A Study to Investigate the Potential Interaction Between Telaprevir and Methadone, at Steady-State

Inclusion Criteria: * Must receive once daily oral methadone maintenance therapy at a stable individualized dose of 30 to 130 mg for at least 2 weeks prior to screening, formulated as commercially available tablets or solution * Must agree not to change the current methadone dose from screening until Day 7 included to have a daily observed and documented methadone intake from Day -14 until Day 8 and a daily observed and documented telaprevir intake from Day 1 until Day 7 * Participants have to obtain approval for participation from his/her addiction physician, and the addiction physician has to agree to provide medical care for the participant after discharge from study center * General medical condition must not interfere with the assessments and the completion of the study * Health assessments will be done on the basis of physical examination, medical history, electrocardiogram, vital signs and the results of blood biochemistry, blood coagulation and hematology tests and a urinalysis carried out at screening Exclusion Criteria: * History of any illness that could confound the results of the study or pose an additional risk in administering study medication to the participant, for eg, history of relevant medication or food allergies, history of cardiovascular or central nervous system disease, history or presence of clinically significant pathology or history of mental disease * Consumption of herbal medications or dietary supplements, vitamins, and grapefruit or grapefruit juice, apple juice or orange juice within 14 days before Day -1 * Current alcohol use, which, in the assessment of the investigator, could compromise participant's safety or compliance with the study protocol procedures * Test positive for drugs of abuse such as cocaine, amphetamines, barbiturates, benzodiazepines, or opiates on Day -2 unless explained by allowed concomitant medications * Participation in a clinical study involving administration of an investigational medication within 60 days or 5 half-lives (whichever was longer) prior to the screening visit