Imaging the Function of P-Glycoprotein with Radiotracers: Pharmacokinetics and In Vivo Applications

Scientists in the United States have been studying the role of P-glycoprotein (P-gp), an efflux transporter, in various disorders, including multidrug-resistant cancer and medication-refractory epilepsy. Researchers at the National Institutes of Health (NIH) have developed radiolabeled P-gp substrates to image P-gp function using single-photon emission computed tomography (SPECT) and positron emission tomography (PET). This study aimed to elucidate the function of P-gp in various disorders and improve the efficacy of treatments.

Key Takeaways:

• P-glycoprotein (P-gp) is an efflux transporter that controls the pharmacokinetics of various compounds under physiological conditions.
• P-gp-mediated drug efflux has been suggested to play a role in various disorders, including multidrug-resistant cancer and medication-refractory epilepsy.
• Radiolabeled P-gp substrates were developed to image P-gp function using SPECT and PET.
• The ideal radiolabeled P-gp substrate should be selective for P-gp, produce a large signal after P-gp blockade, and generate few radiometabolites that enter the target tissue.
• Pharmacological inhibition of P-gp requires knowledge of P-gp density at the target site.
• The study concluded that imaging can elucidate the function of P-gp in various disorders and improve the efficacy of treatments.
• P. Kannan and colleagues published their study in Clinical Pharmacology & Therapeutics.
• The study was conducted at the National Institutes of Health (NIH) in Bethesda, MD, USA.

Statistics:

• The study was published in Clinical Pharmacology & Therapeutics in 2009.
• The article was prepared by Pain & Central Nervous System Week editors from staff and other reports.
• The publisher contact information for the journal Clinical Pharmacology & Therapeutics is: Nature Publishing Group, 75 Varick St., 9TH Flr, New York, NY 10013-1917, USA.

Sources:

• Clinical Pharmacology & Therapeutics (Imaging the Function of P-Glycoprotein With Radiotracers: Pharmacokinetics and In Vivo Applications. Clinical Pharmacology & Therapeutics, 2009;86(4):368-377)
• Contact R.B. Innis, NIMH, Molecular Imaging Branch, National Institutes of Health, Bethesda, MD 20892, USA.