© Copyright Our Wall
Introduction
The evaluation of permeability is a crucial aspect of drug discovery and development. It provides insights into how well a compound can cross biological membranes, which significantly influences its bioavailability and therapeutic efficacy. One of the most widely utilized techniques for assessing permeability is the Parallel Artificial Membrane Permeability Assay (PAMPA). This in vitro method has gained attention for its predictive capacity, simplicity, and ability to replicate the conditions of biological membranes. This article delves into the principles of PAMPA, its methodology, its advantages, and its role in facilitating the drug development process.
The Basics of PAMPA
PAMPA is an assay designed to approximate the passive diffusion of compounds across biological membranes, such as the intestinal barrier. This method employs artificial membranes that mimic the lipid bilayers found in living organisms. The main components of the PAMPA system include:
PAMPA Membrane: The membrane in PAMPA is a porous filter coated with a lipid layer that simulates the properties of a biological membrane. The lipid can vary in composition, allowing for different evaluations of PAMPA permeability under distinct conditions. Commonly, phospholipids forming a bilayer are used to create a model that resembles the intestinal barrier or the blood-brain barrier.
PAMPA Assay Setup: The assay setup consists of two compartments: one side is filled with a test compound solution (donor side), while the other side (acceptor side) contains a receptor solution (often a buffer with or without serum). Over time, compounds can diffuse across the PAMPA membrane from the donor compartment to the acceptor compartment.
Methodology
The PAMPA assay is relatively straightforward:
Preparation of the PAMPA Membrane: A porous filter is coated with a lipid layer to mimic the biological membrane.
Loading the Compound: A solution of the test compound is placed in the donor chamber.
Incubation: The system is incubated for a specified period, typically at a controlled temperature.
Sample Collection: After incubation, samples are taken from the acceptor chamber, and the concentration of the compound is measured, usually through techniques such as High-Performance Liquid Chromatography (HPLC).
Calculation of Permeability: The permeability of the compound is determined by calculating the amount that has diffused across the membrane over time, allowing for the assessment of the compound’s permeability coefficients.
Applications and Advantages of PAMPA
PAMPA has found extensive applications in the pharmaceutical industry for:
Screening Drug Candidates: It serves as an early screening tool for identifying compounds with favorable permeability profiles among libraries of new drug candidates.
Formulating Strategies: By understanding the absorption profiles of compounds, formulators can design appropriate drug delivery systems to enhance bioavailability.
Studying Mechanistic Pathways: PAMPA can help in elucidating the mechanisms of drug absorption and the influence of various physicochemical properties on permeability.
Advantages of PAMPA Include:
High Throughput: PAMPA allows for the simultaneous analysis of multiple compounds, making it ideal for screening large libraries efficiently.
Simplicity and Cost-effectiveness: The equipment required is comparatively simple and cost-effective, reducing the barriers to conducting permeability assessments.
Predictive Capabilities: While PAMPA is an in vitro technique, it has demonstrated good correlation with in vivo data, particularly for passive absorption.
Versatility: The membrane and test conditions can be modified to simulate different physiological environments (e.g., CNS permeability), allowing researchers to evaluate a compound under various conditions.
Limitations of PAMPA
Despite its advantages, PAMPA is not without limitations. The primary concerns include:
Lack of Active Transport Evaluation: PAMPA primarily assesses passive diffusion and does not account for potential active transport mechanisms that could be essential in drug absorption.
Simplified Membrane Model: The artificial membrane may not fully replicate the complexity of biological membranes, including the presence of metabolic enzymes and transporters.
Limited Predictive Power for Highly Polar or Ionized Compounds: Compounds with high polarity or that exhibit pH-dependent ionization may not diffuse accurately through the PAMPA membrane.
Conclusion
The Parallel Artificial Membrane Permeability Assay (PAMPA) is a vital tool in the early phases of drug development, providing critical insights into a compound's permeability characteristics. By simulating biological membrane conditions, PAMPA offers a reliable method for screening drug candidates, thus streamlining the drug discovery process. While recognizing its limitations, the continued advancements in PAMPA methodologies hold promise for enhancing its accuracy and predictive capabilities, ultimately leading to more effective therapeutic agents in clinical use.
BOC Sciences provides a wide range of research chemicals and biochemicals including inhibitors, building blocks, carbohydrates, nucleosides, nucleotides, GMP Products, impurities and metabolites, APIs, natural compounds, ADCs, stem cell molecule and chiral compounds.
BOC Sciences specializes in small molecules synthesis, biosynthesis, purification and characterization. We have been supplying high quality products for our esteemed customers in academia, pharmaceuticals, biotech, CDMO, material sciences and agriculture industry to support their research and production needs. We work closely with our synthetic laboratories, fermentation labs, OEM and global partners and proudly offer a full range of product portfolio.
BOC Sciences is committed to offering customers constant satisfaction and help for their life science research, pharmaceutical research and biotechnology etc. by discovering, developing, manufacturing and delivering innovative quality fluorescent probes.
Learn more about our product fluorophore alkyne
BOC Sciences provides a wide range of research chemicals and biochemicals including inhibitors, building blocks, carbohydrates, nucleosides, nucleotides, GMP Products, impurities and metabolites, APIs, natural compounds, ADCs, stem cell molecule and chiral compounds.
BOC Sciences specializes in small molecules synthesis, biosynthesis, purification and characterization. We have been supplying high quality products for our esteemed customers in academia, pharmaceuticals, biotech, CDMO, material sciences and agriculture industry to support their research and production needs. We work closely with our synthetic laboratories, fermentation labs, OEM and global partners and proudly offer a full range of product portfolio.
As a leading chemical company, BOC Sciences is committed to providing customers with the most comprehensive variety of isotope-Labelled Fatty Acids & Lipids available.
BOC Sciences is committed to providing customers with the most comprehensive variety of isotope-labeled amino acids available. We provide products such as essential amino acids and derivatives, including lysine, phenylalanine, methionine, etc., as well as non-essential amino acids and derivatives, including tyrosine, alanine, serine, glutamic acid, etc.
L-Leucine-[13C6] is the labelled analogue of L-Leucine. Leucine is a non-glucogenic, essential amino acid. It is a branched-chain amino acid that is a structural component of proteins. Leucine positively influences insulin release to eliminate toxic sugars out of the blood.
What are Amino Acids?
Amino acids are organic compounds containing basic amino groups and acidic carboxyl groups and formed by replacing the hydrogen atoms of carboxylic acids with amino groups. Amino acids are important constituents of organisms, reserve irreplaceable biological functions, and play essential roles in metabolic cycles. In addition to being the basic building materials of proteins, amino acids can also be the precursors of many other biomolecules (such as cytosine, adenine, epinephrine, etc.). At the same time, amino acids are widely used in medicine, food, cosmetics, and other fields.
In the field of medicine: Amino acids are used as the raw materials for proteins, antibodies, and hormones synthesis; amino acids can be used as nutrients and metabolic modifiers and have antibacterial and analgesic effects.
In the field of food: Amino acids can be used as food preservatives, deodorants, coloring agents, sterilizers, additives, spices, etc.
In the field of cosmetics: Amino acids can be used as surfactants, hair conditioners, hair dyes, etc.
What are Isotope-labeled Amino Acids?
Isotope-labeled amino acids refer to the replacement of single or multiple atoms of the amino acid with isotopes, which can be radioactive isotopes or stable isotopes. Basically, isotope-labeled amino acids have identical structures and properties as non-labeled amino acids. The trends of isotopes-labeled amino acids can be observed by analytical methods such as mass spectrometry and nuclear magnetic resonance. Therefore, isotope-labeled amino acids serve as safe, effective, and convenient tracer tools for scientific research in medicine, biology, pharmacy, chemistry, etc.
In the field of medicine: Isotope-labeled amino acids can be used for the clinical diagnosis of various diseases. Labeled amino acids can be used as tracers to track the metabolic processes of amino acids and proteins in different physiological and pathological conditions, which allows the exploration of disease mechanism and effective ways to prevent and treat diseases.
In the field of biology: Isotope-labeled amino acids are used as starting materials to study the biosynthetic pathways and mechanisms of natural products in animals, plants, and microorganisms by analyzing the abundance of labeled elements in products.
In the field of pharmacy: Isotope-labeled amino acids are critical tools for the development of new drugs, and are used to determine the transfer, transformation, efficacy, mechanism of action, toxicity, and side effects of drugs in vivo.
In the field of chemistry: Isotope-labeled amino acids can be used as tracers to explore chemical reaction mechanisms and as raw materials for the synthesis of other labeled products, such as labeled polypeptides.
Antiviral drugs are available in a variety of dosage forms, such as oral liquid and solid dosage forms, parenteral formulations, ophthalmic, topical products for oral delivery, nasal/extra-nasal delivery, and pulmonary delivery. The selection of stable formulations ensures consistency in stability, hygroscopicity buccal delivery, nasal/intranasal delivery and pulmonary delivery. Scientists have been working on new formulations of antiviral drugs to improve the penetration.
BOC Sciences focuses on developing formulations that best fit the antiviral drug program. Our team is able to quickly and cost-effectively identify a stable, pharmacologically efficient dosage form for each formulation development project to ensure that it is optimal for the therapeutic indication and the intended route of administration.
Comprehensive Services
We ensure that pharmaceutical formulations of each antiviral drug are prepared and analyzed appropriately by following a standard formulation procedure. Our comprehensive antiviral drug formulation services include:
During the formulation development phase, we can evaluate the quality of different drug products in terms of stability, efficacy and processability. BOC Sciences supports different routes of administration, delivery systems and drug manufacturing technologies, including:
Suspensions (micro-suspensions and nano-suspensions)
Bottled active pharmaceutical ingredients
Micro-filling of active pharmaceutical ingredients
Dry mixing and pottingLiquid capsule filling
Spray drying
Dry/wet granulating and capsule filling/tableting
Direct tableting
Pouch filling
High Potent Formulation
BOC Sciences has decades of experience in the development of antiviral drug formulations, and our dedicated team has extended its expertise to include high potency active pharmaceutical ingredients (HPAPI).
Comprehensive high potency antiviral drug formulation capabilities
Determine the optimal safe handling of formulations based on occupational exposure limits
Antiviral drug formulation risk assessment
Formulation Types
Oral: Solutions, suspensions, emulsions, capsules
Diets
Parenteral
Inhalation
Radiolabeled
Topical
Bioaccumulation refers to the enrichment of chemicals in an organism. The uptake of substances occurs either through food (biomagnification) or directly from the abiotic environment (bioconcentration). Experimentally determined bioaccumulation factors are important factors in the risk assessment of chemical substance. For highly lipophilic chemicals (logP>5), bioconcentration studies are often difficult to perform. The poor water solubility of lipophilic substances makes it difficult to adjust stable test concentrations and, under certain conditions, may lead to inaccurate measurements of the test substances in the medium. The ultimate purpose of these studies is to determine the biomagnification factor (BMF). In recent years, the persistence of pesticides has been observed in terrestrial and aquatic ecosystems. The presence of pesticides in the environment leads to their entry into biological systems where they accumulate in organisms. Bioaccumulation and biomagnification of pesticides have led to lethal and sublethal effects in animals and humans. Therefore, the use of agrochemicals is already regulated and safety is ensured through testing, risk assessment and licensing.
BOC Sciences Agrochemical Bioaccumulation Testing Research
Assessing bioaccumulation plays a key role in understanding the risks posed by agrochemicals to the environment. Persistent chemicals can accumulate in aquatic organisms. At BOC Sciences, the test species include a variety of cold and warm water fish such as trout, bluegill and carp, as well as invertebrates such as oysters, aquatic worms and earthworms.
Agrochemical Biodegradation Testing
Bioaccumulation testing in fish
Aqueous bioaccumulation studies are conducted to assess the bioconcentration factor (BCF) of agrochemicals in fish. The BCF is calculated as the ratio of the concentration in the fish to the dissolved concentration in water at steady-state, or by the ratio of uptake and purification rate constants.
OECD 305: Aqueous and dietary exposure
OCSP 850.1730: Fish BCF
Bioaccumulation testing in sediment-dwelling benthic oligochaetes
We design this testing to assess the bioaccumulation of sediment-associated agrochemicals in endobenthic oligochaetes. Test organisms are exposed to chemicals through multiple uptake pathways, including direct ingestion of sediment, surface contact, and ingestion of pore water. The primary endpoints are bioaccumulation factor (BAF) and biota-sediment accumulation factor (BSAF).
OECD 315: Bioaccumulation in sediment-dwelling benthic oligochaetes
Bioaccumulation testing in terrestrial oligochaetes
Aiming to assess the bioaccumulation of agrochemicals in terrestrial oligochaetes, test organisms are exposed to soil dosed with the test chemicals, and oligochaetes and soil were collected and analyzed at intervals. The primary endpoints are a BAF and a biota-soil accumulation factor (BSAF).
OECD 317: Bioaccumulation in terrestrial oligochaetes
BOC Sciences Advantages
Highly specialized technical and analytical services for the worldwide registration and regulatory compliance of agrochemicals
Robust analytical testing programs that span from research and product development through the production process to final product
Relies on broad industrial experience, ensuring that all of our work meets the high standards expected by our clients
Our regulatory experts, toxicology consultants, scientists and inspectors will ensure that you receive maximum levels of guidance, testing and inspection you need.
Phosphate pseudoUridine belongs to the C-nucleotides, in which the uracil moiety is combined with the sugar through its carbon atom rather than nitrogen atom forming a C-C glycosidic bond. The phosphate pseudoUridine can be divided in pseudoUridine monophosphate (ΨMP), pseudoUridine monophosphate (ΨDP) and pseudoUridine 5ʹ-triphosphate (ΨTP) depending on the number of linked phosphates.
PseudoUridine 5ʹ-monophosphate (ΨMP)
PseudoUridine 5ʹ-monophosphate is an ester of phosphate and nucleoside and consists of a phosphate functional group, a pentose ribose and a base uridine. In theory, ΨMP can be obtained by twice hydrolysis of pseudoUridine 5’-triphosphate, or through pseudoUridine coupled with one phosphate. A study has corroborated a metabolic process of pseudoUridine, including the single phosphorylation of pseudoUridine to afford ΨMP catalyzed by pseudoUridine kinase, then the C-C glycosidic bond cleavage to produce uracil and ribose 5’-phosphate mediated by ΨMP glycosidase. However, the metabolism of PseudoUridine in eukaryotes has not been thoroughly studied. And the functions of ΨMP are also not supported by sufficient literature. Interestingly, one recent study showed that ΨMP is toxic to Arabidopsis thaliana, and ΨMP may cause delayed germination and growth inhibition of this plant.
PseudoUridine 5ʹ-diphosphate (ΨDP)
PseudoUridine 5ʹ-diphosphate consists of two phosphate functional groups, a pentose ribose and a base uridine. The synthesis of ΨDP was reported as early as 1963, but to our knowledge, the biological applications of ΨDP are still to be discovered. The synthesis of PseudoUridine 5’-diphosphate has been achieved from PseudoUridine using the cyanoethylphosphate method to prepare the monophosphate and the nucleoside phosphoramidate method to make the diphosphate. During the synthesis, two side reactions occurred. One of these was an alkylation of the pyrimidine ring, the other involved an anomerization of the C-C glycosyl bond to give a steric isomer of ΨDP.
PseudoUridine 5ʹ-triphosphate (ΨTP)
PseudoUridine 5ʹ-triphosphate consists of three phosphate functional groups, a pentose ribose and a base uridine. It is well known that nucleoside triphosphates (NTPs) are served as the building blocks for the synthesis of RNA molecules whether in vitro or in vivo, both mediated by the polymerase. In addition, the chemical synthesis of ΨTP can be achieved by the reaction of ΨMP with tributylammonium pyrophosphate under basic conditions. In recent years, the applications of mRNA in the field of cancer immunotherapy and other biomedical fields have received increasing attention from researchers. However, the biological therapy of mRNA is limited by the immune toxicity in the host. This issue has been improved via mRNA modification that utilizes the naturally occurring modified nucleotides, such as pseudoUridine-5’-triphosphate. This pseudoUridine modified mRNA can serves as a promising tool for gene replacement and vaccination. For mRNA modification, successful molecular biology applications depend heavily on the quality and purity of NTPs. The simple and efficient synthesis of ΨTP to afford a high purity product can support the modification of RNA.
Self-assembly of small molecule materials
Small molecule assembly technology includes LB technology and self-assembly technology, and the current research mainly focuses on ultra-thin film system. LB membrane and self-assembly membrane are both ultra-thin film assembly of molecules, the difference is that LB membrane and substrate rely on van der Waals force bonding; while self-assembly membrane and substrate are bonded by covalent or ionic bonding, so the latter has higher stability.
Self-assembly of macromolecules materials
Self-assembly of macromolecules refers to the process by which molecules of polymeric materials are spontaneously constructed into aggregates with specific structures and shapes driven by electrostatic interactions, hydrogen bonding, hydrophobic and esterophilic interactions, van der Waals and other weak interaction forces. For example, the self-assembly between poly(endo-alkenoic acid) and poly(vinyl acetal), polyaniline and poly(ethylene glycol) (or poly(vinyl acetal) and poly(vinyl alcohol)), diazo resin and phenolic resin, poly(p-vinyl phenol) and diazo resin, etc. are based on the adsorption or cyclic adsorption of intermolecular hydrogen bonds on the substrate to form monolayer or multilayer super thin films. In addition, side chain liquid crystal polymers can also be self-assembled by special intermolecular interactions such as hydrogen bonding and ionic bonding, which can improve the thermal stability and orderliness of liquid crystals.
Self-assembly of nanomaterials
The self-assembly of nanomaterials is mainly driven by the electrostatic interaction of positive and negative ions to assemble a variety of inorganic nanomaterials into multilayer membranes. Various polymeric nanocomposite membranes have been successfully synthesized, including polyelectrolyte-polyelectrolyte, polyelectrolyte-clay-based sheet materials, polyelectrolyte-inorganic nanoparticles, polyelectrolyte-biomolecules, and other inorganic/polymer hybrid nanolayer structures.
Application
With the development of self-assembling materials, the principle of self-assembly has long been utilized in the manufacture of some common products. For example, cell membranes are mainly composed of molecules called phospholipids, which are dual in nature: one end of the phospholipid is hydrophilic, while the other end is hydrophobic. The researchers used these phospholipids to make liposomes, allowing the liposomes to act as carriers for in vivo drug delivery. In addition, self-assembly allows the production of tiny graphite tubes, comparable to the finest wires that have been made, which are called Bucky tubes, because they have a similar structure to the Bucky sphere of carbon. Breakthroughs in the technology of synthesizing or assembling practical functional molecular assemblies will certainly lead to industrial technological revolutions in the fields of information, materials and biology in the coming period.
Analytical method validation (AMV) is the requirement of the biopharmaceutical industry for all methods used in the testing of raw materials, in-process materials, final containers and excipients. The development and validation of analytical methods are critical to drug development and access to reliable analytical data that you need to reach your next development milestone. The development and validation of methods can be complex, expensive, and labor-intensive. A full understanding of current regulatory expectations and related chemical methods, coupled with advanced instrumentation, is essential for the development of efficient, accurate and reliable analytical methods.
BOC Sciences is pleased to offer Analytical Method Development, Validation and Transfer services:
Methodologies will be developed to assess the ability to measure compounds of interest in the final solution of interest in actual use. Specific analytical methods need to be developed and validated before any quantitative leachate assessment of drugs can be carried out. Although deviations, such as lower validation levels for some applications, are possible, MDV (Method Development, Validation) is based on the ICHQ2 (R1) method validation guide. These tests may include parameter specificity, linearity, method range, accuracy, precision, LOD/LOQ, and robustness.
Method validation
Method transfer
Our Advantages
All our work strictly complies with cGMP requirements, and our analytical operations are based on formal written, detailed standard operating procedures and strict quality assurance measures.
Typical Analytical Characteristics Used: accuracy, precision, specificity, LOD/LOQ, linearity, range, and robustness.
By qualified personnel with adequate resources.
Handled by utilizing a protocol or plan agreed upon by both the client and BOC Sciences.
Communicate efficiently between BOC Sciences and customers.
Our standard reporting format includes a copy of the analytical method, a copy of the agreement, all test results, appropriate charts and calculations, and sample raw data.
BOC Sciences has the latest advanced analytical instruments and top experts in all analytical areas. We can provide drug detection, environmental analysis, explosives investigation and identification of unknown samples even it is a very small amount of a substance.