Open-Label Tolvaptan Study in Subjects With ADPKD

Inclusion Criteria:

Subjects who have successfully completed a Phase 1, 2, or 3 tolvaptan ADPKD or renal
impairment trial, with a confirmed diagnosis of ADPKD

Exclusion Criteria:

- Subjects unable to provide written informed consent

- Subjects (men or women) who will not adhere to the reproductive precautions as
outlined in the Informed Consent Form

- Subjects (women only) with a positive urine pregnancy test

- Subjects who are pregnant or breast-feeding

- Subjects unable to take oral medications

- Subjects who have allergic reactions to tolvaptan or chemically related structures
such as benzazepines (benzazepril, conivaptan, fenoldopam mesylate or mirtazapine)

- Subjects who have disorders in thirst recognition or an inability to access fluids

- Subjects with critical electrolyte imbalances, as determined by the investigator

- Subjects with or at risk of significant hypovolemia, as determined by investigator

- Subjects with anemia, as determined by investigator

- Subjects with a history of substance abuse (within the last 3 years)

- Subjects taking other experimental (ie, non-marketed) therapies or current
participation in another clinical drug or device trial; current participation in the
off-drug follow-up period of another ADPKD trial with tolvaptan is permitted

- Subjects unable to complete MRI assessments(eg, subjects with ferro-magnetic
prostheses, aneurysm clips, severe claustrophobia)

- Subjects who have taken a vasopressin antagonist (outside of previous participation in
a tolvaptan trial)

- Subjects unable to comply with anti-hypertensive or other important medical therapy

- Subjects with advanced diabetes

- Subjects taking medications or having an illness that could confound endpoint
assessments (including taking approved therapies for the purpose of affecting PKD
cysts)