Toxicology Study

We are offering rapid PK TK analysis for drugs, metabolites, and Prodrugs. We provide bioanalysis at an FDA-verified Lab CRO.  Contact us today for for preclinical GLP toxicokinetic study therapeutic index, toxicokinetic (TK) analysis services – for single/acute dose tox, and repeated dose tox studies using ADME assay.

What do Toxicology (Tox) studies entail?

Nonclinical toxicology (tox) studies during preclinical development assess drug exposure for adverse effects and therapeutic index. Before first in humans (FIH) dosing, the FDA requires toxicological studies in a minimum of two animal species. For in vivo toxicology studies, one of the chosen species must not be a rodent, and one species may be. Studies on toxicology can take many different forms, including acute or single dose toxicity studies, dose range finding (DRF) studies, studies on maximum tolerated doses (MTD), and studies on repeated dose toxicity. In accordance with 21 CFR part 58, we carry out regulated nonclinical tox studies using Good Laboratory Practices (GLP). Regular GLP toxicokinetic (TK) studies and Non-Compartmental Analysis for dose ranging studies are two of our toxicology services. Prodrugs, drugs, and metabolites’ systemic exposure time courses can be quantified with the aid of toxicokinetic (TK) studies. To evaluate your therapeutic compound, NorthEast BioLab provides non-GLP and GLP toxicity studies in a timely and high-quality manner. Finally, clinical toxicological analysis is aided by acceptable drug safety during toxic studies that permit FIH testing. This is because nonclinical toxicology data are crucial for this analysis.

Toxicological or toxicology (tox) studies assess adverse effect profiles, organ and tissue exposures, and margins of efficacy vs. toxicity to help determine the safety of drugs. In fact, these toxicology studies in drug development frequently cover the therapeutic index in the dose ranges they examine, defining the range between the lowest effective dose and the highest tolerated (or practicable) dose. The majority of the time, drug discovery leads that are optimized for nonclinical toxicology testing have already had their pharmacokinetics, potency, and efficacy assessed in preclinical disease models. When designing initial toxicology studies, especially when choosing dose levels, routes, and regimens, this preliminary data collection is frequently crucial. Tox studies typically start with nonclinical dose range-finding (7-day repeat dose), maximum tolerated dose (MTD), and single ascending dose studies. These toxicity studies are being conducted in order to determine the proper dosing schedule for the long-term (28-day) repeat dose GLP toxicity study. Typically, repeat dose studies use different toxicology services like gross pathology, histology, and microscopy to examine how the drug affects the entire body. Additionally, more in-depth studies are carried out to assess the safety of specific organ systems or potential risk factors.

What kinds of Tox studies are there?

All novel drug entities, their active metabolites, or metabolites demonstrating significant systemic exposure after drug administration are subject to regulatory authorities’ requirements for toxicological studies. Pharmaceutical and biochemical researchers frequently conduct single dose toxicity studies, maximum tolerated dose (MTD) studies, and dose range finding (DRF) studies in order to establish appropriate dosing margins prior to performing regulated repeated dose toxicity studies. To assess any acute toxicity and determine whether dose accumulation occurs, a short-term (typically 7 to 14 days) repeated dose toxicity study is frequently carried out. This involves performing toxicokinetic (TK) analysis on the first and last days of dosing. Depending on the intended clinical administration of the drug, these results are then used to design conclusive GLP repeat dose toxicology studies, which usually involve dosing for at least 28 days. To interpret the dose-exposure relationships, determine whether saturable metabolism occurs with increasing doses or accumulation occurs with multiple doses, and empirically demonstrate steady-state exposures, TK analysis data are then generated during these studies. Additional analyses and investigations are carried out to evaluate the effects of the drug on the heart, lungs, or reproductive system as well as its potential to cause cancer or genetic mutations.

Comprehensive guide to IND studies that enable Toxicology

Many different drug substances and their formulations are created during the pharmaceutical discovery and development process. The vast majority of these compounds, though, won’t work well enough to be final goods that can be sold. …

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Toxicology (Tox) Analysis Services

From early drug discovery through clinical IND/BLA submission and beyond, we offer bioanalysis and pharmacokinetic/toxicokinetic analysis services.

Bioanalysis: PK/TK analysis

We provide full-service PK/TK analysis solutions, including sample analysis of your formulation and biological samples for test substances, medications, and metabolites, as well as method development, validation, and sample analysis. Our seasoned team handles all of your preclinical and clinical bioanalytical services as necessary using GLP validated tools, software, and techniques. As requested by the sponsor, we deliver thorough audited study reports for sample bioanalysis and toxicokinetics.

Non-compartmental analysis (NCA): analysis of the PK/TK parameters

The non-compartmental analysis (NCA) of small molecules, metabolites, or monoclonal antibodies during clinical and in vivo preclinical toxicology studies can also be handled by our in-house experts. For compliance with requirements for electronic submissions to the FDA and other international regulatory agencies, we can put together Pharmacokinetic Concentration (PC) and Pharmacokinetic Parameter (PP) domains for your results in CDISC SEND or SDTM format.

We are happy to help you further with project and regulatory guidance, protocol design, study prosecution, and data interpretation at all project stages, in keeping with our solution provider philosophy. For your Toxicokinetic (TK) Study analysis, NorthEast BioLab maintains the most recent and fully validated software packages, such as Certara’s WinNonlin, Watson LIMS, Sciex Analyst, Spectramax, etc.

Why do you need Tox studies from us?

Our seasoned team of scientists at NorthEast BioLab has the knowledge and skills required to support tox studies from planning and execution to TK analysis and data interpretation. Your ability to successfully complete toxicokinetic studies, a crucial step in the drug development process, will be aided by our expertise in toxicology studies. To assess systemic exposure, steady-state exposure, and metabolic constraints for your compound, we perform toxicokinetic analysis. These TK parameters assist researchers and medical professionals in choosing the appropriate drug dosage and dosing schedules for preliminary clinical trials. As a result, reliable, effective toxicological studies and analysis are crucial for compound characterization in drug development.

To prepare for regulatory IND submissions, we similarly conduct GLP toxicity studies using a fully validated and trustworthy bioanalytical and TK method. Your pharmacokinetic concentration and non-compartmental TK parameter results are presented in a CDISC SEND format that is compliant with our formal and audited bioanalysis and toxicokinetics eCTD reports.

GLP toxicology studies: what are they?

Before FIH (First In Human) dosing, in-vivo toxicology studies are required and are typically carried out under GLP conditions using specific protocols. Preclinical research on lead compounds before the start of clinical trials generally follows the following pattern: Maximum Tolerated Dose (MTD) study,acute (single-dose) toxicity dose ranging study, Repeat-dose toxicity: 2 to 14 weeks (daily dosing, mandated by regulators in two species, one rodent and one non-rodent); carcinogenicity: up to 2 years of chronic dosing in rodents; mutagenicity: in vitro AMES test; cardiovascular risk by hERG inhibition; chromosome aberration; and, as appropriate, in vivo respiratory and cardiovascular safety pharmacology studies.

Toxicokinetics (TK) Study: What is it?

To assess potentially toxic drug levels, a pharmacokinetic study of the drug given in doses greater than the therapeutic dose is known as a toxicokinetic (TK) study. The study of the systemic kinetics of all substances at exposure levels ranging from therapy to toxicity is thus appropriately referred to as toxicokinetics. The body reaches the maximum feasible dose (MFD), the highest dose level that can be administered based on physicochemical constraints, or the maximum tolerated dose (MTD), the dose level yielding the drug’s exposure to the point of toxicity, during a GLP toxicity study by FDA standards. Toxicology studies must take into account the drug’s dosage and systemic exposure because these factors determine whether a medicine is toxic or therapeutic. The therapeutic index of the drug, which denotes the safety margins between therapy (minimum effective dose) and toxicity (maximum tolerated dose or maximum feasible dose), is explained by this difference. Healing may begin at the site of action when the same medication is administered in a small dose. However, it can even be fatal to the human body if given in high doses. The ability of the study to shed light on how molecules’ systemic exposure relates to adverse effects necessitates toxicokinetic analysis. For assessments of the cardiovascular system, the central nervous system, and the respiratory system, this factor is very crucial. Additionally, the acute single dose toxicity studies included in this analysis help determine whether systemic accumulation happens after multiple drug administrations in repeated dose toxicity studies as well as the duration and rate of exposure at the time of one dosing interval. The appropriate dose levels for later phases of compound development are provided by this benchmark data. The information gathered from toxicokinetic studies evaluates the toxic responses of different drug compounds overall. The findings of this study serve as the foundation for determining the ideal first dose of a novel medication that is secure for use in people. Additionally, the analysis may shed light on the varied ways in which individuals of various ages, genders, and ethnicities may be affected by specific medications.

Which steps make up a Toxicokinetics (TK) Study?

Usually, studies on acute and repeated dose toxicity involve the use of toxicokinetic analysis. Essentially, it is the procedure that explains how a substance enters the body and what happens to it once it is there. To describe the body’s exposure to the drug or toxicant over time, the word “disposition” is frequently substituted for the term “toxicokinetics.” Absorption, distribution, metabolism, and elimination are the four fundamental descriptive underlying processes of disposition that have the greatest influence on toxicokinetic studies. These dispositional principles are mathematically described by TK analysis using compartmental or non-compartmental analyses. In addition to correlating to clinical toxicological analysis of exposure margins and adverse events for safe clinical administration, these stages or processes aid in learning how the body absorbs, metabolizes, and clears the drugs administered.


A substance entering the systemic blood circulation is known as absorption, which is the first dispositional element in toxicokinetic studies. Drugs may need to pass through some obstacles before entering the bloodstream, depending on the route of administration. For instance, a medication must be soluble in the gastrointestinal space and capable of passive or active diffusion across the gut wall after oral administration. When drugs enter the portal vein from the gastrointestinal tract, first pass metabolism takes place there before systemic absorption. The absorption process can be avoided in PK and TK studies by giving an intravenous (IV) dose directly into the systemic circulation. Bioavailability is determined by comparing exposures after extravascular doses (such as oral, subcutaneous, dermal, inhaled, etc.) to exposures after IV doses during PK/TK analysis.


Distribution is the term used to describe the reversible movement of drugs from one part of the body to another. A drug’s distribution is influenced by a number of variables, such as a drug’s solubility in lipids, concentration in plasma and different tissues, and binding to plasma proteins, transport proteins, and tissues. The ability of a drug to enter cells and tissues from systemic circulation is described by the volume of distribution that is calculated during PK or TK analysis.


The term “metabolism” refers to the process by which a drug is changed into different chemical substances (metabolites). Although it can happen anywhere in the body, the liver is where metabolism primarily happens. The body’s xenobiotic chemicals are changed during metabolism through enzymatic or non-enzymatic processes. The goal is to transform lipophilic substances—which are poorly excreted—into more polar substances, which are more easily expelled from the body. Researchers can forecast safe exposure levels and potential drug-drug or drug-food interactions by understanding drug metabolism rates and sites.


Drug substances leave the body either as metabolites or in their original state. While the kidney is crucial for the body’s water-soluble toxin elimination, other compounds must be eliminated through the hepatic, biliary, etc. systems. In toxicokinetic studies, parameters that describe compound metabolism and excretion, such as apparent clearance and elimination half-life, are calculated.

What procedure does toxicokinetics involve?

The four dispositional factors that affect a compound in the ADME biological system are mathematically modelled by the toxicokinetic process. They include absorption of the medication into the bloodstream, also known as systemic circulation, distribution of the medication from the bloodstream to cells and tissues within the body, biotransformation of the medication into new entities, also known as metabolism, and excretion of the medication and its biotransformation products. The transformation of the drug compound into more reactive metabolites is frequently linked to toxicity. By determining systemic exposures through the bioanalysis of active pharmaceutical ingredients and metabolites, we perform toxicokinetic analysis. This is followed by toxicokinetic analysis using the in-vivo time vs. concentration results. No observed effect level (NOEL) is the highest dose or exposure that has no effect, No observed adverse effect level (NOAEL) is the highest dose or exposure that has manageable toxicity, and Therapeutic index (margin of safety) is the range encompassing the minimum effective dosage to the maximum tolerated dose. These parameters can be determined through toxicology studies.

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What various branches of toxicology are there?

Toxicology CROs provide in-silico and in-vitro predictive safety assessments. Using computer simulations, it is possible to predict a compound’s potential mutagenicity and genotoxicity based on its structure and previously recorded information. In-vitro toxicity assays enable testing with a wide range of discovery compounds to anticipate particular toxicity mechanisms and minimize the use of animals. In-vitro toxicity assays use toxicology services such as microsome, hepatocyte, hERG, and AMES assays to check for potential drug-drug interactions (DDI), mutagenicity, cytotoxicity, or organ toxicity. In spite of this, in-vivo toxicology studies are still important because they serve as the best gauge of toxicity. Satellite toxicity and maximum tolerated dose (MTD) study assessments, acute single-dose toxicity studies, repeat-dose GLP toxicology studies, genetic and prenatal toxicology studies, carcinogenic studies, safety pharmacology studies, in vivo erythrocyte micronucleus tests, and other systems biology techniques like metabonomics, proteomics, and transcriptomics are examples of in vivo toxicity studies.

Nonclinical toxicology: What is it?

Before a drug is first tested on humans, nonclinical toxicology and safety pharmacology tests evaluate a drug’s potential for negative and undesirable effects in animal models. Since nonclinical tests are conducted on novel drug entities before clinical trials are launched, the terms nonclinical and preclinical are frequently used interchangeably.

Toxicology: How is it applied?

Prior to submitting the IND, we must first obtain nonclinical GLP toxicology data for all lead candidates. Drug development research on in-vitro toxicology examines mechanisms like metabolic reactivity, inhibition, induction, mutagenicity, and cytotoxicity. These assays’ findings help scientists identify potential issues or constraints. To improve and characterize lead discovery candidates, we conduct in-vivo acute and chronic toxicology studies. Furthermore, cutting-edge methods such as toxicometabonomics, toxicoproteomics, and toxicogenomics can help select particular endogenous biomarkers for both clinical toxicological analysis and preclinical detection of potential toxicities or offer higher throughput approaches to identify in-vivo toxic responses shortly after dosing.

How can drug toxicity be tested?

The Institutional Animal Care and Use Committee (IACUC) of the testing organization must approve toxicological studies before they can be conducted on animals. Single-dose or acute toxicity studies keep an eye on an animal species’ response to a single dose. In testing for acute toxicological studies, we give the investigational product at various doses and track the outcomes for 14 days after a single dose. To identify the maximum tolerated dose, target tissues, PK, and safety pharmacology profiles during late optimization and prior to the compound’s preclinical development and nonclinical toxicology assessment, we conduct non-GLP repeated dose toxicity studies in rodents (mice or rats). We proceed with repeat-dose GLP toxicity studies if the test agent has reached a steady-state, there is a reasonable amount of test article accumulation or none at all, and no acute toxicity has been observed at therapeutic levels. In studies of repeated dose toxicity, the test substance is given every day under GLP guidelines for a minimum of 7, 14, 21, or 28 days. In rodent and non-rodent models, we can also carry out subchronic toxicity studies with daily dosing for 90 days or more.

What distinguishes TK and PK from one another?

The division of PK known as TK is used to investigate the link between systemic drug exposure and toxicity in various species. A drug’s systemic exposure to living things over time after administration is determined by pharmacokinetic studies. Unlike pharmacokinetic studies, toxicokinetic studies are typically conducted with higher doses. Toxicokinetic studies aim to measure the pharmacokinetics of a substance in toxicological study species at toxicological doses. Due to differences in absorption, metabolic saturation, or metabolic changes brought on by long-term use of the test article, TK exposures may increase nonlinearly with dosage. In addition, TK analyses are frequently used to investigate gender differences, drug accumulation after repeated doses, and quantitation of known drug metabolites or pharmacodynamic or toxicodynamic biomarkers.

Do pharmacokinetics and toxicokinetics have any connections?

Absorption, distribution, metabolism, and elimination (ADME) are the four processes that make up a drug’s disposition in the body, and pharmacokinetics (PK) analyzes and describes these processes mathematically. When analyzing the disposition of toxicants and their metabolites in relation to the time course of toxic or adverse events, toxicokinetic (TK) analysis applies PK principles. Non-compartmental analysis (NCA) is used to determine PK or TK parameters in most studies.

Which Tox Studies must submit data in SEND format, and what is SEND?

SEND (Standard for Exchange of Nonclinical Data), developed by CDER, enables data transfer to the FDA and other national regulatory agencies in a standardized format that is readable by Janus Nonclinical software. SEND replicates the Study Data Tabulation Model (SDTM) used to present the findings of clinical trials. At present, tox studies fitting in the electronic Common Technical Document format (eCTD) modules (Safety Pharmacology), (Single Dose Toxicity), (Repeat-Dose Toxicity), and (Carcinogenicity) with study start dates on or after March 15, 2019 for NDA/BLA submissions and on or after March 15, 2020 for commercial IND submissions require data submission following the SENDIG 3.1 (SEND Implementation Guide version 3.1). For any studies that begin within 24 months of the publication of a Federal Register Notice (FRN) announcing FDA support for the standard and listing on the FDA Data Standards Catalog, new data standards will be required. A KickStart Program is currently available from the FDA Office of Computational Science (OCS) to help applicants and reviewers with the SEND standard and data transfers to Janus Nonclinical.