Losing weight to achieve joint or hernia surgery: is the intragastric balloon the answer?

BACKGROUND

Obesity is an epidemic, with its accompanying medical conditions putting patients at increased risk of postoperative complications. For patients undergoing elective surgery, preoperative weight loss provides an opportunity to decrease complications. We sought to evaluate the safety and efficacy of an intragastric balloon in achieving a body mass index (BMI) < 35 kg/m2 prior to elective joint replacement or hernia repair.

METHODS

Retrospective review of all patients who had intragastric balloon placement at a level 1A VA medical center from 1/2019 to 1/2023. Patients who had a scheduled qualifying procedure (knee/hip replacement or hernia repair) and had a BMI > 35 kg/m2 were offered intragastric balloon placement to achieve 30-50lbs (13-28 kg) weight loss prior to surgery. Participation in a standardized weight loss program for 12 months was required. Balloons were removed 6 months after placement, preferentially concomitant with the qualifying procedure. Baseline demographics, duration of balloon therapy, weight loss and progression to qualifying procedure were recorded.

RESULTS

Twenty patients completed intragastric balloon therapy and had balloon removal. Mean age 54 (34-71 years), majority (95%) male. Mean balloon duration was 200 ± 37 days. Mean weight loss was 30.8 ± 17.7lbs (14.0 ± 8.0 kg) with an average BMI reduction of 4.4 ± 2.9. Seventeen (85%) patients were successful, 15 (75%) underwent elective surgery and 2 (10%) were no longer symptomatic after weight loss. Three patients (15%) did not lose sufficient weight to qualify or were too ill to undergo surgery. Nausea was the most frequent side effect. One (5%) patient was readmitted within 30 days for pneumonia.

DISCUSSION

Intragastric balloon placement resulted in an average 30lbs (14 kg) weight loss over 6 months allowing more than 75% of patients to undergo joint replacement or hernia repair at an optimal weight. Intragastric balloons should be considered in patients requiring 30-50lbs (13-28 kg) weight loss prior to elective surgery. More study is needed to determine the long-term benefit of preoperative weight loss prior to elective surgery.

Are Diagnostic Delays Associated with Distress in Breast Cancer Patients?

Introduction

Receiving a new breast cancer diagnosis can cause anxiety and distress, which can lead to psychologic morbidity, decreased treatment adherence, and worse clinical outcomes. Understanding sources of distress is crucial in providing comprehensive care. This study aims to evaluate the relationship between delays in breast cancer diagnosis and patient-reported distress. Secondary outcomes include assessing patient characteristics associated with delay.

Methods

Newly diagnosed breast cancer patients who completed a distress screening tool at their initial evaluation at an academic institution between 2014 and 2019 were retrospectively evaluated. The tool captured distress levels in the emotional, social, health, and practical domains with scores of "high distress" defined by current clinical practice guidelines. Delay from mammogram to biopsy, whether diagnostic or screening mammogram, was defined as >30 days.

Result

745 newly diagnosed breast cancer patients met inclusion criteria. Median time from abnormal mammogram to core biopsy was 12 days, and 11% of patients experienced a delay in diagnosis. The non-delayed group had higher emotional (p = 0.04) and health (p = 0.03) distress than the delayed group. No statistically significant differences in social distress were found between groups. Additionally, patients with higher practical distress had longer time interval between mammogram and surgical intervention compared to those with lower practical distress. Older age, diagnoses of invasive lobular carcinoma or ductal carcinoma in situ, and clinical anatomic stages 0-I were associated with diagnostic delay.

Conclusion

Patients with higher emotional or health-related distress were more likely to have timely diagnoses of breast cancer, suggesting that patients with higher distress may seek healthcare interventions more promptly. Improved understanding of sources of distress will permit early intervention regarding the devastating impact of breast cancer diagnosis.

Surgeon Perceptions of the Integration of Patient-Reported Outcome Measures into Clinical Practice

INTRODUCTION

Patient-reported outcome measures (PROMs/PROM) are standardized, validated instruments used to measure the patient's perception of their own health status including their symptoms, functional wellbeing, and mental health. Although PROMs were initially developed as research tools, their use in clinical practice for shared decision-making and to assess the impact of disease and treatment on quality of life of individual patients has been increasing. There is a paucity of research exploring providers' perspectives on the clinical integration of PROMs. We sought to use a qualitative methodology to understand surgeons' perceptions of integrating PROMs into their clinical practices.

METHODS

Semistructured interviews were performed from November 2019 until August 2020. All interviews were recorded and transcribed verbatim. Thematic saturation was achieved after interviewing nine surgeons representing eight surgical specialties. Qualitative interview data were thematically analyzed using an inductive approach facilitated by Atlas.ti qualitative software.

RESULTS

Forty seven unique codes were identified that fit into 21 themes that revealed five novel insights. Key insights included: (1) PROM data can modify surgical practice on an individual and institutional level, (2) Surgeon's view PROM clinical integration as a potential method of advancing patient-centered care, (3) There are various institutional processes that must be in place, including strong leadership and an integrative platform, to enable successful clinical PROM integration, (4) Surgeons appreciate challenges of integrating PROMs into surgical practice including risks of incorrect use or interpretation, and (5) A PROM platform must be adaptable to the diversity within surgery and to unique physician workflows.

CONCLUSIONS

Surgeons perceived value from integrating PROMs into routine care to better inform patients during preoperative discussions and to help identify at-risk patients in the postoperative period. However, they also identified numerous barriers to the implementation of an integrated system for the routine use of PROMs in clinical practice and expressed concern about using PROMs to compare operative outcomes between surgeons. Based on this work, institutions that want to incorporate PROMs into surgical practice need a leadership team capable of supporting the change management necessary for effective integration and use a PROM platform that gives individual surgeons and surgical teams the ability to customize platforms for their unique practices.

Medically Smart, Fiscally Illiterate: Lack of Financial Education Leads to Poor Retirement Savings Strategies in Surgical Trainees

INTRODUCTION

Resident physicians are uniquely at high financial risk given their long training programs, lack of financial education, and documented poor financial literacy. Budgeting for retirement savings is an important metric for financial literacy.

METHODS

Semi-structured interviews were conducted with residents from two distinct surgery programs to assess their current financial status and their knowledge of and attitudes toward retirement savings strategies. Qualitative analysis was performed and the themes identified were examined in the context of previously reported quantitative survey data.

RESULTS

As previously reported, 105 residents at Site 1 completed a comprehensive financial survey 56% of respondents reported having no retirement savings. On additional analysis, only 26% residents surveyed reported optimal savings habits defined as contributing $5000/year to a retirement account starting their first year of training. 23 residents from both sites and representing all post-graduate-year (PGY) levels then participated in the focused, semi-structured interviews. Site 2 residents were less likely to be female (P = .02) and carried a significantly larger debt burden (p < .01) but were otherwise comparable to residents from Site 1. On qualitative analysis three consistent themes emerged: (1) Resident understanding of strategies for retirement savings is poor; (2) Lack of knowledge is the primary barrier; (3) Surgical residents desire financial education.

CONCLUSIONS

Surgery residents have a large debt burden, minimal retirement savings and an overall lack of understanding of savings strategies. Well-designed, early, and accessible educational interventions may improve the "financial vital signs" of surgical trainees and establish habits for long-term financial success.

Early identification of patients at risk for delayed recovery of ambulation after elective abdominal surgery

BACKGROUND

Recovery of preoperative ambulation levels 1 month after surgery represents an important patient-centered outcome. The objective of this study is to identify clinical factors associated with the inability to regain baseline preoperative ambulation levels 28 days postoperatively.

METHODS

This is a prospective cohort study enrolling patients scheduled for elective inpatient abdominal operations. Daily ambulation (steps/day) was measured with a wristband accelerometer. Preoperative steps were recorded for at least 3 full calendar days before surgery. Postoperatively, daily steps were recorded for at least 28 days. The primary outcome was delayed recovery of ambulation, defined as inability to achieve 50% of preoperative baseline steps at 28 days postoperatively.

RESULTS

A total of 108 patients were included. Delayed recovery (< 50% of baseline preoperative steps/day) occurred in 32 (30%) patients. Clinical factors associated with delayed recovery after multivariable logistic regression included longer operative time (OR 1.37, 95% CI 1.05-1.79), open operative approach (OR 4.87, 95% CI 1.64-14.48) and percent recovery on POD3 (OR 0.73, 95% CI 0.56-0.96). In addition, patients with delayed ambulation recovery had increased rates of postoperative complications (16% vs 1%, p < 0.01) and readmission (28% vs 5%, p < 0.01).

CONCLUSION

After elective inpatient abdominal operations, nearly one in three patients do not recover 50% of their baseline preoperative steps 28 days postoperatively. Factors that can be used to identify these patients include longer operations, open operations and low ambulation levels on postoperative day #3. These data can be used to target rehabilitation efforts aimed at patients at greatest risk for poor ambulatory recovery.

Preliminary data demonstrate the Geriatric Surgery Verification program reduces postoperative length of stay

OBJECTIVES/BACKGROUND

The Geriatric Surgery Verification (GSV) Program promotes clinical standards aimed to optimize the quality of surgical care delivered to older adults. The purpose of this study was to determine if preliminary implementation of the GSV Program standards improves surgical outcomes.

DESIGN

Prospective study with cohort matching.

SETTING

Data from a single institution compared with a national data set cohort.

PARTICIPANTS

All patients aged ≥75 years undergoing inpatient operations between January 2018 and December 2019 were included. Cohort matching by age and procedure code was performed using a national data set.

MEASUREMENTS

Baseline pre- and intraoperative characteristics prospectively recorded using Veterans Affairs Surgical Quality Improvement Program (VASQIP) variable definitions. Postoperative outcomes were recorded including complications as defined by VASQIP, 30-day mortality, and length of stay.

RESULTS

A total of 162 patients participated in the GSV program, and 308 patients comprised the matched comparison group. There was no difference in postoperative occurrence of one or more complications (p = 0.81) or 30-day mortality (p = 0.61). Patients cared for by the GSV Program had a reduced postoperative length of stay (median 4 days [range 1,31] vs. 5 days [range 1,86]; p < 0.01; and mean 5.4 ± 4.8 vs. 8.8 ± 11.8 days; p < 0.01) compared with the matched cohort. In a multivariable regression model, the GSV Program's reduced length of stay was independent of other associated covariates including age, operative time, and comorbidities (p < 0.01).

CONCLUSION

Preliminary implementation of the GSV Program standards reduces length of stay in older adults undergoing inpatient operations. This finding demonstrates both the clinical and financial value of the GSV Program.

Postoperative delirium is associated with decreased recovery of ambulation one-month after surgery

BACKGROUND

We hypothesized that postoperative delirium is associated with diminished recovery toward baseline preoperative ambulation levels one-month postoperatively.

METHODS

Patients included were ≥60 years old undergoing inpatient operations. Ambulation was measured as steps/day using an accelerometer worn for ≥3-days preoperatively and ≥28-days postoperatively. Primary outcome was the percent recovery of preoperative steps.

RESULTS

109 patients were included; 17 (16%) developed postoperative delirium. Recovery of ambulation toward preoperative baseline at postoperative day-28 was decreased in delirium group (34% vs. 69%; p < 0.01). Immediate postoperative ambulation was similar in the delirium vs. no-delirium groups (p = 0.79). Delirium occurred on average on postoperative 3 ± 4 days. Subsequently, ambulation was decreased in the delirium group compared to non-delirium group at postoperative week-1 (p = 0.01), week-2 (p = 0.02), week-3 (p < 0.01) and week-4 (p < 0.01).

CONCLUSION

Patients undergoing inpatient operations who develop delirium recover only one-third of their baseline steps one-month postoperatively. Postoperative delirium results in a decreased recovery towards baseline ambulation for at least 4-weeks following major operations in comparison to non-delirious patients. The decrease in ambulation in the delirium versus no-delirium groups occurred after the occurrence of postoperative delirium.

Reevaluation of Hepatic Angioembolization for Trauma in Stable Patients: Weighing the Risk

BACKGROUND

Angioembolization (AE) is recommended for extravasation from liver injury on CT. Data supporting AE are limited to retrospective series that have found low mortality but high morbidity. These studies did not focus on stable patients. We hypothesized that AE is associated with increased complications without improving mortality in stable patients.

STUDY DESIGN

We queried the 2016 Trauma Quality Improvement Project database for patients with grade III or higher liver injury (Organ Injury Score ≥ 3), blunt mechanism, with stable vitals (systolic blood pressure ≥ 90 mmHg and heart rate of 50 to 110 beats/min). Exclusion criteria were nonhepatic intra-abdominal or pelvic injury (Organ Injury Score ≥ 3), laparotomy less than 6 hours, and AE implementation more than 24 hours. Patients were matched 1:2 (AE to non-AE) on age, sex, Injury Severity Score, liver Organ Injury Score, arrival systolic blood pressure and heart rate, and transfusion in the first 4 hours using propensity score logistic modeling. Primary outcomes were in-hospital mortality, length of stay, transfusion, hepatic resection, interventional radiology drainage, and endoscopic procedure.

RESULTS

There were 1,939 patients who met criteria, with 116 (6%) undergoing hepatic AE. Median time to embolization was 3.3 hours. After successfully matching on all variables, groups did not differ with respect to mortality (5.4% vs 3.2%; p = 0.5, AE vs non-AE, respectively) or transfusion at 4 to 24 hours (4.4% vs 7.5%; p = 0.4). A larger percentage of the AE group underwent interventional radiology drainage (13.3% vs 2.2%; p < 0.001), with more ICU days (4 vs 3 days; p = 0.005) and longer length of stay (10 vs 6 days; p < 0.001).

CONCLUSIONS

Hepatic AE was associated with increased morbidity without improving mortality, suggesting the benefits of AE do not outweigh the risks in stable liver injury. Observing these patients is likely a more prudent approach.

The Waiting Game: How Long Are Breast Cancer Patients Waiting for Definitive Diagnosis?

BACKGROUND

Receiving a new breast cancer (BC) diagnosis can cause significant patient anxiety, which is amplified by delays in diagnosis. There is a lack of defined time periods for delays in the workup of BC. This study aims to evaluate national variations in timing from first abnormal mammogram to first biopsy and to determine independent predictors of delay in diagnosis.

PATIENTS AND METHODS

Data were derived from SEER-Medicare linked claims database from 2007 to 2013. Time intervals from abnormal mammogram, either screening or diagnostic, to biopsy were assessed. The fourth quartile for timing from first mammogram to first biopsy was utilized to define delay in diagnosis. Multivariate analyses were used to evaluate the association between clinicopathologic variables and delays in diagnosis.

RESULTS

We analyzed 53,758 patients with stage 0-II BC who underwent upfront surgery. Significant variations in timing of care were identified, with mean times from mammogram to biopsy, surgeon visit, and breast surgery of 23.3, 31.6, and 52.6 days, respectively. Over the study period, there was a decrease in delays from mammogram to biopsy. Non-White race, Northeast location, and earlier stage disease were found to be independent predictors of delays in the diagnosis of BC (p < 0.0001).

CONCLUSIONS

The study demonstrates significant variations in time to diagnostic biopsy. More efficient processes of care to address these delays should be implemented, and further studies are needed to determine whether improved efficiency decreases patient anxiety. The large variations in time to diagnosis speak to the need for consensus guidelines to establish a standard of care.

Choosing between Muscle and Fasciocutaneous Free Flap Reconstruction in the Treatment of Lower Extremity Osteomyelitis: Available Evidence for a Function-Specific Approach

Background Limb salvage in the setting of extremity osteomyelitis, though previously dependent on amputation, has been markedly improved through the application of free tissue flaps. Concern exists as to the utility of the fasciocutaneous flap to combat infection verses the traditional muscle flap. Prior studies have shown success with fasciocutaneous flaps in these patients, but given the small series, the choice remains controversial. The goal of this article was to determine if there is statistical evidence for flap choice in the setting of extremity osteomyelitis.

Methods A systematic review utilizing Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was completed of the current literature pertaining to the treatment of extremity osteomyelitis and flap reconstruction within the MedLine and PubMed databases. Six hundred forty-six studies were reviewed and ultimately 31 were included in the final analysis.

Results Eight hundred seventy-eight flap reconstructions were identified. Of the 588 muscle flaps, 7.8% (n = 46) had recurrence of osteomyelitis after an average of 36.1 (8.0–111.6) months follow-up. There were seven cases (4.3%) of osteomyelitis recurrence in the 163 fasciocutaneous flap group after an average of 29.8 (18.2–44.6) months follow-up (p = 0.165). Secondary outcomes such as flap loss, hematomas, and infection were analyzed without statistically significant differences between the muscle and fasciocutaneous flap groups.

Conclusion Selection of flap type is less important than adequate debridement, appropriate antibiotic selection, and sufficient duration of treatment. This study demonstrates that within the literature, fasciocutaneous flaps have a lower recurrence rate of osteomyelitis compared with muscle flaps. As such, fasciocutaneous flaps are appropriate for reconstruction and treatment of extremity osteomyelitis.

The Extremity/Mechanism/Shock Index/GCS (EMS-G) score: A novel pre-hospital scoring system for early and appropriate MTP activation

BACKGROUND

Numerous in-hospital scoring systems to activate massive transfusion protocols (MTP) have been proposed; however, to date, pre-hospital scoring systems have not been robustly validated. Many trauma centers do not have blood or pre-thawed plasma available in the trauma bay, leading to delays in balanced transfusion. This study aims to assess pre-hospital injury and physiologic parameters to develop a pre-hospital scoring system predictive of need for massive transfusion (MT) prior to patient arrival.

METHODS

A retrospective review of all adult full and partial trauma team activations from July 2014-July 2018 from an urban level 2 trauma center was performed utilizing our trauma registry. Stepwise logistic regression analysis was performed to develop a new scoring system, with point totals assigned proportional to the odds ratios of requiring MT for each variable. Internal validation of the EMS-G score was performed using a subset of the data which was not utilized for development of the scoring system, and sensitivity and specificity were compared to previously validated in-hospital scoring systems applied in the pre-hospital setting.

RESULTS

763 patients were included with 94 patients (12.3%) receiving early MT, defined as 4 units pRBC in 4 h or ED death. In-hospital models for predicting MT such as Assessment of Blood Consumption (ABC) or Shock Index (SI) have sensitivities and specificities of 46/85% and 94/79% respectively for early MTP utilization based on pre-hospital data. Pre-hospital variables found to be predictive of MT were used to develop the EMS-G (Extremity, Mechanism, Shock Index, GCS) score. This system assigns obvious extremity injury-1-point, penetrating mechanism -2 points, shock index ≥0.9-2 points, GCS ≤8-3 points. A score of 3 or greater was chosen to maximize sensitivity and specificity for pre-hospital MT activation. EMS-G score based on pre-hospital report is 89% sensitive, 84% specific, with a PPV of 44% and NPV of 98% for early MT. Using this system, 25% of full and partial trauma team activations met criteria for pre-hospital MTP activation.

CONCLUSION

The EMS-G Score has increased sensitivity and specificity compared to the ABC Score in the pre-hospital setting and appears more appropriate than shock index alone at predicting massive transfusion. This scoring system allows trauma centers to activate MTP prior to patient arrival to ensure early and appropriate blood product administration without blood product wastage.

Population pharmacokinetic data analysis of three phase I studies of matuzumab, a humanised anti-EGFR monoclonal antibody in clinical cancer development

A population pharmacokinetic model based on data from three phase I studies was to be developed including a covariate analysis to describe the concentration–time profiles of matuzumab, a novel humanised monoclonal antibody. Matuzumab was administered as multiple 1 h i.v. infusions with 11 different dosing regimens ranging from 400 to 2000 mg, q1w–q3w. For analysis, 90 patients with 1256 serum concentration–time data were simultaneously fitted using the software NONMEM™. Data were best described using a two-compartment model with the parameters central (V₁) and peripheral distribution volume (V₂), intercompartmental (Q) and linear (CLL) clearance and an additional nonlinear elimination pathway (K_m, V_max). Structural parameters were in agreement with immunoglobulin characteristics. In total, interindividual variability on V_max, CLL, V₁ and V₂ and interoccasion variability on CLL was 22–62% CV. A covariate analysis identified weight having an influence on V₁ (+0.44% per kg) and CLL (+0.87% per kg). All parameters were estimated with good precision (RSE<39%). A robust population pharmacokinetic model for matuzumab was developed, including a nonlinear pharmacokinetic process. In addition, relevant and plausible covariates were identified and incorporated into the model. When correlated to efficacy, this model could serve as a tool to guide dose selection for this ‘targeted’ cancer therapy.

Pharmacokinetics of sarizotan after oral administration of single and repeat doses in healthy subjects

OBJECTIVE

Sarizotan is a 5-HTIA receptor agonist with high affinity for D3 and D4 receptors. Here we report the pharmacokinetic and tolerability results from four Phase 1 studies.

MATERIALS

Two single-dose (5 -25 mg, n = 25, 0.5 - 5 mg, n = 16) and two multiple-dose (10 and 20 mg b.i.d., n = 30, 5 mg b.i.d., n = 12) studies with orally administered sarizotan HCl were carried out in healthy subjects.

METHODS

Plasma sarizotan HCl concentrations were measured using a validated HPLC method and fluorescence or MS/MS detection. Pharmacokinetic parameters were obtained using standard non-compartmental methods.

RESULTS

Sarizotan was rapidly absorbed, group-median times to reach maximum concentration (tmax) ranged from 0.5 -2.25 h after single doses and during steady state. Maximum plasma concentration (Cmax) and tmax were slightly dependent on formulation and food intake, whereas area under the curve (AUC) was unaffected by these factors. AUC and Cmax increased dose-proportionally over the tested dose range. Independently of dose and time, sarizotan HCl plasma concentrations declined polyexponentially with a terminal elimination half-life (t1/2) of 5 - 7 h. Accumulation factors corresponded to t1/2 values, and steady state was reached within 24 h. Plasma metabolite concentrations were considerably lower than those of the parent drug. The ratio metabolite AUC : parent drug AUC was time- and dose-independent for all three metabolites suggesting that the metabolism of sarizotan is non-saturable in the tested dose range.

CONCLUSIONS

The pharmacokinetics of sarizotan were dose-proportional and time-independent for the dose range 0.5 -25 mg). The drug was well-tolerated by healthy subjects up to a single dose of 20 mg.

The role of pharmacokinetics and pharmacodynamics in phosphodiesterase-5 inhibitor therapy

Differences in clinical pharmacology of the currently marketed phosphodiesterase (PDE)5 inhibitors sildenafil, vardenafil and tadalafil are largely determined by their pharmacokinetic (PK) properties and their PDE5 inhibitory activity profile. This review outlines the basic concepts of pharmacokinetics and pharmacokinetic pharmacodynamic (PK/PD) relationships and their relevance to dose selection and applied pharmacotherapy. It is followed by a detailed comparative discussion on the pharmacokinetics and exposure-response relationship of the currently available PDE5 inhibitors, including known drug-drug interactions and dosage adjustments in special populations. The review is aimed at providing a critical assessment of the pharmacokinetics of PDE5 inhibitors, which may assist clinicians in tailoring drug and/or treatment regimens to the unique needs of each individual patient with erectile dysfunction.

Clinical trial with escalating doses of the antiepidermal growth factor receptor humanized monoclonal antibody EMD 72 000 in patients with advanced squamous cell carcinoma of the larynx and hypopharynx

In this open uncontrolled phase I study, nine patients with stage III and IV squamous cell carcinoma of the head and neck (SCCHN) were treated with five administrations of the humanized antiepidermal growth factor receptor monoclonal antibody EMD 72000 in three consecutive ascending dose groups. Loading doses of 100 mg (group I), 200 mg (group II), and 400 mg (group III) were followed by four weekly maintenance doses of half the loading doses, i.e. 50, 100, and 200 mg, respectively. Two EMD 72000 administrations were scheduled before and three after surgery. The objectives of this trial were (a) to investigate the safety and toxicity of multiple EMD 72000 doses, (b) to determine the cumulative maximum tolerated dose of EMD 72000 at dosages between 300 mg and 1,200 mg, and (c) to determine the serum pharmacokinetics of EMD 72000. In total, 102 adverse events (AEs) were reported: five of toxicity grade 3, 18 of toxicity grade 2, 66 of toxicity grade 1, and 38 of toxicity grade 0. All AEs of toxicity grade 3 were considered to be not or remotely related to EMD 72000. The most frequent study drug-related AEs were fever and a transient elevation of liver enzymes. In all patients, the time to reach peak serum concentrations (tmax) was within 1-3 h of the start of each EMD 72000 infusion. Average peak serum concentrations (Cmax) after correction for dosage appeared to be dose-independent, whereas the half-life (t1/2) showed dose dependency. In conclusion, EMD 72000 was very well tolerated in patients with advanced stage SCCHN. The pharmacokinetic data from this trial suggest the feasibility of conducting future studies with weekly doses of 200 mg EMD 72000.

Pharmacokinetic/pharmacodynamic evaluation of the NHE inhibitor eniporide

The aim of this study was to investigate the pharmacokinetics and pharmacodynamics of the new cardioprotective sodium/proton exchange (NHE-1) inhibitor eniporide in humans. Eniporide was administered intravenously to healthy volunteers in doses between 2.5 and 100 mg. Concentrations of parent drug and its metabolite were measured by HPLC, and the data were analyzed by noncompartmental and compartmental pharmacokinetic methods. Platelet-swelling time was determined in each subject as a biomarker to assess pharmacodynamic activity. Eniporide showed linear pharmacokinetics with an average half-life of approximately 2 hours. The mean total body clearance was 34.4 L/h. The mean volume of distribution (Vdss) was 77.5 L, and the mean residence time was 2.3 hours. An average of 43% of the dose was recovered unchanged from urine. A pharmacokinetic two-compartment model was found suitable to provide excellent curve fits of the measured plasma concentration profiles. Plasma concentrations of the major metabolite were lower than that of the parent drug. An average of 27% of the dose was found in urine as that metabolite. The effect on platelet swelling could be well characterized by a direct Emax model. The average concentration for half-maximum effect (IC50) was 12 ng/mL. Eniporide was found to have predictable linear pharmacokinetics in the investigated dose range. Platelet-swelling time was shown to be a reproducible individual biomarker for pharmacodynamic activity, with great potential for a surrogate that predicts clinical outcome, since this effect is mediated through the same mechanism of action (NHE-1 inhibition) as the desired cardioprotective activity. Pharmacokinetic/pharmacodynamic modeling allowed a first estimate of the degree of NHE inhibition in the investigated dose range.

Determination of free interstitial concentrations of piperacillin-tazobactam combinations by microdialysis

The investigation of tissue penetration and distribution of antibiotics is of great importance, since infections occur mostly in the tissues. The aim of this study was to investigate the pharmacokinetics of piperacillin and tazobactam, alone and in combination, by measuring total plasma and free interstitial concentrations, and to examine the relationship between free levels of both drugs in blood and those in the extracellular space. Piperacillin and tazobactam were administered, alone and in combination, to anaesthetized rats as a single iv bolus dose. Total plasma concentrations and free extracellular concentrations were quantified by HPLC. In-vivo microdialysis sampling was used to study the free tissue distribution patterns of both drugs. The pharmacokinetics of piperacillin and tazobactam in plasma were consistent with a two-compartment body model. Piperacillin pharmacokinetics were not influenced by co-administration of tazobactam. Tazobactam's volumes of distribution and clearance were decreased by the co-administration of piperacillin and the area under the curve was significantly increased. Comparisons between calculated free concentrations in the peripheral compartment for both drugs and measured free extracellular concentrations revealed excellent agreement. For piperacillin and tazobactam, alone and in combination, predictions of the concentration-time profiles of free drug in the peripheral compartment can be made on the basis of plasma data.

Relationship between serum and free interstitial concentrations of cefodizime and cefpirome in muscle and subcutaneous adipose tissue of healthy volunteers measured by microdialysis

Microdialysis is a suitable method to monitor unbound concentrations of antimicrobial drugs in the interstitial tissue space which is the site of many infections. The aim of this investigation was to examine whether free tissue levels of cefodizime (81% plasma protein binding) and cefpirome (10% plasma protein binding) in muscle and subcutaneous adipose tissue of healthy volunteers obtained by microdialysis are consistent with the extent of their respective plasma protein binding. Healthy volunteers were given cefodizine and cefpirome at a single intravenous 2-g dose in a randomized crossover design. Microdialysis probes were inserted into a medial vastus muscle and into the periumbilical subcutaneous layer. After calibration of the probe, samples of serum and microdialysis fluid were obtained and drug concentrations were measured using a microagar diffusion-bioassay. There was a reasonable agreement between plasma protein binding data and the tissue penetration of both cephalosporins (AUC0-infinity tissue, free/AUC0-infinity serum, total-ratios) into the interstitial fluid of the muscle tissue, but not for the subcutaneous tissue layer. Furthermore, the serum and tissue concentrations of both drugs were fitted to an open two-compartment body model. The measured free-tissue concentrations were compared with calculated unbound concentrations in the peripheral compartment. Good agreement was observed for the free muscle concentrations, but unbound concentrations in the subcutaneous tissue was somewhat higher (cefpirome) or lower (cefodizime) than predicted. This may be due to the different lipophilicities of the two compounds.

Comparison of plasma and free tissue levels of ceftriaxone in rats by microdialysis

Ceftriaxone has a very high plasma protein binding (up to 98%) that is saturable and decreases with higher concentrations. This high protein binding results in high concentrations in plasma that are frequently related to the anti-infective activity. However, because only the free fraction of the drug is pharmacologically active and most of the infections are located in the tissues, it is more relevant to evaluate unbound concentrations in the interstitial space. Plasma and tissue pharmacokinetics of ceftriaxone in rats after single intravenous administration were investigated at two different concentrations (50 and 100 mg/kg). Both plasma and tissue samples were taken simultaneously from the same animal and analyzed by reversed-phase high-performance liquid chromatography. Free tissue levels in the thigh muscle were measured by microdialysis. The concentration in plasma is much higher than the free concentration in tissue. After determination of nonlinear protein binding by microdialysis and including these parameters in the pharmacokinetic model, it is possible to predict free concentrations in the interstitial space from plasma levels for any given dose.

Sleep EEG effects of 3,4-methylenedioxyethamphetamine (MDE; "eve") in healthy volunteers

3,4-methylenedioxyethamphetamine (MDE; "Eve") exerts similar psychotropic effects in humans as 3,4-methylenedioxymethamphetamine (MDMA; "Ecstasy") and is less toxic in animal studies. We conducted a double-blind, placebo-controlled, cross-over sleep electroencephalogram (EEG) study with healthy volunteers. One hundred forty milligrams of MDE or placebo were administered PO in six subjects at 11 PM. Sleep EEG was registered from 11 PM-7 AM the next morning. All subjects had a normal sleep onset latency. They all awoke 60 to 120 min after administration of MDE and stayed awake for at least 150 min (total sleep time, TST MDE < placebo and intermittent time awake MDE > placebo: p < 0.001). After again falling asleep rapid eye movement (REM) sleep was totally suppressed (REM during time in bed, TIB MDE < placebo: p < 0.001). A cyclic alternation of relatively long periods of slow wave sleep (SWS) with periods of light sleep occurred in three subjects during the second part of the night (stage 4 in second part of night MDE > placebo: p = 0.16). The effects of MDE on sleep variables largely demonstrate the stimulant, amphetamine-like properties of MDE.