Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Single Blind Pharmacodynamic Study to Assess the Phosphate Binding Characteristics of K2CG Chewing Gum
Brief Summary: The specific purpose of this study is to describe the characteristics of the K2CG chewing gum, specifically as it relates to duration of gum chewing (exposure), timing of gum chewing in relation to a meal, and dose of K2CG chewing gum.


Options:
A: 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.
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 and all study visits;
4. Subject must be able to communicate and be able to understand and comply with the requirements of the study;
5. For subjects not on dialysis estimated GFR at screening \< or equal to 60 ml/min + 10 % that in the opinion of the investigator is stable and not expected to initiate dialysis within 3 months;
6. Subject must have serum phosphorus at screening of greater than or equal to 3.5 mg/dL;
7. Subjects must have a screening salivary flow rate by Saxon test ≥ 1 g/2 min;
8. All subjects must have NO change in prescribed dose or frequency of any of the following medications ≥ 14 days prior to Run-In Visit 2 (Day -15):

a. Phosphate binding products including prescribed and over-the counter b. Oral or injectable active vitamin D c. Oral nutritional vitamin D d. Calcium supplements e. Anti-osteoporotic medication (e.g. bisphosphonates) f. Cinacalcet i. Subject must be prescribed a diet appropriate for patients with their stage of CKD, must be willing to avoid intentional changes in diet and must have stable nutritional status in the opinion of the investigator.

j. Subjects on dialysis must, in the opinion of the investigator, have a stable dialysis prescription, stable dialysis access and a URR \>/= 65% for at least 4 weeks prior to Day -15.

Exclusion Criteria:

1. Subject is receiving or has received an investigational product (or is currently using an investigational device) within 14 days prior to Visit 2 (Day -15);
2. Subject has a known sensitivity to chitin or allergy to shellfish;
3. Subject has had dental work other than cleaning, cavity filling or crown placement within 48 hours prior to Visit 4 (Day 1) or at any time during the course of the trial;
4. Subject has a clinically significant infection requiring treatment with antibiotics (within 7 days prior to Visit 2 (Day -15));
5. Subject has had an inpatient hospitalization within 14 days prior to Visit 2 (Day -15) with the exception of hospitalizations related to vascular access procedures;
6. Subject has a known history of immunodeficiency diseases, including a positive HIV (ELISA and Western blot) test result;
7. Active drug or alcohol dependence or abuse (excluding tobacco use) in the opinion of the principal investigator;
8. In the opinion of the investigator, subject is unable to chew gum for 30 minutes;
9. Subject has an unstable medical condition which in the opinion of the investigator would compromise successful completion of the study;
10. Subject is receiving calcimimetic therapy (acceptable if subject is on dialysis);
11. Subject has known salivary gland dysfunction or Sjogren's syndrome;
12. Subjects is receiving niacin therapy within 7 days prior to Run- In Visit 2(Day -15) (use as part of standard multivitamin is acceptable);
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;

a. Acute myocardial infarction b. Acute cerebral vascular event c. Vascular surgical intervention d. Coronary Revascularization e. Decompensated congestive heart failure

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C: Inclusion Criteria:

1. Patients with a GFR of \< 45 ml/min;
2. Intact serum PTH \> 37 pg/ml;
3. Age \> 35 years (both genders and all races);
4. Able to perform two three-week balance studies;
5. Not on oral calcium or vitamin D other than multi vitamin, or willing to stop calcium or vitamin D for one month prior to entry in the study (day 1 of first calcium balance period);
6. Female patients must be post-menopausal (defined as last menstrual period at least 12 months prior to screening visit) or surgically sterile by hysterectomy;
7. On stable doses of diuretics, bisphosphonates, anti-epileptics (except dilantin) for at least 2 months.

Exclusion Criteria:

1. Serious underlying systemic disease (including uncontrolled diabetes, lupus, hypertension, amyloid, etc);
2. Taking drugs that alter calcium and phosphate balance or homeostasis including high dose cholecalciferol or ergocalciferol (1000 U/day or 50,000U/ wk, respectively), active vitamin D metabolites, calcimimetics, PTH analogues in the last 30 days;
3. Taking drugs that the investigator feels will alter calcium balance;
4. Plan to initiate dialysis in the next six months;
5. Hypercalcemia defined as serum calcium \> 10.5 mg/dl;
6. Hyperphosphatemia defined as serum phosphate \>5.5mg/ml;
7. Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, bariatric surgery;
8. Smoking
D: 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

Answer: D