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The Design of Receptor-Binding Radiotracers
Published in Lelio G. Colombetti, Principles of Radiopharmacology, 2019
William C. Eckelman, Raymond E. Gibson, Waclaw J. Rzeszotarski, Victor Jiang, J. Krijn Mazaitis, Chang Paik, Toru Komai, Richard C. Reba
At 2.5 hr in rats C-14 talinolol, a cardioselective drug, gives an H/B ratio of 3.8, which increases to 26.3 at 24 hr. The H/L ratio is 0.62 and 0.67 at the same time for this relatively lipid soluble compound.3514C practolol, another cardioselective drug in the physiologic sense, gives an H/L ratio of 0.66 and an H/B ratio of 2 at 3 hr.36 Metroprolol gives an H/L ratio of 0.21 at 10 min and 0.24 at 2 hr, whereas the heart to plasma ratio is 5.4 at 10 min and 6.5 at 2 hr in rat.37
Lung transporters and absorption mechanisms in the lungs
Published in Anthony J. Hickey, Heidi M. Mansour, Inhalation Aerosols, 2019
Mohammed Ali Selo, Hassan H.A. Al-Alak, Carsten Ehrhardt
Thus, a significant body of data shows the expression and functional activity of P-gp in the lung, where it transports its substrates out to the apical surface (37,48). However, several studies have also shown a negligible role for pulmonary P-gp on limiting the airway to blood absorption of its inhaled substrates. One example is an in vivo study conducted in rats that revealed a high bioavailability for the two P-gp substrates, talinolol and losartan, with 81% and 92%, respectively (49). Similarly, an ex vivo study performed in an isolated perfused rat lung (IPRL) model reported a high overall absorption for losartan. Despite having the physicochemical properties indicative of a high permeability drug, losartan displayed one of the slowest absorption half-lives (t1/2 of 26 min) among the range of investigated drugs (49).
Effects of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats
Published in Xenobiotica, 2019
Qingling Zhao, Jinlan Wei, Hongying Zhang
It is now well known that undesired drug–drug interactions can be caused by CYP450 enzymes or transporters (Joyce et al., 2015; Kim et al., 1998; Li et al., 2014; Wen et al., 2015; Wrighton & Stevens, 1992; Ye et al., 2011; Zhang et al., 2007). For example, the antifungal ketoconazole, a potent inhibitor of CYP3A4, causes drug–drug interactions with drugs that are substrates of CYP3A4 (Xiaoyang et al., 2015). Verapamil, a typical P-gp inhibitor, could increase the bioavailability of talinolol by inhibiting the activity of P-gp (Nguyen et al., 2014).
The in vitro metabolism and in vivo pharmacokinetics of the bacterial β-glucuronidase inhibitor UNC10201652
Published in Xenobiotica, 2022
Anna Kerins, Marta Koszyczarek, Caroline Smith, Phil Butler, Rob Riley, Vamsi Madgula, Nilkanth Naik, Matthew R. Redinbo, Ian D. Wilson
Reduced nicotinamide adenine dinucleotide phosphate (NADPH) was purchased from Roche Diagnostics (Mannheim, Germany). Diazepam, diphenhydramine, dextromethorphan, verapamil, Williams E media, l-glutamine, HEPES, non-essential amino acids, lucifer yellow, umbelliferone, metoprolol, raloxifene, atenolol, antipyrine, oestrone 3-sulfate, elacridar, MK-571 and warfarin were purchased from Sigma-Aldrich (St. Louis, MO). Talinolol was purchased from Toronto Research Chemicals (Toronto, ON, Canada).