| 1. |
- Eriksson, Bengt I., 1946, et al.
(författare)
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Comparative pharmacodynamics and pharmacokinetics of oral direct thrombin and factor xa inhibitors in development
- 2009
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Ingår i: Clin Pharmacokinet. - 0312-5963. ; 48:1, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- For the past five decades, there has been little progress in the development of oral anticoagulants, with the choices being limited to the vitamin K antagonists (VKAs). The situation is changing with the development of orally active small molecules that directly target thrombin or activated factor X (FXa). The two agents in the most advanced stages of development are dabigatran etexilate and rivaroxaban, which inhibit thrombin and FXa, respectively. Both are approved in the EU and Canada for venous thromboprophylaxis in patients undergoing elective hip- or knee-replacement surgery. Other agents in the early stages of development include several FXa inhibitors (apixaban, DU 176b, LY 517717, YM 150, betrixaban, eribaxaban [PD 0348292] and TAK 442) and one thrombin inhibitor (AZD 0837). With a predictable anticoagulant response and low potential for drug-drug interactions, these new agents can be given in fixed doses without coagulation monitoring. This renders them more convenient than VKAs. While the anticoagulant effect of the new thrombin and FXa inhibitors is similar, differences in the pharmacokinetic and pharmacodynamic parameters may influence their use in clinical practice. Here, we compare the pharmacokinetic and pharmacodynamic features of these new oral agents.
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| 2. |
- Hovd, M., et al.
(författare)
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Neither Gastric Bypass Surgery Nor Diet-Induced Weight-Loss Affect OATP1B1 Activity as Measured by Rosuvastatin Oral Clearance
- 2023
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 62:5, s. 725-735
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionRosuvastatin pharmacokinetics is mainly dependent on the activity of hepatic uptake transporter OATP1B1. In this study, we aimed to investigate and disentangle the effect of Roux-en-Y gastric bypass (RYGB) and weight loss on oral clearance (CL/F) of rosuvastatin as a measure of OATP1B1-activity.MethodsPatients with severe obesity preparing for RYGB (n = 40) or diet-induced weight loss (n = 40) were included and followed for 2 years, with four 24-hour pharmacokinetic investigations. Both groups underwent a 3-week low-energy diet (LED; < 1200 kcal/day), followed by RYGB or a 6-week very-low-energy diet (VLED; < 800 kcal/day).ResultsA total of 80 patients were included in the RYGB group (40 patients) and diet-group (40 patients). The weight loss was similar between the groups following LED and RYGB. The LED induced a similar (mean [95% CI]) decrease in CL/F in both intervention groups (RYGB: 16% [0, 31], diet: 23% [8, 38]), but neither induced VLED resulted in any further changes in CL/F. At Year 2, CL/F had increased by 21% from baseline in the RYGB group, while it was unaltered in the diet group. Patients expressing the reduced function SLCO1B1 variants (c.521TC/CC) showed similar changes in CL/F over time compared with patients expressing the wild-type variant.ConclusionsNeither body weight, weight loss nor RYGB per se seem to affect OATP1B1 activity to a clinically relevant degree. Overall, the observed changes in rosuvastatin pharmacokinetics were minor, and unlikely to be of clinical relevance.
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| 3. |
- Kvitne, K. E., et al.
(författare)
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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
- 2023
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Ingår i: Clinical Pharmacokinetics. - 0312-5963.
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Mukonzo, Jackson K, et al.
(författare)
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HIV/AIDS Patients Display Lower Relative Bioavailability of Efavirenz than Healthy Subjects.
- 2011
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Ingår i: Clinical pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 50:8, s. 531-40
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pharmacokinetic studies of antiretroviral drugs are often conducted in adult healthy subjects, and the results are extrapolated to HIV/AIDS patients. HIV/AIDS, however, is known to cause morphological and physiological changes that may alter the pharmacokinetics of antiretroviral drugs. We examined the effect of HIV/AIDS on the pharmacokinetics of efavirenz in Ugandans. Methods: After a first oral dose of efavirenz 600 mg in treatment-naïve HIV-infected patients, blood samples were collected at nine time points up to 24 hours. The plasma-concentration time data from these patients were merged with previously reported data from adult healthy subjects. Population pharmacokinetic models were fitted to the data, using NONMEM VI software. Covariate analyses were performed to estimate the effects of HIV/AIDS disease, demographic characteristics (sex, bodyweight, age), biochemical variables (serum creatinine, urea, alanine aminotransferase) and pharmacogenetic variation in cytochrome P450 (CYP) 2B6, CYP3A5 and adenosine triphosphate-binding cassette, sub-family B, member 1 (ABCB1) on the population pharmacokinetic parameters. Results: Efavirenz plasma concentration-time data obtained from 29 HIV-1-infected, treatment-naïve patients were merged with previously reported data from 32 adult healthy subjects. The model identified sex and HIV/AIDS disease as statistically significant categorical predictors of efavirenz pharmacokinetics. Females were predicted to have a 2-fold higher volume of distribution of the peripheral compartment after oral administration (V(2)/F) than males (95% CI 1.53, 2.63), while HIV/AIDS patients were found to have 30% lower relative bioavailability (95% CI 18.7, 40.7) than healthy subjects. The increased V(2)/F in females resulted in a 2-fold longer elimination half-life than in males. Conclusion: On the basis of the findings of this analysis, we conclude that, apart from bodyweight-based differences, both HIV/AIDS disease and sex affect efavirenz pharmacokinetics in Ugandans. HIV/AIDS disease is associated with reduced relative bioavailability of efavirenz. We recommend that findings from healthy subject studies be confirmed in HIV/AIDS patients and that caution be applied in direct extrapolation of exposure data to the target patient population.
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| 5. |
- Siegmund, Werner, et al.
(författare)
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Pharmacokinetics and pharmacodynamics of propiverine in children aged between 5 and 10 years with symptoms of overactive bladder
- 2010
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 49:5, s. 335-342
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND OBJECTIVES: Pharmacokinetic studies in children are particularly required for drugs with intensive hepatic and regioselective intestinal elimination and pharmacological effects that may be critical for absorption at therapeutic doses, such as a delay in intestinal transit. One example is the antimuscarinic drug propiverine, the pharmacokinetics of which were evaluated in the present study in children with symptoms of overactive bladder. METHODS: The pharmacokinetics of immediate-release propiverine were studied in a dose-escalating, parallel-group study (propiverine 5, 10 and 15 mg twice daily for 14 days) in 25 subjects (11 females and 14 males aged 5-10 years; bodyweight 17-44 kg; body mass index 14-21 kg/m2) with symptoms of overactive bladder during waking hours. Serum concentration-time curves of propiverine and its major metabolite propiverine N-oxide (M-5) were evaluated up to 3 hours and 8 hours after the first and last administration, respectively, using liquid chromatography with tandem mass spectrometry. The voiding frequency, number of incontinence and urgency episodes, single voided volume and urine flow variables were measured before and after treatment. RESULTS: Significant dose-related increases in the serum exposure (the area under the concentration-time curve, the maximum concentration and the minimum concentration) with propiverine and M-5 in the dose groups < or =0.3 mg/kg and 0.3 to < or =0.45 mg/kg after both single-dose and repeated-dose administration were found. The elimination half-lives of propiverine and M-5 at steady state were no different (mean +/- SD 12.2 +/- 11.2 and 14.5 +/- 9.94 hours, respectively). Higher doses did not result in additional dose-proportional increases in the respective pharmacokinetic parameters, particularly not after repeated-dose treatment. The voiding frequency, voided volume and urge symptoms were beneficially changed from baseline; significant dose-dependent changes were not observed. Most of the adverse events that were probably or possibly drug related were reported for patients in the high-dose group (>0.45 mg/kg). CONCLUSIONS: The disposition of propiverine is dose related after repeated administration of the recommended doses below 0.45 mg/kg (0.3-0.45 mg/kg) twice daily in children aged 5-10 years with symptoms of overactive bladder and urinary incontinence. (Trial registration numbers: [clinicaltrials.gov] NCT00795925; [EudraCT] 2004-001243-30).
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