BCKDK

The purpose of this study is to learn about the effect of cyclosporine, an immunosuppressant (medicine that suppresses the immune system), on the pharmacokinetics (PK) of PF-07328948 in healthy participants (Part A). The study may also estimate the effect of clarithromycin, an antibiotic, on the PK of PF-07328948 in healthy participants (Part B is optional).
This study is seeking participants who:
* are 18 years of age or older
* are male or female who are not of childbearing potential
* are healthy (do not have a disease) The study will consist of two parts - Part A and Part B.
Part A will consist of two treatments:
* one dose of PF-07328948 solution to be taken by mouth on day 1.
* one cyclosporine 600 mg capsule taken together with a dose of PF-07328948 solution by mouth on day 12.
Before study Part A starts, all participants will go through a screening process which may last for a period of up to 28 days. During this period, the participant's medical history and past and current medications will be reviewed. A series of tests will also be performed.
If the participants meet all required criteria and want to continue, they will be brought into the study clinic to stay overnight for 17 days. During this period, the experiences of participants receiving the study medicine will be examined. Samples for laboratory assessments will be collected. Vital signs and medical assessments will also be performed. This will help determine if it is safe to take the study medicines together and what happens to these medicines in one's body (called PK assessment). After Part A, participants will be discharged from the clinic.
Based upon the results of Part A, study participants may proceed to Part B. If Part B occurs, participants will return to the study clinic and remain in the clinic for 8 days. There will be a gap of at least 7 days between Part A and Part B.
Part B will consist of a third treatment:
- clarithromycin 500 mg tablet to be taken 2 times a day for 6 days. On day 4, the tablet will be taken together by mouth with a dose of PF-07328948 solution.
During this period, similar laboratory and medical assessments as done in Part A will occur. After Part B, participants will be discharged from the clinic.
The participant will be contacted for a follow up visit by telephone about 30 days after final treatment. This is to check up on how the participant is doing and to conclude the study. If only Part A occurs, a participant will be in the study about 44 days. If Part B occurs, a participant will be in the study for about 64 days.

This study has two parts: Part A and Part B.
The purpose of Part A of this study is to learn about the safety, tolerability, and how PF-07328948 is processed by the body when multiple doses of PF-07328948 are given to healthy participants.
The purpose of Part B of this study is to understand the amount of PF-07328948 that would be available in the body after taking a single pill. The amount will be compared to the amount of PF-07328948 in a suspension in healthy adults.
Part B will be conducted if the results of Part A support further study of PF-07328948.
The study is seeking participants who:
* are females who are not able to give birth to a child of 18 years of age or older.
* are males of 18 years of age or older.
* have a BMI of 20.0 to 35.0 kg/m2.
* have total body weight of more than 50 kg (110 lbs).
Participants in Part A will be randomly selected to receive either PF-07328948 or placebo (a pill that has no medicine in it).
Participants in Part B will receive PF-07328948 as suspension and tablet form, both taken by mouth after food or during fasting.
For a given participant in Part A, the total study is going to last up to about 12 weeks. This includes from the time of selection till the last follow-up phone call. The participants will be selected if they are fit for the study 28 days before the first dose of the study medicines. Participants who are selected will be admitted to the study site on Day -2 for around 19 days. Following discharge, participants will return for an on-site follow-up visit 7 to 10 days after receiving the final dose of the study medicine. The follow-up contact may be via a telephone call and will happen 28 to 35 days after the final dose of study medicine is given.
For a given participant in Part B, the total study is going to last up to about 10-12 weeks. Participants will stay overnight at the CRU for 23 days (Sequence 1) or 18 days (Sequence 2), starting with check-in. In Sequence 1, there will be a minimum of 10 days between doses in Period 1 and 2, and at least 7 days between doses in Period 2 and Period 3. In Sequence 2, there will be a minimum of 7 days between each dose.

This study is the first clinical study with PF-07328948. The safety, tolerability, and plasma pharmacokinetics and pharmacodynamics of PF-07328948 after administration of escalating, single, oral doses will be evaluated.