This is a drug-drug interaction study in volunteers to evaluate the effect of ritonavir or cobicistat on the pharmacokinetics (PK) of PBI-200.

This is an open-label, single-sequence, three-period drug-drug interaction study in healthy male and female volunteers to evaluate the effect of a potent CYP3A inhibitor, ritonavir or cobicistat, on the single dose PK of orally administered PBI-200. It is expected that co-administration of ritonavir or cobicistat with PBI-200 will increase the exposure of PBI 200.

Inclusion Criteria:

• Male or female between 18 and 55 years of age (inclusive).
• Body Mass Index (BMI) between 18.0 and 32.0 kg/m² (inclusive).
• Non-smoking/non-vaping, healthy, with no history of clinically relevant medical illness.

Exclusion Criteria:

• History or presence of clinically significant cardiovascular, pulmonary, respiratory, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, neurological, or psychiatric disease which, in the opinion of the Investigator, would jeopardize the safety of the volunteer or impact the validity of the study results.
• History of gastrointestinal/hepatobiliary or other surgery that may affect PK profiles (i.e., hepatectomy, gastric, bypass, or digestive organ resection).
• Intolerance to repeated venipuncture.
• Smoking or use of tobacco products (including vaping) within 3 months prior to the first study drug administration.
• Have a positive drug/alcohol screen, or history or presence of alcoholism or drug abuse within 6 months of first study drug administration.
• Volunteers with a corrected QT using Fridericia's formula (QTcF) prolongation over 450 milliseconds at Screening.