Technical Notes

Cell Viability Assessment

Cell viability or cytotoxicity assessments are based on cellular functions that are particularly sensitive to toxic drugs and as such provide convenient in vitro high-throughput screens (HTS) for comparing relative toxicities of a drug....

Caco-2 Permeability

The human colon epithelial cancer cell line, Caco-2, is used as a model of human intestinal absorption of drugs. This model is suitable to test compound suitability for oral dosing, predict intestinal permeability and...

Chemical Stability

The measurement of the stability of a drug in conditions that mimic the gastrointestinal tract, physiological conditions and/or in vitro biological conditions helps in identifying and understanding the lability of molecules due to non-enzymatic...

Cytochrome P450 Inhibition (Reversible)

The cytochrome P450 (CYP450) enzymes play a significant role in the metabolism of both endogenous and exogenous compounds. Within this family, CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 are predominantly involved in the...

Hepatocyte Metabolic Stability

The liver is the major site of drug metabolism in the body, with well over 50 % of marketed drugs are eliminated via hepatic mediated metabolism. Hence, measurement of the rate of clearance and...

LogD (Micro Shake-Flask)

Lipophilicity (distribution coefficient) is an important physicochemical property of a drug as it provides an understanding of how well a drug will cross lipid membranes (and thereby penetrate tissues), how well a drug will...

Microsomal Protein Binding

Understanding the non-specific binding of drugs to microsomal protein and fuinc is beneficial in generating an accurate prediction of in vivo clearance and drug-drug interactions. The leading approach for assessing microsomal protein binding is...

Microsomal Metabolic Stability

The liver is the major site of drug metabolism in the body, with well over 50% of marketed drugs being eliminated via hepatic mediated metabolism.  Hence, measurement of the rate of clearance and the...

MRP2 Inhibition

Multidrug resistant associated protein 2 (MRP2; ABCC2) is member of a family of ATP-binding cassette drug efflux transporters located in the cannalicular (apical) membrane of hepatocytes. Loss of function mutations of this transporter have...

Plasma Protein Binding

Drugs may bind to a wide variety of plasma proteins, including albumin, and the degree of binding can impact on the pharmacokinetics and pharmacodynamics parameters of a drug, given that only the free drug...

Plasma Stability

The measurement of the stability of a new chemical entity in a matrix such as plasma helps in identifying and understanding the lability of known structural moieties (e.g. amides, sulphonamide, esters, lactones, lactams to...

Tubidimetric Solubility

Low solubility can be a major obstacle during drug discovery and development, as low solubility can impact the generation of quality in vitro DMPK or biology data, can cause issues in the generation of...

BSEP inhibition

The bile salt export pump, BSEP (ABCB11), is located at the canalicular (apical) membrane of hepatocytes and is involved in the secretion of bilirubin/bile salts from the liver. Since bile formation and secretion are...

MDCK-WT/MDR1 Permeability

Wild-type MDCK (Madin-Darby canine kidney) cells, when transfected with either the Multidrug Resistance gene-1 (MDR1; P-gp) or Breast Cancer Resistance gene (BCRP), are used as a model of brain penetration and to understand the...

Thermodynamic Solubility

Low solubility can be a major obstacle during drug discovery and development, as low solubility can impact the generation of quality in vitro DMPK or biology data, can cause issues in the generation of...

Cytochrome P450 Inhibition (Time dependent IC50 shift)

The cytochrome P450 (CYP450) enzymes play a significant role in the metabolism of both endogenous and exogenous compounds. Within this family, CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 are predominantly involved in the...

Metabolic Stability of Low Clearance Compounds

Sygnature’s routine hepatocyte stability assay monitors the disappearance of a substrate in suspension, over 1-2 hours incubation.  Evaluating low clearance compounds can be a challenge using existing methods.  To accurately determine intrinsic clearance and...

Aldehyde Oxidase (AO) Reaction Phenotyping

Aldehyde Oxidase is a homo-dimeric molybdo-flavo protein located in the cytosolic fraction of various tissues (e.g. brain, kidney, lung, GIT) and species, but is predominantly expressed in liver. The enzyme shows activity differences across...

NTCP (Na⁺-Taurocholate Cotransporting Polypeptide)

The Na+-Taurocholate Cotransporting Polypeptide (NTCP) transporter is involved in the disposition and recirculation of bile acids; bile salts secreted into the bile are often re-absorbed into the portal circulation and back into the liver via...

OATP1B1 and OATP1B3 inhibition

OATP1B1/OATP1B3 (Organic Anion Transporter Protein B1 and B3) are uptake transporters involved in the transport and disposition of endogenous and exogenous compounds. Expressed exclusively on the sinusoidal side of hepatocytes, these transporters are responsible...

Mitochondrial Toxicity in Glu/Gal HepG2 Model

Mitochondrial dysfunction due to drug-induced effects, has been highlighted as a potential contributor to a number of organ toxicities including those associated with cardiac, muscular and liver systems (1). Mitochondrial toxicity has been indicated...

UGT1A1/UGT1A3 Inhibition Assay

Uridine 5’-diphospho‐glucuronosyltransferases (UGTs) are a superfamily of enzymes which catalyse the glucuronidation reaction, a major phase II metabolism pathway. Approximately 15% of approved drugs have glucuronide metabolites1, highlighting the importance of UGT enzymes. UGT...

Metabolite Profiling and Identification

It is important to understand the routes of metabolism for compounds in drug discovery in order to design more metabolically stable drug candidates and to be aware of any potentially toxic metabolites that could...

Phospholipidosis

Drug-induced phospholipidosis (PLD) is an adverse drug reaction characterised by the intracellular accumulation of phospholipids and the appearance of cytosolic lamellar bodies. It is recognised by the pharmaceutical industry and regulatory bodies as a...

Parallel Artificial Membrane Permeability Assay (PAMPA)

Permeability is an important physicochemical property of a drug, governing the availability of the drug in the systematic circulation. PAMPA measures passive diffusion and is therefore the first port of call when looking into...

Steatosis

Steatosis describes increased accumulation of lipids, mainly triglycerides, in the liver and can be induced by a number of factors including pre-existing conditions, pregnancy and exposure to certain xenobiotics1. These events are usually present...

Mitochondrial Toxicity Glu/Gal Assay (MitoTox Glo)

Mitochondrial dysfunction due to drug-induced effects, has been highlighted as a potential contributor to a number of organ toxicities including those associated with cardiac, muscular and liver systems (1). Mitochondrial toxicity has been indicated...