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The importance of support services in pre-clinical toxicology research

by David Milstein on May 27, 2014

Prior to any clinical trial testing of new therapeutic compounds on human subjects, safety and metabolic data from animal models may be collected in a series of pre-clinical trials.  Once these studies are completed, the new drug is ready for application to receive Investigational New Drug (IND) status, which allows for clinical testing to commence.  Although these tests vary widely in complexity, they all require specialized analyses which involve significant equipment, personnel and resources.  Below are some common pre-clinical studies, with their required supporting analyses and services summarized.


Dose formulation analysis should be performed in conjunction with most pre-clinical studies.  Upon preparation of the therapeutic compound into a dosing unit, a subset of this preparation must be analyzed to ensure that the therapeutic agent exists at the appropriate concentration.  This can be accomplished by numerous methods, but it is routinely accomplished via chromatography, either with high performance liquid chromatography (HPLC) or liquid chromatography with tandem mass spectrometry (LC-MS/MS).  Often times, the contract research organization (CRO) performing the in vivo portion of the study does not have the required equipment or technical skills to perform this work.  In these cases, it must be either performed by the sponsor themselves, or utilizing another CRO, driving up costs and delaying study initiation.  Nucro-Technics offers the option of not only performing the dose formulation analysis, but can also perform the pre-clinical studies on-site, saving on shipping fees and centralizing the oversight of a client’s pre-clinical pipeline.


Pharmacokinetic (PK) studies are a common test that may occur prior to a novel drug moving into the clinic.  These studies track the absorption, distribution, metabolism, and excretion of a drug product in an organism.  PK studies describe the drug levels and kinetics of drug exposure to the tissues and hence the performance and pharmacological activity of the compound being tested.  This is accomplished in general by dosing an animal with the therapeutic compound being tested, and then bodily fluids are collected at multiple time-points to track the concentration of the compound and its metabolites.  These fluids may also be used to identify specific biomarkers for drug activity or toxicity.

Tracking these variables requires specialized machinery and expertise, and many CROs outsource this aspect of PK studies to a dedicated laboratory.  Using advance liquid chromatography with tandem mass spectrometry, blood samples can be analyzed for the aforementioned compounds, but not without first developing and validating a method to find them within the dense mixture of complex molecules found in the blood.  This time-consuming and research-focused process is a standard requirement for GLP studies and is necessary for eventual approval by the FDA or other country-appropriate agency.  If the CRO running the PK study cannot perform this work in-house, the samples must be shipped to another laboratory or back to the sponsor, adding additional time and related cost.


These studies make up the bulk of the testing required for demonstrating that a new therapeutic compound is safe for assessment in human clinical trials, in terms of both time and cost.  The main component of these studies is typically two weeks to six months in length, with additional time required prior to the study for acclimation and after the study for recovery.

Typically, these studies are conducted in two species; a rodent and non-rodent species (as per ICH M3, revision 2 guidelines, 2008) begin with a simple dose-range finding study to determine an expected safe dosage range to administer to the test animals.  This dose is typically many orders of magnitude larger than the dosages expected to be administered to human patients and thus, establishes a wide safety margin.  A dose range finding study relies mainly on clinical observations, such as weight and behavior.  These studies can involve single or multiple doses of the test compound.  These preliminary studies direct appropriate selection of doses within the main study thus accomplishing possible ethical goals for animal usage reduction and welfare.

Once the prestudy health checks and the required acclimation period have been completed, the study commences.  Animals are typically dosed based on the expected human dosing regimen which may include daily, weekly or some other schedule, and observed weekly for fluctuations in weight and food intake, as well as for signs of other health issues using qualitative and quantitative behavioral testing.  Dosing solution analysis should be undertaken on the first day of dosing and typically the last day of dosing to show uniformity and accuracy of the dosing administration.

Over the course of the in-life period of dosing, animals may have detailed observations / samples collected.  These additional parameters may include clinical pathology, ophthalmology, cardiology, and histopathology.  Ophthalmology and cardiology require board certified specialty veterinarians to perform these detailed observations.  Clinical pathology is the analysis of urine and blood for standard health measures, such as hematology (e.g. red blood cell counts), clinical chemistry (electrolyte quantification), and clotting ability, which are important for determining the health of the animals undergoing testing.  These specialty parameters are typically performed at the beginning and end of the study to allow for easy comparison of the animals health prior to and after administration of the test substance.  Pathology, including gross pathology and histopathology, is performed on a subset of test animals, and involves humanely sacrificing them before collection of target organs for processing and staining and analysis via microscope.  Again the histopathology analysis of the tissues/organs is performed by a board certified veterinarian.  Both the clinical pathology and pathology analyses require large specialized equipment and technical support to complete.

Typically on the first and last day of dosing, a subset of the test organisms undergo pharmacokinetic sampling and analysis.  This allows the researchers to determine the rate and extent of systemic exposure of the drug candidate before and after the repeated dosing period, yielding statistically powerful measures of the sub-acute toxic effects of the compound.

Because these studies involve multiple rounds of in-depth analysis with a variety of instruments on a large number of animals (i.e. hundreds of rodents), they can be quite costly.  Indeed, the major component of the cost is determined by the supporting services – dose formulation analysis, bioanalysis (PK) of the therapeutic compound in blood samples, clinical and histopathology.  If these services cannot be performed by the CRO performing the in vivo portion of the study, samples must be prepared and shipped to other facilities for analysis.  Preparation and shipping times, as well as shipping costs, for hundreds of samples at multiple points through the studies, as well as specialized shipping requirements/regulations (e.g. dry ice, permits, etc.), add up quickly.  It is to the sponsor’s advantage if they are able to find a single CRO that can perform all of these services in-house.

In addition to the support services mentioned above, Nucro-Technics research science teams will help you to accelerate your early pre-clinical drug discovery by designing and carrying out cost-effective, preliminary studies.  These studies include genetic toxicology, in-vivo safety testing, facilitating dose formulation and analysis, developing and validating bioanalytical methods and evaluating the pharmacokinetic profile of your drug candidate to ensure successful pivotal studies for an IND submission.

In addition to capabilities in performing in vivo research on a multitude of guidance document driven animals for studies of up to 2 years in length, Nucro-Technics also performs all of these required analyses in-house.  This one-stop solution for pre-clinical testing is of major benefit to pharma and biotech firms looking to consolidate their testing needs in one location, thus greatly reducing cost and turn-around times.

For more information on any of the pre-clinical tests and services that Nucro-Technics offers, please feel free to explore our website (www.nucro-technics.com/services/toxicology) or by emailing our offices directly at info@nucro-technics.com.

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