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Isavuconazole Kinetic Exploration for Clinical Practice
Léa Darnaud1, Fabien Lamoureux2, Cendrine Godet3
1Laboratoire de Pharmacocinétique et Toxicologie, Institut Fédératif de Biologie, 330 Avenue Grande Bretagne, 31059, Toulouse Cedex 09, France.
Background:
Isavuconazole is a new antifungal prodrug for the treatment of invasive aspergillosis and mucormycosis. As no clear pharmacokinetic-pharmacodynamic relationship has been established for patients, therapeutic drug monitoring is not currently required. However, as isavuconazole is a new drug, clinicians are sometimes sceptical about the exposure achieved in their patients and seek pharmacokinetic exploration. A minimal response consists of determining that the patient's pharmacokinetic profile agrees with profiles reported by Desai et al. using concentrations from the SECURE study.
Methods:
Based on one concentration and Desai et al.'s population-pharmacokinetic model, it is possible to estimate a patient's most likely pharmacokinetic profile. If a patient's pharmacokinetic profile is close to the profiles reported by Desai et al., therapeutic drug monitoring is not required. In contrast, when the pharmacokinetic profile differs from the Desai et al. profiles, isavuconazole concentration monitoring and pharmacokinetic profile modeling are the only methods for obtaining information on a patient's exposure and the efficacy of isavuconazole.
Results:
Four patients presented with surprising pharmacokinetic profiles, unexplained by drug interactions or cytochrome P450 3A4/5 polymorphisms. For two of them, a drug dosage adjustment was proposed and applied by clinicians, together with a check for a new pharmacokinetic profile a few days later.
Conclusions:
Collecting one blood sample just before the first maintenance dose to make an early estimation of the patient's most likely pharmacokinetic profile is one method of identifying patients with outlier pharmacokinetic behavior.
Insights
Early pharmacokinetic profiling of isavuconazole (ISA) can identify patients with outlier profiles. This approach helps clinicians assess drug exposure and efficacy, especially for new antifungal treatments like ISA.
Area of Science:
- Pharmacology
- Mycology
- Clinical Pharmacy
Background:
- Isavuconazole is a novel antifungal prodrug for invasive aspergillosis and mucormycosis.
- Therapeutic drug monitoring for isavuconazole is not routinely required due to an undefined pharmacokinetic-pharmacodynamic relationship.
- Clinicians often seek pharmacokinetic data to confirm adequate drug exposure in patients.
Purpose of the Study:
- To evaluate a method for estimating patient isavuconazole pharmacokinetic profiles using a single concentration measurement.
- To identify patients with potentially outlier pharmacokinetic profiles early in treatment.
- To guide potential therapeutic drug monitoring and dosage adjustments.
Main Methods:
- Utilized a population pharmacokinetic model (Desai et al.) with a single patient concentration to estimate the pharmacokinetic profile.
- Compared individual patient profiles to established population profiles from the SECURE study.
- Investigated outlier profiles and their potential causes, including drug interactions and genetic polymorphisms.
Main Results:
- Four patients exhibited unexpected pharmacokinetic profiles not explained by known factors.
- Dosage adjustments were made for two patients based on their pharmacokinetic profiles.
- Follow-up pharmacokinetic assessments were conducted after dosage adjustments.
Conclusions:
- A single pre-dose blood sample before the first maintenance dose can estimate a patient's pharmacokinetic profile.
- This method aids in the early identification of patients with outlier isavuconazole exposure.
- Facilitates informed clinical decisions regarding isavuconazole therapy and monitoring.
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