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- Kvitne, K. E., et al.
(author)
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Digoxin Pharmacokinetics in Patients with Obesity Before and After a Gastric Bypass or a Strict Diet Compared with Normal Weight Individuals
- 2024
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In: Clinical Pharmacokinetics. - 0312-5963. ; 63:1, s. 109-120
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Journal article (peer-reviewed)abstract
- Background and Objective Several drugs on the market are substrates for P-glycoprotein (P-gp), an efflux transporter highly expressed in barrier tissues such as the intestine. Body weight, weight loss, and a Roux-en-Y gastric bypass (RYGB) may influence P-gp expression and activity, leading to variability in the drug response. The objective of this study was therefore to investigate digoxin pharmacokinetics as a measure of the P-gp phenotype in patients with obesity before and after weight loss induced by an RYGB or a strict diet and in normal weight individuals. Methods This study included patients with severe obesity preparing for an RYGB (n = 40) or diet-induced weight loss (n = 40) and mainly normal weight individuals scheduled for a cholecystectomy (n = 18). Both weight loss groups underwent a 3-week low-energy diet (<1200 kcal/day) followed by an additional 6 weeks of <800 kcal/day induced by an RYGB (performed at week 3) or a very-low-energy diet. Follow-up time was 2 years, with four digoxin pharmacokinetic investigations at weeks 0, 3, and 9, and year 2. Hepatic and jejunal P-gp levels were determined in biopsies obtained from the patients undergoing surgery. Results The RYGB group and the diet group had a comparable weight loss in the first 9 weeks (13 +/- 2.3% and 11 +/- 3.6%, respectively). During this period, we observed a minor increase (16%) in the digoxin area under the concentration-time curve from zero to infinity in both groups: RYGB: 2.7 mu g h/L [95% confidence interval (CI) 0.67, 4.7], diet: 2.5 mu g h/L [95% CI 0.49, 4.4]. In the RYGB group, we also observed that the time to reach maximum concentration decreased after surgery: from 1.0 +/- 0.33 hours at week 3 to 0.77 +/- 0.08 hours at week 9 (-0.26 hours [95% CI -0.47, -0.05]), corresponding to a 25% reduction. Area under the concentration-time curve from zero to infinity did not change long term (week 0 to year 2) in either the RYGB (1.1 mu g h/L [-0.94, 3.2]) or the diet group (0.94 mu g h/L [-1.2, 3.0]), despite a considerable difference in weight loss from baseline (RYGB: 30 +/- 7%, diet: 3 +/- 6%). At baseline, the area under the concentration-time curve from zero to infinity was -5.5 mu g h/L [95% CI -8.5, -2.5] (-26%) lower in patients with obesity (RYGB plus diet) than in normal weight individuals scheduled for a cholecystectomy. Further, patients undergoing an RYGB had a 0.05 fmol/mu g [95% CI 0.00, 0.10] (29%) higher hepatic P-gp level than the normal weight individuals. Conclusions Changes in digoxin pharmacokinetics following weight loss induced by a pre-operative low-energy diet and an RYGB or a strict diet (a low-energy diet plus a very-low-energy diet) were minor and unlikely to be clinically relevant. The lower systemic exposure of digoxin in patients with obesity suggests that these patients may have increased biliary excretion of digoxin possibly owing to a higher expression of P-gp in the liver.
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| 3. |
- Kvitne, K. E., et al.
(author)
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Short- and long-term effects of body weight loss following calorie restriction and gastric bypass on CYP3A-activity - a non-randomized three-armed controlled trial
- 2022
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In: Cts-Clinical and Translational Science. - : Wiley. - 1752-8054 .- 1752-8062. ; 15:1, s. 221-233
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Journal article (peer-reviewed)abstract
- It remains uncertain whether pharmacokinetic changes following Roux-en-Y gastric bypass (RYGB) can be attributed to surgery-induced gastrointestinal alterations per se and/or the subsequent weight loss. The aim was to compare short- and long-term effects of RYGB and calorie restriction on CYP3A-activity, and cross-sectionally compare CYP3A-activity with normal weight to overweight controls using midazolam as probe drug. This three-armed controlled trial included patients with severe obesity preparing for RYGB (n = 41) or diet-induced (n = 41) weight-loss, and controls (n = 18). Both weight-loss groups underwent a 3-week low-energy-diet (<1200 kcal/day) followed by a 6-week very-low-energy-diet or RYGB (both <800 kcal/day). Patients were followed for 2 years, with four pharmacokinetic investigations using semisimultaneous oral and intravenous dosing to determine changes in midazolam absolute bioavailability and clearance, within and between groups. The RYGB and diet groups showed similar weight-loss at week 9 (13 +/- 2.4% vs. 11 +/- 3.6%), but differed substantially after 2 years (-30 +/- 7.0% vs. -3.1 +/- 6.3%). At baseline, mean absolute bioavailability and clearance of midazolam were similar in the RYGB and diet groups, but higher compared with controls. On average, absolute bioavailability was unaltered at week 9, but decreased by 40 +/- 7.5% in the RYGB group and 32 +/- 6.1% in the diet group at year 2 compared with baseline, with no between-group difference. No difference in clearance was observed over time, nor between groups. In conclusion, neither RYGB per se nor weight loss impacted absolute bioavailability or clearance of midazolam short term. Long term, absolute bioavailability was similarly decreased in both groups despite different weight loss, suggesting that the recovered CYP3A-activity is not only dependent on weight-loss through RYGB.
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