D-cellobiose

Direct observations: clinical cases, poisoning incidents and other

Administrative data

Endpoint:

direct observations: clinical cases, poisoning incidents and other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

fall 2017 to spring 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

publication (copyright not owned for reproduction)

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Study type:

study with volunteers

Endpoint addressed:

other: maximum tolerated dose (oral route), acute and subacute

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The goal of this single-arm, dose-escalation study was to evaluate the safety and tolerability of cellobiose and to determine the maximum tolerated dose of cellobiose in healthy subjects. Following a baseline period, consecutive cohorts of six subjects each consumed either single doses of 10, 15, 20 and 25 g, while 12 subjects each received multiple doses of 15 g or 20 g cellobiose (twice daily, 14 days). The main recorded parameters were stool consistency, gastrointestinal well-being (Gastrointestinal Symptom Rating Scale) and adverse events.

GLP compliance:

not specified

Remarks:

The study was in conformity with the ethical principles for medical research involving human subjects of the World Medical Association Declaration of Helsinki as well as the EU recommendations for Good Clinical Practice (CPMP/ICH/135/95), ICH E6 (R2)

Test material

Test material information

Constituent 1

Reference substance name:

D-cellobiose

EC Number:

208-436-5

EC Name:

D-cellobiose

Cas Number:

528-50-7

Molecular formula:

C12H22O11

IUPAC Name:

(2R,3S,4S,5R,6S)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R,6R)- 4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol

Method

Type of population:

general

Subjects:

- Number of subjects exposed: 52 (total
- Sex: females and males
- Age: adults
- Race: no information ,but likely kaukasian
- Demographic information: none
- Known diseases: none
- Other: mean BMI approx. 24

Ethical approval:

confirmed, but no further information available

Route of exposure:

oral

Reason of exposure:

intentional

Exposure assessment:

not specified

Details on exposure:

see 'Any other information on materials and methods incl. tables'

Examinations:

- gastrointestinal symptoms
- stool consistency acc. to the Bristol Stool Form Scale (BSFS)
- full blood count parameters (haemoglobin, haematocrit, erythrocytes, thrombocytes, and leucocytes) and liver and renal function parameters (alanine transaminase, aspartate aminotransferase, gamma-GT, alkaline phosphatase, bilirubin; creatinine, urea, uric acid)
- lipid metabolism parameters (total cholesterol, HDL- and LDL-cholesterol), the carbohydrate metabolism parameter glycated haemoglobin HbA1c, glucose and thyroidal parameter TSH
- Dipstick urinalyses for the assessment of glucose, proteins and infection parameters
- Sitting blood pressure and pulse rate

Results and discussion

Clinical signs:

When administered as a single dose, adverse events like flatulence plus borborygmus (n = 2) and diarrhoea (n = 1) occurred in 50% of the subjects (3 of 6) after consuming 25 g cellobiose, whereas 20 g cellobiose resulted in only one case of flatulence plus borborygmus among six subjects (17%). No adverse GI events were caused by 10 g or 15 g cellobiose. There were no significant stool consistency changes (three days after V2 compared to baseline) when comparing the cohorts of the SAD phase. In one case, diarrhoea occurred after consuming 25 g cellobiose, this normalised again one day later. In all single-dose groups, the mean GSRS scores remained in the same range (15.0 ± 0 and 19.5 ± 4.7). Based on the observed low level of adverse events, BSFS types and the GSRS results, as well as on the 100% global tolerability rating, the tolerable cellobiose intake level was set to 20 g cellobiose daily for single use. Higher acute doses may result in a substantial level of adverse GI events, as observed in this study with 25 g cellobiose. This dose approximately corresponds to the literature data with a single dose no-observed-effect level of 0.36 g/kg bw/day [15] (25.2 g for a 70 kg person) [15].
There were clear differences between the two multiple-dose groups (20 g bid versus 15 g cellobiose bid): Whereas 20 g cellobiose bid caused a GI adverse event rate of 58%, the GI AE rate was 8% in the 15 g bid group. The mean stool consistency was significantly thinner in the 20 g cellobiose bid group compared to the 15 g bid group three days after V2; also, in the 20 g bid group (but not in the 15 g bid group), the GSRS values were elevated during intake (Figure 5). These results, as well as the 92.6% global tolerability rating for the 15 g bid group, support a tolerable dose of repeated cellobiose consumption of 15 g twice daily (30 g total). This daily dose is 6 × higher than what was previously reported as the multiple-dose in literature [14].
Some parameters did not result in any group differences, e.g., time of bowel movement, bowel movement frequency, occurrence of headache/thirst or safety laboratory parameters and vital signs. Considering that the upper SAD and MAD dosage groups only had slightly more loose stools, this is plausible. Increased bowel movement frequencies would only be expected for more severe diarrhoea. To confirm safety, it is reassuring that laboratory safety parameters did not change in a clinically relevant manner. The occurrence of headache or thirst did not correlate with the dosages and may therefore not be related to cellobiose intake.
As to be expected, some individuals were more sensitive to cellobiose than others, regarding gastrointestinal disturbances. For example, the two subjects that suffered from the adverse event recurrent diarrhoea after the intake of 20 g cellobiose bid also suffered from flatulence. At the same time, five of 12 individuals did not experience any GI events at this high dose.
Additionally, some of the recorded GI events may have been unspecific and not related to the cellobiose intake. In this regard, one subject that ingested 15 g cellobiose bid experienced diarrhoea three days after cellobiose discontinuation (Figure 4A). However, the same subject also experienced diarrhoea on day five of the baseline period; accordingly, the observed diarrhoea on day 17 may have been a result of a general tendency towards GI disturbance, rather than a (late) cellobiose effect.

Applicant's summary and conclusion

Conclusions:

In a study evaluating cellobiose in healthy subjects for 14 days evidence of gastrointestinal tolerance at lower dosages (up to 15 g twice daily or 20 g once daily) and a fairly good safety profile at the highest dosage tested (25 g daily or 20 g twice daily). Mild signs of intolerance expressed as gastrointestinal complaints were observed in sensitive subjects. Based on the study results, the tolerable dose of cellobiose consumption is proposed to be 20 g cellobiose daily for single-use and 15 g twice daily (30 g total) for repeated consumption.

Executive summary:

In a study evaluating cellobiose in healthy subjects for 14 days evidence of gastrointestinal tolerance at lower dosages (up to 15 g twice daily or 20 g once daily) and a fairly good safety profile at the highest dosage tested (25 g daily or 20 g twice daily). Mild signs of intolerance expressed as gastrointestinal complaints were observed in sensitive subjects. Based on the study results, the tolerable dose of cellobiose consumption is proposed to be 20 g cellobiose daily for single-use and 15 g twice daily (30 g total) for repeated consumption.