Microsampling study designs

Here we include examples of study designs that may be used for microsampling from either main study animals or from satellite groups of animals.  These examples are intended to be a starting point for study design and it may be necessary to amend them to take into account the number of timepoints required for a toxicokinetic profile for a specific compound and the inclusion of additional endpoints (e.g. anti-drug antibody and pharmacodynamic analysis).

[Group sizes will be annotated as XM + XF with X being the number of animals, M representing males and F representing females]

Rat study (four to 13 weeks duration) - example designs

Example study design (1)

Microsampling can reduce the number of satellite animals required to 3M + 3F (rather than 9M + 9F with conventional sampling).  This gives a total reduction of 48 animals.

Using 3M + 3F satellite animals per group is sufficient to give up to six timepoints on day one of the study and again at week four or 13.
 

Dose group	Low	Medium	High	Control
No. of animals	10M + 10F	10M + 10F	10M + 10F	10M + 10F
No. of recovery animals			5M + 5F	5M + 5F
No. of toxicokinetic satellites	3M + 3F	3M + 3F	3M + 3F	3M + 3F
Maximum total for one study				124

Example study design (2)

Microsampling can be used to sample from main study animals and avoid the use of satellite animals.  Composite toxicokinetic profiles (made up from samples from sub groups of animals) are obtained from main study animals.  This leads to a total reduction of 72 animals from a standard study design.
 

Dose group	Low	Medium	High	Control
No. of animals	10M + 10F	10M + 10F	10M + 10F	10M + 10F
No. of recovery animals			5M + 5F	5M + 5F
Maximum total for one study				100

An example of how to split the sampling at the different time points is presented below.  This is a balanced study design with ten animals/sex/group, a composite toxicokinetic profile with six time points and three samples per animal.  
 

Main study rat number	TP 1	TP 2	TP 3	TP 4	TP 5	TP 6
1	X			X	X
2	X			X		X
3		X		X	X
4		X	X			X
5	X		X			X
6	X		X		X
7	X		X			X
8		X		X	X
9		X	X		X
10		X		X		X

Rat study (six month duration) - example designs

Example study design (1)

Microsampling can reduce the number of satellite animals required to 3M + 3F (rather than 9M + 9F with conventional sampling).  This gives a total reduction of 48 animals.

Using 3M + 3F satellite animals per group is sufficient to give up to six timepoints on day one and again at weeks 13 and/or 26.   
 

Dose group	Low	Medium	High	Control
No. of animals	12M + 12F	12M + 12F	12M + 12F	12M + 12F
No. of toxicokinetics	3M + 3F	3M + 3F	3M + 3F	3M + 3F
No. of recovery animals			5M + 5F	5M + 5F
Maximum total for one study				140

Example study design (2)

Microsampling can be used to sample from main study animals and avoid the use of satellite animals.  Composite toxicokinetic profiles (made up from samples from sub groups of animals) are obtained from main study animals.  This leads to a total reduction of 72 animals compared to a standard study design.

Using 15M + 15F main study animals, with composite sampling and each animal being sampled up to three times, a toxicokinetic profile with up to nine timepoints on day one and again at Week 13 and/or 26 can be obtained.  
 

Dose group	Low	Medium	High	Control
No. of animals	15M + 15F	15M + 15F	15M + 15F	15M + 15F
No. of recovery animals			5M + 5F	5M + 5F
Maximum total for one study				140

Example study design (3) incorporating male fertility

As Table 5 with an additional five males added to each group for male fertility assessment and 20 undosed females for mating.  This leads to a total reduction of 60-80 animals from a standard study where male fertility was carried out separately. 
 

Dose group	Low	Medium	High	Control
No. of animals	15M + 15F	15M + 15F	15M + 15F	15M + 15F
Extra males for mating	5M	5M	5M	5M
Undosed females	20F	20F	20F	20F
Maximum total for one study				220*

Mouse study designs (one and six month)

The following study designs are real examples from two companies demonstrating flexibility in approach while still reducing and refining animal use.

Example study design (1)

Microsampling can reduce the number of satellite animals required to 6M + 6F (rather than 18M + 18F with conventional sampling) giving a total reduction of 102 animals. 

Using 6M + 6F satellite animals per group and composite sampling is sufficient to give up to six timepoints on day one and again at the end of the study.   
 

Dose group	Low	Medium	High	Control
No. of animals	12M + 12F	12M + 12F	12M + 12F	12M + 12F
No. of toxicokinetic satellites	6M + 6F	6M + 6F	6M + 6F	3M + 3F
Maximum total for one study				138

Example study design (2)

Microsampling can reduce the number of satellite animals required to 9M + 9F (rather than 18M + 18F with conventional sampling). This is a total reduction of 84 animals. 

Using 9M + 9F satellite animals per group and composite sampling (see table 9), is sufficient to give six timepoints on day one and again at the end of the study.
 

Dose group	Low	Medium	High	Control
No. animals	10M + 10F	10M + 10F	10M + 10F	10M + 10F
No. of toxicokinetics satellites	9M + 9F	9M + 9F	9M + 9F	3M + 3F
Maximum total for one study				140

An example of how to split the sampling at the different time points is presented below.  This is a balanced study design with nine animals/sex/group, composite toxicokinetic profile with six time points and two samples per animal.  
 

Satellite mouse number	1 h	3 h	6 h	9 h	12 h	24 h
1	X			X
2	X			X
3	X			X
4		X			X
5		X			X
6		X			X
7			X			X
8			X			X
9			X			X