Rubella virus (RV)-specific immunoglobulin G antibodies were studied by enzyme-linked immunosorbent assay (ELISA) techniques in sera from RV (RA 27/3)-vaccinated individuals, patients experiencing natural RV infection, congenital rubella syndrome patients, and individuals failing to respond to repeated RV immunization. Results obtained by using whole-RV ELISAs (detergent-solubilized M33 strain or intact Gilchrist strain) and hemagglutination inhibition (HAI) and neutralization (NT) assays were compared with results obtained with the same sera by using ELISAs employing a synthetic peptide, BCH-178, representing a putative neutralization domain on the RV El protein. Murine RV El-specific monoclonal antibodies with HAI and NT activities exhibited strong reactivity in ELISAs with BCH-178 peptide. In sera from RA 27/3-vaccinated individuals collected at 0 (prevaccine), 1, 2, 3, 4, 5, 6, 12, and 24 to 52 weeks postvaccine, the development of El-peptide-reactive antibodies closely paralleled increases in RV-specific antibodies measured by whole-RV ELISAs and HAI and NT assays. Similarly, sequential serum samples obtained from patients during acute and convalescent phases of natural RV infection showed a coordinate increase in RV-specific antibodies as measured by whole-RV and peptide ELISAs. Conversely, congenital rubella syndrome patient sera, although exhibiting high levels of antibody in whole-RV ELISAs, had little or no antibody directed to the neutralization domain peptide. Sera from patients failing to respond to repeated RV immunization contained very low levels of RV-specific antibody in all ELISAs. Our results suggest that the sequence represented by BCH-178 peptide may be a previously unidentified neutralization epitope for human antibodies on the RV El protein and may prove useful in determining effective RV immunity.
Mycophenolate mofetil (MMF) use is increasing in solid organ transplantation. Mycophenolic acid (MPA), the active metabolite of MMF, is highly protein bound and only free MPA is pharmacologically active. The average MPA free fraction in healthy adult individuals, stable renal transplant recipients, and heart transplant recipients is approximately 2 to 3%. However, no data are currently available on MPA protein binding in stable lung transplant recipients and little is known regarding MPA's pharmacokinetic characteristics after lung transplantation. The purpose of this study was to characterize the pharmacokinetic profile and protein binding of MPA in this patient population. Seven patients were entered into the study. On administration of a steady-state morning MMF dose, blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 8, 9, 10, and 12 hours post-dose. Total MPA concentrations were measured by a validated HPLC method with UV detection and followed by ultrafiltration of pooled samples for free MPA concentrations. Area under the curve (AUC), peak concentration (Cmax), time to peak concentration (Tmax), trough concentration (Cmin), free fraction (f), and free MPA AUC were calculated by traditional pharmacokinetic methods. Patient characteristics included; 3 males and 4 females, an average of 4.4 years post-lung transplant (range, 0.3-11.5 yr), mean (+/- SD) age of 50 +/- 10 years and weight 69 +/- 20 kg. Mean albumin concentration was 37 +/- 3 g/L and serum creatinine was 142 +/- 49 micromol/L. All patients were on cyclosporine and prednisone. MMF dosage ranged from 1 to 3 g daily (35.5 +/- 14.1 mg/kg/d; range, 15.2-60.0 mg/kg/d). Mean (+/- SD) AUC was 45.78 +/- 18.35 microg.h/mL (range, 16.56-74.22 microg.h/mL), Cmax was 17.37 +/- 7.69 microg/mL (range, 4.92-26.63 microg/mL), Tmax was 1.2 +/- 0.4 hours (range, 1.0-2.0 h), Cmin was 3.12 +/- 1.41 microg/mL (range, 1.47-4.82 microg/mL), f was 2.90 +/- 0.56% (range, 2.00-3.40%), and free MPA AUC was 1.29 +/- 0.50 microg.h/mL (range, 0.54-1.88 microg.h/mL). This is the first study to determine these pharmacokinetic characteristics of MPA in the lung transplant population. Further studies should focus on identification of MMF dosing strategies that optimize immunosuppressive efficacy and minimize toxicity in lung allograft recipients.
As of September 26, 2003, this is the first study to systematically evaluate MPA pharmacokinetics in thoracic transplant recipients at 3 different time points during the early posttransplant period. Wide interpatient variability in MPA pharmacokinetics was observed, thus emphasizing the need to individualize dosing of MMF and to further evaluate important pharmacokinetic/pharmacodynamic parameters and endpoints that impact on clinical outcomes. Further studies involving more patients and pharmacodynamic outcomes are underway to help identify optimal MMF strategies.
Background: Solutions of vancomycin for oral administration are not available commercially in Canada or the United States but are needed for patients who cannot swallow capsules.Objective: To evaluate the stability of vancomycin solutions stored in unit-dose cups and plastic bottles under refrigeration (4°C) and at room temperature (25°C) for up to 75 days. Methods:Vancomycin 25 mg/mL in Ora-Sweet vehicle and water (1:1 ratio by volume) was dispensed into opaque blue polyethylene unit-dose cups with aluminum seal (14 replicates) or amber plastic prescription bottles (6 replicates). Seven cups and 3 bottles were refrigerated (4°C), and the remainder of the containers were stored at room temperature (25°C). At the time of preparation and at 15, 30, 40, 50, 63, and 75 days, 3 aliquots were collected from one of the cups and from every bottle and were stored frozen (-85°C) until the time of analysis. Physical characteristics were evaluated at each time point, including measurement of pH and visual assessment of colour and precipitation. After thawing, the samples were analyzed in triplicate by a validated stability-indicating high-performance liquid chromatography method. A solution was considered stable if 90% of the initial concentration of vancomycin was maintained. Results:No notable changes in colour, taste, or pH were observed in vancomycin solutions stored in the unit-dose cups at 4°C or 25°C or in the plastic bottles stored at 4°C over the 75-day study period. Starting on day 63, a white precipitate was observed in the solutions stored in plastic bottles at 25°C, but there were no notable changes in taste or pH during the 75-day period. The 95% confidence interval of the slope of the curve relating concentration to time, determined by linear regression, indicated that vancomycin solutions stored in cups or bottles at 4°C would maintain at least 93.6% of the initial vancomycin concentration for 75 days and that solutions stored at 25°C would maintain at least 90.0% of the initial concentration for 30 days (cups) or 26 days (bottles), with 95% confidence. Conclusions:Vancomycin 25 mg/mL stored in unit-dose cups or plastic bottles at 4°C was stable for at least 75 days, whereas solutions stored in cups or bottles at 25°C are expected to be stable for 30 or 26 days, respectively.
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