The findings of this review have indicated that hypoxia may play a key role in the PK changes of drugs at high altitude. It is suggested that patient living at or traveling to high altitude should be closely monitored, and the dosages of some drugs metabolized should be reduced.
Background: Radiation is the fourth most prevalent type of pollution following the water, air and noise pollution. It can adversely affect normal bodily functions. Radiation alters the protein and mRNA expression of drugmetabolizing enzymes and drug transporters and the pharmacokinetic characteristics of drugs, thereby affecting drug absorption, distribution, metabolism, and excretion. Therefore, it is important to study the pharmacokinetic changes in drugs under radiation. Methods: To update data on the effects of ionizing radiation and non-ionizing radiation caused by environmental pollution or clinical treatments on the protein and mRNA expression of drug-metabolizing enzymes and drug transporters. Data and information on pharmacokinetic changes in drugs under radiation were analyzed and summarized. Results: The effect of radiation on cytochrome P450 is still a subject of debate. The widespread belief is that higherdose radiation increased the expression of CYP1A1 and CYP1B1 of rat, zebrafish or human, CYP1A2, CYP2B1, and CYP3A1 of rat, and CYP2E1 of mouse or rat, and decreased that of rat’s CYP2C11 and CYP2D1. Radiation increased the expression of multidrug resistance protein, multidrug resistance-associated protein, and breast cancer resistance protein. The metabolism of some drugs, as well as the clearance, increased during concurrent chemoradiation therapy, whereas the half-life, mean residence time, and area under the curve decreased. Changes in the expression of cytochrome P450 and drug transporters were consistent with the changes in the pharmacokinetics of some drugs under radiation. Conclusion: The findings of this review indicated that radiation caused by environmental pollution or clinical treatments can alter the pharmacokinetic characteristics of drugs. Thus, the pharmacokinetics of drugs should be rechecked and the optimal dose should be re-evaluated after radiation.
Concurrent chemoradiation with irinotecan hydrochloride (CPT‐11) is accepted for cancer treatment. However, the effects of X‐ray irradiation on chemotherapeutics in the plasma remain unclear. We evaluated the pharmacokinetics of CPT‐11 in rats after exposure to X‐ray irradiation and examined the changes of protein and mRNA expression of CES1 and CYP3A1. The X‐ray irradiation with 1 Gy and 5 Gy was delivered to the whole body of rats. CPT‐11 at 30 and 60 mg/kg, respectively, was intravenously infused 24 h after irradiation. CPT‐11 was determined by RP‐HPLC in plasma. ELISA and PCR were used to analyze the protein and mRNA expression of CES1 and CYP3A1, respectively. Compared with control rats, the X‐ray irradiation decreased the AUC of CPT‐11 (30 mg/kg) by 15.6% at 1 Gy and 39.0% at 5 Gy and increased the CL by 60.0% at 5 Gy. The X‐ray irradiation could also decrease the AUC of CPT‐11 (60 mg/kg) and increase the CL. In addition, the protein and mRNA expression of CES1 and CYP3A1 were increased significantly in rats after irradiation. This study found significant changes in the pharmacokinetics of CPT‐11 in rats after exposure to X‐ray irradiation, and they might be due to significant increases in the expressions of CYP3A1 and CES1. The pharmacokinetics of CPT‐11 should be rechecked, and the optimal CPT‐11 dose should be reevaluated during concurrent chemoradiation therapy.
The objective of this study was to investigate the regulation of X-ray irradiation and its effect on the activity and protein and mRNA expression levels of CYP1A2 and CYP2E1 in rats. Rats were randomly divided into 0 Gy (control), 1 Gy (low-dose irradiation), and 5 Gy (high-dose irradiation) groups. CYP1A2 and CYP2E1 activity was evaluated from changes in pharmacokinetic parameters of caffeine and chlorzoxazone, respectively. The plasma concentrations of the probe drugs were determined by high-performance liquid chromatography (HPLC). Enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (PCR) tests were used to analyze the protein and mRNA expression levels of CYP1A2 and CYP2E1, respectively. The AUC 0-12 of caffeine was decreased by 1.7-and 2.5-fold, and the CL was increased by 1.8-and 2.6-fold in the 1 Gy and 5 Gy groups, respectively, compared to the 0 Gy group. The AUC 0-10 of chlorzoxazone was 1.4-and 1.8-fold lower, and the CL was 1.4-and 1.9-fold higher in the 1 Gy and 5 Gy groups, respectively, compared to the 0 Gy group. The metabolism of caffeine and chlorzoxazone increased under X-ray irradiation as CL levels increased and AUC levels decreased, suggesting that CYP1A2 and CYP2E1 activity is enhanced in rats after X-ray irradiation. Compared to that of the 0 Gy group, the protein expression level of CYP1A2 was measured as 28.3% and 38.9% higher in the 1 Gy and 5 Gy groups, respectively. The protein expression level of CYP2E1 was 48.4% higher in the 5 Gy group compared to the 0 Gy group, and there was no statistically significant difference between 0 Gy and 1 Gy. Compared to the 0 Gy group, the mRNA expression level of CYP1A2 was 200% and 856.3% higher in the 1 Gy and 5 Gy group, respectively, whereas the mRNA expression level of CYP2E1 was 89.0% and 192.3% higher in the 1 Gy and 5 Gy groups, respectively. This study reveals significant changes in the activity and protein and mRNA expression levels of CYP1A2 and CYP2E1 in rats after exposure to X-ray irradiation. AnimalsSprague Dawley SPF rats (200 ± 20 g, certificate No. 2007-001) of both sexes were provided by the laboratory animal center at Xi'an Jiaotong University Medical College, China. They were adapted for a week at 23 ± 2°C with a constant humidity level of 55% ± 5% under a cycle of 12 h of dark conditions and given ad libitum Li et al. X-Ray Irradiation and CYP1A2 and CYP2E1 Frontiers in Pharmacology | www.frontiersin.org January 2020 | Volume 10 | Article 1575 2
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