Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 31100
The Effect of Loperamide and Fentanyl on the Distribution Kinetics of Verapamil in the Lung and Brain in Sprague Dawley Rats

Authors: Iman A. Elkiweri, Ph.D, Martha C. Tissot van Patot, Ph.D., Yan Ling Zhang, Ph.D., Uwe Christians, Ph.D., Thomas K. Henthorn, M.D.,


Verapamil has been shown to inhibit fentanyl uptake in vitro and is a potent P-glycoprotein inhibitor. Tissue partitioning of loperamide, a commercially available opioid, is closely controlled by the P-gp efflux transporter. The following studies were designed to evaluate the effect of opioids on verapamil partitioning in the lung and brain, in vivo. Opioid (fentanyl or loperamide) was administered by intravenous infusion to Sprague Dawley rats alone or in combination with verapamil and plasma, with lung and brain tissues were collected at 1, 5, 6, 8, 10 and 60 minutes. Drug dispositions were modeled by recirculatory pharmacokinetic models. Fentanyl slightly increased the verapamil lung (PL) partition coefficient yet decreased the brain (PB) partition coefficient. Furthermore, loperamide significantly increased PLand PB. Fentanyl reduced the verapamil volume of distribution (V1) and verapamil elimination clearance (ClE). Fentanyl decreased verapamil brain partitioning, yet increased verapamil lung partitioning. Also, loperamide increased lung and brain partitioning in vivo. These results suggest that verapamil and fentanyl may be substrates of an unidentified inward transporter in brain tissue and confirm that verapamil and loperamide are substrates of the efflux transporter P-gp.

Keywords: partition coefficient, Efflux transporter, elimination clearance, verapamil

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1488


[1] Roerig DL, Kotrly KJ, Dawson CA, Ahlf SB, Gualtieri JF, Kampine JP: First-pass uptake of verapamil, diazepam, and thiopental in the human lung. Anesthesia & Analgesia 1989; 69: 461-6.
[2] Roerig DL, Kotrly KJ, Vucins EJ, Ahlf SB, Dawson CA, Kampine JP: First pass uptake of fentanyl, meperidine, and morphine in the human lung. Anesthesiology 1987; 67: 466-72.
[3] Taeger K, Weninger E, Schmelzer F, Adt M, Franke N, Peter K: Pulmonary kinetics of fentanyl and alfentanil in surgical patients. British Journal of Anaesthesia 1988; 61: 425-34.
[4] Waters CM, Krejcie TC, Avram MJ: Facilitated uptake of fentanyl, but not alfentanil, by human pulmonary endothelial cells. Anesthesiology 2000; 93: 825-31.
[5] Henthorn TK, Krejcie TC, Avram MJ, Jensen TR, Waters CM: Transporter-mediated pulmonary endothelial uptake of fentanyl. International Journal of Clinical Pharmacology & Therapeutics 1998; 36: 74-5.
[6] Waters CM, Avram MJ, Krejcie TC, Henthorn TK: Uptake of fentanyl in pulmonary endothelium. Journal of Pharmacology & Experimental Therapeutics 1999; 288: 157-63.
[7] Henthorn TK, Liu Y, Mahapatro M, Ng KY: Active transport of fentanyl by the blood-brain barrier. Journal of Pharmacology & Experimental Therapeutics 1999; 289: 1084-9.
[8] Bhatti MM, Foster RT: Pharmacokinetics of the enantiomers of verapamil after intravenous and oral administration of racemic verapamil in a rat model. Biopharmaceutics & Drug Disposition 1997; 18: 387-96.
[9] Gustafsson LL, Ebling WF, Osaki E, Harapat S, Stanski DR, Shafer SL: Plasma concentration clamping in the rat using a computer-controlled infusion pump. Pharmaceutical Research 1992; 9: 800-7.
[10] Ludden TM, Beal SL, Sheiner LB: Comparison of the Akaike Information Criterion, the Schwarz criterion and the F test as guides to model selection. Journal of Pharmacokinetics & Biopharmaceutics 1994; 22: 431-45.
[11] Hagenbuch B, Meier PJ: The superfamily of organic anion transporting polypeptides. Biochimica et Biophysica Acta 2003; 1609: 1-18.
[12] Gao B, Stieger B, Noe B, Fritschy JM, Meier PJ: Localization of the organic anion transporting polypeptide 2 (Oatp2) in capillary endothelium and choroid plexus epithelium of rat brain. Journal of Histochemistry & Cytochemistry 1999; 47: 1255-64.
[13] Cvetkovic M, Leake B, Fromm MF, Wilkinson GR, Kim RB: OATP and P-glycoprotein transporters mediate the cellular uptake and excretion of fexofenadine. Drug Metabolism & Disposition 1999; 27: 866-71.
[14] Schinkel AH, Wagenaar E, Mol CA, van Deemter L: P-glycoprotein in the blood-brain barrier of mice influences the brain penetration and pharmacological activity of many drugs. Journal of Clinical Investigation 1996; 97: 2517-24.
[15] Dagenais C, Graff CL, Pollack GM: Variable modulation of opioid brain uptake by P-glycoprotein in mice. Biochemical Pharmacology 2004; 67: 269-76.
[16] Ayrton A, Morgan P: Role of transport proteins in drug absorption, distribution and excretion. Xenobiotica 2001; 31: 469-97.
[17] Verschraagen M, Koks CH, Schellens JH, Beijnen JH: P-glycoprotein system as a determinant of drug interactions: the case of digoxinverapamil. Pharmacological Research 1999; 40: 301-6.
[18] Iman A Elkiweri, Yan Ling Zhang, Uwe Christians, Ka-Yun Ng, Martha C Tissot van Patot, Thomas K Henthorn : Competitive substrates for P-glycoprotein and organic anion protein transporters differentially reduce blood organ transport of fentanyl and loperamide: pharmacokinetics and pharmacodynamics in Sprague-Dawley rats. Anesth Analg.2009; 108: 149-159.