A Randomized, Crossover, Pharmacokinetic and Pharmacodynamic Study to Determine the Safety and Efficacy of Cysteamine Bitartrate Delayed-release Capsules (RP103), Compared to Cystagon® in Patients with Nephropathic Cystinosis

Male or female subject with a documented diagnosis of nephropathic cystinosis.
Subject must be on a stable dose of Cystagon® sufficient to maintain their white blood cell (WBC) cystine level at <= 1.0 nmol/half-cystine/mg protein.
Subject must be able to swallow their typically administered Cystagon® capsule with the capsule intact.
Within the last 6 months, no clinically significant change from normal in liver function tests [i.e., 1.5 times ULN for ALT and AST, and/or 1.5 times ULN for total bilirubin] and renal function
[i.e., estimated GFR (corrected for body surface area)] at Screening as determined by the Investigator.
Subject must have an estimated GFR (corrected for body surface area) > 30 mL/minute/1.73 m2.
Sexually active female subjects of childbearing potential (i.e., not surgically sterile [tubal ligation, hysterectomy, or bilateral oophorectomy] or at least 2 years naturally postmenopausal)
must agree to utilize the same acceptable form of contraception from Screening through completion of the study. The acceptable forms of contraception for this study include hormonal
contraceptives (oral, implant, transdermal patch, or injection) at a stable dose for at least 3 months prior to Screening, barrier (spermicidal condom, diaphragm with spermicide), IUD, or a
partner who has been vasectomized for at least 6 months. For pre-pubescent children, a documented attestation of abstinence from their parent or guardian will be acceptable.
Subject must be willing and able to comply with the study restrictions and requirements.
Subject or their parent or guardian must provide written informed consent and assent (where applicable) prior to participation in the study.

Subject*s age < 6 years old or subjects weight < 21 kg.
Subjects with current history of the following conditions or any other health issues that make it, in the opinion of the Investigator, unsafe for them to participate:
- Inflammatory bowel disease (if currently active) or prior resection of small intestine;
- Heart disease (e.g., myocardial infarction, heart failure, unstable arrhythmias, or poorly controlled hypertension) 90 days prior to Screening;
- Active bleeding disorder 90 days prior to Screening;
- History of malignant disease within the last 2 years.
Subject with a hemoglobin level of < 10 g/dL at Screening or, in the opinion of the Investigator, a hemoglobin level that would make it unsafe for the subject to participate.
Subjects receiving any form of cysteamine medication through a gastric tube.
Subjects who are receiving maintenance dialysis or who have had a kidney transplant.
Subjects who are on an active kidney transplant list or who are planning to receive a kidney transplant within 3 months of Screening.
Subjects with known hypersensitivity to cysteamine and penicillamine.
Female subjects who are nursing, planning a pregnancy, known or suspected to be pregnant, or with a positive serum pregnancy screen.
Subjects who have a made a blood donation within 30 days of Screening.
Subjects who, in the opinion of the Investigator, are not able or willing to comply with the protocol.