Effect of obesity on the pharmacokinetics of drugs in humans

A Phase 1 Randomized, Placebo-Controlled Study Assessing the Pharmacokinetics, Safety, and Tolerability of Retosiban in Healthy, Nonpregnant Japanese Subjects

This study characterized the pharmacokinetics, safety, and tolerability of retosiban in healthy, nonpregnant Japanese women prior to the enrollment of Japanese women in preterm labor in phase 3 trials. This study had 2 cohorts. Cohort 1 was a double-blind, sponsor-open, randomized study in Japanese women. Cohort 2 was an open-label study in white women to compare the pharmacokinetics with those of Japanese women. Retosiban was administered as a 6 mg/h infusion for 24 hours, followed by a 12 mg/h infusion over the next 24 hours; each infusion was preceded by a 6 mg loading dose administered over 5 minutes. Plasma concentrations of retosiban and its major metabolite, GSK2847065, were determined with an informal comparison of pharmacokinetics between Japanese and white women. There was minimal difference in exposure to retosiban or GSK2847065 between Japanese and white women (ratio of 1.03 in retosiban AUC and C_max ). The 2 doses of retosiban were well tolerated across both populations, and no ethnic difference was observed in the safety profile. Given the results of this study and the known safety profile and dosing flexibility in the phase 3 trials, ethnic-specific dose adjustment of retosiban is not considered necessary for the Japanese and general Asian population.

Changes in drug transport and metabolism and their clinical implications in non-alcoholic fatty liver disease

INTRODUCTION

The incidence of non-alcoholic fatty liver disease (NAFLD) is rising, especially in Western countries. Drug treatment in patients with NAFLD is common since it is linked to other conditions like diabetes, obesity, and cardiovascular disease. Consequently, changes in drug metabolism may have serious clinical implications. Areas covered: A literature search for studies in animal models or patients with obesity, fatty liver, non-alcoholic steatohepatitis (NASH) or NASH cirrhosis published before November 2016 was performed. After discussing epidemiology and animal models for NAFLD, we summarized both basic as well as clinical studies investigating changes in drug transport and metabolism in NAFLD. Important drug groups were assessed separately with emphasis on clinical implications for drug treatment in patients with NAFLD. Expert opinion: Given the frequency of NAFLD even today, a high degree of drug treatment in NAFLD patients appears safe and well-tolerated despite considerable changes in hepatic uptake, distribution, metabolism and transport of drugs in these patients. NASH causes changes in biliary excretion, systemic concentrations, and renal handling of drugs leading to alterations in drug efficacy or toxicity under specific circumstances. Future clinical drug studies should focus on this special patient population in order to avoid serious adverse events in NAFLD patients.

Association between CACNA1C gene polymorphisms and ritodrine-induced adverse events in preterm labor patients

PURPOSE

As a tocolytic agent, ritodrine has been used in European and Asian countries but has lost popularity due to safety concerns. This study aimed to investigate the relationship between adverse drug events caused by ritodrine and the CACNA1C polymorphisms in preterm labor patients.

METHODS

Data were collected from medical records including maternal age, gestational age, body mass index, dilation score, effacement score, modified Bishop score, maximum infusion rate, and adverse drug events. Five single-nucleotide polymorphisms of the CACNA1C gene (rs10774053, rs215994, rs215976, rs2239128, and rs2041135) were analyzed.

RESULTS

One hundred eighty-six patients were included, 33 of whom had adverse drug events. A allele carriers of rs10774053 showed about 0.293-fold lower adverse drug events than GG genotype carriers (p = 0.012, absolute risk reduction = 16.5%) after adjusting for other confounding variables; the number needed to genotype for preventing one patient with GG genotype from suffering higher incidence of adverse drug events was calculated to be 14.6. Increase in maximum infusion rate of 1 mL/h was associated with a 1.03-fold (95% CI 1.01~1.06, p = 0.005) increased risk of adverse drug events. None of the patients with a CC genotype of rs215994 had adverse drug events, whereas 22.1% of the T allele carriers had adverse drug events.

CONCLUSION

This study showed that CACNA1C gene polymorphisms could alter the probability of adverse drug event risk when ritodrine is used in preterm labor.

Review of current evidence available for guiding optimal Enoxaparin prophylactic dosing strategies in obese patients-Actual Weight-based vs Fixed

BACKGROUND

The current debate over the optimal Enoxaparin prophylactic dosing strategies in obese patients centre around whether it should be based on the actual weight of the patient (i.e. weight-based), or at an artificially fixed amount, as it is the case in Australia (40mg daily). The vast majority of the evidence available today is laboratory-based, measuring serum Antifactor-X_a activities as a marker for physiological response.

AIM

The aim of the parent study is to compare the clinical outcomes for obese patients who received fixed doses of enoxaparin compared to those who received weight-based doses within the licensed dosage recommendations. This review was conducted to examine whether a gap in knowledge exists in relation to dosing obese patients with enoxaparin as VTE prophylaxis after hospital admission to aid in development of the parent study concept.

METHOD

Databases such as Medline, EBSCOhost, ProQuest were interrogated using combinations of words such as "enoxaparin", AND "dosing strategy", AND "obese/obesity" AND "prophylaxis". Only eleven out of 14 primary studies which were considered to be sufficiently similar in methodology and anticipated outcomes were reviewed and analysed.

RESULTS

Pooled data from the eleven studies suggested that weight-based or higher-than-fixed dosing had a 36.2% higher success rate than fixed dosing, and was more likely to achieve the desired serum Anti-X_a activity levels (52.2% and 16% respectively). The rate of failure to achieve this is significantly lower in the weight-based groups (13.3%) than in fixed-dose groups (18.5%). These eleven studies reviewed included 601 patients in total.

CONCLUSION

There is insufficient evidence to support or negate the current enoxaparin health outcomes in obese and very obese patients due to the lack of post-discharge follow-up from hospitals. Further research is required to compare long-term outcomes after fixed and weight-based dosing of enoxaparin. The optimal dose of enoxaparin per kilogram of body weight for prophylaxis remains to be determined.

A Review of the Field on Children's Exposure to Environmental Contaminants: A Risk Assessment Approach

Background: Children must be recognized as a sensitive population based on having biological systems and organs in various stages of development. The processes of absorption, distribution, metabolism and elimination of environmental contaminants within a child's body are considered less advanced than those of adults, making them more susceptible to disease outcomes following even small doses. Children's unique activities of crawling and practicing increased hand-to-mouth ingestion also make them vulnerable to greater exposures by certain contaminants within specific environments. Approach: There is a need to review the field of children's environmental exposures in order to understand trends and identify gaps in research, which may lead to better protection of this vulnerable and sensitive population. Therefore, explored here are previously published contemporary works in the broad area of children's environmental exposures and potential impact on health from around the world. A discussion of children's exposure to environmental contaminants is best organized under the last four steps of a risk assessment approach: hazard identification, dose-response assessment, exposure assessment (including children's activity patterns) and risk characterization. We first consider the many exposure hazards that exist in the indoor and outdoor environments, and emerging contaminants of concern that may help guide the risk assessment process in identifying focus areas for children. A section on special diseases of concern is also included. Conclusions: The field of children's exposures to environmental contaminants is broad. Although there are some well-studied areas offering much insight into children exposures, research is still needed to further our understanding of exposures to newer compounds, growing disease trends and the role of gene-environment interactions that modify adverse health outcomes. It is clear that behaviors of adults and children play a role in reducing or increasing a child's exposure, where strategies to better communicate and implement risk modifying behaviors are needed, and can be more effective than implementing   changes in the physical environment.

Pediatric Obesity: Pharmacokinetic Alterations and Effects on Antimicrobial Dosing

Limited data exist for appropriate drug dosing in obese children. This comprehensive review summarizes pharmacokinetic (PK) alterations that occur with age and obesity, and these effects on antimicrobial dosing. A thorough comparison of different measures of body weight and specific antimicrobial agents including cefazolin, cefepime, ceftazidime, daptomycin, doripenem, gentamicin, linezolid, meropenem, piperacillin-tazobactam, tobramycin, vancomycin, and voriconazole is presented. PubMed (1966-July 2015) and Cochrane Library searches were performed using these key terms: children, pharmacokinetic, obesity, overweight, body mass index, ideal body weight, lean body weight, body composition, and specific antimicrobial drugs. PK studies in obese children and, if necessary, data from adult studies were summarized. Knowledge of PK alterations stemming from physiologic changes that occur with age from the neonate to adolescent, as well as those that result from increased body fat, become an essential first step toward optimizing drug dosing in obese children. Excessive amounts of adipose tissue contribute significantly to body size, total body water content, and organ size and function that may modify drug distribution and clearance. PK studies that evaluated antimicrobial dosing primarily used total (or actual) body weight (TBW) for loading doses and TBW or adjusted body weight for maintenance doses, depending on the drugs' properties and dosing units. PK studies in obese children are imperative to elucidate drug distribution, clearance, and, consequently, the dose required for effective therapy in these children. Future studies should evaluate the effects of both age and obesity on drug dosing because the incidence of obesity is increasing in pediatric patients.

Impact of Norepinephrine Weight-Based Dosing Compared With Non-Weight-Based Dosing in Achieving Time to Goal Mean Arterial Pressure in Obese Patients With Septic Shock

Obesity presents a growing challenge in critically ill patients because of variable medication pharmacokinetics and pharmacodynamics. Vasopressors used in the treatment of septic shock, including norepinephrine, are dosed using weight-based (WB) or non-weight-based (NWB) strategies. Retrospective research has evaluated the effect of total body weight and body mass index on vasopressor requirements, consequently finding that obese patients require less total vasopressor per kilogram to obtain clinical end points such as mean arterial pressure. Although this effect is not completely understood, this may suggest that a NWB dosing strategy is preferred over a WB strategy in obese patients to minimize potential for error.

The Influence Of Obesity On Results Of AT (Doxorubicin Plus Docetaxel) Neoadjuvant Chemotherapy In Locally Advanced Breast Cancer Patients

The achieve pathologic complete response is proven to be the most important parameter of prognosis. Thereports evaluating the impact of obesity on the obtained pathologic response to chemotherapy are unequal. The aim of the study was to evaluate in locally advanced breast cancer patients, treated with AT(doxorubicin plus docetaxel) neoadjuvant chemotherapy: 1. The relationship of obesity with obtaining pathological response. 2. The relationship of obesity and free of disease recurrence survival (DFS) and overall survival (OS) associated with the tumour.

MATERIAL AND METHODS

A retrospective study was carried out in a group of 105 patients with locally advanced breast cancer, treated with AT neoadjuvant chemotherapy and then treated with radical surgery. Two variants of pathological response have been adopted: a pCR (T0N0) and pCR1 (TisN0, TxN1, T1N0, T1N1, T0N1). The relationship of obesity with pathological response and survival was investigated.

RESULTS

In univariate analysis the pCR1 was obtained with its arising from the borderline of statistical significance with lower incidence of obesity. In pCR1 multivariate analysis, negative pCR1 relationship with obesity was on the borderline of the statistical significance. The multivariate analysis showed a significant negative association OS with obesity (p=0.047) and positive with the occurrence of menopause (p = 0.029).

CONCLUSIONS

In patients with locally advanced breast cancer treated with AT neoadjuvant chemotherapy. 1. Obesity seems to be an independent and unfavourable predictor of the lack of obtaining pCR1 pathological response 2. In the multivariate analysis, the obesity was a significant independent factor related to shorter OS.

A review of the fixed dose use of new oral anticoagulants in obese patients: Is it really enough?

Obesity is a significant cause of morbidity and mortality, and it is becoming increasingly prevalent worldwide. Altered pharmacodynamics and pharmacokinetics of drugs in obese patients require dose adjustment according to body weight. New oral anticoagulants (NOACs), which are more frequently used for anticoagulation, are recommended to be used at a fixed dose based on data derived from phase 2 and 3 studies. However, the representation of obese patients [>100 kg or a body mass index (BMI) of >30 kg/m²] in subgroups with a small sample size and reports of various emboli cases under drug treatment have raised suspicions about the adequacy of fixed dose use. To address this issue, we analyzed several patients with a body weight of >100 kg or BMI of >30 kg/m² participating in NOAC studies and evaluated whether these numbers were sufficient to enable an accurate recommendation of fixed dose use in obese patients.

Body mass index and response to abatacept in rheumatoid arthritis

BACKGROUND

Previous studies suggested that obesity could negatively affect the response to antitumour necrosis factor-α (TNFα) agents in rheumatoid arthritis (RA). However, data are lacking on whether obesity affects the response to abatacept (ABA). We aimed to determine whether body mass index (BMI) affects the response to ABA in RA.

MATERIALS AND METHODS

In this multicenter retrospective study, we included RA patients who received ABA. BMI was calculated at the initiation of treatment. After 6 months of treatment, change from baseline in DAS28, pain on a visual analog scale, erythrocyte sedimentation rate and C-reactive protein level, tender and swollen joint count were analysed. The primary endpoint was decrease in DAS28 ≥ 1·2. Secondary outcomes were good response and remission by EULAR criteria.

RESULTS

At baseline, among 141 RA patients included, the median [interquartile range] BMI was 26·0 [22·9-30·8] kg/m². The number of patients with normal weight, overweight and obesity was 64 (45·4%), 38 (27%) and 39 (27·6%), respectively. Baseline characteristics did not differ among the three BMI subgroups. Univariate analysis revealed no difference in BMI between responders and nonresponders: DAS28 decrease ≥ 1·2 (25·0 [23·4-31·3] vs. 26·3 [22·9-30·2], P = 0·95), EULAR good response (26·4 [23·5-30·9] vs. 26·0 [22·9-30·6], P = 0·96) and remission (26·7 [21·7-30·3] vs. 26·0 [23·0-30·1], P = 0·83).

CONCLUSION

In our real-life study, BMI did not affect the response to ABA in RA. If confirmed, these results suggest that obesity is not a limitation of ABA use in RA.

Low-Dose Urinary Human Chorionic Gonadotropin Is Effective for Oocyte Maturation in In Vitro Fertilization/ Intracytoplasmic Sperm Injection Cycles Independent of Body Mass Index

BACKGROUND

Currently, there is no agreement on the optimal urinary derived human chorionic gonadotropin (u-hCG) dose requirement for initiating final oocyte maturation prior to oocyte collection in in vitro fertilization (IVF), but doses that range from 2500- 15000 IU have been used. We intended to determine whether low dose u-hCG was effective for oocyte maturation in IVF/intracytoplasmic sperm injection (ICSI) cycles independent of body mass index (BMI).

MATERIALS AND METHODS

We retrospectively evaluated a cohort of 295 women who underwent their first IVF/ICSI cycles between January 2003 and December 2010 at the Division of Reproductive Endocrinology and Infertility, Wayne State University, Detroit, MI, USA. Treatment cycles were divided into 3 groups based on BMI (kg/ m²): <25 (n=136), 25- <30 (n=84), and ≥30 (n=75) women. Patients received 5000, 10000 or 15000 IU u-hCG for final maturation prior to oocyte collection. The primary outcome was clinical pregnancy rates (CPRs) and secondary outcome was live birth rates (LBRs).

RESULTS

Only maternal age negatively impacted (P<0.001) CPR [odds ratio (OR=0.85, confidence interval (CI: 0.79-0.91)] and LBR (OR=0.84, CI: 0.78-0.90).

CONCLUSION

Administration of lower dose u-hCG was effective for oocyte maturation in IVF and did not affect the CPRs and LBRs irrespective of BMI. Women's BMI need not be taken into consideration in choosing the appropriate dose of u-hCG for final oocyte maturation prior to oocyte collection in IVF. Only maternal age at the time of IVF negatively influenced CPRs and LBRs in this study.

IV fosphenytoin in obese patients: Dosing strategies, safety, and efficacy

Background

Previous studies evaluated the disposition of IV phenytoin loading doses and found that obese patients had increased drug distribution into excess body weight, larger volumes of distribution, and longer half-lives when compared to their nonobese counterparts. We assess the safety and efficacy of fosphenytoin loading doses in patients with different body mass indices (BMIs).

Methods

A retrospective chart review was conducted in 410 patients who received fosphenytoin. Patients were divided into 2 groups: BMI <30 (nonobese) and BMI ≥30 (obese). Patient demographics, fosphenytoin dose administered in mg/kg body weight, renal and liver function tests, fosphenytoin drug levels, and pre- and post-fosphenytoin administration vital signs were collected to assess for adverse events. Necessity of additional antiepileptic loading doses was used as a surrogate for clinical efficacy.

Results

The median dose of fosphenytoin administered was 19 mg/kg (interquartile range 15-20). The most frequently encountered adverse event was hypotension, which occurred in 39% of the cohort. Using a Bonferroni adjustment for multiple comparisons, there were no differences in adverse events between the 2 groups. The need for additional antiepileptic loading doses was not different between the 2 groups (p = 0.07).

Conclusions

The incidence of adverse events and the need for repeat loading antiepileptic medications was similar between the 2 groups. From our findings, the patients in our study did not receive empiric loading dose adjustments and the current method of loading fosphenytoin achieves similar outcomes, regardless of the patient's BMI.

A high-fat high-energy diet influences hepatic CYP3A expression and activity in low-birth-weight developing female rats

BACKGROUND

The objective of this study was to investigate the effects of a high-fat, high-energy (HFHE) diet on the hepatic expression of CYP3A in low-birthweight developing female rats.

METHODS

Pregnant rats were divided into nourished and undernourished groups. The offspring of the nourished rats were defined as the normal-birth-weight (NBW) group, and those of undernourished rats were defined as the low-birth-weight (LBW) group. According to their birth weights and diets, the rats were subdivided into the following four groups: NBW-normal diet (NN) group; NBW-HFHE (NH) group; LBW-normal diet (LN) group; and LBW-HFHE (LH) group. Liver samples were isolated on days 3, 7, 14, 21, 28, 56 and 84 after birth.

RESULTS

The CYP3A1 mRNA levels in the LH group on days 3, 56 and 84 were significantly higher than those of the NN group (P<0.05). CYP3A1 expression was significantly higher in the LH group than that in the NH group on days 21, 28 and 84 (P<0.05). CYP3A1 mRNA expression was higher in the LH group than that in the LN group on days 3 and 21 (P<0.05). No zonal CYP3A1 expression pattern was observed in the LH developmental group. The LH group had significantly higher mean activity than the LN group on days 7, 14, 28 and 56.

CONCLUSION

Our results indicated that an HFHE diet can result in alterations of CYP3A expression in a developmental LBW rat model.

Body mass index (BMI) but not body weight is associated with changes in the metabolism of risperidone; A pharmacokinetics-based hypothesis

OBJECTIVE

We sought to unravel the influence of body weight and body mass index (BMI), both consistently reported as pharmacokinetic relevant parameters, on metabolism of risperidone in a naturalistic sample.

METHODS

Conducting non parametrical tests we sought for correlations between plasma concentrations of RIS, 9-OH-RIS and AM and body weight and BMI in patients out of a therapeutic drug monitoring (TDM) database. Further, we stratified patients to three groups based upon BMI values and compared drug concentrations between groups.

RESULTS

Although body weight failed to correlate with pharmacokinetic parameters, BMI was positively correlated with plasma concentrations of the active metabolite (9-OH-RIS) (r_s=0.121, p=0.002) and active moiety (sum of RIS+9-OH-RIS) (r_s=0.128, p=0.001) as well as dose adjusted plasma concentrations of the active moiety (r_s=0.08, p=0.04). The comparison of pharmacokinetic parameters between different BMI groups yielded lower plasma concentrations of 9-OH-RIS in patients with low BMI (<20kg/m²) and higher plasma concentrations of the active moiety in obese patients (BMI ≥30kg/m²) when compared with the control group (30>BMI≥20kg/m²). By comparing low vs. high BMI patients, the latter group showed higher 9-OH-RIS plasma concentrations.

CONCLUSIONS AND LIMITATIONS

Considerable alterations in metabolism of risperidone were detected when comparing obese and cachectic patients with the control group in alignment with the positive correlation between BMI values and plasma concentrations of the active metabolite and active moiety as well as dose adjusted plasma concentrations of the active moiety. We suggest changes in CYP2D6 or CYP3A4 activity or differences in P-glycoprotein function in obese patients with greater BMI as a plausible mechanism underlying these alterations.

Population Pharmacokinetics and Pharmacodynamics of Meropenem in Nonobese, Obese, and Morbidly Obese Patients

The study objective was to evaluate meropenem population pharmacokinetics and pharmacodynamics in nonobese, obese, and morbidly obese patients. Forty adult patients-11 nonobese (body mass index [BMI] < 30 kg/m² ), 9 obese (30 kg/m² ≤ BMI < 40 kg/m² ), and 20 morbidly obese (BMI ≥ 40 kg/m² )-received meropenem 500 mg every 6 hours (q6h), q8h, or q12h or 1 g q6h or q8h, infused over 0.5 hour. Population pharmacokinetic modeling was performed using NONMEM, and 5000-patient Monte-Carlo simulations were performed to calculate probability of target attainment (PTA) for 5 dosing regimens, infused over 0.5 and 3 hours, using fT>MIC of 40%, 54%, and 100% of the dosing interval. A 2-compartment linear-elimination model best described the serum concentration-time data, and creatinine clearance was significantly associated with systemic clearance. Pharmacokinetic parameters were not significantly different among patient groups. In patients with creatinine clearances ≥50 mL/min, all simulated dosing regimens achieved >90% PTA at 40% fT>MIC in all patient groups at MICs ≤2 mg/L. Only 500 mg q8h, infused over 0.5 hour, did not achieve >90% PTA at 54% fT>MIC in nonobese and morbidly obese patients. At 100% fT>MIC, 1 g q6h and 2 g q8h, infused over 3 hours, reliably achieved >90% PTA in all patient groups. Meropenem pharmacokinetics are comparable among nonobese, obese, and morbidly obese patients. Standard dosing regimens provide adequate pharmacodynamic exposures for susceptible pathogens at 40% and 54% fT>MIC, but prolonged infusions of larger doses are needed for adequate exposures at 100% fT>MIC. Dosage adjustments based solely on body weight are unnecessary.

Pharmacokinetic and Pharmacodynamic Principles of Anti-infective Dosing

PURPOSE

An understanding of the pharmacokinetic (PK) and pharmacodynamic (PD) principles that determine response to antimicrobial therapy can provide the clinician with better-informed dosing regimens. Factors influential on antibiotic disposition and clinical outcome are presented, with a focus on the primary site of infection. Techniques to better understand antibiotic PK and optimize PD are acknowledged.

METHODS

PubMed (inception-April 2016) was reviewed for relevant publications assessing antimicrobial exposures within different anatomic locations and clinical outcomes for various infection sites.

FINDINGS

A limited literature base indicates variable penetration of antibiotics to different target sites of infection, with drug solubility and extent of protein binding providing significant PK influences in addition to the major clearing pathway of the agent. PD indices derived from in vitro studies and animal models determine the optimal magnitude and frequency of dosing regimens for patients. PK/PD modeling and simulation has been shown an efficient means of assessing these PD endpoints against a variety of PK determinants, clarifying the unique effects of infection site and patient characteristics to inform the adequacy of a given antibiotic regimen.

IMPLICATIONS

Appreciation of the PK properties of an antibiotic and its PD measure of efficacy can maximize the utility of these life-saving drugs. Unfortunately, clinical data remain limited for a number of infection site-antibiotic exposure relationships. Modeling and simulation can bridge preclinical and patient data for the prescription of optimal antibiotic dosing regimens, consistent with the tenets of personalized medicine.

Biochemical characterization of a factor X activator protein purified from Walterinnesia aegyptia venom

Factor X of blood coagulation cascade can be activated by both intrinsic and extrinsic activating complex, trypsin and some kind of snake venom. A factor X activator protein is reported in Elapidae snake venom. The aim of this study was to evaluate biochemical properties of factor X activator protein because of its prospective application in biochemical research and therapeutics. Crude venom was fractionated on a HPLC system Gold 126/1667 using a combination of Protein PAK 125 and Protein PAK 60 Columns. Molecular weight was determined using SDS-PAGE. Walterinnesia aegyptia venom was fractionated into several protein peaks, but procoagulant and factor X activation activity coexisted into peak no.6. It appeared as single band on native PAGE and molecular weight was 60,000 ± 3. Purified up to 37-fold over crude venom. It shortened recalcification time, effect was dose-dependent and strictly Ca(2++)-dependent. Factor X activator seems to be able to activate factor X specifically because it showed no activation activity on human prothrombin, plasminogen, or protein C. It did not hydrolyze factor Xa substrate S-2222, thrombin substrate S-2238, plasmin substrate S-2251 or S-2302 and kalikrein substrate S-2266. It did not hydrolyze synthetic ester benzoyl arginine ethyl ester. Procoagulant activity was completely inhibited by irreversible serine protease inhibitors phenylmethylsulphonyl fluoride and N-p-tosylphenylalanine chloromethyl ketone. This study illustrates that factor X activator from W. aegyptia is though different in many aspects from factor X activators of Viperidae and Crotalidae venoms, but shows several properties identical to factor X activators from Elapidae venoms.

Clarification of contraceptive drug pharmacokinetics in obesity

Related to concerns about the role of obesity in the efficacy of contraceptive drugs, a review of the literature was carried out in regard to the pharmacokinetics of ethinyl estradiol and various progestins given by various routes of administration. Most studies show that obese women exhibit modestly lower plasma concentrations of these drugs (circa 30%) when given the same doses as normal-weight women. While the mechanism is uncertain, precedence in the literature suggests that this is due to body weight-related differences in metabolism rates. Confusing in some of the literature is that a few studies have reported erroneously calculated pharmacokinetic parameters after multiple dosing of oral contraceptives. A demonstration of appropriate pharmacokinetic methodology is provided.

Effect of antenatal betamethasone on blood glucose levels in women with and without diabetes

OBJECTIVE

To characterize the maternal glycemic response to betamethasone in subjects without diabetes compared to subjects with diabetes.

STUDY DESIGN

Blood glucose levels in 22 gravidae without diabetes and 11 gravidae with diabetes were recorded for 48h following betamethasone administration for threatened preterm delivery. Maximum blood glucose value and time to maximum value were compared. Area under the curve calculations were used to express the duration and degree of significant hyperglycemia for individual subjects. These summary measures were then correlated to subject characteristics and laboratory values to determine a risk profile of those subjects without diabetes at risk for significant hyperglycemia.

RESULTS

All subjects with diabetes and the majority of those without diabetes had significant hyperglycemia during the study period. Mean maximum blood glucose was higher for those with diabetes (205mg/dL vs. 173mg/dL, p⩽0.01). Mean time to reach the maximum glucose level was similar for both groups. Result of a glucose tolerance test given immediately prior to betamethasone correlated strongly with amount of time spent with hyperglycemia for subjects without diabetes (rho=0.59, p⩽0.01). Morbidly obese subjects spent less time with hyperglycemia than those with lower body mass indices (p=0.03).

CONCLUSION

Both subjects with and without diabetes demonstrate significant hyperglycemia after receipt of antenatal betamethasone.

The Effect of Patient Weight and Provider Training and Experience on Dosing of Rocuronium

Introduction. Maintenance dosing of neuromuscular blocking agents is complex and varies with patient, procedure, and clinical situation. With this in mind, we sought to identify factors impacting the maintenance dosing of neuromuscular blockers as a step toward identifying best practice with respect to minimizing residual neuromuscular blockade. Methods. Cases utilizing rocuronium from July 1, 2010, to June 30, 2014, at the sponsoring institution were analyzed. Using a mixed model to account for repeated measures, patients were analyzed by dose and weight category as defined by the World Health Organization (eight categories ranging from very severely underweight to very severely obese) as well as by the administering provider's level of experience. Results. The study included 12,671 patients with a mean age of 49.7 (SD 16.7). Increasing weight category and higher levels of provider experience were associated with higher doses for rocuronium. There were no differences in initial dose or in frequency of maintenance dosing by weight category after controlling for case length. Discussion. The two dosing patterns identified, higher doses for overweight patients and higher doses administered by experienced providers, are modifiable factors that could enhance patient safety.

Daily vancomycin dose requirements as a continuous infusion in obese versus non-obese SICU patients

Background

Limited data are available assessing vancomycin concentrations in obese critically ill patients. Currently, there are no studies evaluating dosing requirements in this population who receive vancomycin administered as a continuous infusion (CI). The aim of this study was to assess whether there was a difference in the weight-based maintenance dose required to reach a therapeutic vancomycin concentration at 24 hours when given as a CI in obese versus non-obese critically ill patients.

Methods

A retrospective cohort study of adult obese patients admitted to the SICU between 2013 and 2015 receiving a vancomycin CI (CIV), and with 24-hour serum measurements were included. Obese patients (body mass index (BMI) ≥35 kg/m²) were matched with non-obese patients (BMI <30 kg/m²) based on renal function, age and acute physiology and chronic health evaluation (APACHE)-II score at admission. All patients in this study received a loading dose of 25 mg/kg then a maintenance dose based on renal function according to the protocol. The study was approved by the Institutional Review Board. The primary outcome was the weight-based total daily maintenance dose required to achieve a vancomycin level of 20 mg/L. The secondary endpoints included the achievement of a therapeutic level at 24 hours.

Results

Twenty-six matched pairs of patients met the inclusion criteria. Of these, 17 pairs had preserved renal function and 9 pairs required continuous venovenous hemofiltration. Mean BMI was 40.9 kg/m² in obese and 24.8 kg/m² in non-obese patients. To achieve a vancomycin concentration of 20 mg/L, the weight-based daily maintenance dose in obese patients was 25.6 mg/kg versus 43.8 mg/kg in non-obese patients (p <0.01). Therapeutic 24-hour levels were achieved in 24/26 obese versus 23/26 no-obese patients (p = 0.63). Mean 24-hour vancomycin level was 20.3 ± 3.81 mcg/ml in obese compared to 20.03 ± 3.79 mcg/ml in non-obese patients (p = 0.77). Mean daily maintenance doses required to achieve a level of 20 mcg/ml were 2961 ± 1670 mg in obese compared to 3189 ± 1600.69 mg in non-obese (p = 0.61).

Conclusions

The results of our study suggest that critically ill obese patients treated with CIV required a significantly lower maintenance dose per unit of body weight than non-obese patients to achieve the same target level.

Safety and Efficacy of High-Dose Unfractionated Heparin for Prevention of Venous Thromboembolism in Overweight and Obese Patients

STUDY OBJECTIVE

To determine the safety and efficacy of high-dose subcutaneous unfractionated heparin (UFH) for prevention of venous thromboembolism (VTE) in overweight and obese patients.

DESIGN

Single-center retrospective observational cohort study.

SETTING

Large academic tertiary care medical center.

PATIENTS

A total of 1335 adults who weighed more than 100 kg on admission and received either subcutaneous UFH 7500 units every 8 hours (751 patients [high-dose group]) or 5000 units every 8 hours (584 patients [low-dose group]) for VTE prophylaxis during their hospitalization between January 1, 2013, and August 31, 2014.

MEASUREMENTS AND MAIN RESULTS

The incidences of VTE and bleeding complications were assessed in each group. Each group was further divided into four groups based on their body mass index (BMI): overweight (BMI 25-29.9 kg/m(2) ), obese class I (BMI 30-34.9 kg/m(2) ), obese class II (BMI 35-39.9 kg/m(2) ), and obese class III (BMI ≥ 40 kg/m(2) ). The incidence of VTE was similar for patients in the high-dose group versus those in the low-dose group for all BMI categories. Bleeding complications were significantly higher for patients in the high-dose group. The proportion of patients with at least a 2-g/dl hemoglobin drop from admission was higher in patients in the high-dose groups in obese classes II and III: obese class II, 46 (30%) of 152 patients in the high-dose group versus 30 (18%) of 171 patients in the low-dose group (p<0.01); obese class III, 109 (25%) of 432 patients in the high-dose group versus 31 (12%) of 249 patients in the low-dose group (p<0.01). In addition, the proportion of patients who received at least 2 units of packed red blood cell transfusion was significantly higher in patients in the high-dose group who were in obese class III: 47 (11%) of 432 in the high-dose group versus 13 (5%) of 249 in the low-dose group (p<0.01).

CONCLUSION

Administering a higher dose of heparin to patients weighing more than 100 kg may not impart additional efficacy in reducing the incidence of VTE. However, it may increase the risk for bleeding.

Effect of Body Mass Index- and Actual Weight-Based Neoadjuvant Chemotherapy Doses on Pathologic Complete Response in Operable Breast Cancer

INTRODUCTION

The effect of body mass index (BMI) and chemotherapy dose reduction on pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) for locoregional breast cancer remains unclear. Contemporary studies have reported largely on trial populations and used dose-capping.

PATIENTS AND METHODS

Patient registries at the University of Iowa were queried to identify patients with operable breast cancer who received NAC. Dose reductions were calculated for taxanes (T), anthracyclines (A) and non-A-T chemotherapy. Clinical-pathologic characteristics, chemotherapy dose reductions, and adverse events were compared between normal (BMI <25) and overweight/obese patients (BMI ≥25). Additionally, the synergistic effect of BMI and chemotherapy dose reduction on pCR was assessed.

RESULTS

Of 171 eligible patients, 112 were overweight/obese. Chemotherapy dosing was capped in 2 patients; all others initiated full weight-based treatment. Overweight/obese patients required more frequent taxane (44.6% vs. 25.4%; P = .01) and any chemotherapy dose reductions (50.9% vs. 33.9%; P = .03). pCR was attained in 29.2% of patients. In a multivariable model, the interaction term for BMI as a continuous variable and any chemotherapy dose reduction was significant independent of the clinical stage and tumor receptor status (P = .04). For obese patients, any chemotherapy dose reduction was significantly associated with increased odds of not attaining pCR.

CONCLUSION

During NAC, overweight/obese patients more often have chemotherapy dose reductions. Chemotherapy dose reduction in obese patients was a powerful predictor of not attaining pCR. This was not seen for normal or overweight patients. Opportunities might exist to improve pCR rates in this higher-risk group.

Development of a pharmacist-driven protocol for automatic medication dosage adjustments in obese patients

PURPOSE

A hospital protocol utilizing automatic dosage adjustments and pharmacist consultations to optimize the use of certain medications in obese patients is described.

SUMMARY

After conducting a literature search focused on medication dosing in obese patients, pharmacists at a large community hospital developed a list of commonly ordered medications appropriate for inclusion in a pharmacy-driven institutional protocol for automatic medication dosage adjustment in adult patients with obesity. Evidence-based recommendations on initial dosing of eight antimicrobials and two anticoagulant agents according to weight and renal function were formulated. Under the protocol, pharmacists receive electronic alerts regarding protocol-eligible patients during initial order verification and automatically adjust medication dosages as appropriate. For patients prescribed anticoagulants at specified dosage levels, clinical pharmacists consult with prescribers to help ensure safe and effective initial and ongoing therapy. Multidisciplinary educational initiatives were conducted prior to protocol implementation. During two designated three-week postimplementation data collection periods, pharmacists received a total of 372 protocol-eligible medication orders. Pharmacists adjusted a total of 149 dosages and verified an additional 183 dosages consistent with the protocol as originally ordered. Clinical pharmacy consults were completed for 10-15% of patients, with laboratory monitoring ordered in 25-30% of those cases (all patients were found to have appropriate test values). There have been no documented adverse drug reactions in patients whose medication dosages were adjusted per protocol.

CONCLUSION

Pharmacists implemented weight- and renal function-based dosage adjustments for obese patients in 40% of evaluated protocol-eligible cases to achieve 89% compliance with the protocol. Heparin and cefazolin were the medications most likely to require obesity-related dosage adjustments.

Perioperative support reduces mortality of obese BALB/c mice after ovariectomy

The incidence of obesity is on the rise in most western countries and represents major risks to health. Obesity causes complex metabolic dysfunctions and can be associated with a large number of secondary diseases. To investigate causal mechanisms of obesity and develop better options for treatment, researchers study the condition in animal models. In addition to genetically engineered animal models, diet-induced obesity is often used because it occurs similarly in animals as it does in humans. For several types of investigations that use obesity models, investigators must carry out surgical interventions and they frequently encounter severe perioperative complications induced by anesthesia. In an example of this problem, we observed 100% mortality in obese BALB/c mice after ovariectomy, despite no obvious surgical complications. We supposed that a failure to recover from surgery was the primary cause of this increased mortality. Therefore, to support their recovery from surgery we administered atropine to obese mice in order to facilitate blood circulation, and we also increased the oxygen content of the ambient air. With this specific support before and after surgery, we increased the survival rate of obese ovariectomized mice up to 83%. These results confirm the assumption that obesity is a risk factor for the recovery of obese animal models after ovariectomy, and they highlight the need to provide additional interventions for such experimental animals.

Evaluation of cephalexin failure rates in morbidly obese patients with cellulitis

WHAT IS KNOWN AND OBJECTIVE

Identification of adequate antimicrobial dosing regimens for morbidly obese patients is essential given the simultaneous increase in morbid obesity and cellulitis prevalence in recent years. Insufficient data currently exist to describe the effectiveness of extrapolating traditional antibiotic dosing strategies to morbidly obese patients with cellulitis. The primary objective of this study was to compare therapeutic failure rates in non-obese and morbidly obese patients with cellulitis when treated with cephalexin at standard dosing.

METHODS

This was a single-centre, retrospective cohort analysis. Adult patients hospitalized or under inpatient observation at a 1265-bed academic medical centre who received cephalexin monotherapy for non-purulent cellulitis from 2005 to 2015 were evaluated for inclusion. Patients were divided into two cohorts based on body mass index (BMI), where BMI <30 kg/m(2) was defined as non-obese and BMI ≥40 kg/m(2) as morbidly obese. Patients with critical risk factors for purulent or polymicrobial cellulitis were excluded. The primary outcome, therapeutic failure, was defined as a need for extended or additional antimicrobial therapy, surgical intervention, emergency department visit, or re-hospitalization within two to thirty days after cephalexin initiation.

RESULTS AND DISCUSSION

A total of 94 patients (69 non-obese and 25 morbidly obese) met inclusion and exclusion criteria, which was below the estimated sample size needed to reach desired power. The rate of therapeutic failure in the morbidly obese group was similar to the non-obese group (20% vs. 14·5%, P = 0·53). Patients most commonly had extended or additional antibiotics prescribed in response to therapeutic failure with cephalexin.

WHAT IS NEW AND CONCLUSION

Cephalexin failure rates for cellulitis did not differ statistically between morbidly obese and non-obese patients. The underpowered nature of this study is a limitation. Until further study with a larger sample size is completed, empiric adjustment of cephalexin dosing based solely on BMI may not be necessary.

Obesity and lower limb venous disease - The epidemic of phlebesity

Introduction Lower limb venous disease affects up to one half, and obesity up to one quarter, of the adult population. Many people are therefore affected by, and present to health services for the treatment of both conditions. This article reviews the available evidence of pathophysiological and clinical relationship between obesity and varicose veins, chronic venous insufficiency and ulceration and deep vein thrombosis. Methods A literature search of PubMed and Cochrane libraries was performed in accordance with PRISMA statement from 1946 to 2015, with further article identification from following cited references for articles examining the relationship between obesity and venous disease. Search terms included obesity, overweight, thrombosis, varicose veins, CEAP, chronic venous insufficiency, treatment, endovenous, endothermal, sclerotherapy, bariatric surgery and deep vein thrombosis. Results The proportion of the population suffering from lower limb venous disease and obesity is increasing. Obesity is an important risk factor for all types of lower limb venous disease, and obese patients with lower limb venous disease are more likely to be symptomatic as a result of their lower limb venous disease. The clinical diagnosis, investigation, imaging and treatment of lower limb venous disease in obese people present a number of challenges. The evidence base underpinning medical, surgical and endovenous management of lower limb venous disease in obese people is limited and such treatment may be associated with worse outcomes and increased risks when compared to patients with a normal body mass index. Conclusion Lower limb venous disease and obesity are both increasingly common. As such, phlebologists will be treating ever greater numbers of obese patients with lower limb venous disease, and clinicians in many other specialties are going to be treating a wide range of obesity-related health problems in people with or at risk of lower limb venous disease. Unfortunately, obese people have been specifically excluded from many, if not most, of the pivotal studies. As such, many basic questions remain unanswered and there is an urgent need for research in this challenging and increasingly prevalent patient group.

A physiome interoperability roadmap for personalized drug development

The goal of developing therapies and dosage regimes for characterized subgroups of the general population can be facilitated by the use of simulation models able to incorporate information about inter-individual variability in drug disposition (pharmacokinetics), toxicity and response effect (pharmacodynamics). Such observed variability can have multiple causes at various scales, ranging from gross anatomical differences to differences in genome sequence. Relevant data for many of these aspects, particularly related to molecular assays (known as '-omics'), are available in online resources, but identification and assignment to appropriate model variables and parameters is a significant bottleneck in the model development process. Through its efforts to standardize annotation with consequent increase in data usability, the human physiome project has a vital role in improving productivity in model development and, thus, the development of personalized therapy regimes. Here, we review the current status of personalized medicine in clinical practice, outline some of the challenges that must be overcome in order to expand its applicability, and discuss the relevance of personalized medicine to the more widespread challenges being faced in drug discovery and development. We then review some of (i) the key data resources available for use in model development and (ii) the potential areas where advances made within the physiome modelling community could contribute to physiologically based pharmacokinetic and physiologically based pharmacokinetic/pharmacodynamic modelling in support of personalized drug development. We conclude by proposing a roadmap to further guide the physiome community in its on-going efforts to improve data usability, and integration with modelling efforts in the support of personalized medicine development.

Assessing an enoxaparin dosing protocol in morbidly obese patients

The effect of obesity on the pharmacokinetics of enoxaparin is not clearly understood and traditional treatment doses in morbidly obese patients (body mass index [BMI] > 40 kg/m(2)) can lead to over anticoagulation. Our institution developed an inpatient protocol with reduced enoxaparin doses (0.75 mg/kg/dose based on actual body weight) for patients with a weight >200 kg or BMI > 40 kg/m(2). The primary objective was to determine if modified enoxaparin treatment doses would achieve therapeutic anti-Xa levels (goal range 0.6-1.0 IU/mL) in morbidly obese patients. Thirty-one patients were included in our study and had a median body weight of 138 kg (range 105-197) and a median BMI of 46.2 kg/m(2) (range 40.1-62). The initial peak anti-Xa levels were in therapeutic range in 15 of 31 patients (48 %) with an initial mean anti-Xa level of 0.92 IU/mL. Twenty-four patients (77 %) achieved therapeutic anti-Xa levels in goal range during their hospitalization, with a mean enoxaparin dose of 0.71 mg/kg. Bleeding and thrombotic events were minimal and all patients that achieved an anti-Xa level in goal range did so with a dose less than 1 mg/kg of enoxaparin.

Population pharmacokinetics of oseltamivir and oseltamivir carboxylate in obese and non-obese volunteers

AIMS

The aims of the present study were to compare the pharmacokinetics of oseltamivir and its active antiviral metabolite oseltamivir carboxylate in obese and non-obese individuals and to determine the effect of obesity on the pharmacokinetic properties of oseltamivir and oseltamivir carboxylate.

METHODS

The population pharmacokinetic properties of oseltamivir and oseltamivir carboxylate were evaluated in 12 obese [body mass index (BMI) ≥30 kg m(-2) ) and 12 non-obese (BMI <30 kg m(-2) ) Thai adult volunteers receiving a standard dose of 75 mg and a double dose of 150 mg in a randomized sequence. Concentration-time data were collected and analysed using nonlinear mixed-effects modelling.

RESULTS

The pharmacokinetics of oseltamivir and oseltamivir carboxylate were described simultaneously by first-order absorption, with a one-compartment disposition model for oseltamivir, followed by a metabolism compartment and a one-compartment disposition model for oseltamivir carboxylate. Creatinine clearance was a significant predictor of oseltamivir carboxylate clearance {3.84% increase for each 10 ml min(-1) increase in creatinine clearance [95% confidence interval (CI) 0.178%, 8.02%]}. Obese individuals had an approximately 25% (95% CI 24%, 28%) higher oseltamivir clearance, 20% higher oseltamivir volume of distribution (95% CI 19%, 23%) and 10% higher oseltamivir carboxylate clearance (95% CI 9%, 11%) compared with non-obese individuals. However, these altered pharmacokinetic properties were small and did not change the overall exposure to oseltamivir carboxylate.

CONCLUSIONS

The results confirmed that a dose adjustment for oseltamivir in obese individuals is not necessary on the basis of its pharmacokinetics.

Comparative analysis of the influence of clinical factors including BMI on adalimumab and infliximab trough levels

INTRODUCTION

Optimal trough levels of the anti-tumour necrosis factor agents, infliximab and adalimumab, are correlated with clinical remission. Obesity adversely affects response to infliximab and adalimumab, but the influence of BMI on trough levels has not been adequately investigated. We investigated the relationship between clinical variables, including BMI, and trough levels of infliximab and adalimumab.

METHODS

This prospective cross-sectional study included patients treated with infliximab and adalimumab on maintenance therapy, with concurrent measurements of trough levels and BMI. The associations between categorical trough levels and clinical variables, including BMI, were estimated.

RESULTS

Of the 122 patients included in the study, 80 (66%) were on infliximab and 42 (34%) were on adalimumab. Eighty-three per cent had Crohn's disease and the remainder had ulcerative colitis. None of the clinical variables, including smoking, BMI, concurrent immunosuppression, duration of disease and treatment, were associated with categorical trough levels of infliximab or adalimumab. The effect of BMI did not differ between the two anti-tumour necrosis factor agents, although there was a trend towards a lower trough level in adalimumab-treated patients with a BMI greater than 30 (P=0.09). In infliximab-treated patients, antibodies to infliximab (P<0.001) and a C-reactive protein level of at least 5 mg/dl were associated with trough levels less than 3 µg/ml (P=0.008).

CONCLUSION

BMI does not differentially influence trough levels of adalimumab and infliximab, although a trend towards a lower trough level was observed in adalimumab-treated patients with a BMI greater than 30. Raised C-reactive protein levels and antibodies to infliximab were associated with subtherapeutic levels of infliximab.

Can paracetamol (acetaminophen) be administered to patients with liver impairment?

Although 60 years have passed since it became widely available on the therapeutic market, paracetamol dosage in patients with liver disease remains a controversial subject. Fulminant hepatic failure has been a well documented consequence of paracetamol overdose since its introduction, while short and long term use have both been associated with elevation of liver transaminases, a surrogate marker for acute liver injury. From these reports it has been assumed that paracetamol use should be restricted or the dosage reduced in patients with chronic liver disease. We review the factors that have been purported to increase risk of hepatocellular injury from paracetamol and the pharmacokinetic alterations in different pathologies of chronic liver disease which may affect this risk. We postulate that inadvertent under-dosing may result in concentrations too low to enable efficacy. Specific research to improve the evidence base for prescribing paracetamol in patients with different aetiologies of chronic liver disease is needed.

Body mass index and response to tocilizumab in rheumatoid arthritis: a real life study

Several studies have suggested that obesity could have a negative effect on response to anti-tumor necrosis factor α (anti-TNFα) in rheumatoid arthritis (RA). Little is known about the impact of body mass index (BMI) on other biologic agents. We aimed to evaluate the effect of BMI on response to tocilizumab (TCZ) in RA. RA patients treated with TCZ were included in this multicenter retrospective study. BMI was calculated at the initiation of treatment. After 6 months of treatment, change from baseline in DAS28, pain on a visual analog scale, erythrocyte sedimentation rate and C-reactive protein level, and tender and swollen joints were analyzed. The primary endpoint was decrease in DAS28 ≥ 1.2. Secondary outcomes were good response and remission by EULAR criteria. At baseline, among 115 RA patients included, the median (interquartile range) BMI was 25.4 (22.0-28.8) kg/m(2). The number of patients with normal weight, overweight, and obesity was 53 (46 %), 37 (32 %), and 25 (22 %), respectively. Baseline characteristics did not differ between the three subgroups of BMI. The median BMI did not differ between responders and non-responders for DAS28 decrease ≥1.2 (25.7 [22.1-29.9] vs 24.9 [22.0-27.1], P = 0.38), EULAR good response (25.9 [22.8-30.0] vs 25.4 [22.0-28.4], P = 0.61), and remission (25.1 [22.5-28.6] vs 25.4 [22.0-28.9], P = 0.76). BMI did not affect the response to TCZ in RA. If confirmed, these results could be helpful for the selection of a biologic agent in obese RA patients.

Creatinine-based equations for the adjustment of drug dosage in an obese population

AIM

For drug dosing adaptation, the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend using estimated glomerular filtration rate (eGFR) by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, after 'de-indexation' by body surface area (BSA). In pharmacology, the Cockcroft-Gault (CG) equation is still recommended to adapt drug dosage. In the context of obesity, adjusted ideal body weight (AIBW) is sometimes preferred to actual body weight (ABW) for the CG equation. The aim of the present study was to compare the performance of the different GFR-estimating equations, non-indexed or de-indexed by BSA for the purpose of drug-dosage adaptation in obese patients.

METHODS

We analysed data from patients with a body mass index (BMI) higher than 30 kg m(-2) who underwent a GFR measurement. eGFR was calculated using the CKD-EPI and Modification of Diet in Renal Disease (MDRD) equations, de-indexed by BSA, and the CG equation, using either ABW, AIBW or lean body weight (LBW) for the weight variable and compared with measured GFR, expressed in ml min(-1).

RESULTS

In our population of obese patients, use of the AIBW instead of the ABW in the CG equation, markedly improved the overall accuracy of this equation [57% for CGABW and 79% for CGAIBW (P < 0.05)]. For high BMI (over 40 kg m(-2)), the accuracy of the CG equations is no different when using LBW than when using AIBW. The MDRD and CKD-EPI equations de-indexed by the BSA also performed well, with an overall higher accuracy for the MDRD de-indexed equation [(80% and 76%, respectively (P < 0.05)].

CONCLUSIONS

The de-indexed MDRD equation appeared to be the most suitable for estimating the non-indexed GFR for the purpose of drug dosage adaptation in obese patients.

Risk of breast cancer in relation to combined effects of hormone therapy, body mass index, and alcohol use, by hormone-receptor status

BACKGROUND

Alcohol consumption, increased body mass index (BMI), and hormone therapy are risk factors for postmenopausal breast cancer, but their combined effects are not well understood. Because hormone therapy is effective for the relief of menopausal symptoms, the identification of "high-risk" users is important for therapeutic reasons. We investigated interactions between hormone therapy use and alcohol-use/high BMI status in relation to invasive breast cancer risk, both overall and according to estrogen receptor (ER) status.

METHODS

Two Danish prospective cohorts were pooled, including 30,789 women ages 50+ years (study period 1981 to 2009). Information on risk factors was obtained in baseline questionnaires. We performed analyses using the Aalen additive hazards model. Serum estradiol and testosterone measurements were obtained in a subsample of approximately 1000 women.

RESULTS

During 392,938 person-years of follow-up, 1579 women developed invasive breast cancer. Among nonusers of hormone therapy, the risk of breast cancer was slightly increased with overweight/obesity and increasing alcohol consumption. Compared with normal-weight nonusers, the risk of breast cancer was higher in hormone therapy users across all BMI strata (P for interaction = 0.003). A markedly higher risk of breast cancer was also observed for alcohol combined with hormone therapy use compared with abstinent nonusers (P for interaction = 0.02). These effects were primarily restricted to ER-positive cases. Combined effects of hormone therapy/high BMI and hormone therapy/alcohol on serum estradiol and testosterone supported the hypothesis of a hormonal pathway linking these exposures to breast cancer.

CONCLUSION

These analyses suggest an increased risk of breast cancer associated with hormone therapy use-a risk that may be particularly strong among women consuming alcohol.

Cefoxitin Plasma and Subcutaneous Adipose Tissue Concentration in Patients Undergoing Sleeve Gastrectomy

PURPOSE

Antibiotic dosing in obese surgical patients has not been adequately evaluated. The objective of this study was to identify whether currently prescribed doses of cefoxitin achieve adequate and sustained plasma and tissue concentrations in obese patients undergoing sleeve gastrectomy.

METHODS

A prospective evaluation of plasma and tissue cefoxitin concentrations in patients undergoing sleeve gastrectomy was performed. On the day of the surgical procedure, venous blood samples (5 mL) were collected just before cefoxitin administration and then at 5, 30, 60, 120, and 240 minutes after dose administration. In addition, subcutaneous adipose tissue was collected from the surgical site at the time of surgical incision and at closure. Cefoxitin concentrations in the collected samples were quantified by using an HPLC-ultraviolet method. A standard noncompartmental analysis was performed for each individual cefoxitin plasma concentration-time profile. In addition, the ratio of tissue to plasma concentration was calculated for all patients.

FINDINGS

Plasma and tissue pharmacokinetics of cefoxitin were evaluated in 6 patients undergoing sleeve gastrectomy. The mean age and BMI were 48.7 (6.2) years and 42.8 (7.1) kg/m(2), respectively. At the time of surgical closure, subcutaneous adipose tissue concentrations of cefoxitin were subtherapeutic (<8 µg/mL) in all evaluated patients.

IMPLICATIONS

Current dosing strategies for cefoxitin in obese surgical patients may be inadequate, and there is an urgent need to define the appropriate dosage.

Factors affecting the quality of anticoagulation with warfarin: experience of one cardiac centre

Introduction

The risk of complications in anticoagulation therapy can be reduced by maximising the percentage of time spent by the patient in the optimal therapeutic range (TTR). However, little is known about the predictors of anticoagulation control. The aim of this paper was to assess the quality of anticoagulant therapy in patients on warfarin and to identify the factors affecting its deterioration.

Material and methods

We studied 149 patients who required anticoagulant therapy with warfarin due to non-valvular atrial fibrillation and/or venous thromboembolism. Each patient underwent proper training regarding the implemented treatment and remained under constant medical care.

Results

The mean age of the patients was 68.8 ± 12.6 years, and 59% were male. A total of 2460 international normalised ratio (INR) measurements were collected during the 18-month period. The mean TTR in the studied cohort was 76 ± 21%, and the median was 80%. The level at which high-quality anticoagulation was recorded for this study was based on TTR values above 80%. Seventy-five patients with TTR ≥ 80% were included in the stable anticoagulation group (TTR ≥ 80%); the remaining 74 patients constituted the unstable anticoagulation group (TTR < 80%). According to multivariate stepwise regression analysis, the independent variables increasing the risk of deterioration of anticoagulation quality were: arterial hypertension (OR 2.74 [CI 95%: 1.06-7.10]; p = 0.038), amiodarone therapy (OR 4.22 [CI 95%: 1.30-13.70]; p = 0.017), and obesity (OR 1.11 [CI 95%: 1.02-1.21]; p = 0.013).

Conclusions

The presence of obesity, hypertension, or amiodarone therapy decreases the quality of anticoagulation with warfarin. High quality of anticoagulation can be achieved through proper monitoring and education of patients.