This study is a Phase 1, single-center, open-label study to investigate the absorption, metabolism, and excretion of BTZ-043 after a single oral administration of 500 mg BTZ-043 containing 3.7 MBq of [14C]BTZ-043 in 4 healthy adult male subjects

A total of 4 evaluable subjects completing all procedures are required. Six (6) subjects will be enrolled in the cohort in order to have 4 evaluable subjects.

The study will consist of a screening period (Day -21 to -2), a baseline period (Day -1), a single dose treatment on Day 1 with a minimum of 96 hours (=4 days) post dose in-house observation period (Days -1 up to afternoon Day 5), and a follow-up visit 30 days (±2 days) after the [14C]BTZ-043 dose.

Subjects will be administered a single 500 mg [14C]BTZ-043 dose as drinking suspension. Subjects will be confined to the clinical site for at least 96 hours following drug administration (ie, afternoon of Day 5). During this time, blood, feces, and urine samples for measurement of [14C]BTZ-043 and metabolites will be collected.

The subjects will be released from the clinic approximately 96 hours to 168 hours after dose administration and upon satisfactory recovery of radioactivity (at least 90%) approved by the Sponsor's scientific advisor after consulation of the Sponsor.

Inclusion Criteria:

1. Sex : male
2. Age : 18 years to 55 years, inclusive, at screening.
3. Body mass index (BMI) : 18.0 to 29.0 kg/m2, inclusive, at screening.
4. Weight : 55 to 90 kg, inclusive, at screening.
5. Status : healthy subjects.
6. Male subjects, if not surgically sterilized, must agree to use adequate contraception and not donate sperm from admission to the clinical research center until 90 days after the follow-up visit. Adequate contraception for the male subject (and his female partner, if she is of childbearing potential) is defined as using hormonal contraceptives or an intrauterine device combined with at least 1 of the following forms of contraception: a diaphragm, a cervical cap, or a condom. Total abstinence, in accordance with the lifestyle of the subject, is also acceptable.
7. All prescribed medication must have been stopped at least 30 days prior to admission to the clinical research center.
8. All over-the-counter medications, vitamin preparations (especially vitamin C), other food supplements, and herbal medications (eg, St. John's wort) must have been stopped at least 14 days prior to admission to the clinical research center. An exception is made for paracetamol, which is allowed up to 48 hours prior to study drug administration.
9. No vaccination within 14 days prior to study drug administration.
10. Ability and willingness to abstain from alcohol from 48 hours (2 days) prior to screening and admission to the clinical research center.
11. Ability and willingness to abstain from methylxanthine-containing beverages or food (coffee, tea, cola, chocolate, and energy drinks), grapefruit (juice), corn (whole corn kernels and popcorn), cruciferous vegetables, and bitter oranges from 48 hours (2 days) prior to admission to the clinical research center.
12. Good physical and mental health on the basis of medical history, physical examination, clinical laboratory, ECG, and vital signs, as judged by the Investigator.
13. Willing and able to sign the ICF.

Exclusion Criteria:

1. Participation in another study with a radiation burden of >0.1 mSv and ≤1 mSv in the period of 1 year prior to screening; a radiation burden of >1.1 mSv and ≤2 mSv in the period of 2 years prior to screening; a radiation burden of >2.1 mSv and ≤3 mSv in the period of 3 years prior to screening, etc.
2. Exposure to radiation for diagnostic reasons (except dental X-rays and plain X-rays of thorax and bony skeleton [excluding spinal column]), or during work within 1 year prior to drug administration.
3. Irregular defecation pattern (less than once per day on average).
4. Employee of PRA, Nuvisan, or the Sponsor.
5. History of relevant drug and/or food allergies.
6. Using tobacco products within 60 days prior to drug administration.
7. History of alcohol abuse or drug addiction (including soft drugs like cannabis products).
8. Positive drug and alcohol screen (opiates, methadone, cocaine, amphetamines [including ecstasy], cannabinoids, barbiturates, benzodiazepines, gamma-hydroxybutyric acid, tricyclic antidepressants, and alcohol) at screening or admission to the clinical research center.
9. Average intake of more than 24 grams of alcohol per day.
10. Positive screen for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies, or HIV 1 and 2 antibodies.
11. Participation in a drug study within 30 days prior to drug administration in the current study. Participation in more than 4 drug studies in the 12 months prior to drug administration in the current study.
12. Donation or loss of more than 450 mL of blood within 60 days prior to drug administration. Donation or loss of more than 1.5 liters of blood in the 10 months prior to drug administration in the current study.
13. Significant and/or acute illness within 5 days prior to drug administration that may impact safety assessments, in the opinion of the Investigator.
14. Unwillingness to consume the Food and Drug Administration (FDA)-recommended high-fat breakfast.
15. Unsuitable veins for infusion or blood sampling.
16. Positive nasopharyngeal PCR test for SARS-CoV-2 on Day -1.