The majority of drugs are intended for chronic or multiple dose therapy in the treatment of a specific medical condition. Even if the pharmacokinetics has been shown to be linear over the intended therapeutic dosing interval after single doses, this may not hold true after repeated dosing. Therefore, the pharmacokinetics of the drug after repeated administration needs to be investigated. Time-dependencies in the pharmacokinetics, such as autoinduction or inhibition of the drug's own metabolism, may occur. A qualitative indicator can be obtained from in vitro studies or preclinical pharmacokinetic studies in animals; however, the magnitude of the potential time-dependency, or lack thereof, can only be assessed in vivo in humans.
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