Safety and Tolerability Study of MCI-196

• Children aged 2 years to \<18 years with CKD stages 3b to 5, not on dialysis (stage 3b is defined as a glomerular filtration rate below 45 mL/min/1.73 m²).
• The subject has a documented diagnosis of hyperphosphataemia, as demonstrated by serum phosphorus (P) levels above the age-related upper limit of normal (ULN) (Kidney Disease Outcomes Quality Initiative [KDOQI] Clinical Practice Guidelines for Nutrition in Children with CKD updated 2008).
• The subject is on a stable P diet at baseline (as judged by the Investigator).

Inclusion criteria for subjects not currently treated with phosphate binders:

• The subject, with serum P not controlled despite being on an appropriate P diet, must demonstrate serum P levels >1.5 standard deviation (SD) above the KDOQI 2008 age-related mean value at any time during the screening period. Such subjects do not require wash-out and should proceed to baseline for the next visit if additional screening visits are not required.

Baseline inclusion criteria for subjects treated with phosphate binders:

• The subject must enter the wash-out period, during which he/she must demonstrate serum P levels >1.5 SD above the KDOQI 2008 age-related mean value at any time during the wash-out period (after stopping phosphate binders), and;
• The subject must demonstrate an increase in serum P levels by at least 10% above the pre wash-out level (after stopping phosphate binders).

Note: should a subject fail to meet any of the above criteria, the subject is permitted to be re-screened once after an interval of at least three months.

Exclusion Criteria:

• The subject has been diagnosed with hypocholesterolaemia (i.e., cholesterol levels below age-related normal ranges, per local practices)
• The subject has current clinically significant medical comorbidities, which may substantially compromise subject safety, or expose him/her to undue risk, or interfere significantly with study procedures and which, in the opinion of the Investigator, make the subject unsuitable for inclusion in the study (e.g., the subject currently has or has had a history of seizure disorders, dysphagia, swallowing disorders, predisposition to or current bowel obstruction, ileus or gastrointestinal [GI] disorders such as chronic or severe constipation [as judged by the Investigator], intestinal stenosis, intestinal diverticulum, sigmoid colitis, GI ulcers, current or a history of GI bleeding, or major GI tract surgery)
• The subject cannot stop treatment (prescription or over the-counter) of any of the following orally taken medications during the wash-out period: any product containing calcium (Ca), magnesium (Mg), aluminium compounds, sevelamer, lanthanum, ketosteril
• The subject is receiving immunosuppressant treatment for any medical condition at the baseline visit or is expected to receive such treatment during the course of the study
• The subject is considered as unstable on his/her current treatment for CKD within one month prior to screening (e.g., subjects starting treatment with vitamin D or its analogues, or other agents/procedures that may influence bone mineral metabolism [i.e, serum P and Ca levels]

Exclusion criteria for subjects treated with phosphate binders:

• The subject was treated with a combination of two or more phosphate binders within one month prior to screening