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1.  Aspects of statin prescribing in Norwegian counties with high, average and low statin consumption – an individual-level prescription database study 
Background
A previous study has shown that variations in threshold and intensity (lipid goal attainment) of statins for primary prevention contribute to regional differences in overall consumption of statins in Norway. Our objective was to explore how differences in prevalences of use, dosing characteristics, choice of statin and continuity of therapy in individual patients adds new information to previous results.
Methods
Data were retrieved from The Norwegian Prescription Database. We included individuals from counties with high, average, and low statin consumption, who had at least one statin prescription dispensed during 2004 (N = 40 143).
1-year prevalence, prescribed daily dose (PDD), statin of choice, and continuity of therapy assessed by mean number of tablets per day.
Results
The high-consumption county had higher prevalence of statin use in all age groups.
Atorvastatin and simvastatin were dispensed in 79–87% of all statin users, and the proportion was significantly higher in the high-consumption county.
The estimated PDDs were higher than the DDDs, up to twice the DDD for atorvastatin. The high-consumption county had the highest PDD for simvastatin (25.9 mg) and atorvastatin (21.9 mg), and more users received tablets in the upper range of available strengths. Continuity of therapy was similar in the three counties.
Conclusion
Although differences in age-distribution seems to be an important source of variation in statin consumption, it cannot account for the total variation between counties in Norway. Variations in prevalences of use, and treatment intensity in terms of PDD and choice of statin also affect the total consumption. The results in this study seems to correspond to previous findings of more frequent statin use in primary prevention, and more statin users achieving lipid goal in the highest consuming county.
doi:10.1186/1472-6904-7-14
PMCID: PMC2234392  PMID: 18053228
2.  Antimalarial activity of the anticancer and proteasome inhibitor bortezomib and its analog ZL3B 
Background
The high rate of mortality due to malaria and the worldwide distribution of parasite resistance to the commonly used antimalarial drugs chloroquine and pyrimethamine emphasize the urgent need for the development of new antimalarial drugs. An alternative approach to the long and uncertain process of designing and developing new compounds is to identify among the armamentarium of drugs already approved for clinical treatment of various human diseases those that may have strong antimalarial activity.
Methods
Proteasome inhibitor bortezomib (Velcade™: [(1R)-3-methyl-1-[[(2S)-1-oxo-3-phenyl-2-[(pyrazinylcarbonyl) amino]propyl]amino]butyl] boronic acid), which has been approved for treatment of patients with multiple myeloma, and a second boronate analog Z-Leu-Leu-Leu-B(OH)2 (ZL3B), were tested against four different strains of P. falciparum (3D7, HB3, W2 and Dd2) that are either sensitive or have different levels of resistance to the antimalarial drugs pyrimethamine and chloroquine.
Results
Bortezomib and ZL3B are equally effective against drug-sensitive and -resistant parasites and block intraerythrocytic development prior to DNA synthesis, but have no effect on parasite egress or invasion.
Conclusion
The identification of bortezomib and its analog as potent antimalarial drugs will set the stage for the advancement of this class of compounds, either alone or in combination therapy, for treatment of malaria, and emphasize the need for large-scale screens to identify new antimalarials within the library of clinically approved compounds.
doi:10.1186/1472-6904-7-13
PMCID: PMC2213633  PMID: 17956613
3.  Influence of an e-mail with a drug information attachment on sales of prescribed drugs: a randomized controlled study 
Background
To provide doctors with producer-independent information to facilitate choice of treatment is an important task. The objective of the present study was to evaluate if an e-mail with a drug information attachment has effects on sales of prescribed drugs and if the design of the attachment is of importance.
Methods
The Swedish pharmaceutical benefit board found rizatriptan (Maxalt®) 10 mg to be the most cost-effective triptan. All 119 heads of primary care units in western Sweden were randomized to receive information concerning this conclusion via (i) e-mail with attachment I, (ii) e-mail with attachment II or (iii) no information (control). Attachment I was a short one (heading plus three lines text), whereas attachment II was a long one (heading plus one page text and one page with tables). The change in percentage rizatriptan of total triptans sold before and after the intervention (May – July 2004 and May – July 2005, respectively) was compared between the groups.
Results
Totally 48,229 (2004) and 50,674 (2005) defined daily doses of triptans were prescribed and sold during May – July in primary care units in the western part of Sweden. The absolute change in percentage rizatriptan was greater in the intervention groups compared with the control group 2 (25th – 75th percentile: -3 – 7) vs 0 (-7 - 5), P = 0.031). The absolute change in percentage rizatriptan did not differ between the two attachment groups (P = 0.93).
Conclusion
An e-mail with a drug information attachment may influence sales of prescribed drugs. No difference between different designs of the attachment could be detected.
doi:10.1186/1472-6904-7-12
PMCID: PMC2203966  PMID: 17942000
4.  Pharmacokinetics, safety and efficacy from randomized controlled trials of 1 and 2 mg nicotine bitartrate lozenges (Nicotinell®) 
Background
The use of nicotine replacement therapy (NRT) can almost double the chances of success for smokers to quit. Nevertheless, there is still a considerable number of cessation attempts that are made without any treatment. This novel oral formulation, (lozenge containing nicotine bitartrate dihydrate) has been developed to enlarge the offer for efficient smoking cessation drug therapies, assuming that increasing treatment options will bring more smokers to find the support they personally need to stop smoking.
Methods
Three pharmacokinetic (PK), one safety and two efficacy studies were carried out with Nicotinell lozenges. PK trials were: (1) a single-dose, three-way crossover study comparing 1 and 2 mg lozenges with 2 mg nicotine gum; (2) a multiple-dose, two-way crossover study comparing 1 mg lozenge with 2 mg gum; (3) a multiple-dose, three-way crossover study comparing 1 and 2 mg lozenges with 4 mg gum. Safety trial: (4) a single dose study to assess the safety of swallowing up to 12 lozenges containing 1 mg nicotine. Efficacy trials: two efficacy studies in (5) France and (6) the USA, including more than 900 smokers followed-up for up to one year, conducted with the 1 mg lozenge.
Results
The results of the individual PK trials showed that the 1 mg Nicotinell lozenge is bioequivalent to 2 mg polacrilex gum, as demonstrated by similar blood PK parameters (tmax, Cmax, AUC). The 2 mg lozenge was found to deliver quantities of nicotine that were intermediate between those delivered by 2 and 4 mg polacrilex gum.
The short-term efficacy of the 1 mg lozenge in comparison with placebo was also demonstrated with significantly more subjects continuously abstinent from smoking with active lozenges on week 6 in two different populations: moderate to heavy smokers (FTND between 4 and 7) OR = 1.72 [95% CI: 1.05–2.80]; heavy to very heavy smokers (FTND 6 and over) OR = 2.87 [95% CI: 1.18–6.97].
Nicotinell lozenges were found to be safe with mainly mild and reversible adverse events. The safety of the 1 mg lozenge formulation, even when misused was also demonstrated.
Conclusion
The data presented in this review demonstrate high nicotine bioavailability, excellent safety profile and proven short-term efficacy of Nicotinell lozenges. At nominal equivalent doses 1 and 2 mg Nicotinell lozenges were shown to deliver larger amounts of bioavailable nicotine compared to the nicotine polacrilex gum. According to the data developed here, the systemic exposure to nicotine could be ranked: 4 mg polacrilex gum > 2 mg Nicotinell lozenge > 1 mg Nicotinell lozenge = 2 mg polacrilex gum.
Adverse events observed during the clinical trials were mild or moderate in severity, transient and completely reversible. With respect to efficacy in smoking cessation, significantly higher continuous abstinence rates were achieved with lozenge compared to placebo. In conclusion, Nicotinell lozenges offer a valuable addition to the therapeutic armamentarium available for smoking cessation.
doi:10.1186/1472-6904-7-11
PMCID: PMC2194660  PMID: 17922899
5.  Pharmacokinetics of recombinant human growth hormone administered by cool.click™ 2, a new needle-free device, compared with subcutaneous administration using a conventional syringe and needle 
Background
Growth hormone (GH) is used to treat growth hormone deficiency (GHD, adult and paediatric), short bowel syndrome in patients on a specialized diet, HIV-associated wasting and, in children, growth failure due to a number of disorders including Turner's syndrome and chronic renal failure, and in children born small for gestational age. Different brands and generic forms of recombinant human growth hormone (r-hGH) are approved for varying indications in different countries. New ways of administering GH are required because the use of a needle and syringe or a device where a patient still has to insert the needle manually into the skin on a daily basis can lead to low adherence and sub-optimal treatment outcomes. The objective of this study was to assess the relative bioavailability of r-hGH (Saizen®, Merck Serono) administered by a new needle-free device, cool.click™ 2, and a standard needle and syringe.
Methods
The study was performed with 38 healthy volunteers who underwent pituitary somatotrope cell down-regulation using somatostatin, according to a randomized, two-period, two-sequence crossover design. Following subcutaneous administration of r-hGH using cool.click™ 2 or needle and syringe, pharmacokinetic parameters were analysed by non-compartmental methods. Bioequivalence was assessed based on log-transformed AUC and Cmax values.
Results
The 90% confidence intervals for test/reference mean ratio of the plasma pharmacokinetic variables Cmax and AUC0-inf were 103.7–118.3 and 97.1–110.0, respectively, which is within the accepted bioequivalence range of 80–125%. r-hGH administered by cool.click™ 2 is, therefore, bioequivalent to administration by needle and syringe with respect to the rate and extent of GH exposure. Treatment using cool.click™ 2 was found to be well tolerated. With cool.click™ 2 the tmax was less (3.0 hours) than for needle and syringe delivery (4.5 hours), p = 0.002 (Friedman test), although this is unlikely to have any clinical implications.
Conclusion
These results demonstrate that cool.click™ 2 delivers subcutaneous r-hGH exposure that is bioequivalent to the conventional mode of injection. The new device has the additional advantage of being needle-free, and should help to increase patient adherence and achieve good therapeutic outcomes from r-hGH treatment.
doi:10.1186/1472-6904-7-10
PMCID: PMC2093927  PMID: 17922895
6.  Trends in hospital admissions for adverse drug reactions in England: analysis of national hospital episode statistics 1998–2005 
Background
Adverse drug reactions (ADRs) are a frequent cause of mortality and morbidity to patients worldwide, with great associated costs to the healthcare providers including the NHS in England. We examined trends in hospital admissions associated with adverse drug reaction in English hospitals and the accuracy of national reporting.
Methods
Data from the Hospital Episode Statistics database (collected by the Department of Health) was obtained and analysed for all English hospital episodes (1998–2005) using ICD-10 codes with a primary (codes including the words ('drug-induced' or 'due to') or secondary diagnosis of ADR (Y40–59). More detailed analysis was performed for the year 2004–2005
Results
Between 1998 and 2005 there were 447 071 ADRs representing 0.50% of total hospital episodes and over this period the number of ADRs increased by 45%. All ADRs with an external code increased over this period. In 2005 the total number of episodes (all age groups) was 13,706,765 of which 76,692 (0.56%) were drug related. Systemic agents, which include anti-neoplastic drugs, were the most implicated class (15.7%), followed by analgesics (11.7%) and cardiovascular drugs (10.1%). There has been a 6 fold increase in nephropathy secondary to drugs and a 65% decline in drug induced extra-pyramidal side effects. 59% of cases involving adverse drug reactions involved patients above 60 years of age.
Conclusion
ADRs have major public health and economic implications. Our data suggest that national Hospital Episode Statistics in England have recognised limitations and that consequently, admissions associated with adverse drug reactions continue to be under-recorded. External causes of ADR have increased at a greater rate than the increase in total hospital admissions. Improved and more detailed reporting combined with educational interventions to improve the recording of ADRs are needed to accurately monitor the morbidity caused by ADRs and to meaningfully evaluate national initiatives to reduce adverse drug reactions.
doi:10.1186/1472-6904-7-9
PMCID: PMC2093926  PMID: 17894876
7.  Evaluation of the prevalence and economic burden of adverse drug reactions presenting to the medical emergency department of a tertiary referral centre: a prospective study 
Background
Adverse drug reactions (ADRs) are now recognized as an important cause of hospital admissions, with a proportion ranging from 0.9–7.9%. They also constitute a significant economic burden. We thus aimed at determining the prevalence and the economic burden of ADRs presenting to Medical Emergency Department (ED) of a tertiary referral center in India
Methods
A prospective, observational study of adult patients carried out over a 6 week period in 2005. The prevalence of ADRs, their economic burden from the hospital perspective, severity, and preventability were assessed using standard criteria.
Results
A total 6899 patients presented during the study period. Of these, 2046 were admitted for various reasons. A total of 265/6899 patients had ADRs (3.84 %). A total of 141/265 was admitted due to ADsR, and thus ADRs as a cause of admissions were 6.89% of total admissions. A majority (74.71%) were found to be of moderate severity. The most common ADRs were anti-tubercular drug induced hepatotoxicity, warfarin toxicity and chloroquine induced gastritis. The median duration of hospitalization was 5 days [95% CI 5.37, 7.11], and the average hospitalization cost incurred per patient was INR 6197/- (USD 150). Of total ADRs, 59.62% (158/265) were found to be either definitely or potentially avoidable.
Conclusion
The study shows that ADRs leading to hospitalization are frequent and constitute a significant economic burden. Training of patients and prescribers may lead to a reduction in hospitalization due to avoidable ADRs and thus lessen their economic burden.
doi:10.1186/1472-6904-7-8
PMCID: PMC1963321  PMID: 17662147
8.  Expression of thymidine phosphorylase in peripheral blood cells of breast cancer patients is not increased by paclitaxel 
Background
A synergistic cytotoxic effect has been hypothesized for taxanes and capecitabine, a prodrug of 5-fluorouracil. Based on preclinical studies, this synergism has been attributed to an up-regulation of the enzyme thymidine phosphorylase (TP). Beside tumour tissue, TP is highly expressed in white blood cells, possibly causing increased hematotoxicity, when taxanes are combined with capecitabine. So far, this hypothesis has not been investigated in humans.
Methods
A total of 128 consecutive blood samples were collected from eight patients with advanced breast cancer receiving paclitaxel weekly at a dose of 80 mg/m2. To assess the expression of TP in blood cells, samples were collected prior to first therapy, at the end of infusion, and up to 15 days thereafter. This procedure was repeated during the sixth application of paclitaxel. After isolation of the peripheral mononuclear blood cells, the expression of TP was assessed by ELISA. In parallel, paclitaxel level in plasma was evaluated at three selected time points as pharmacokinetic control parameter.
Results
Paclitaxel concentrations at the end of infusion did not change significantly from week 1 to week 6. The expression of TP in peripheral mononuclear blood cells decreased significantly after infusion below pretherapeutic values (p = 0.023; n = 8). After the nadir on day 3, the expression of TP increased moderately returning to baseline levels within one week. The overall picture in week 6 was similar to week 1. Using a trend analysis, neither a short-term nor a long-term induction of TP was observed.
Conclusion
TP in peripheral mononuclear blood cells was hardly regulated under therapy with paclitaxel. Therefore, no increased haematotoxicity due to TP upregulation is expected from the combination of taxanes and capecitabine.
doi:10.1186/1472-6904-7-7
PMCID: PMC1939983  PMID: 17640356
9.  Phenotype-genotype analysis of CYP2C19 in Colombian mestizo individuals 
Background
Omeprazole is metabolized by the hepatic cytochrome P450 (CYP) 2C19 enzyme to 5-hydroxyomeprazole. CYP2C19 exhibits genetic polymorphisms responsible for the presence of poor metabolizers (PMs), intermediate metabolizers (IMs) and extensive metabolizers (EMs). The defective mutations of the enzyme and their frequencies change between different ethnic groups; however, the polymorphism of the CYP2C19 gene has not been studied in Colombian mestizos. The aim of this study was to evaluate the genotype and phenotype status of CYP2C19 in Colombian mestizos, in order to contribute to the use of appropriate strategies of drug therapy for this population.
Methods
189 subjects were genotyped using the multiplex SNaPshot technique and a subgroup of 44 individuals received 20 mg of omeprazole followed by blood collection at 3 hours to determine the omeprazole hydroxylation index by HPLC.
Results
83.6%, 15.3% and 1.1% of the subjects were genotyped as EMs, IMs and PMs, respectively. The frequencies of the CYP2C29*1 and CYP2C19*2 alleles were 91.3% and 8.7% respectively whereas the *3, *4, *5, *6 and *8 alleles were not found. No discrepancies were found between the genotype and phenotype of CYP2C19.
Conclusion
The frequency of poor metabolizers (1.1%) in the Colombian mestizos included in this study is similar to that in Bolivian mestizos (1%) but lower than in Mexican-Americans (3.2%), West Mexicans (6%), Caucasians (5%) and African Americans (5.4%). The results of this study will be useful for drug dosage recommendations in Colombian mestizos.
doi:10.1186/1472-6904-7-6
PMCID: PMC1950696  PMID: 17623107
10.  Methadone vs. buprenorphine/naloxone during early opioid substitution treatment: a naturalistic comparison of cognitive performance relative to healthy controls 
Background
Both methadone- and buprenorphine-treated opioid-dependent patients frequently show cognitive deficits in attention, working memory, and verbal memory. However, no study has compared these patient groups with each other during early opioid substitution treatment (OST). Therefore, we investigated attention, working memory, and verbal memory of opioid-dependent patients within six weeks after the introduction of OST in a naturalistic setting and compared to those of healthy controls.
Methods
The sample included 16 methadone-, 17 buprenorphine/naloxone-treated patients, and 17 healthy controls matched for sex and age. In both groups buprenorphine was the main opioid of abuse during the recent month. Benzodiazepine codependence, recent use, and comedication were also common in both patient groups. Analysis of variance was used to study the overall group effect in each cognitive test. Pair-wise group comparisons were made, when appropriate
Results
Methadone-treated patients, as a group, had significantly slower simple reaction time (RT) compared to buprenorphine/naloxone-treated patients. In Go/NoGo RT methadone patients were significantly slower than controls. Both patient groups were significantly debilitated compared to controls in working memory and verbal list learning. Only methadone patients were inferior to controls in story recall. In simple RT and delayed story recall buprenorphine/naloxone patients with current benzodiazepine medication (n = 13) were superior to methadone patients with current benzodiazepine medication (n = 13). When methadone patients were divided into two groups according to their mean dose, the patient group with a low dose (mean 40 mg, n = 8) showed significantly faster simple RT than the high dose group (mean 67 mg, n = 8).
Conclusion
Deficits in attention may only be present in methadone-treated early phase OST patients and may be dose-dependent. Working memory deficit is common in both patient groups. Verbal memory deficit may be more pronounced in methadone-treated patients than in buprenorphine/naloxone-treated patients. In sum, to preserve cognitive function in early OST, the use of buprenorphine/naloxone may be more preferable to methadone use of, at least if buprenorphine has been recently abused and when benzodiazepine comedication is used. Longitudinal studies are needed to investigate if the better performance of buprenorphine/naloxone-treated patients is a relatively permanent effect or reflects "only" transient opioid switching effect.
doi:10.1186/1472-6904-7-5
PMCID: PMC1914339  PMID: 17565668
11.  Does atenolol differ from other β-adrenergic blockers? 
Background
A recent meta-analysis of drug effects in patients with hypertension claims that all β-adrenergic blockers are equally effective but less so than other antihypertensive drugs. Published comparisons of the β-adrenergic blocker atenolol and non-atenolol β-adrenergic blockers indicate different effects on death rates, arrhythmias, peripheral vascular resistance and prognosis post myocardial infarction, all in disfavour of atenolol. In keeping with these findings, the data presented in the meta-analysis indicate that atenolol is less effective than the non-atenolol β-adrenergic blockers both when compared with placebo and with other antihypertensive drugs. These findings were not, however, statistically significant.
Methods
We performed an additional analysis with a Bayesian statistical method in order to make further use of the published data.
Results
Our calculations on the clinical data in the meta-analysis showed 13% lower risk (risk ratio 0.87) of myocardial infarction among hypertensive patients taking non-atenolol β-adrenergic blockers than among hypertensive patients taking atenolol. The 90 % credibility interval ranged from 0.75 to 0.99, thereby indicating statistical significance. The probability of at least 10% lower risk (risk ratio ≤ 0.90), which could be considered to be of clinical interest, was 0.69.
Conclusion
Taken together with the other observations of differences in effects, we conclude that the claim that all β-adrenergic blockers are inferior drugs for hypertensive patients should be rejected. Atenolol is not representative of the β-adrenergic blocker class of drugs as a whole and is thus not a suitable drug for comparisons with other antihypertensive drugs in terms of effect. The non-atenolol β-adrenergic blockers should thus continue to be fundamental in antihypertensive drug treatments.
doi:10.1186/1472-6904-7-4
PMCID: PMC1876203  PMID: 17488499
12.  Pharmacokinetic profile of a 24-hour controlled-release OROS® formulation of hydromorphone in the presence and absence of food 
Background
The objective of this study was to compare the pharmacokinetic profile of a novel, once-daily, controlled-release formulation of hydromorphone (OROS® hydromorphone) under fasting conditions with that immediately after a high-fat breakfast in healthy volunteers. The effect of the opioid antagonist naltrexone on fasting hydromorphone pharmacokinetics also was evaluated.
Methods
In an open-label, three-way, crossover study, 30 healthy volunteers were randomized to receive a single dose of 16 mg OROS® hydromorphone under fasting conditions, 16 mg OROS® hydromorphone under fed conditions, or 16 mg OROS® hydromorphone under fasting conditions with a naltrexone 50-mg block. Plasma samples taken pre-dose and at regular intervals up to 48 hours post-dose were assayed for hydromorphone concentrations. Analysis of variance was performed on log-transformed data; for mean ratios of 0.8 to 1.2 (20%), differences were considered minimal. Bioequivalence was reached if 90% confidence intervals (CI) of treatment mean ratios were between 80% and 125%.
Results
The mean geometric ratios of the fed and fasting treatment groups for maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC0-t; AUC0-∞) were within 20%. Confidence intervals were within 80% to 125% for AUC0-t and AUC0-∞ but were slightly higher for Cmax (105.9% and 133.3%, respectively). With naltrexone block, the hydromorphone Cmax increased by 39% and the terminal half-life decreased by 4.5 hours. There was no significant change in Tmax, AUC0-t or AUC0-∞.
Conclusion
Standard bioavailability measures show minimal effect of food on the bioavailability of hydromorphone from OROS® hydromorphone. Naltrexone co-administration results in a slight increase in the rate of absorption but not the extent of absorption.
Trial Registration
Clinical Trials.gov NCT00399295
doi:10.1186/1472-6904-7-2
PMCID: PMC1810515  PMID: 17270055
13.  Pharmacokinetic investigation of dose proportionality with a 24-hour controlled-release formulation of hydromorphone 
Background
The purpose of this study was investigate the dose proportionality of a novel, once-daily, controlled-release formulation of hydromorphone that utilizes the OROS® Push-Pull™ osmotic pump technology.
Methods
In an open-label, four-way, crossover study, 32 healthy volunteers were randomized to receive a single dose of OROS® hydromorphone 8, 16, 32, and 64 mg, with a 7-day washout period between treatments. Opioid antagonism was provided by three or four doses of naltrexone 50 mg, given at 12-hour intervals pre- and post-OROS® hydromorphone dosing. Plasma samples for pharmacokinetic analysis were collected pre-dose and at regular intervals up to 48 hours post-dose (72 hours for the 64-mg dose), and were assayed for hydromorphone concentration to determine peak plasma concentration (Cmax), time at which peak plasma concentration was observed (Tmax), terminal half-life (t1/2), and area under the concentration-time curve for zero to time t (AUC0-t) and zero to infinity (AUC0–∞). An analysis of variance (ANOVA) model on untransformed and dose-normalized data for AUC0-t, AUC0–∞, and Cmax was used to establish dose linearity and proportionality.
Results
The study was completed by 31 of 32 subjects. Median Tmax (12.0–16.0 hours) and mean t1/2 (10.6–11.0 hours) were found to be independent of dose. Regression analyses of Cmax, AUC0–48, and AUC0–∞ by dose indicated that the relationship was linear (slope, P ≤ 0.05) and that the intercept did not differ significantly from zero (P > 0.05). Similar analyses with dose-normalized parameters also indicated that the slope did not differ significantly from zero (P > 0.05).
Conclusion
The pharmacokinetics of OROS® hydromorphone are linear and dose proportional for the 8, 16, 32, and 64 mg doses.
Trial Registration
Clinical Trials.gov NCT00398957
doi:10.1186/1472-6904-7-3
PMCID: PMC1808051  PMID: 17270058
14.  Heterogeneity of human adipose blood flow 
Background
The long time pharmacokinetics of highly lipid soluble compounds is dominated by blood-adipose tissue exchange and depends on the magnitude and heterogeneity of adipose blood flow. Because the adipose tissue is an infinite sink at short times (hours), the kinetics must be followed for days in order to determine if the adipose perfusion is heterogeneous. The purpose of this paper is to quantitate human adipose blood flow heterogeneity and determine its importance for human pharmacokinetics.
Methods
The heterogeneity was determined using a physiologically based pharmacokinetic model (PBPK) to describe the 6 day volatile anesthetic data previously published by Yasuda et. al. The analysis uses the freely available software PKQuest and incorporates perfusion-ventilation mismatch and time dependent parameters that varied from the anesthetized to the ambulatory period. This heterogeneous adipose perfusion PBPK model was then tested by applying it to the previously published cannabidiol data of Ohlsson et. al. and the cannabinol data of Johansson et. al.
Results
The volatile anesthetic kinetics at early times have only a weak dependence on adipose blood flow while at long times the pharmacokinetics are dominated by the adipose flow and are independent of muscle blood flow. At least 2 adipose compartments with different perfusion rates (0.074 and 0.014 l/kg/min) were needed to describe the anesthetic data. This heterogeneous adipose PBPK model also provided a good fit to the cannabinol data.
Conclusion
Human adipose blood flow is markedly heterogeneous, varying by at least 5 fold. This heterogeneity significantly influences the long time pharmacokinetics of the volatile anesthetics and tetrahydrocannabinol. In contrast, using this same PBPK model it can be shown that the long time pharmacokinetics of the persistent lipophilic compounds (dioxins, PCBs) do not depend on adipose blood flow. The ability of the same PBPK model to describe both the anesthetic and cannabinol kinetics provides direct qualitative evidence that their kinetics are flow limited and that there is no significant adipose tissue diffusion limitation.
doi:10.1186/1472-6904-7-1
PMCID: PMC1797001  PMID: 17239252

Results 1-14 (14)