. Smoke > 10 cigarettes/day for a minimum of 2 yrs. and have an expired carbon monoxide (CO) concentration of ≥ 10 ppm (to confirm inhalation at screening and scanning)
5. If female, provide a negative urine pregnancy test.
6. Agrees to refrain from all other tobacco (i.e., dip/chew, cigars, cigarillos) and/or nicotine products (i.e., e-cigs, patches, gum/lozenges, inhalers/sprays) for the duration of study participation

Exclusion Criteria all subjects:

1. Sensitivity or allergy to clavulanic acid/antibiotics
2. Past head injury or primary neurological disorder associated with MRI abnormalities, including dementia, MCI, brain tumors, epilepsy, Parkinson's disease, or demyelinating diseases
3. Any physical or intellectual disability affecting completion of assessments
4. Any contraindication to MRI
5. Use of antidepressants medications with smoking cessation efficacy
6. Presence of an untreated illness or serious medical condition
7. Current or past psychosis
8. Electroconvulsive therapy in last 6 months
9. Positive pregnancy test (Urine pregnancy testing at screening and prior to fMRI scan) or currently breast feeding or BAC greater than 0.0
10. Use of carbamazepine or nitroglycerin (or any other medication deemed to be hazardous if taken with CLAV) within 14 days of study participation
11. Abnormal liver function determined by Complete Metabolic Panel - liver enzymes outside normal ranges of AST (SGOT) 5-40 unites/L and ALT( SGPT) 7-56units/L
12. Abnormal renal function determined by Complete Metabolic Panel - outside normal ranges of BUN 6-24 mg /dl and Creatinine level 0.6 -1.2 mg /dl male, 0.5-1.1mg /dl female
13. Any other condition or concern that in the investigator's opinion would impact participant safety, compliance with study instructions, or potentially confound the interpretation of the study results