This is a Phase III, multicenter, open-label study, which will quantify the improvement of nutrient absorption when participants are receiving Ultrase® MT20. The improvement will be demonstrated by comparing the CFA percent (%) and CNA% obtained during a washout of enzyme with the CFA% and CNA% obtained during a period of treatment with Ultrase® MT20. The study is also designed to obtain safety data in CF children suffering also from PI taking Ultrase® MT20. The total duration for the participation of children in this study will be approximately up to 38 days and will include 3 phases: screening phase, the washout phase and treatment phase.
Screening phase: this phase will last 15 days and all participants will take Ultrase® MT20 as per investigator's discretion during this period. During the last 4 days, participants will be stabilized on a high fat diet and with Ultrase® MT20. The individual 'stabilized dose' of Ultrase® MT20 capsules will be determined for each participant based on the average number of capsules of Ultrase® MT20 taken during last 4 days.
Washout phase: this phase will last 6 to 7 days. The participants will continue the high-fat diet but will refrain from taking Ultrase® MT20 or any other enzymes. A 72-hour stool collection will be performed and all food consumed by the participants will be recorded to assess the CFA% and CNA%.
Treatment phase: this phase will last 7 to 11 days. The participants will continue the high-fat diet and will take the 'stabilized dose' of Ultrase® MT20 established during screening. Another 72-hour stool collection will be performed and all food consumed by the participants will be recorded to assess the CFA% and CNA%.