Many people, particularly small children, must take drugs in liquid form because they cannot swallow pills or capsules. The bad taste of some liquid drugs can keep patients from taking drugs they need for their health. Our main goal in this research study is find ingredients that might make drugs taste better.

Participants in this research study will be healthy adults between the ages of 18 and 60 years old. Participants will taste samples (liquids or gels) containing active pharmaceutical ingredients (substances in medications that produce desired health effects). After tasting each sample participants will spit out the sample and rinse with water (no samples will be swallowed). Active pharmaceutical ingredients of current interest are: 1) tenofovir alafenamide, used to treat HIV infection and hepatitis B, 2) rifampicin, used to treat tuberculosis, 3) rifapentine, used to treat tuberculosis, and 4) levofloxacin, used to treat various bacterial infections). Other active pharmaceutical ingredients may be added as the study goes forward. Participants will be instructed to taste samples both with and without experimental flavor ingredients added and judge how the samples taste. People who volunteer for the study will be instructed to complete many repeated visits to the Monell Center (University City area of Philadelphia) for tasting sessions. Tasting visits will last between 1 and 2 hours.

Inclusion Criteria:

• Between the ages of 18 and 60;
• Generally healthy by self-report;
• All races/ethnicities, both men and women;
• Able to provide informed consent;
• Able to attend repeated visits to Monell for sensory testing;
• Willing to follow instructions (e.g., refrain from eating or drinking for at least 1 hour before sessions, willing to remain on site for one hour after tasting an API that the participant has never tasted before). -

Exclusion Criteria:

• Under 18 or over 60;
• Pregnant, nursing, or plans to become pregnant;
• Unable to provide consent (including limited ability to understand written and spoken English);
• Tobacco, vape, marijuana, or tetrahydrocannabinol cartridge users. We will accept people who have used tobacco or marijuana products on occasion, but not regular users;
• Known drug or food allergies of any kind;
• Diabetes or other metabolic disorder;
• Liver issues of any kind, including viral hepatitis;
• Kidney issues of any kind;
• Other chronic illness, including cardiovascular, neurological, immune disorders, or any other serious acute or chronic condition
• Dentures or other major dental implants;
• Condition affecting the oral cavity, including dry mouth, burning mouth syndrome, active sores or blisters, geographic tongue, or other disorders
• Current infection or cold, flu, or infection with SARS-CoV-2 within the last four weeks;
• Unable to taste or smell
• Daily use, or use within the last four weeks, of either prescription or over-the-counter medications (except for birth control)
• History of tuberculosis (including latent tuberculosis), positive skin or other tuberculosis test at any time in the past, birth in or residence in a country with high tuberculosis rates, known contact with someone who is tuberculosis positive
• HIV infection

De-identified data will be shared with qualified researchers upon request, and may be made available in managed repositories as allowed by funder and journal policy.

De-identified data will be made available upon publication of results, as consistent with applicable Journal policies. Once available, data will be available indefinitely. Note, however, that individual participants will have the option to opt out of the data-base upon request to the study PI. Once such a request is received, data for the individual participant concerned will no longer be available.

Data will be made available to qualified researchers by the study PI upon request (after publication). If data are placed in managed repositories (e.g., NIH-run managed repository), qualifications will be determined by the managers of the repository

Samples for tasting will be presented with numeric identification codes (no verbal descriptors) and be presented in random order within a tasting session.