Opiates inhibit paclitaxel uptake by P-glycoprotein in preparations of human placental inside-out vesicles

Abstract

The use of either methadone or buprenorphine for treatment of the pregnant opiate dependent patient improves maternal and neonatal outcome. However, patient outcomes are often complicated by neonatal abstinence syndrome (NAS). The incidence and severity of NAS should depend on opiate concentration in the fetal circulation. Efflux transporters expressed in human placental brush border membranes decrease fetal exposure to medications by their extrusion to the maternal circulation. Accordingly, the concentration of either methadone or buprenorphine in the fetal circulation is, in part, dependent on the activity of the efflux transporters. The objective of this study was to characterize the activity of P-gp and its interaction with opiates in the placental apical membrane. Therefore, brush border membrane vesicles were prepared from human placenta. The vesicles were oriented approximately 75% inside out, exhibited saturable ATP-dependent uptake of P-gp substrate [3H] paclitaxel with an apparent Kt of 66 ± 38 nM and Vmax of 20 ± 3 pmol*mg protein−1min−1. Methadone, buprenorphine, and morphine inhibited paclitaxel transport with apparent Ki of 18, 44, and 90 μM, respectively. Our data indicate that a method has been established to determine the activity of the efflux transporter P-gp, expressed in placental brush border membranes, and the kinetics for the transfer of its prototypic substrate paclitaxel. Furthermore, the method was used to determine the effects of methadone, buprenorphine, and morphine on paclitaxel transfer by placental P-gp and revealed that they have higher affinity to the transporter than its classical inhibitor verapamil (Ki, 300 μM).

Placental Transfer of Maraviroc in an Ex Vivo Human Cotyledon Perfusion Model and Influence of ABC Transporter Expression

“…Besides, it could also be suggested that maraviroc inductive properties toward ABCC2 could counterbalance ABCC2 rather low placental expression (28). Regarding ABCB1, one hypothesis that could partly explain the lack of correlation we observed could be the variability of frequency between ethnic groups of the 3435C¡T substitution, which has been associated with a decrease of ABCB1 mRNA and protein expression (33,34). Indeed, in European Caucasians, 3435T frequencies of 0.52 to 0.57 were reported, whereas in Africa, the prevalence is much lower, 0.17 to 0.27 (35,36).…”

Transport of digoxin-loaded Polymeric Nanoparticles Across BeWo cells, an In Vitro Model of Human Placental Trophoblast

“…Figure 3 shows that encapsulation of digoxin in nanoparticles resulted in an increase in the apparent permeability of the drug in the apical (maternal) to basolateral (fetal) direction by 2.5-fold (p < 0.05). The transport studies were repeated in the presence of 100 μM verapamil, a P-gp inhibitor [16]. The concentration of verapamil selected for this study matches the concentration used by Polachek et al as an inhibitor of P-gp in BeWo cells [32].…”

“…The transport of digoxin as free drug or encapsulated in nanoparticles was compared using the BeWo b30 cell line, an in vitro model of human placental t rophoblast cells separating the maternal and fetal circulations [15]. Finally, the effect of nanoencapsulation on the interaction of digoxin with P-gp was investigated by means of transport studies in the presence of verapamil, a P-gp inhibitor [16].…”

Transporter-Mediated Disposition of Opioids: Implications for Clinical Drug Interactions

“…The same group demonstrated that methadone transfer was significantly higher in the fetal-tomaternal direction, likely due to the unidirectional activity of P-gp (142). Methadone was also shown to inhibit the transfer of paclitaxel in human placental inside-out vesicles, demonstrating a greater affinity for P-gp than the classic inhibitor verapamil (143). Similarly, methadone was shown to stimulate P-gp activity at higher concentrations (100 μM), and Caco-2 monolayer transport studies demonstrated that verapamil and GF120918 significantly reduced methadone efflux (111).…”