In Vitro ADME
We develop, validate and employ a variety of biochemical and cellular screening assays combined with efficacy testing in animal models of disease, to meet the drug discovery needs of our innovator clients. With an emphasis on translational research, we work with our clients to develop and evaluate cellular assays and animal models that are a close approximation of the human disease. Our capabilities include the measurement of target, pathway and disease biomarkers that quantify the specific contributions of a biological target to one or more disease phenotypes.
1. Aqueous Solubility
- Simulated GI fluids (SGF, SIF, FaSSIF)
2. Lipophilicity (LogP/LogD)
- Shake flask method
- Simulated GI fluids (SGF, SIF, FaSSIF)
- Aqueous buffers at different pH
- Plasma and blood stability
Permeability / Absorption
- Mono directional
- Bidirectional with and without P-gp inhibitor
3. MDR1 expressing MDCK II cells
1. Metabolic stability / intrinsic clearance
- Microsomes (alone / using UDPGA/ alamethacin)
- S9 fractions
2. Drug-Drug interaction (DDI)
- Competitive CYP inhibition (Human liver microsomes and Human recombinant enzymes)
- Time dependent inhibition (TDI)
- CYP3A4 induction
3. CYP phenotyping using human recombinant enzymes
Metabolite identification and biotransformation
- Identify stable metabolites using LC-MS Q-trap fragmentation patterns
- Identify reactive metabolites using GSH trapping assay and neutral loss by LC-MS/MS
- Direct glucuronidation in human liver microsomes fortified with UDPGA
- Plasma protein binding inter species comparison
- Microsomal protein binding
- Brain tissue binding
- Blood-to-plasma ratio (RBC partitioning)
In Vivo Pharmacokinetics (PK)
Sai performs in vivo animal pharmacokinetic (PK) and other ADME studies in mice and rats in our CPCSEA approved AAALAC-accredited animal facility. Also, we have a third party collaboration (CPCSEA approved facility) to perform pharmacokinetic studies in dogs.
In a typical animal PK study, blood samples are obtained from animals at pre-determined time points following a single dose of a test compound using various routes of administration viz oral, intravenous (bolus and infusion), intraperitoneal, sub-cutaneous, intra-muscular, intra-nasal, intra-rectal or intra-ocular.
Relative oral bioavailability studies with different formulations can be carried out to enable selection of appropriate preclinical formulations for any compound. In toxicology studies we also assess the NOAEL (No Observable Adverse Effect Level).
- Ten working days from the receipt of compound
In Vivo Pharmacokinetic Dosing
- Pharmacokinetics by various routes viz; oral, intravenous (bolus and infusion), intraperitoneal, sub-cutaneous, intra-muscular, intra-nasal, intra-rectal, intra-ocular, etc.
- Cerebrospinal fluid
- Various tissues brain, lung, heart, liver, kidney, spleen, skeletal muscle, etc.
- Ocular tissues like aqueous humor, vitreous humor, sclera, conjunctiva, lens, cornea, iris, optic nerve and choroid retina
- Intravenous (infusion and bolus) PK in conscious rat
- Neuro PK (plasma, brain and CSF)
- Ocular PK (Ocular tissues like aqueous humor, vitreous humor, sclera, conjunctiva, lens, cornea, iris, optic nerve and choroid retina)
- Single, multiple and cassette dosing of compound(s)
- Entero-hepatic recirculation in rat
- Metabolite characterization and identification of in vivo samples
- Dose escalation study (dose linearity and range finding)
- Tissue distribution study (brain, heart, liver, lung, kidney, etc.)
- Site specific absorption studies via intra-duodenal, intra-portal, etc.
- Bile collection and analysis for biliary excretion studies
- Micro sampling using Dried Blood Spots (DBS) cards
Because of the complexity of brain physiology, preclinical NeuroPK is an efficient way to define relationships of drug concentrations in CNS compartments (brain, CSF, and plasma). Sai offers services in NeuroPK during lead optimization and candidate selection stages of drug discovery and development.
In a typical rodent NeuroPK study, samples are collected with our expertise in surgery techniques and bio-analysis using highly sensitive LC-MS/MS instrument for exposure analysis.
The species selected is based on efficacy and toxicology models. NeuroPK studies may employ any dosing routes, which have low experimental variability.
Below figure represents plasma vs brain concentration (bound and unbound concentrations) of a standard CNS drug. During clinical development, data generated from preclinical NeuroPK and transporter studies help project teams to predict human CNS penetration and hence to decide whether unbound plasma or CSF can be used as surrogates for unbound brain exposure in humans.
CSF contains very little protein, and no protein binding is applied to CSF for unbound calculation.
Modeling and Simulation (M&S)
We offer Modeling and Simulation services to predict single ascending and multiple ascending dose study to understand the pharmacokinetic exposures. It helps to design toxicokinetics and clinical studies and its correlation with NOAEL exposure. We use Phoenix WinNonlin software tool to perform Modeling and Simulation.
Interspecies allometric scaling provides a simple and fast option to interpolate or extrapolate drug dose or pharmacokinetic parameters to a species of interest. Allometric scaling can be perform for prediction of human pharmacokinetics for any test compound using PK data from mouse, rat and dog.
A correlation can be established using data from PK and pharmacology studies.
Biotransformation: Metabolite Profiling and Identification Services
Metabolite identification, metabolite profiling and metabolic pathway elucidation are specialized capabilities employing a range of in vitro and in vivo techniques to deliver a detailed picture of how a candidate drug is metabolized. Sai can deliver consistent, high quality data with the flexibility to adapt protocols based on specific customer requirements.
Our laboratories employ sensitive ion traps for qualitative metabolite analysis using UPLC-DAD-MS/MS Q-Trap system for metabolite screening. Metabolite identification can be coupled to reaction phenotyping assays to elucidate various metabolic pathways.
Reactive metabolite trapping using glutathione, N-acetyl cysteine, glutathione ethyl ester and other relevant nucleophiles can be performed. Additionally, glutathione oxidation products formed as a result of oxidative stress such as glutathione disulfide, sulfenic and sulfonic acid can also be measured.
Bioanalysis provides quantitative measurement of an active drug and/or its metabolites in biological matrices (blood, plasma, urine, tissue, etc.). The bioanalytical laboratories at Sai are well equipped with Triple Quad LC-UV/MS/MS and UPLC/HPLC systems with sample manager for high throughput bioanalysis.
The bioanalytical laboratory supports in vitro ADME, pharmacokinetics and toxicokinetics studies. These services
include bioanalytical method development, validation and study sample analysis. We have expertise in Dried Blood Spots (DBS) analysis, Prodrug stabilization and quantification of parent as well as circulating prodrugs, Sample stability (plasma or formulation) analysis is also conducted routinely by the bioanalytical laboratories.
Our bioanalytical capabilities include various sample extraction procedures such as protein precipitation, liquid-liquid extraction, solid phase extraction and extraction from DBS cards.