Study Evaluating Subjects With Distal Renal Tubular Acidosis

The study will target enrolling at least 4 subjects in each of the following age groups: 6
months - 23 months; 2-11 years, and ≥ 12 years. After screening and enrollment, subjects will
participate in an 8-12 week open label period where there dose of ADV7103 will be titrated to
effect, then continued for the remainder of the open label period. Periodic measurements of
bicarbonate and potassium levels will be collected during this period. Following the
open-label period, subjects will enter a 6-day randomized withdrawal period. For this portion
of the study, subjects will be admitted to a monitored setting. A four-week follow-up period
on re-established therapy completes the trial. Subjects will have the opportunity to
subsequently enter a long-term, open label extension.

Inclusion Criteria:

1. Female or male subjects ≥ 6 months of age and ≤ 65 years of age at time of consent;

2. Subject presents with a previous diagnosis of primary dRTA of at least 4 months
duration for subjects < 12 years of age, and at least one year for those ≥ 12 years of
age, based on documented history of non-anion gap, hyperchloremic, hypokalemic
metabolic acidosis;

3. Subject requires ≥ 0.9 mEq/kg/day of alkali therapy to maintain serum bicarbonate
levels above the LLN for the laboratory providing results;

4. Urine pH > 5.5; serum bicarbonate > 18 mEq/L for subjects ≥ 4 years old or > 17 mEq/L
for subjects < 4 years old; and serum potassium ≥ 3.0 mEq/L on alkali therapy and
potassium supplementation (if indicated) on at least one occasion for each within 6
months prior to Visit 1;

Exclusion Criteria:

1. Female subject who is pregnant or lactating or has plans for pregnancy during the
study;

2. Subject has evidence of proximal tubule dysfunction (eg, hypophosphatemia, low serum
uric acid, glycosuria, or amino aciduria);

3. Subject presents with another diagnosed condition as a potential etiology for her/his
dRTA (eg, systemic lupus erythematosus, Sjogren's syndrome), in the opinion of the
Investigator;

4. Subject requires therapy with potassium sparing diuretics, angiotensin converting
enzyme inhibitors, angiotensin II receptor blockers, trimethoprim, drospirenone and
other progestins, nephrotoxic antibiotics, penicillins, tacrolimus, or medications
known to delay gastric emptying or otherwise interfere with absorption of study
product;

5. Subject has evidence of obstructive uropathy or other findings on renal ultrasound
associated with Visit 1 expected to require intervention during the course of the
study, in the opinion of the Investigator;

6. Subject has any of the following laboratory abnormalities associated with Visit 1:

1. AST and/or ALT > 1.5x upper limit of normal (ULN)

2. Potassium > 5.0 mEq/L or symptomatic hypokalemia

3. Estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 (according to the
updated Schwartz formula for children and Chronic Kidney Disease - Epidemiology
Collaboration [CKD-EPI] formula for adults)

4. Total bilirubin > ULN, except with known Gilbert's disease.

7. Subject has been hospitalized or had outpatient surgery (other than minor skin and
dRTA disease-related procedures or ear tube placement) in the past 6 months or is
planning surgery in the next 6 months;