Prospective use of population pharmacokinetics/pharmacodynamics in the development of cisatracurium

PURPOSE

The population PK/PD approach was prospectively used to determine the PK/PD of cisatracurium in various subgroups of healthy surgical patients.

METHODS

Plasma concentration (Cp) and neuromuscular block data from 241 patients in 8 prospectively-designed Phase I-III trials were pooled and analyzed using NONMEM. The analyses included limited Cp-time data randomly collected from 186 patients in efficacy/safety studies and full Cp-time data from 55 patients in pharmacokinetic studies. The effects of covariates on the PK/PD parameters of cisatracurium were evaluated. The time course of neuromuscular block was predicted for various patient subgroups.

RESULTS

The population PK/PD model for cisatracurium revealed that anesthesia type, gender, age, creatinine clearance, and presence of obesity were associated with statistically significant (p < 0.01) effects on the PK/PD parameters of cisatracurium. These covariates were not associated with any clinically significant changes in the predicted recovery profile of cisatracurium. Slight differences in onset were predicted in patients with renal impairment and patients receiving inhalation anesthesia. Based on the validation procedure, the model appears to be accurate and precise.

CONCLUSIONS

The prospective incorporation of a population PK/PD strategy into the clinical development of cisatracurium generated information which influenced product labeling and reduced the number of studies needed during development.

Identification and resolution of contamination causes found in flexible endoscopes

Although not a requirement for quality control in acute care hospitals, one method of maintaining objective data to verify that endoscopes are contaminant free and not a causative factor in nosocomial infectious is the collection of cultures. There are methods of obtaining cultures from the air, water, and suction channels of flexible endoscopes that require adapters and specific procedures. When automatic disinfectors are connected to public water supplies, this factor should be considered when determining a source of contamination.

Give me discipline and give me death: neoliberalism and health in Chile

The authors examine the connections between apartheid-like social relations and health in pre-Pinochet/neoliberal “democratic” Chile and explore how these intersections have rearticulated with the perpetuation of a neoliberal regime imposed during 20 years of military dictatorship and continued by a Christian Democrat/Socialist neoliberal regime.

Inspiratory muscle endurance in patients with chronic heart failure

OBJECTIVE

To assess the significance of changes in respiratory muscle endurance in relation to respiratory and limb muscle strength in patients with mild to moderate chronic heart failure using a threshold loading technique.

SUBJECTS

20 patients with chronic heart failure (17 male) aged 63.8 (SD 7.4) years and 10 healthy men aged 63.1 (5.6) years. Heart failure severity was New York Heart Association (NYHA) grade II (n = 11) and NYHA grade III/IV (n = 9).

METHODS

Respiratory muscle strength was measured from mouth pressures during maximum inspiratory effort (MIP) at functional residual capacity (FRC) and limb muscle strength was measured using a hand grip dynamometer. Inspiratory muscle endurance was measured using a threshold loading technique. The total endurance duration, the maximum threshold pressure achieved (P-Max), and the inspiratory load (% ratio of P-Max/MIP) were recorded in all subjects.

RESULTS

Inspiratory muscles were weaker in patients with heart failure than in the controls [MIP 53.6 (16.5) v 70.9 (20.2) cm H2O, P < 0.05]. Hand grip strength was similar in both subject groups [31.6 (SD) v 36.1 (15.9) dynes]. Total endurance duration was significantly reduced in the patient group [494 (223) v 996 (267) s, P < 0.01], as was the maximal threshold pressure achieved [P-Max 18.5 (6.4) v 30.7 (6.6) cm H2O, P < 0.01]. When expressed as a percentage of MIP, P-Max was also lower in the patients [35.2 (11.8) v 44.8 (11.4)%, P < 0.05]. There was no significant correlation between any measure of endurance and limb muscle strength.

CONCLUSIONS

Respiratory muscle endurance is reduced in patients with chronic heart failure. These changes probably reflect a generalised skeletal myopathy and provide further evidence of respiratory muscle dysfunction in patients with this disease. Respiratory muscle endurance needs now to be related to symptoms and the effects of treatment and respiratory muscle training should also be explored.

Longitudinal changes in peritoneal kinetics: the effects of peritoneal dialysis and peritonitis

BACKGROUND

Peritoneal infection and poor ultrafiltration continue to be the major causes of treatment failure in CAPD. The combined effects of peritonitis and the continuous exposure to dialysis fluid remain the most likely candidates affecting the peritoneum in the long term. The purpose of this study was to observe the effects of peritonitis and dialysis on longitudinal peritoneal function.

METHODS

The peritoneal equilibration test (PET) was utilized to quantify longitudinal changes in low-molecular-weight solute transfer (D/P(creat)) and ultrafiltration (UF) in 233 patients treated with CAPD. Of these, 166 represented an unselected cohort (Group 1) studied prospectively from commencing treatment for up to 54 months, and 67 were selected patients (Group 2) with PET data available at commencement of the study, having been on dialysis for a minimum of 18 months. PETs were performed either 6-monthly or following peritonitis episodes.

RESULTS

Data on the short-term effect of peritonitis kinetics were pooled for groups 1 and 2. Single, isolated episodes (n = 86) had no significant effect on D/P(creat) or UF, whereas recurrences or clusters of infection (n = 70) caused increases in D/P(creat) and reductions in UF, the significance of which increased with the number of episodes. There were significant correlations between both changes in D/P(creat) and UF with the cumulative dialysate leukocyte count, regardless of infecting organism, suggesting that intensity of peritoneal inflammation is also important. Those organisms associated with greater change in peritoneal kinetics, e.g. S. aureus, Pseudomonas, also had the highest neutrophil counts. The longitudinal changes in peritoneal kinetics were analysed for patients in group 1 only. There was a highly significant increase in D/P(creat) after 6 months treatment; this increased further with time on treatment, reaching further significance at 42 and 48 months. There was an associated reduction in UF. In view of the short-term effects of peritonitis on kinetics group 1 was further subdivided into patients who were either peritonitis free or only experienced isolated infections, group 1a, and those that had multiple infection episodes, group 1b. Treatment drop-out, due to death or technical failure occurred at double the rate in group 1b, who also had significantly higher D/P(creat) and lower UF at 1, 6, 12, 18 and 24 months of treatment. Group 1a subsequently caught up, however, indicating that peritonitis is not the only factor influencing long-term changes in peritoneal kinetics.

CONCLUSIONS

These data suggest that solute transfer increases and UF declines with time on peritoneal dialysis. This process is exacerbated and accelerated by peritonitis, and appears to be proportional to the degree of associated inflammation and number of infections in close proximity.

LP(01)-LP(02) interference using a spectrally extended light source: measurement of the non-step-refractive-index profile of optical fibers

LP(01)-LP(02) interference over an extended wavelength region is used to describe a new spectroscopic technique for determining the refractive-index profile of non-step-index optical fibers. The technique is illustrated with a fiber that shows an alpha-profile variation of the refractive index.

LP(01)-LP(02) interferometric fiber-optic sensing using phase-dependent loss in a light tap

The intensity of light radiated from a fiber-optic light tap is observed to depend sensitively on the phase difference between LP(01) and LP(02) modes in a few-mode fiber. This observation is used to design a novel dual-mode interferometer in which light loss through the light tap is monitored, eliminating the need for a bulky spatial filter at the exit end of the fiber. Application of the device as an interferometric temperature sensor is described.

Functional status of CAPD patients and their mood state, dialysis dose, comorbidity and quality of life

Whilst Continuous Ambulatory Peritoneal Dialysis (CAPD) has sustained the lives of thousands of patients with End Stage Renal Disease (ESRD), renal team members are increasingly confronted with concerns about quality of life. Uraemic symptoms in patients with ESRD are reported to be a source of functional and psychosocial problems, thus diminishing quality of life (1).

This skeptic thought she'd seen it all, but a revolutionary community initiative made her a ... true believer

The board of the Fort Sanders Health System wanted to reach out and improve its community's health. As the largest provider in eastern Tennessee, the communities it served had dramatically different health problems. So they created community councils and put them to work planning for creative ways to respond to their own health needs.

Impact of peritoneal absorption of glucose on appetite, protein catabolism and survival in CAPD patients

Dietary protein and calorie intake, protein catabolism and peritoneal kinetics were measured in 97 CAPD patients to establish the effect of peritoneal glucose absorption on appetite and survival. There was a large variability in the number of calories obtained from the dialysate, mean 5.89 cal/kg (median 5.43 cal/kg), with a skewed distribution, due to the increased requirement for hypertonic solutions by patients with more rapid glucose absorption and poor ultrafiltration. On average calories derived from peritoneal absorption accounted for 19% of the total energy intake which in itself was well below that recommended. Patients with > 6 cal/kg, obtained from the dialysate (top 20th percentile, n = 19) were compared with those with < 6 cal/kg, but no significant differences in oral protein or calorie intake, protein catabolism or total calorie intake were found. Age, body mass index (BMI) and KT/V were also similar in both groups. Patients were followed-up prospectively for a minimum of 24 months and a comparison made of actuarial survival. Patients with high peritoneal calorie intake tended to survive longer but this was not significantly different (p = 0.25). This study suggests that calories derived from the peritoneum in CAPD patients do not suppress appetite, provide a useful and significant proportion of the total energy intake, that does not cause excessive obesity or have a negative effect on patient survival.