Evaluation by monte carlo simulation of the pharmacokinetics of two doses of meropenem administered intermittently or as a continuous infusion in healthy volunteers

Meropenem is a broad-spectrum carbapenem antibacterial agent. In order to optimize levels in plasma relative to the MICs, the ideal dose level and dosage regimen need to be determined. The pharmacokinetics of meropenem were studied in two groups, each comprising eight healthy volunteers who received the following doses: 500 mg as an intravenous infusion over 30 min three times a day (t.i.d.) versus a 250-mg loading dose followed by a 1,500 mg continuous infusion over 24 h for group A and 1,000 mg as an intravenous infusion over 30 min t.i.d. versus a 500-mg loading dose followed by a 3,000-mg continuous infusion over 24 h for group B. Meropenem concentrations in plasma and urine were determined by liquid chromatography-mass spectrometry/mass spectrometry and high-performance liquid chromatography with UV detection, respectively. Pharmacokinetic calculations were done by use of a two-compartment open model, and the data were extrapolated by Monte Carlo simulations for 10,000 simulated subjects for pharmacodynamic evaluation. There were no significant differences in total clearance and renal clearance between group A and group B or between the intermittent treatment and the continuous infusion. The analyses of the probability of target attainment by MIC for the high- and low-dose continuous infusions were robust up to MICs of 4 mg/liter and 2 mg/liter, respectively. The corresponding values for intermittent infusions were only 0.5 mg/liter and 0.25 mg/liter. When these observations were correlated with MICs obtained from the MYSTIC database, intermittent infusion results in adequate activity against two of the most common nosocomially acquired pathogens, Klebsiella pneumoniae and Enterobacter cloacae. However, against Pseudomonas aeruginosa, the evaluation shows a clear advantage of high-dose therapy administered as a continuous infusion. We believe that in the empirical therapy situation, the continuous-infusion mode of administration is most worth the extra efforts. We conclude that clinical trials for evaluation of the continuous infusions of meropenem in critically ill patients are warranted.     

Comparison of electrically evoked cortical potential thresholds generated with subretinal or suprachoroidal placement of a microelectrode array in the rabbit

The aim of the study was to directly compare the threshold electrical charge density of the retina (retinal threshold) in rabbits for the generation of electrical evoked potentials (EEP) by delivering electrical stimulation with a custom-made microelectrode array (MEA) implanted into either the subretinal or suprachoroidal space. Nine eyes of seven Dutch-belted rabbits were studied. The electroretinogram (ERG), visual evoked potentials (VEP) and EEP were recorded. Electrodes for the VEP and EEP were placed on the dura mater overlying the visual cortex. The EEP was recorded following electrical stimulation of the MEA placed either subretinally beneath the visual streak of the retina or in the suprachoroidal space in the rabbit eye. An ab externo approach was used for placement of the MEA. Liquid perfluorodecaline (PFCL; 0.4 ml) was placed within the vitreous cavity to flatten the neurosensory retina on the MEA after subretinal implantation. The retinal threshold for generation of an EEP was determined for each MEA placement by three consecutive measurements consisting of 100 computer-averaged recordings. Animals were sacrificed at the conclusion of the experiment and the eyes were enucleated for histological examination. The retinal threshold to generate an EEP was 9 +/- 7 nC (0.023 +/- 0.016 mC cm(-2)) within the subretinal space and 150 +/- 122 nC (0.375 +/- 0.306 mC cm(-2)) within the suprachoroidal space. Histology showed disruption of the outer retina with subretinal but not suprachoroidal placement. The retinal threshold to elicit an EEP is significantly lower with subretinal placement of the MEA compared to suprachoroidal placement (P < 0.05). The retinal threshold charge density with a subretinal MEA is well below the published charge limit of 1 mC cm(-2), which is the level below which chronic stimulation of the retina is considered necessary to avoid tissue damage (Shannon 1992 IEEE Trans. Biomed. Eng. 39 424-6).     

Comparison of olanzapine and risperidone in 367 first-episode patients with non-affective or affective psychosis: results of an open retrospective medical record study

INTRODUCTION: Previous studies comparing olanzapine (OLZ) and risperidone (RIS) have tended to focus on multiple-episode patients, with no studies examining their comparative efficacy in a non-selective sample of first-episode psychosis. METHODS: The Early Psychosis Prevention and Intervention Centre in Australia had admitted 786 first-episode psychosis (FEP) patients between 1998-2000. Data were collected from the medical records (MR) of 367 patients, which met inclusion criteria. The primary objective was to evaluate the efficacy of OLZ vs. RIS as measured by CGI-S, CGI-BP (symptomatic level), GAF and SOFAS (functioning level). RESULTS: 367 FEP patients were entered into the study, 278 in the RIS- (2.7 mg/day) and 89 in the OLZ group (10.2 mg/day). No between-group differences were found in non-affective FEP (n = 273). In affective FEP patients (n = 94), mainly treated for acute mania (86.7 %), OLZ treatment was related to better response on the symptomatic (CGI-S; p = .002), but not on the functioning level (GAF and SOFAS; ns). There were trends in the OLZ group towards a higher rate of remission of positive symptoms ( p = .054) and a shorter treatment duration to reach this remission in affective FEP patients ( p = .077). More extrapyramidal side effects ( p <.001) were related to RIS and more weight gain to OLZ-treatment ( p <.001). DISCUSSION: Despite the limitations of a retrospective MR design, study results suggest equal therapeutic efficacy of OLZ and RIS in non-affective FEP and some therapeutic advantages of OLZ compared to RIS in affective FEP patients, especially in those with acute mania. Results may serve as hypotheses for future randomised controlled trials.     

Cellular and physiological effects of medium-chain triglycerides

From a nutritional standpoint, saturated triglycerides with a medium (6 to 12) carbon chain length (MCT) have traditionally been regarded as biologically inert substances, merely serving as a source of fuel calories that is relatively easily accessible for metabolic breakdown compared with long chain triglycerides (LCT). This quality of MCT has been shown to offer both benefits and risks depending on the clinical situation, with potential positive effects on protein metabolism in some studies on one side, and an increased risk for ketogenesis and metabolic acidosis on the other. At another level, studies regarding lipid effects of MCT on the immune system, as with LCT, so far have yielded equivocal results, although there is a recent experimental evidence to suggest that MCT possess immune modulating properties and should in fact be regarded as bioactive mediators. Most of this information comes from studies where effects of MCT have been compared with those of LCT in lipid emulsions, as part of parenteral (intravenous) nutrition formulations. Unfortunately, the relevance of these observations for clinical practice remains largely unclear because adequately powered trials that clearly point out the position of MCT in relation to structurally different lipids have not been performed. In the present paper we review the experimental and clinical evidence for cellular and physiological effects of nutritional MCT. In addition, studies describing possible mechanisms behind the observed effects of MCT will be discussed.     

Successful reduction of in-stent restenosis in long lesions using beta-radiation--subanalysis from the RENO registry

PURPOSE: Long lesions remain a challenging task in interventional cardiology, with a high propensity of restenosis, especially within the stented segment. Although intracoronary gamma-radiation has been proved to reduce diffuse in-stent restenosis in long lesions, such an effect remains to be determined using beta-radiation. METHODS AND MATERIALS: Of 1098 consecutive patients at 46 European centers treated with localized beta-radiation ((90)Sr, Novoste Beta-Cath System), 139 patients (mean age 61.5 +/- 10.7 years, 84% male, 22% with diabetes mellitus) with lesions treated using a >40-mm source length underwent radiation using a single 60-mm source train (34%) or a stepping/pullback procedure with a 30-mm (12%) or 40-mm (87%) source length after conventional interventional procedures. The mean lesion length was 35.3 +/- 17.9 mm. RESULTS: Technical success was achieved in 96% of cases. Geographic miss was noted in 9 patients (6.5%). The reference (placebo) group was obtained from the Washington Hospital Center for In-Stent Restenosis Trial (WRIST) and the WRIST Trial for long lesions (LONG WRIST) studies by selecting the cases (94 patients) that required a dummy source length >/=13 seeds (or >51 mm in length). Statistically significant improvement was noted in late angiographic restenosis (34.7% vs. 76.5%, p <0.0001), target vessel revascularization (14.9% vs. 60.6), and major adverse cardiac events (i.e., death, myocardial infarction, or total vessel revascularization) (17.9% vs. 64.9%, p <0.0001) at 6 months in reference to the nonradiation group. CONCLUSION: This subanalysis from the Radiation in Europe with Novoste study confirms the safety and efficacy of beta-radiation combined with conventional interventional procedures in patients with diffuse, long, in-stent restenosis     

Subjective well-being under antipsychotic treatment and its meaning for compliance and course of disease

Since the introduction of atypical antipsychotics success criteria of an effective antipsychotic treatment are more comprehensive. For instance these criteria include negative symptoms as well as cognitive deficits which are both important for the long-term prognosis of schizophrenia. However, the most fundamental change was the inclusion of the patients' perspective with respect to the treatment. Quality of life assessments as well as evaluation of subjective well-being are of increasing scientific interest and have been assessed in numerous studies. Accordingly there has been ascertained that schizophrenic patients are indeed able to fill out self reports consistently and reliably and it has been shown that patients' perspective differs enormously from the evaluation of psychiatrists with regard to antipsychotic treatment. In consideration of the variety of atypical antipsychotics and different resulting effects for compliance and prognosis of schizophrenia it seems needful to strengthen patients' perspective as an important success criterion of antipsychotic treatment.     

Extended-release ciprofloxacin (Cipro XR) for treatment of urinary tract infections

Symptomatic urinary tract infections (UTIs) constitute a major health problem throughout the Western world. In the USA, UTIs are responsible for 7-8 million outpatient visits each year and for over one-third of all hospital-acquired infections. Empiric antimicrobial therapy for UTIs, which are primarily caused by Escherichia coli, is increasingly being complicated by the emergence of resistance to the most widely used agents. Recent studies indicate that the prevalence of E. coli resistance to trimethoprim/sulphamethoxazole (TMP/SMX), the current first-line therapy for UTIs, exceeds 20% in many North American regions. Importantly, antibiotic resistance often translates into clinical failure. The use of antibiotics with favourable pharmacokinetic/pharmacodynamic profiles and convenient dosing schedules, which effectively increase bacterial eradication and patient compliance, can help to curb the current epidemic of resistance and reduce the rate of clinical failure associated with resistance. Fluoroquinolones have well-established efficacy in the treatment of multiple bacterial infections and, over the years, the rates of resistance to these antibiotics have remained very low. Fluoroquinolones are currently recommended for therapy of uncomplicated UTIs when the local incidence of TMP/SMX resistance is >or=10-20%, as well as for the treatment of complicated UTIs and acute pyelonephritis. Ciprofloxacin, one of the most widely used fluoroquinolones, has a potent bactericidal effect across the full spectrum of uropathogens, as well as a long and excellent efficacy and safety record in the management of UTI and other infections. A recently developed extended (modified)-release formulation of ciprofloxacin (Cipro XR or Cipro XL) provides higher maximum plasma concentrations with lower inter-patient variability than the conventional, immediate-release, twice-daily formulation. Additionally, therapeutic drug levels with extended-release ciprofloxacin are achieved rapidly and maintained over the course of 24 h, allowing once-daily dosing. Clinical trials in patients with cystitis and those with complicated UTIs or acute uncomplicated pyelonephritis indicate that extended-release ciprofloxacin is at least as effective as the immediate-release formulation. These studies have also confirmed good tolerability and safety of extended-release ciprofloxacin, similar to the immediate-release formulation. Therefore, extended-release ciprofloxacin is a convenient, well-tolerated and effective therapy for UTIs that may improve patients' compliance with treatment and thus decrease the risk of treatment failure and the spread of antibiotic resistance.