Minimization of CYP2D6 Polymorphic Differences and Improved Bioavailability via Transdermal Administration: Latrepirdine Example
Transdermal delivery has the potential to offer improved bioavailability by circumventing first-pass gut and hepatic metabolism. This study evaluated the pharmacokinetics of oral immediate release and transdermal latrepirdine in extensive and poor CYP2D6 metabolizers (EM/PM).
Latrepirdine transdermal solution was prepared extemporaneously. The solution was applied with occlusive dressing to upper or middle back for 24 h. Each subject received a single dose of 8.14 mg oral, 5 mg transdermal, and 10 mg transdermal (EMs only) latrepirdine free base in a fixed sequence.
Twelve EMs and 7 PMs (50–79 years) enrolled and completed the study. Latrepirdine was well tolerated following both routes of administration. Dose-normalized latrepirdine total exposures were approximately 11-fold and 1.5-fold higher in EMs and PMs, respectively following administration of transdermal relative to oral. Differences between EM and PM latrepirdine exposures were decreased, with PMs having 1.9- and 2.7-fold higher peak and total exposures, respectively, following transdermal administration compared to 11- and 20-fold higher exposures, respectively, following oral administration.
Transdermal delivery can potentially mitigate the large intersubject differences observed with compounds metabolized primarily by CYP2D6. Transdermal delivery was readily accomplished in the clinic using an extemporaneously prepared solution [NCT00990613].
KEY WORDSbioavailability CYP2D6 latrepirdine pharmacokinetics transdermal
Area under the curve
- HPLC MS/MS
High performance liquid chromatography tandem mass spectrometry
ACKNOWLEDGMENTS AND DISCLOSURES
This study was sponsored and funded by Medivation and Pfizer Inc, both of whom were involved in the study design, the collection, analysis, and interpretation of the data, the writing of the report, and the decision to submit the paper for publication. Marci L. Chew, Thean Yeoh, Gautam Ranade, Ruolun Qiu, Yali Liang, and Brian Corrigan are all full-time employees of Pfizer Inc. and hold stock in Pfizer Inc. Pfizer has not maintained any patents or applications covering latrepirdine. Juanzhi Fang was an employee of Pfizer Inc at the time this study was conducted and holds stock in Pfizer Inc. Joyce Mordenti was an employee of Medivation at the time this study was conducted and holds stock in Medivation.
Compliance with Ethical Standards
All procedures in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants in the study. The final protocol and informed consent documentation were reviewed and approved by the Institutional Review Board IntegReview, Austin, TX. This article does not contain any studies with animals performed by any of the authors.
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