A Drug-Drug Interaction Study in Healthy Volunteers of the Effects of Tucatinib on Metformin

Inclusion Criteria: * Healthy status, as defined by the absence of evidence of any clinically significant findings * Males must agree to use a barrier method of birth control and not donate sperm during study plus 30 days after last dose of study drug * Weight of ≥60kg * Body mass index between 18.0 and 32.0 kg/m² (inclusive) * Ability to abstain from alcohol-, caffeine-, and xanthine-containing food and beverages from 48 hours prior to admission through study discharge * All nonregular medication (including over-the-counter medication, health supplements, and herbal remedies) must be stopped at least 28 days prior to admission Exclusion Criteria: * Females who are of childbearing potential or lactating * Males with female partners who are pregnant, lactating, or planning to become pregnant within 30 days of the study * Use of any investigational drug or device within 30 days of study start * Use of tobacco products within 21 days prior to admission * Routine or chronic use of more than 3 grams of acetaminophen daily * Strenuous activity, sunbathing, and contact sports within 72 hours prior to first admission and for the duration of the study * Blood transfusion within 90 days of study drug administration * History of alcoholism or drug abuse within 2 years * History of alcohol consumption exceeding 7 drinks/week for female participants or 14 drinks/week for male subjects * History of donation of more than 450 mL of blood within 60 days prior to dosing, or planned donation before 30 days have elapsed since intake of study drug * Plasma or platelet donation within 7 days of initial study drug administration * Positive screening test for Hepatitis B, Hepatitis C, or HIV 1 or 2 (human immunodeficiency virus) * Acute or chronic metabolic acidosis, including diabetic ketoacidosis * Renal disease or dysfunction as suggested by serum creatinine levels or abnormal creatinine clearance