Inclusion Criteria: 

• Capable of understanding the written informed consent, provides signed and witnessed written informed consent, and agrees to comply with protocol requirements and study-related procedures.
• Male or female, between 18 and 65 years of age (inclusive) at the time of Screening.
• Body mass index (BMI) between 18 and 35 kg/m2 (inclusive) at the time of Screening.
• Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m2 (Cohort 1 and 3), or eGFR ≥ 30 to < 60 mL/min/1.73 m2 (Cohort 2 and 4), with eGFR calculated by the CKD-EPI equation.
• Subject has been diagnosed with ADPKD by modified Ravine criteria: 
  • For subjects with family history of ADPKD, a minimum of 3 cysts per kidney by sonography or 5 cysts by CT or MRI; or
  • For subjects without family history of ADPKD, a minimum of 10 cysts per kidney by any radiologic method and exclusion of other cystic kidney diseases.
• To verify the cyst count, medical records may be used in association with the Screening visit. Alternatively, in the absence of sonography or radiography evidence from medical records, subjects may be included at the discretion of the Investigator until a modified Ravine diagnosis can be confirmed through the baseline MRI assessment.
• Considered by the Investigator to be in good health relative to underlying CKD status and clinically stable with respect to underlying CKD, based on medical evaluation that includes medical and surgical history, as well as a complete physical examination including vital signs, ECG, and laboratory test results. A single repeat assessment is permitted for any laboratory, ECG, or vital sign parameter required for enrollment.
• Female subjects must: 
  • be non-pregnant and non-lactating;
  • be either postmenopausal (defined as amenorrhea for ≥ 12 months and, if confirmation is necessary based on Investigator discretion, a confirmed follicle stimulating hormone [FSH] ≥ 40 mIU/mL), surgically sterile (defined as having undergone hysterectomy and/or bilateral oophorectomy), practice total abstinence from sexual intercourse as the preferred lifestyle (periodic abstinence is not acceptable), or agree to use an appropriate method of birth control consistently throughout the study and continue to use this method for 30 days after study drug administration;
  • Double barrier methods of non-hormonal contraception are permitted in this study. Acceptable forms of contraception include the following:
    • intrauterine device, including Mirena®;
    • female condom with spermicide (cream, spray, gel, suppository, contraceptive sponge, or polymer film);
    • diaphragm with spermicide (with or without a condom);
    • cervical cap with spermicide (with or without a condom);
    • male sexual partner who agrees to use a male condom in addition to female subject’s use of spermicide (cream, spray, gel, suppository, contraceptive sponge, or polymer film);
    • male sexual partner who has been vasectomized for at least 3 months prior to Screening and who has obtained a follow-up negative sperm count;
    • bilateral tubal ligation;
    • Essure® procedure;
    • Estrogen-based hormonal contraception is not permitted in this pharmacokinetic study due to the potential for interaction with lixivaptan.
• Male subjects who are sexually active with a partner of child-bearing potential must either be sterile (vasectomy with history of a negative sperm count following the procedure); practice total abstinence from sexual intercourse as the preferred lifestyle (periodic abstinence is not acceptable); use a male condom with any sexual activity; or agree to use a birth control method considered to be appropriate by the Investigator (such as hormonal contraception or one of the methods identified above for female subjects of childbearing potential) from the time of Screening until 90 days after study drug administration. Male subjects must agree not to donate sperm for a period of 90 days after study drug administration.
• Patients who are smokers will be allowed to smoke ≤ 10 cigarettes per day during the study.
• Subjects must be willing to be confined to the CRU for the entire duration required by the protocol, able to comply with all study-related requirements and able to adhere to study restrictions and visit schedules.

Exclusion Criteria: 

• Subjects with known sensitivity or idiosyncratic reaction to any compound present in lixivaptan, its related compounds such as benzazepines (e.g., tolvaptan, conivaptan, benazepril, fenoldopam, or mirtazapine), or any compound listed as being present in the study formulation.
• Women who are pregnant or breast feeding.
• Subjects who have taken any investigational drug or used an investigational device within 30 days or 5 half-lives, whichever is longer, prior to Day 1.
• Subjects who have taken tolvaptan, conivaptan, somatostatin analogs (e.g. lanreotide, pasireotide, octreotide, etc.), mTOR kinase inhibitors (e.g. everolimus, sirolimus, etc.), or oral or intravenous antibiotics within 30 days or 5 half-lives, whichever is longer, prior to Day 1.
• Subjects will be allowed to take their chronic medications unless excluded by the protocol including remaining constant throughout the duration of the study.
• Subjects who have taken, or are expected to be taking, strong or moderate CYP3A4 or CYP2C8 inhibitors (e.g., aprepitant, boceprevir, clarithromycin, chloramphenicol (not eye drops), cimetidine, ciprofloxacin, clopidogrel, clotrimazole (if used orally), cobicistat and cobicistat-containing products, crizotinib, cyclosporine, danazol, deferasirox, diltiazem, dronedarone, erythromycin, fluconazole, fluvoxamine, gemfibrozil, HIV protease inhibitors, imatinib, isoniazid, itraconazole, josamycin, ketoconazole, nefazodone, posaconazole, quinupristin/dalfopristin, ritonavir and ritonavir-containing products, telaprevir, teriflunomide, tofisopam, troleandomycin, verapamil, voriconazole) within 14 days or 5 half-lives, whichever is longer, of dosing; or weak CYP3A4 or CYP2C8 inhibitors (e.g., chlorzoxazone, cilostazol, fosaprepitant, istradefylline, ivacaftor, lomitapide, ranitidine, ranolazine, tacrolimus, ticagrelor, trimethoprim) within 7 days or 5 half-lives, whichever is longer, from dosing. For weak CYP3A4 or CYP2C8 inhibitors, medications may be allowed in consultation with the Medical Monitor (MM).
• Subjects who have taken, or are expected to be taking, strong or moderate CYP3A4 or CYP2C8 inducers (e.g., barbiturates, bosentan, carbamazepine, efavirenz, enzalutamide, etravirine, modafinil, mitotane, nevirapine, oxcarbazepine, phenytoin, pioglitazone, rifabutin, rifampin, St. John’s wort) within 14 days or 5 half-lives, whichever is longer, of dosing; or weak CYP3A4 or CYP2C8 inducers (e.g., armodafinil, rufinamide) within 7 days or 5 half-lives, whichever is longer, from dosing. For weak CYP3A4 or CYP2C8 inducers, medications may be allowed in consultation with the Medical Monitor (MM).
• Subject who have a transplanted kidney, or absence of a kidney.
• Subjects with a history of clinically significant drug or alcohol abuse within the past 5 years.
• Subjects with a history of testing positive for hepatitis B surface antigen (HBsAg), hepatitis C (HCV), or human immunodeficiency virus (HIV).
• Subjects who have consumed grapefruit or Seville oranges (or their juices, or foods containing their extract) from 7 days prior to the first dose of study medication and until after the final dose.
• Subjects with clinically significant incontinence, overactive bladder, or urinary retention (e.g., benign prostatic hyperplasia).
• Subjects with clinically significant nocturia/urgency at Screening outside of the 2 to 4 times awakening per night expected for ADPKD patients.
• Subjects with clinically significant liver disease, or clinically significant liver function abnormalities or serology other than that expected for ADPKD with cystic liver disease at baseline.
• Subjects with aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP) or total bilirubin ≥ 1.5 × upper limit of normal (ULN) at Screening. Subjects with elevated bilirubin due to Gilbert’s Syndrome may be allowed at the discretion of the Investigator.
• Subjects with any history of significant bleeding or hemorrhagic tendencies.
• Subjects with contraindications to or interference with MRI assessments (ferromagnetic metal prostheses, aneurysm clips, severe claustrophobia, or large abdominal/back tattoos) will be excused from this procedure, but may participate in the study providing that all other eligibility criteria are met. Investigator should seek MRI safety guidance from the local MRI facility.
• Subjects who have experienced an illness that is considered by the Investigator to be clinically significant within 2 weeks of study drug administration on Day 1.
• Subjects with a history of difficulty in donating blood, or who have donated or lost a significant volume (> 450 mL) of blood within 56 days, or plasma within 7 days, prior to Day -1.
• Subjects who are unable to swallow medication.
• Subjects who participated in strenuous exercise within 48 hours prior to Check-in (Day -1).
• Subjects with New York Heart Association Functional Class 3 or 4 heart failure.
• Exclusion criteria for Screening ECG (a single repeat is allowed for eligibility determination):
  • Sinus pauses > 3 seconds;
  • Any significant arrhythmia or conduction abnormality, which, in the opinion of the Investigators and Medical Monitor, could interfere with the safety for the individual subject;
  • Non-sustained or sustained ventricular tachycardia, or ≥ 3 consecutive ventricular ectopic beats.
• Subjects with any clinically significant concomitant disease or condition other than ADPKD (including treatment for such conditions) that, in the opinion of the Investigator, could either interfere with the study drug or pose an unacceptable risk to the subject.
• Subjects with any other clinically significant abnormalities in laboratory test results at Screening that would, in the opinion of the Investigator, increase the subject's risk of participation, jeopardize complete participation in the study, or compromise interpretation of study data.
• Subjects who have experienced elevated AST or ALT (defined as ≥ 2.0 × ULN) while taking tolvaptan.
• Any other reason; e.g., serious mental disorders, that would render the subject unsuitable for study enrollment at the discretion of the Investigator.