[11C]desmethyl-loperamide

[11C]desmethyl-loperamide ([11C]dLop) is a Carbon-11 labeled positron emission tomography (PET) radiopharmaceutical used primarily as a probe to quantify the function of P-glycoprotein (P-gp) at the blood-brain barrier. P-gp is an ATP-binding cassette efflux transporter (encoded by the ABCB1 gene) that limits the entry of many drugs into the central nervous system. While loperamide itself is a P-gp substrate, it undergoes rapid metabolism, making its desmethylated metabolite, [11C]dLop, a more effective tracer for measuring transporter activity. Under normal physiological conditions, brain penetration of [11C]dLop is extremely low due to active efflux; however, brain uptake increases significantly when P-gp is inhibited or downregulated. Consequently, [11C]dLop is a valuable tool in clinical research for evaluating drug-drug interactions, assessing blood-brain barrier integrity, and studying neurodegenerative disorders or refractory epilepsy.

Other names

[11C]desmethyl-loperamideCarbon-11 desmethyl-loperamideCarbon11 desmethyl-loperamideCarbon 11 desmethyl-loperamide