Table 1.
Advantages, disadvantages, and limitations of laxative models
| Model | Advantages | Disadvantages and limitations |
|---|---|---|
| Isolated organ bath system | Uses very small amounts of substances/products | Requires many instrument setups |
| Can be used to test many substances/products in multiple experiments until the tissues become unresponsive | May show no contractile response when spontaneous contraction of the intestines is greater than that induced by the substances/products | |
| Can be modified to evaluate receptor-mediated intestinal contraction | Cannot test substances/products that do not dissolve in water | |
| Mimics an intact intestine in the body without interfering with external influences | Cannot evaluate bulking and osmotic activities | |
| Can use several intestinal sections from one animal | ||
| In vivo fecal assessment | Simple to observe fecal parameters | Requires many animal cages per experiment (one animal per cage) |
| Affordable instruments | Requires to keep track of the amount of food and water consumption | |
| Can be used in multiple experiments using the same set of animals | Requires workforce to observe wet feces as soon as possible to avoid water evaporation | |
| Not necessary to euthanize animals which can be transferred to other experiments after a washout period of 7 days | ||
| Intestinal transit assay | Easy to track an ingested tracer in the GI tract | Provides only one result from each animal |
| Requires a short period of time for one experiment to be done | Can only be performed on euthanized animals (except when using radiopaque or fluorescent tracers, which require advanced imaging techniques for live animals) | |
| Should be done within a specific time before the tracer moves into the large intestine | ||
| In vivo constipation model | Verifies the overall laxative effects on constipation | Mimics secondary constipation but not primary constipation |
| Appropriate for experiments in various dimensions, e.g., fecal parameters, molecular assays, signaling pathways, and pathology | Takes time to induce constipation which may result in different symptom levels of constipation in each animal | |
| Requires model optimization to avoid the strong symptoms of constipation that cannot be relieved by substances or products |