| 1. |
- Ederoth, Per, et al.
(författare)
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Blood-brain barrier transport of morphine in patients with severe brain trauma
- 2004
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 57:4, s. 427-435
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: In experimental studies, morphine pharmacokinetics is different in the brain compared with other tissues due to the properties of the blood-brain barrier, including action of efflux pumps. It was hypothesized in this clinical study that active efflux of morphine occurs also in human brain, and that brain injury would alter cerebral morphine pharmacokinetics. METHODS: Patients with traumatic brain injury, equipped with one to three microdialysis catheters in the brain and one in abdominal subcutaneous fat for metabolic monitoring, were studied. The cerebral catheter locations were classified as 'better' and 'worse' brain tissue, referring to the degree of injury. Morphine (10 mg) was infused intravenously over a 10-min period in seven patients in the intensive care setting. Tissue and plasma morphine concentrations were obtained during the subsequent 3-h period with microdialysis and regular blood sampling. RESULTS: The area under the concentration-time curve (AUC) ratio of unbound morphine in brain tissue to plasma was 0.64 (95% confidence interval 0.40, 0.87) in 'better' brain tissue (P < 0.05 vs. the subcutaneous fat/plasma ratio), 0.78 (0.49, 1.07) in 'worse' brain tissue and 1.00 (0.86, 1.13) in subcutaneous fat. The terminal half-life and T(max) were longer in the brain vs. plasma and fat, respectively. The relative recovery for morphine was higher in 'better' than in 'worse' brain tissue. The T(max) value tended to be shorter in 'worse' brain tissue. CONCLUSIONS: The unbound AUC ratio below unity in the 'better' human brain tissue demonstrates an active efflux of morphine across the blood-brain barrier. The 'worse' brain tissue shows a decrease in relative recovery for morphine and in some cases also an increase in permeability for morphine over the blood-brain barrier.
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| 2. |
- Petersen, AH, et al.
(författare)
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The effect of exercise on the absorption of inhaled human insulin in healthy volunteers
- 2008
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 1365-2125 .- 0306-5251. ; 65:2, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- What is already known about this subject * Exercise is known to affect absorption of other inhaled substances, but so far there are no reports on the effect of exercise on the absorption of inhaled insulin in humans. What this paper adds * This report is the first to investigate the effect of exercise on the absorption of inhaled insulin. * In this study in healthy volunteers we found that exercise early after dosing increased absorption (15-20%) of inhaled insulin over the first 2 h after start of exercise, with an approximately 30% increase in maximal insulin concentration, and unchanged overall absorption. Aims To investigate the effect of moderate exercise on the absorption of inhaled insulin. Methods A single-centre, randomized, open-label, three-period cross-over trial was carried out in 12 nonsmoking healthy subjects. A dose of 3.5 mg inhaled human insulin was administered via a nebulizer and followed in random order by either 1) no exercise (NOEX), 2) 30 min exercise starting immediately after dosing (EX0), or 3) 30 min exercise starting 30 min after dosing (EX30). The study was carried out as a 10 h euglycaemic glucose clamp (90 mg dl(-1) (5.0 mmol l(-1))). Results The absorption of insulin over the first 2 h after start of exercise was 16% increased for EX0 (ratio (95%CI) 1.16 (1.04, 1.30), P = 0.01) and 20% increased for EX30 (1.20 (1.05, 1.36), P < 0.01), both compared with NOEX; the overall insulin absorption during 6 h and 10 h after dosing was not influenced by exercise. The maximum insulin concentration (C(max)) increased by 32% for EX0 and 35% for EX30 (both P < 0.01) compared with NOEX, while the time to C(max) was 31 min faster for EX0 (P < 0.01), but not significantly different after EX30, compared with NOEX. Conclusions A significant and clinically relevant increase of insulin absorption over the first 2 h after the beginning of exercise was observed. Until data from studies using the specific insulin inhalers exists, patients using inhaled insulin should be made aware of a potential increased absorption and higher concentration of insulin in connection with exercise.
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| 3. |
- Bondesson, Eva, et al.
(författare)
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Site of deposition and absorption of an inhaled hydrophilic solute
- 2007
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 1365-2125 .- 0306-5251. ; 63:6, s. 722-731
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Tidskriftsartikel (refereegranskat)abstract
- Aims To characterize the absorption kinetics and bioavailability of an inhaled hydrophilic solute deposited at various sites within the airways. Methods Nine healthy nonsmokers received one intravenous, one oropharyngeal and two pulmonary doses of technetium-99 m-labelled diethylene triamine pentaacetic acid (Tc-99m-DTPA) in an open and crossover fashion. Pulmonary doses were administered as nebulized large and fine droplet-sized aerosols by Pari and UltraVent nebulizers at fairly rapid and slow inhalation flows, respectively. Plasma concentration-time profiles and 24 h urinary excretion of radioactivity were determined. One dose of Tc-99m-labelled Nanocoll, as a marker of mucociliary clearance (MCC), was also administered by Pari for similar lung deposition as the Tc-99m-DTPA and followed by repeated chest gamma-imaging. Results Intrapulmonary deposition patterns of Tc-99m-DTPA differed significantly (the mean ratio of penetration index (Pari : UltraVent) was 76% with 95% CI 63%, 91%). However, no differences in rate or extent of Tc-99m-DTPA absorption were detected. Mean absorption time was 1.8 h (mean difference (Pari-UltraVent): -0.1 h with 95% CI -0.6 h, 0.3 h) and the bioavailability was 70% (mean ratio (Pari : UltraVent): 101% with 95% CI 90%, 115%). The pulmonary elimination half-life of Tc-99m-Nanocoll (8 h and 45 min) was significantly longer than that of Tc-99m-DTPA (less than 2 h). The oral bioavailability of Tc-99m-DTPA was estimated to be 3.1%. Conclusions The main elimination pathway of the inhaled hydrophilic solute Tc-99m-DTPA from the lungs is trans-epithelial absorption. Despite different intrapulmonary radioaerosol deposition patterns, as verified by gamma scintigraphy, no differences in Tc-99m-DTPA absorption kinetics or bioavailability were detected.
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| 4. |
- Magnusson, Marie, et al.
(författare)
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A placebo-controlled study of retinal blood flow changes by pentoxifylline and metabolites in humans
- 2006
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 61:2, s. 138-147
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To investigate the possible effects of pentoxifylline metabolites on retinal blood flow in humans. METHODS: A randomized, placebo-controlled, four-period cross-over study that was observer blinded and partly blinded for the eight participants. On one occasion a placebo was given as an intravenous (i.v.) infusion over 100 min. On the other three occasions pentoxifylline was administered as i.v. infusions over 100 min at a rate of 3 mg min(-1). Before two of the pentoxifylline infusions the subjects were pretreated with either ciprofloxacin or rifampicin. Retinal blood flow was measured by scanning laser doppler flowmetry (SLDF) in a selected area of the central temporal retina before, during and until 5 h after the end of infusion. Blood samples for concentration analyses of pentoxifyllin, R-M1, S-M1, M4 and M5 were taken serially and areas under the curves (AUCs) were calculated. Linear mixed models were used for the statistical analyses. RESULTS: Mean AUCs (ng h ml(-1)) were significantly increased for pentoxifylline (1964 vs. 1453) and S-M1 (5804 vs. 4227), but not R-M1 when pentoxifylline was co-administered with ciprofloxacin. The mean AUC for M5 was significantly reduced when subjects were pretreated with rifampicin (2041 vs. 3080). Pentoxifylline with and without pretreatment with rifampicin significantly increased retinal blood flow assessed as mean flow, pulsation (i.e. 1-systole/diastole), and diastolic flow (but not during systole), compared with placebo. The increases over placebo were more pronounced on diastolic flow, 9.7% (95% confidence interval 4.2, 15.5) than on mean flow, 4.6% (1.1, 8.3) after pentoxifylline administration. With pentoxifylline after rifampicin pretreatment the corresponding differences were 11.7% (5.8, 17.9) and 5.1% (1.4, 7.8) over placebo, respectively. After co-administration of pentoxifylline and ciprofloxacin we saw only a nonsignificant trend towards increased flow during diastole, but a significant decrease in pulsation. When AUCs for pentoxifylline and its metabolites were used as regressor variables to retinal mean flow we found that pentoxifylline, R-M1 and M5 had coefficients with a positive sign indicating that they enhanced the retinal blood flow. In contrast, S-M1 and M4 had coefficients with negative sign and thus appeared to decrease the blood flow in subjects treated with pentoxifylline. CONCLUSION: The R-M1 and M5 metabolites of pentoxifylline contributed significantly to the effects of pentoxifylline on retinal blood flow.
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| 5. |
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| 6. |
- Petersen, Astrid H., et al.
(författare)
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The effect of terbutaline on the absorption of pulmonary administered insulin in subjects with asthma
- 2010
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 1365-2125 .- 0306-5251. ; 69:3, s. 271-278
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Tidskriftsartikel (refereegranskat)abstract
- center dot People with mild and moderate asthma have been shown to absorb less inhaled insulin than healthy subjects. center dot In people with moderate asthma, the administration of a bronchodilator before inhalation of insulin has been shown to lead to increased uptake of inhaled insulin compared with no prior administration of bronchodilator. WHAT THIS STUDY ADDS center dot This study is the first to show that in people with asthma, reduction of bronchoconstriction leads to increased absorption of inhaled insulin. center dot This study illustrates that due to the effect of terbutaline on glucose metabolism, the effect of insulin on plasma glucose is complex when terbutaline is administered concomitantly. AIM To investigate the effect of prior administration of a bronchodilator on the absorption of inhaled insulin in people with asthma treated with inhaled corticosteroids. METHODS A single-centre, randomized, open-label, two-period cross-over trial was carried out in 41 nondiabetic subjects with asthma treated with inhaled steroids, with reversible bronchoconstriction (Rev+; n = 25) or without reversible bronchoconstriction (Rev-; n = 16). A dose of 0.10 U kg-1 inhaled human insulin was administered on each dosing day with or without prior administration of the bronchodilator terbutaline (in random order). RESULTS Prior administration of terbutaline led to a 44% increase in absorption of insulin over 6 h for the Rev+ group compared with no prior administration of bronchodilator [ratio (95% confidence interval) 1.44 (1.13, 1.82), P = 0.004], whereas no effect was seen for the Rev- or the whole group. The maximum insulin concentration (C-max) increased by 34% for the Rev+ group (P = 0.018) and 17% for the whole group (P = 0.046), whereas no significant effect of prior terbutaline administration was seen for Rev-. The time to C-max was not significantly different for the Rev+ group, whereas it was approximately 30% longer after bronchodilator administration for the Rev- group (P = 0.044) and the whole group (P = 0.032). CONCLUSIONS In people with asthma and reversible bronchoconstriction, the administration of a bronchodilator prior to administration of inhaled insulin led to increased absorption of insulin, whereas no effect on insulin absorption in subjects without significant reversibility could be detected.
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| 7. |
- Pettersson, Jonas, et al.
(författare)
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Muscular exercise can cause highly pathological liver function tests in healthy men.
- 2008
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 1365-2125 .- 0306-5251. ; 65:2, s. 253-259
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Tidskriftsartikel (refereegranskat)abstract
- What is already known about this subject • The occurrence of idiosyncratic drug hepatotoxicity is a major problem in all phases of clinical drug development and the leading cause of postmarketing warnings and withdrawals. • Physical exercise can result in transient elevations of liver function tests. • There is no consensus in the literature on which forms of exercise may cause changes in liver function tests and to what extent. What this study adds • Weightlifting results in profound increases in liver function tests in healthy men used to moderate physical activity, not including weightlifting. • Liver function tests are significantly increased for at least 7 days after weightlifting. • It is important to impose relevant restrictions on heavy muscular exercise prior to and during clinical studies. Aim To investigate the effect of intensive muscular exercise (weightlifting) on clinical chemistry parameters reflecting liver function in healthy men. Methods Fifteen healthy men, used to moderate physical activity not including weightlifting, performed an 1 h long weightlifting programme. Blood was sampled for clinical chemistry parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LD), gamma-glutamyl transferase (γGT), alkaline phosphatase (ALP), bilirubin, creatine kinase (CK) and myoglobin] at repeated intervals during 7 days postexercise and at a follow-up examination 10–12 days postexercise. Results Five out of eight studied clinical chemistry parameters (AST, ALT, LD, CK and myoglobin) increased significantly after exercise (P < 0.01) and remained increased for at least 7 days postexercise. Bilirubin, γGT and ALP remained within the normal range. Conclusion The liver function parameters, AST and ALT, were significantly increased for at least 7 days after the exercise. In addition, LD and, in particular, CK and myoglobin showed highly elevated levels. These findings highlight the importance of imposing restrictions on weightlifting prior to and during clinical studies. Intensive muscular exercise, e.g. weightlifting, should also be considered as a cause of asymptomatic elevations of liver function tests in daily clinical practice.
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| 8. |
- Thorsson, Lars, et al.
(författare)
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Pharmacokinetics and systemic activity of fluticasone via Diskus and pMDI, and of budesonide via Turbuhaler
- 2001
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 1365-2125 .- 0306-5251. ; 52:5, s. 529-538
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To determine the basal pharmacokinetics, lung uptake and plasma cortisol suppression for two commonly prescribed inhaled corticosteroids. METHODS: Twenty-one subjects (13 healthy and 8 mild asthmatic patients) received fluticasone propionate via a chlorofluorocarbon-propelled pressurized metered-dose inhaler (pMDI) (healthy subjects only) and Diskus and budesonide via Turbuhaler, 1000 microg twice daily for 7 days. Intravenous doses (200 microg) of both compounds were used as references. Plasma concentrations of fluticasone and budesonide were determined during 48 h by liquid chromatography plus tandem mass spectrometry (LC-MS-MS). Plasma concentrations of cortisol were determined by LC-MS every second hour for 24 h at baseline, and following each treatment. RESULTS: The volume of distribution was found to be larger and the elimination half-life and mean absorption time longer for fluticasone than for budesonide. The systemic availability of budesonide via Turbuhaler (39%) was significantly higher than that of fluticasone via Diskus (13%) (ratio 3.0 [2.5, 3.6] with 95% confidence interval [CI]), and via pMDI (21%) (ratio 1.8 [1.3, 2.3]). In addition, at steady state the systemic availability of fluticasone via pMDI was significantly higher than via Diskus (ratio 1.6 [1.1, 2.2]). The lung deposition of budesonide via Turbuhaler was 2.2-fold [1.7, 2.9] higher than that of fluticasone pMDI and 3.4-fold [2.8, 4.0] higher than that of fluticasone Diskus. In addition, the lung deposition of fluticasone via pMDI was 1.5-fold [1.1, 2.9] higher than that via the Diskus inhaler. Plasma cortisol (24 h) was significantly reduced vs baseline for all three treatments. The cortisol concentration vs baseline was 12% for fluticasone pMDI, which was significantly lower (ratio 0.32 [0.24, 0.42]) than that for fluticasone Diskus (39%), and for budesonide Turbuhaler (46%) (ratio 0.27 [0.21, 0.37]). The plasma cortisol concentration did not differ significantly between treatments with fluticasone Diskus and budesonide Turbuhaler (ratio 0.87 [0.65; 1.15]). CONCLUSIONS: Budesonide and fluticasone differ in their pharmacokinetic properties in that although clearance is the same, the rate of uptake and elimination is slower for fluticasone. Despite a significantly higher pulmonary availability of budesonide via Turbuhaler, the plasma cortisol suppression is less than that of fluticasone via pMDI and similar to that of fluticasone via Diskus. There is no indication of any difference between healthy subjects and mild asthmatic patients in the pharmacokinetics and plasma cortisol suppression of fluticasone and budesonide.
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| 9. |
- Asimus, Sara, 1976, et al.
(författare)
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Retrospective analysis of artemisinin pharmacokinetics: application of a semiphysiological autoinduction model.
- 2007
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Ingår i: British journal of clinical pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 63:6, s. 758-62
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To describe the time-course of the autoinduction of artemisinin by applying a semi-physiological pharmacokinetic model. METHODS: Plasma concentration-time data from six clinical studies involving oral administration of artemisinin to healthy subjects and malaria patients were included in the analysis. NONMEM was used to apply a semi-physiological model incorporating metabolizing enzymes and a pharmacokinetic model including a separate hepatic compartment. RESULTS: The model described the data well. The hepatic extraction ratio increased from 0.74 at pre-induced conditions to 0.98 after autoinduction of metabolism. CONCLUSIONS: Our model successfully described the time-course of autoinduction of metabolism of artemisinin in subjects receiving oral artemisinin.
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| 10. |
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