The objective was to estimate the annual interaction management cost of agonist opioid treatment (AOT) for opioid-dependent (OD) patients with buprenorphine-naloxone (Suboxone®) (B/N) or methadone associated with concomitant treatments for infectious (HIV) or psychiatric comorbidities. A costs analysis model was developed to calculate the associated cost of AOT and interaction management. The AOT cost included pharmaceutical costs, drug preparation, distribution and dispensing, based on intake regimen (healthcare center or take-home) and type and frequency of dispensing (healthcare center or pharmacy), and medical visits. The cost of methadone also included single-dose bottles, monthly costs of custody at pharmacy, urine toxicology drug screenings and nursing visits. Potential interaction…