Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Double Blind, Randomized, Placebo Controlled Trial to Evaluate the Efficacy and Safety of FOSTRAP Chewing Gum in Patients With Chronic Kidney Disease and Hyperphosphatemia.
Brief Summary: The phosphorus content in saliva is increased in chronic kidney disease. We hypothesize that a chewing gum that binds salivary phosphorus would be a novel, effective agent to reduce serum levels of phosphorus in patients with chronic kidney disease. We are testing this hypothesis using a chewing gum called FOSTRAP which has been shown to be effective in a small, non-randomized study in patients with chronic kidney disease on hemodialysis.


Options:
A: Inclusion Criteria:

* Age \> 18 years
* Capable of giving informed consent
* Duration of peritoneal dialysis \> 3 months
* Dose of phosphate binder(s) stable over previous 2 week period
* Plasma phosphours \> 4.9 mg/dL based on most recent laboratory data within 1 month of enrollment

Exclusion Criteria:

* Pregnancy
* Known liver disease
* Active peptic ulcer disease
* Treatment with carbamazepine
* Intolerance to niacinamide or niacin
* Current medication regimen including niacin or niacinamide \> 100 mg daily
* Planned or expected surgical procedure in the next 4 months
* Patients in nursing home or extended care facilities where administration of the study drug may not be appropriately given
B: Inclusion Criteria:

1. Men or women \> 18 years of age;
2. The subject has voluntarily signed and dated the most recent informed consent form approved by an Institutional Review Board (IRB);
3. The subject will, in the opinion of the investigator, be compliant with prescribed therapy;
4. Subject must be able to communicate and be able to understand and comply with the requirements of the study;
5. For subjects with CKD not on dialysis- kidney function at any stage that in the opinion of the investigator is stable and not expected to initiate dialysis within 3 months;
6. For subjects with CKD not on dialysis- a screening serum phosphorus value greater than or equal to 4.5 mg/dL;
7. For subjects with ESRD - a screening serum phosphorus value greater than or equal to 4.6 mg/dL and less than or equal to 9.0 mg/dL and one of the two conditions: A mean historical value of the most recent 2 phosphorus measurements ≥ 4.6 and less than or equal to 9.0 mg/dL at the time of written informed consent or A second screening serum phosphorus value greater than or equal to 4.6 mg/dL and less than or equal to 9.0 mg/dL performed not less than 7 days from the date of the previous screening;
8. In the opinion of the investigator, subjects with ESRD must be prescribed a stable dialysis regimen (3x/week) for ≥ 4 weeks prior to baseline and must have a stable dialysis access;
9. Subjects with ESRD must have an historical URR ≥ 65% for at least 4 weeks prior to baseline;
10. All subjects must have NO change in prescribed dose or frequency of any of the following medications ≥ 14 days prior to baseline:

    1. Phosphate binding products including prescribed and over-the counter
    2. Oral or injectable active vitamin D
    3. Oral nutritional vitamin D
    4. Calcimimetics
    5. Calcium supplements
    6. Anti-osteoporotic medication (e.g. bisphosphonates)
11. Subject must be prescribed a diet appropriate for patients with their stage of kidney disease, and must be willing to avoid intentional changes in diet; and
12. Subjects must have a screening salivary flow rate by Saxon test ≥ 1 g/2 min.

Exclusion criteria:

1. Receiving or has received an investigational product (or is currently using an investigational device) within 28 days prior to baseline;
2. Known sensitivity to chitin or allergy to shellfish;
3. Clinical evidence of active malignancy and/or receiving systemic chemotherapy/radiotherapy with the exception of basal cell or squamous carcinoma of the skin;
4. Clinically significant infection requiring treatment with antibiotics (within 7 days prior to baseline);
5. Inpatient hospitalization within 14 days prior to baseline with the exception of hospitalizations related to vascular access procedures;
6. Planned surgical intervention for secondary hyperparathyroidism;
7. In the opinion of the investigator, inability to chew gum for 60 minutes;
8. Planned relocation to another area within the next 4 months;
9. Subject has a known history of immunodeficiency diseases, including a positive HIV (ELISA and Western blot) test result;
10. Active drug or alcohol dependence or abuse (excluding tobacco use) in the opinion of the principal investigator;
11. Unstable medical condition which in the opinion of the investigator would compromise successful completion of the study;
12. Known active liver disease with AST or ALT levels greater than 3X the upper limit of normal; and
13. Subject has had a major cardiovascular event within 90 days of screening. The investigator should be guided by evidence of any of the following;

    1. Acute myocardial infarction
    2. Acute cerebral vascular event
    3. Vascular surgical intervention
    4. Coronary Revascularization
    5. Decompensated congestive heart failure
C: Inclusion Criteria:

* Men or women \> 18 years of age;
* Must have no dietary restriction that would preclude eating standardized meal (both a meat based and vegan option available)
* The subject has voluntarily signed and dated the most recent informed consent form approved by an Institutional Review Board (IRB).
* Must be able to chew gum for at least 60 minutes.
* Must have historical eGFR appropriate for the study.

Exclusion Criteria:

* Receiving or has received an investigational product (or is currently using an investigational device) within 30 days prior to Visit 2;
* Evidence of active (clinically significant) infection at the time of study enrollment (in the opinion of the investigator);
* Dental work within 48 hours of enrollment (Visit 2); and
* Known sensitivity to chitin, or allergy to shellfish
D: Inclusion Criteria:

* Men and women 18 years of age or greater and able to comply with the study protocol.
* eGFR within appropriate target ranges (15-40 ml/min/m² for late stage CKD stage 3 stage 4, and eGFR \> 60 ml/min/m² for normal subjects)
* Stable kidney function defined as an eGFR which remains within a 10ml/min range over a 3 to 6 month period prior to study enrollment. This will be determined from historical laboratory data.
* Willing to follow study protocol
* Have a level of understanding and willingness to cooperate with all visits and procedures as described by the study personnel
* Overall stable medical condition, defined as no malignancy, metabolic condition or gastrointestinal condition that would make it difficult to comply with the study protocol and complete both dietary study periods
* Able to read the consent form and provide informed consent.
* Serum calcium and phosphorus within the normal range off of vitamin D analogues, calcium supplements, and phosphate binders for 1 month.

Exclusion Criteria:

* 1. Age less than 18 years
* Are pregnant, plan on becoming pregnant during the study period, or breast-feeding, if female.
* Patient declines participation.
* GI malabsorption, short bowel syndrome, frequent vomiting, or gastroparesis.
* Subject receiving synthetic parathyroid hormone, glucocorticoids, calcitonin or bisphosphonates.

Answer: B