A Phase IIIb Study to Investigate the Effect of Baxdrostat in Chinese Participants With Uncontrolled Hypertension.

Inclusion Criteria: Participants are eligible to be included in the study only if all of the following criteria apply: Age 1. Participant must be ≥18 years old, at the time of signing the informed consent. Type of Participant and Disease Characteristics 1. Mean seated SBP on AOBPM ≥140 mmHg and \<170 mmHg at screening. Seated BP will be measured using standardised automated BP machines and using standardised procedures. 2. Have a stable regimen (≥ 4 weeks before the screening visit) of ≥ 2 antihypertensive medications, from different therapeutic classes (should not be a diuretic), at full doses per guidelines or maximum tolerated doses in the judgement of the Investigator, for at least 4 weeks prior to screening (participants who do not meet this criterion may be rescreened at the Investigator's discretion. Beta blockers used to treat other conditions (i.e., migraine, heart failure \[HF\], coronary artery disease) should not be counted as an antihypertensive medication for the purpose of qualifying for this study. 3. Have eGFR ≥45 mL/min/1.73m2 at screening. 4. Serum potassium (K+) level ≥3.5 and \<5.0 mmol/L at screening, determined as per central laboratory. Sex and Contraceptive/Barrier Requirements 5. Only female participants: Contraceptive use by females should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. a) Female participants: i. Females not of childbearing potential are defined as females who are either permanently sterilised (hysterectomy, bilateral oophorectomy, or bilateral salpingectomy), or who are postmenopausal. Females will be considered postmenopausal if they have been amenorrhoeic for 12 months prior to the planned date of randomisation without an alternative medical cause. The following age specific requirements apply: * Women \<50 years old would be considered postmenopausal if they have been amenorrhoeic for 12 months or more following cessation of exogenous hormonal treatment and follicle-stimulating hormone levels within the postmenopausal range. * Women ≥50 years old would be considered postmenopausal if they have been amenorrhoeic for 12 months or more following cessation of all exogenous hormonal treatment ii. Female participants of child-bearing potential must use one highly effective form of birth control. A highly effective method of contraception is defined as one that can achieve a failure rate of less than 1% per year when used consistently and correctly. Females of child-bearing potential who are sexually active with a non-sterilised male partner must agree to use one highly effective method of birth control, as defined below, from 30 days before enrolment and throughout the study, and until at least 30 days after last dose of study intervention. Cessation of contraception after this point should be discussed with a responsible physician. iii. The following are not acceptable methods of contraception: periodic abstinence (calendar, symptom-thermal, post-ovulation methods), withdrawal (coitus interruptus), spermicides only and lactational amenorrhoea. Female condom and male condom should not be used together. iv. All females of child-bearing potential must have a negative pregnancy test result at screening and not be at stage of breastfeeding v. Highly effective birth control methods include: Total sexual abstinence is an acceptable method provided it is the usual lifestyle of the participant (defined as refraining from heterosexual intercourse during the entire period of risk associated with the study treatments) (\[periodic abstinence - e.g., calendar, ovulation, sympto-thermal, post-ovulation methods - declaration of abstinence for the duration of exposure to study intervention and withdrawal are not acceptable methods of contraception\]); a vasectomised partner; subdermal contraceptive implants; bilateral tubal occlusion; intrauterine device/levonorgestrel intrauterine system; injectable contraceptive; oral contraceptive associated with inhibition of ovulation; and contraceptive transdermal patch, or vaginal ring. Informed Consent 6. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the ICF and in this protocol. 5.1.1 Randomisation Criteria Participants are eligible to be randomised to a treatment group only if all the following criteria apply: 7. Ambulatory 24-hour average SBP ≥130 mmHg. 8. Have an 80% to 120% adherence to placebo during the Run-in period, based on pill counts on the morning of randomization. Adherence will be derived for each patient based on pill counts as the number of pills taken (dispensed - returned), divided by the expected number of pills taken. 9. Have no change in background therapy regimen and dose consisting of ≥ 2 antihypertensive medications (none of which is a diuretic), for at least 4 weeks prior to randomisation. Beta-blockers used to treat other conditions (i.e., migraine, HF, coronary artery disease) should not be counted as an antihypertensive medication for the purpose of qualifying for this study. 10. Demonstrated good adherence to the prescribed antihypertensive medications by performing DOT. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: Medical Conditions 1. As judged by the investigator, any evidence of which in the investigator's opinion makes it undesirable for the participant to participate in the study. 2. Mean seated SBP on AOBPM ≥170 mmHg (participants who do not meet this criterion may be rescreened at the Investigator's discretion, see Section 5.4.2 for rescreening criteria and Section 8.2.1 for BP measurement procedures). 3. Mean seated DBP on AOBPM ≥110 mmHg (participants who do not meet this criterion may be rescreened at the Investigator's discretion). 4. Serum sodium level (Na+) \<135 mmol/L at screening, determined as per central laboratory. 5. Has the foll