Frequently Asked Questions
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Other Information
Are there gender differences in human CYP enzymes?
Are there ethnic differences in human CYP enzymes?
The properties of the CYP enzymes do not vary from one ethnic group to the next. However, CYP levels and the incidence of genetic polymorphisms vary among ethnic groups. In other words, there are quantitative but not qualitative differences in CYP enzymes.
For more information, see our poster on the topic: The Effects of Gender, Age and Ethnicity on Human Cytochrome P450 Activity
Are XenoTech's human-derived products biohazardous?
Results of serum tests for known pathogens (HIV, Hepatitis B and C, CMV) are included with your order. XenoTech does not sell subcellular fractions from donors known to harbor infectious diseases, such as HIV, hepatitis or syphilis. However, we recommend that all human products be handled as potential biohazards and universal precautions be followed.
My drug is insoluble in water. How much organic solvent can be used without inhibiting CYP enzyme activities?
| Recommended solvent concentrations in the final incubation mixtures are as follows: |
| Methanol |
< 1.0%, |
| Dimethylsulfoxide (DMSO) |
< 0.2% |
| Acetonitrile |
< 1.0% |
| % PEG 400 |
< 1.0% |
| Note: organic solvents potently inhibit CYP2E1, therefore, we recommend the following final concentrations for CYP2E1: |
| Methanol |
< 0.2% |
| Acetonitrile |
< 0.2% |
| % PEG 400 |
< 1.0% |
| Do not use DMSO if you are interested in CYP2E1 enzyme activity. |
Is it possible to get donor information for human-derived products?
Certain demographics are available on all human donors, including sex, age, race, limited medical history (major illnesses, recent medications, etc.) and limited social history (smoking, alcohol, drug habits, etc.). Information that may reveal the identity of the donor is not available.
Can cryopreserved hepatocytes be used for metabolism and induction studies?
This table provides a quick reference for the potential use of cryopreserved hepatocytes from different species.
Species |
Recommended Application |
Metabolism Studies
(short-term incubations) |
Induction Studies
(long-term incubations) |
Human |
Yes |
Sometimes * |
Monkey |
Yes |
Not recommended * |
Dog |
Yes |
Not recommended * |
Rat |
Yes |
Yes |
* Most cryopreserved human, monkey and dog hepatocytes do not attach in culture; therefore, they may not be suitable for enzyme induction studies. Please
contact us for availability of inducible human hepatocytes.
What contract services are available through XenoTech?
We routinely perform the following types of contract services:
- Enzyme Inhibition
- Enzyme Induction (in vitro and ex vivo)
- Reaction Phenotyping (enzyme mapping)
- Metabolite Identification and/or characterization
- Drug Transporter studies
- Species Comparison
- Drug metabolism studies in hepatic and extrahepatic subcellular fractions
- Drug metabolism studies in hepatocytes
- Custom services involving other drug-metabolizing enzymes (e.g., UDP-glucuronosyltransferase)
- Covalent binding
- Hepatotoxicity
- Consultation services and courses in drug metabolism
Can XenoTech ship products overseas?
Yes, XenoTech ships products all over the world. We currently have distributors throughout Europe and Japan. For more information, check the Distributor section of this website.