Inclusion Criteria:

• Written informed consent.
• ≥ 18 years old (male/female)).
• CKD with eGFR < 60 mL/min/1.73m²; not expected to need dialysis/ transplant during study.
• 2 SBC values 12-21 mmol/L within 6 months pre-screening
• During screening: 2 central SBC values 12-21 mmol/L
• Willing to maintain stable diet
• Expect to keep oral alkali therapy dose stable.
• Women of childbearing potential: negative pregnancy test and agree to abstinence or contraception.

Exclusion Criteria:

• Any participant deemed by the Investigator to be an inappropriate candidate for physical performance testing (e.g., severe musculoskeletal pain, non-ambulatory status) or with a screening STS5 time < 10 seconds (i.e., very mobile).
• Any participant deemed by the Investigator to be an inappropriate candidate for CPET (e.g., advanced chronic obstructive pulmonary disease [COPD], major cardiovascular [CV] event in last 6 months, systolic blood pressure [SBP] > 200 mmHg or diastolic blood pressure [DBP] > 120 mmHg). Only applicable to sites performing CPET and if the participant will take part in CPET.
• History or current diagnosis of:
  1. Clinically significant gastroparesis or a history of bariatric surgery.
  2. Bowel obstruction, swallowing disorders, severe gastrointestinal disorders, including inflammatory bowel disease, major gastrointestinal surgery, or known active gastric/duodenal ulcers.
  3. Severe recurrent diarrhea or severe recurrent constipation, in the opinion of the Investigator.
  4. Pernicious anemia, atrophic or autoimmune gastritis, achlorhydria or hypochlorhydria.
• Active Helicobacter pylori infection at screening.
• Active, recurrent, or metastatic malignancy at the start of screening.
• History of malignancy, except under the following conditions:
  1. Carcinoma in situ (e.g., of the cervix, breast, or bladder) that has been completely excised and shows no evidence of residual disease.
  2. Non-melanoma skin cancers (e.g., basal cell carcinoma, squamous cell carcinoma) that have been completely excised and show no evidence of recurrence.
  3. Low grade prostate cancer, in the opinion of the Investigator (i.e., no metastasis, Gleason score < 6), with no significant worsening for > 6 months prior to the screening visit.
  4. Any other malignancy that was treated with curative intent and has been in complete remission for ≥ 5 years prior to the screening visit.
• Evidence of acute fluid overload or history of recurrent fluid overload, in the opinion of the Investigator.
• Screening hemoglobin < 10 g/dL.
• Presence of primary respiratory alkalosis, as assessed by venous blood gas (VBG) analysis at time of screening.
• Serum gastrin level > 500 pg/mL.
• Investigational medication administration within 28 days prior to start of screening.
• Use of GI polymer binders or sodium zirconium cyclosilicate within 28 days prior to the start of screening or have an expectation to initiate treatment during the study.
• Use of acid reducing drugs, including potassium competitive acid blockers, H2-blockers or PPIs within 28 days prior to the start of screening or have an expectation to initiate treatment during the study.
• Use of GLP-1 inhibitors within 6 months prior to the start of screening or have an expectation to initiate treatment during the study.
• Participants that are taking any of the following medications and have not been on a stable dose for at least 28 days prior to screening or have an expectation to change dose during the study: diuretics, non-ophthalmic carbonic anhydrase inhibitors, diabetes drugs, RAAS inhibitors, calcium or magnesium supplements, non polymer phosphate binders, and SGLT-2 inhibitors. These medications also should not be started during the study.
• Participants that are taking more than 30 units of insulin daily.
• History of alcoholism or drug/chemical abuse within 1 year prior to the start of screening, in the opinion of the Investigator.
• Current, regular use of inhaled/ingested cannabis/THC products.
• Inability to take the IP or otherwise comply with the protocol.
• Any medical condition, uncontrolled systemic disease or serious concurrent illness that would significantly decrease study compliance or jeopardize the safety of the participant or affect the validity of the trial results, in the opinion of the Investigator.