A simplified protocol employing elacridar in rodents: a screening model in drug discovery to assess P-gp mediated efflux at the blood brain barrier.
In the present study we have developed a simple, time, and cost effective in vivo rodent protocol to screen the susceptibility of a test compound for P-glycoprotein (P-gp) mediated efflux at the blood brain barrier (BBB) during early drug discovery. We used known P-gp substrates as test compounds (quinidine, digoxin, and talinolol) and elacridar (GF120918) as a chemical inhibitor to establish the model. The studies were carried out in both mice and rats. Elacridar was dosed intravenously at 5 mg/kg, 0.5 h prior to probe substrate administration. Plasma and brain samples were collected and analyzed using UPLC-MS/MS. In the presence of elacridar, the ratio of brain to plasma area under the curve (B/P) in mouse increased 2, 4, and 38-fold, respectively, for talinolol, digoxin, and quinidine; whereas in rat, a 70-fold increase was observed for quinidine. Atenolol, a non P-gp substrate, exhibited poor brain penetration in the presence or absence of elacridar in both species (B/P ratio ~ 0.1). Elacridar had no significant effect on the systemic clearance of digoxin or quinidine; however, a trend towards increasing volume of distribution and half life was observed. Our results support the utility of elacridar in evaluation of the influence of P-gp mediated efflux on drug distribution to the brain. Our protocol employing a single intravenous dose of elacridar and test compound provides a cost effective alternative to expensive P-gp knockout mice models during early drug discovery.
Biocon Bristol-Myers Squibb Research and Development Center (BBRC), Syngene International Limited, Biocon Park Plot 2 & 3, Bommasandra IV Phase, Bangalore - 560 099, India.
Rajareddy
R
Kallem
Chetan P
CP
Kulkarni
Dakshay
D
Patel
Megha
M
Thakur
Michael
M
Sinz
Sheelendra P
SP
Singh
S Shahe
SS
Mahammad
Sandhya
S
Mandlekar
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000166:Acridines / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D019540:Area Under Curve; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002853:Chromatography, Liquid; D003362:Cost-Benefit Analysis; D004077:Digoxin / Q000493:pharmacokinetics; D015195:Drug Design; D004347:Drug Interactions; D006207:Half-Life; D007275:Injections, Intravenous; D008297:Male; D051379:Mice; D011412:Propanolamines / Q000493:pharmacokinetics; D011802:Quinidine / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry; D044005:Tetrahydroisoquinolines / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D014018:Tissue Distribution
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000166:Acridines; D011412:Propanolamines; D044005:Tetrahydroisoquinolines; C011550:talinolol; D004077:Digoxin; D011802:Quinidine; C083501:Elacridar