Essential Tools Every Drug Discovery Lab Should Have For Your Toxicokinetic Analysis

Toxicokinetic analysis forms a crucial component of toxicology studies in drug development. They assess absorption, distribution, metabolism, and excretion of toxicants against time. Once a toxicant is absorbed in the body, it diffuses to different parts of the body. Depending on its metabolism, the toxicant may stay in the body for a while or be excreted out of the body. Hence, toxicokinetic studies (tox study or TK analysis) are critical early toxicological analyses that evaluate the safety and efficacy of drug products.

Primary nonclinical toxicology data help decode the compound of interest before subjecting it to more definitive GLP-toxicology studies. TK data derived from these definitive studies provide a more comprehensive drug exposure profile, which is necessary for determining initial doses in human clinical trials. Not to mention, TK analysis is beneficial in reducing the number of study animals used in drug experiments. Therefore, having powerful tools in the arsenal is always helpful for a robust toxicokinetic analysis. In the current article, we present tools and systems that drug discovery labs should have for toxicokinetic analysis.

Tools for a robust toxicokinetic analysis

A toxicokinetic analysis is necessary for assessing toxicity and determining experimental dosage in study animals. The ultimate goal is to evaluate toxicity in test animals for selecting starting doses in first-in-human studies. However, it is challenging to extrapolate data from animal results and use it to predict potential effects in the human population. Let us understand some systems that are essential for overcoming this challenge.

A toxicokinetic analysis is a prerequisite in nonclinical toxicology studies, or sponsors may conduct them as additional supportive studies. Hence, all drug products undergo toxicokinetic/pharmacokinetic (PK/TK) evaluations to understand their toxic properties. Sponsors conduct PK/TK analysis in both animal and human subjects. They assess these basic parameters through in-vitro and in-silico studies. Out of these two approaches, in-vitro studies are vital in toxicokinetic analysis. Apart from these studies, drug discovery labs also need highly-sensitive instruments and techniques for accurate TK analysis. Some of these requirements include:

• Sensitive determination of drug concentration
• Discovering metabolite structure and profiles through LC-MS/MS
• Accurate calculation of TK parameters such as Tmax, Cmax, AUC, and volume of distribution
• Microsampling of biological samples
• And the availability of robust immunological methods such as ELISA and bead-based arrays.

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TK services lab should also have expertise in toxicokinetic modeling. These models help drug developers understand the uptake, metabolism, and excretion of toxic chemicals in an organism. Toxicokinetic models are based on compartmental analysis, requiring limited time-series data for estimating PK/TK characteristics. These compartmental models include single-compartment, multi-compartment, and physiological based TK-models. Multi-compartmental models are more complex, and hence these compartments are defined characteristically with no physiological relationships. On the other hand, physiological-based TK models divide individual TK parameters into functionally relevant chambers.

Conclusion

Toxicokinetic studies are critical to understanding systemic drug toxic exposure in animals with time. Hence, increased awareness and advances in toxicokinetics analyses will be necessary to improve the efficacy, reliability, and safety of drug products.