Learning Centre

Selecting the drug concentration range of linearity working standard solutions
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The linearity of an analytical method enables (over the range of dissolution concentration) generation of test results which are directly proportional to the concentration of drug substance in the dissolution sample.
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Importance of filtration in dissolution sample preparation for HPLC analysis
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Filtration is a crucial step in preparing a dissolution sample. It involves passing the sample through a filter to separate solid particles or undissolved materials...
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What is filter compatibility and why is it so important?
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There are two aspects of filter compatibility that the dissolution scientist should consider...
Sample requirements for a drug filter adsorption study
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To conduct a drug filter adsorption study, typically, a sample representing around 10% to 20% of drug release from the immediate-release dosage form in the dissolution vessel is needed.
What is 'specificity'?
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Specificity is an integral part of analytical method validation and must be performed by carrying out multiple injections to eliminate potential errors that can occur during experimental sequence.
What is 'precision'?
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The degree of deviation between a set of measurements obtained from multiple analysis of the same homogenous sample under the specified conditions expresses the precision of an analytical method.
Why are specificity and precision required with biorelevant media?
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Biorelevant dissolution media contain natural surfactants which can affect chromatographic properties leading to erroneous analytical results.
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When is a filter adsorption study necessary?
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Filter adsorption studies should always be conducted before dissolution studies are carried out when a) a new drug is being tested or b) a different biorelevant medium is being used.
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Key requirements for filters used in biorelevant dissolution testing
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We recommend the use of glass filters with pre-filters built-in. These filters have excellent efficiency in removing particles and do not leach substances into the biorelevant media.
When are specificity and precision required when testing drugs in biorelevant media using HPLC??
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Specificity and precision when analysing drugs in biorelevant media by HPLC
Checking interference by injecting the dosage form in biorelevant medium
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Interference of non-drug peaks (originating for example from excipients) should also be evaluated via specificity and precision using a sample which contains the dosage form.
How many HPLC injections are needed when carrying out specificity and precision?
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For specificity and precision tests, it is recommended to carry out a similar number of injections that cover the number of samples that will be analysed by HPLC.
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Two-stage biorelevant dissolution
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This experiment simulates the in vivo process when a drug product is transferred from the fasted stomach to the fasted intestine.
What to do if the retention time of a drug is reduced during HPLC analysis
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Reduced retention time during HPLC analysis
Which factors can increase the retention time of an analyte during HPLC analysis
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Which factors can increase the retention time of an analyte during HPLC analysis
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How to apply a washing cycle when running an HPLC sequence
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How to apply a washing cycle when running an HPLC sequence