1. Although drug interactions between epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and gastric acid-suppressing medications (AS) are considered clinically significant, there is limited data regarding the influence of various gastric pH conditions on the pharmacokinetics of EGFR-TKIs. We aimed to clarify the changes in the pharmacokinetics of the EGFR-TKIs, gefitinib, erlotinib and osimertinib, due to the changes in gastric pH after administration of omeprazole or vonoprazan. 2. Omeprazole (10-100 mg/kg, p.o.) and vonoprazan (1-5 mg/kg, p.o.) led to a significant and dose-dependent increase in gastric pH. 3. AUC of gefitinib and erlotinib (5 mg/kg, p.o.) started to decrease at gastric pH 3.3 and 5.6, respectively, reached a plateau at pH > 6, and then significantly decreased up to 47 and 59% of control levels, respectively. AUC of osimertinib (5 mg/kg, p.o.) was not significantly changed by omeprazole and vonoprazan. 4. Although there are some issues regarding the extrapolation of the results of our rat study to humans, careful monitoring of patients treated with gefitinib and erlotinib is needed in cases in which the gastric pH increases from 3 to 5 and especially when the gastric pH is >5 in patients who are co-administered both the EGFR-TKIs and AS.
Denosumab‐induced hypocalcemia is sometimes severe, and although a natural vitamin D/calcium combination is used to prevent hypocalcemia, some patients rapidly develop severe hypocalcemia even under supplementation. It is clinically important to predict this risk. This study aimed to develop a risk prediction model for grade ≥2 hypocalcemia within 28 days after the first denosumab dose under natural vitamin D/calcium supplementation. Using a large database containing multicenter practice data, 2399 patients with bone metastasis who were treated with denosumab between June 2013 and May 2020 were retrospectively analyzed. Background factors in patients who developed grade ≥2 hypocalcemia within 28 days after the first denosumab dose and those who did not were compared by univariate analysis. Multivariate analysis was conducted to develop a risk prediction model. The model was evaluated for discriminant performance (receiver operating characteristic–area under the curve, sensitivity, specificity) and predictive performance (calibration slope). A total of 124 patients in the hypocalcemia group and 1191 patients in the nonhypocalcemia group were extracted. A risk prediction model consisting of sex, calcium, albumin, alkaline phosphatase, osteoporosis, breast cancer, gastric cancer, proton pump inhibitor combination, and pretreatment with zoledronic acid was developed. The receiver operating characteristic–area under the curve was 0.87. Sensitivity and specificity were 83% and 81%, respectively, and the calibration slope indicated acceptable agreement between observed and predicted risk. This model appears to be useful to predict the risk of denosumab‐induced hypocalcemia and thus should be helpful for risk management of denosumab treatment in patients with bone metastases.
To prevent denosumab-induced hypocalcemia in patients with renal dysfunction, combination therapy with 1α,25-dihydroxy-vitamin D 3 (active vitamin D) is recommended. We previously developed a risk prediction model for hypocalcemia in patients with cholecalciferol/calcium (natural vitamin D). However, the prescription status and the risk factors of patients with active vitamin D have not been identified, so we designed this retrospective observational study using a large practice database covering June 2013 to May 2020 to analyze prescription status and risk factors. Patients were classified according to vitamin D type. After that, factors associated with development of hypocalcemia in patients with active vitamin D were explored. Univariate analysis was conducted to compare patient backgrounds between the hypocalcemia and nonhypocalcemia groups. Receiver operating characteristic analysis was conducted to evaluate the predictive potential of the extracted factors. Of the 33442 patients who received denosumab, 22347 and 3560 patients were co-administered natural and active vitamin D, respectively. Patients with active vitamin D had significantly lower renal function (estimated glomerular filtration rate (eGFR) median: 74.0 vs. 69.7 mL/min/1.73 m 2 ), but some patients (23.6%) with sufficient renal function (eGFR ≥90) were also receiving active vitamin D. Of the 3560 patients with active vitamin D, non-hypocalcemia (n 166) and hypocalcemia (n 17) groups who met the study criteria were analyzed. Renal function was lower in the hypocalcemia group, and alkaline phosphatase gave the best discrimination. High aspartate aminotransferase (AST), renal dysfunction, high alkaline phosphatase (ALP), and low hemoglobin may be significant factors in risk prediction for hypocalcemia in patients with active vitamin D.
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