The guidelines for the US FDA, EMA and Japanese PMDA are constantly evolving as our understanding of potential drug-drug interactions (DDI) expands. Over recent years, there has been a greater focus on transporter interactions with the panel of recommended transporter assays increasing significantly. It is anticipated that these additions will improve safety once the drug reaches the patient population where multiple therapies are often being co-administered. The obvious downside of this expansion in testing requirements is that the cost can increase significantly. As a consequence, it is important to take the time to design these studies appropriately so that there are no difficulties in interpreting the data, and there is no need to repeat the study at a later time to confirm the results. This will involve reviewing existing data, understanding any potential pitfalls and designing the studies accordingly.
Cyprotex have considerable experience in designing, implementing and interpreting in vitro regulatory DDI studies. The initial step in these studies is to have a full review of existing data to ensure what gaps need filling, whether there are any special assay requirements e.g., solubility or stability issues, and the concentration range tested based on any prior data such as human PK studies, protein binding studies and solubility data.
Cyprotex have released a series of educational guides including ‘Everything You Need to Know about ADME’, ‘Mechanisms of Drug-Induced Toxicity’ and ‘DDI Regulatory Guidance – an Easy to Follow Guide’. Our ADME and DDI guides are especially useful in helping to understanding DDI and the requirements for the regulatory authorities in terms of DDI studies.
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