Designer drugs drug interactions

Studies in Phase IV are all studies (other than routine surveillance) performed after drug approval and related to the approved indication. They are studies that were not considered necessary for approval but are often important for optimizing the drug s use. They may be of any type but should have valid scientific objectives. Commonly conducted studies include additional drug-drug interaction, dose-response or safety studies, and studies designed to support use under the approved indication, for instance, mortality/morbidity studies, epidemiological studies. 

Apart from patient-specific parameters, external factors - most importantly the concomitant uptake of certain other chemicals present in diet, environment and especially other drugs - influence drug actions. Possible effects are manifold and can affect all stages of pharmacokinetic and pharmacodynamic processes in the body. Also direct interaction and inactivation of concomitantly administered substances are possible. Drug-drug interactions via modulation of metabolism present a very hot topic in pharmaceutical research and drug design. 

There are several factors to take into account in the design of drug interaction studies. Singledose studies have been criticised but may be useful to exclude major effects. If an interaction is detected with single doses, it maybe necessary to conduct a study at steady state, mimicking the dosage used in clinical practice to determine the true clinical consequences of interaction. 

Huang S-M, Lesko LJ, Williams RL. Assessment of the quality and quantity of drug-drug interaction studies in NDA submissions study design and data analysis issues. J Clin Pharmacol 1999 39 1006-1014. 

The design of a typical drug-drug interaction study is presented below. For the purposes of simplicity, the... 

This book, written with a definite clinical bias (as the editors and contributors are practising prescribers from a range of disciplines), is designed to be an easily accessible reference for busy prescribers/dispensers who may not have access to, or the time to search, the more comprehensive resources on adverse drug-drug interactions both in print and online. We have considered interactions which we... 

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