A study in healthy volunteers to look at the effect of the test medicine, GLPG3667, on how midazolam (MDZ) is taken up and eliminated by the body.

Inclusion Criteria:

• Male or female between 18 and 55 years of age (extremes included), on the date of signing the informed consent form. Female subjects should be of non-childbearing potential, defined as permanently surgically sterile (bilateral oophorectomy, i.e. surgical removal of ovaries, bilateral salpingectomy, i.e. surgical removal of the fallopian tubes, or hysterectomy, i.e. surgical removal of uterus), or with no menses for 12 or more months without an alternative medical cause AND a follicle-stimulating hormone level in the postmenopausal range. These female subjects must also have a negative pregnancy test. For surgical sterilization, documented confirmation will be requested.
• A body mass index between 18.0 and 30.0 kg/m², inclusive.
• Judged to be in good health by the investigator based upon the results of a medical history, physical examination, vital signs, 12-lead electrocardiogram (ECG), and fasting clinical laboratory safety tests available at screening and prior to enrolment. Neutrophil, lymphocyte, and platelet counts must be above the lower limit of normal range. Total bilirubin, aspartate aminotransferase, and alanine aminotransferase must be within normal ranges. Other clinical laboratory safety test results must be within the reference ranges or test results that are outside the reference ranges need to be considered not clinically significant in the opinion of the investigator.

This list only contains the key inclusion criteria.

Exclusion Criteria:

• Known hypersensitivity to investigational product (IP) and/or MDZ ingredients or history of a significant allergic reaction to IP and/or MDZ ingredients as determined by the investigator.
• Treatment with any medication (including over-the-counter and/or prescription medication, dietary supplements, nutraceuticals, vitamins and/or herbal supplements, and hormonal replacement therapy for postmenopausal subjects) except occasional paracetamol (maximum dose of 2 g/day and maximum of 10 g/2 weeks) in the last 2 weeks or 5 half-lives of the drug, whichever is longer, prior to the first dosing.

This list only contains the key exclusion criteria.