Pharmacokinetics and safety of multiple doses of daptomycin 6 mg/kg in noninfected adults undergoing hemodialysis or continuous ambulatory peritoneal dialysis.

AIMS: The purpose of this study was to characterize the pharmacokinetics and tolerability of daptomycin in subjects undergoing hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). METHOD: 16 noninfected adults on stable dialysis regimens were enrolled. Daptomycin 6 mg/kg was administered after HD during a 48 h - 48 h - 72 h dialysis week or before a CAPD dwell time over a 48 h - 48 h - 48 h dialysis week. Pharmacokinetic parameters were described, and adverse events were monitored. RESULTS: Daptomycin had mean half-lives in HD subjects of 28.0 and 35.9 h on Days 1 and 5, with corresponding values of 25.8 and 26.7 h in CAPD subjects. Steady state was reached by Day 5 in both groups. At steady state, HD subjects had a mean peak plasma concentration (Cmax) of 81.6 µg/ml and a mean trough concentration of 15.3 µg/ml (on Day 8). In CAPD subjects, Cmax was 93.9 µg/ml and the trough was 20.7 µg/ml (on Day 7). Adverse events were experienced by 71.4% and 66.7% of HD and CAPD subjects, respectively. Most of these were mild or moderate in intensity; however, 2 subjects experienced muscle spasms and mild creatine phosphokinase elevations although neither event was considered to be related to study drug. CONCLUSIONS: The pharmacokinetics of daptomycin 6 mg/kg support a dosing regimen of every 48 h in CAPD and thrice-weekly dosing in HD.

The value, qualification, and regulatory use of surrogate end points in drug development.

The acceptance and use of either surrogate end points (SEPs) or efficient clinical end points are associated with greater and more rapid availability of new medicines as compared with disease situations for which clinical end points are inefficient or no surrogates exist. This review of the history of the development, qualification, and acceptance of key SEPs shows that both successes and failures had three key characteristics: (i) apparent biologic plausibility, (ii) prognostic value for the outcome of the disease, and (iii) an association between changes in the SEP and changes in outcome with therapeutic intervention--the three factors recommended for SEPs in the International Conference on Harmonisation's "Statistical Principles for Clinical Trials." We recommend that only prognostic value be an absolute prerequisite for surrogacy, because therapeutic interventions may not exist a priori, and biological plausibility can be subjective. Ideally, all three of these factors would be traded off against one another in a consistent and transparent risk-management process.

The efficacy and safety of daptomycin vs. vancomycin for the treatment of cellulitis and erysipelas.

BACKGROUND: Results from previous trials suggest that daptomycin may result in faster clinical improvement than penicillinase-resistant penicillins or vancomycin for patients with complicated skin and skin structure infections. OBJECTIVE: The objective was to evaluate whether daptomycin treatment of cellulitis or erysipelas would result in faster resolution compared with vancomycin. DESIGN: The study was a prospective, evaluator-blinded, multi-centre trial. Patients were randomised to receive daptomycin 4 mg/kg once daily or vancomycin according to standard of care for 7-14 days. PATIENTS: Adults diagnosed with cellulitis or erysipelas requiring hospitalisation and intravenous antibiotic therapy were eligible for enrolment. RESULTS: The clinical success rates were 94.0% for daptomycin and 90.2% for vancomycin (95% confidence interval for the difference, -6.7%, 14.3%). There were no statistically significant differences between treatment arms in the time to resolution or improvement in any of the predefined clinical end-points. Both daptomycin and vancomycin were well tolerated. CONCLUSIONS: There was no difference in the rate of resolution of cellulitis or erysipelas among patients treated with daptomycin or vancomycin. Daptomycin 4 mg/kg once daily appeared to be effective and safe for treating cellulitis or erysipelas.

Acute bacterial maxillary sinusitis: time to symptom resolution and return to normal activities with moxifloxacin.

OBJECTIVES: This prospective, single-arm, open-label, multicentre phase IV (postmarketing surveillance) study determined time to resolution of key symptoms and return to normal activities in adults with acute bacterial maxillary sinusitis treated with moxifloxacin 400 mg qd for 10 days. The study also assessed whether responses to the Sino-Nasal Outcome Test-16 (SNOT-16) questionnaire [not yet validated for acute bacterial sinusitis (ABS)] accurately reflect clinical findings in these patients. METHODS: Adults with a clinical diagnosis of acute bacterial maxillary sinusitis with signs/symptoms present for > or = 7 but < 28 days took part. Patients were evaluated bacteriologically and clinically on day 1 (pretherapy), days 2-4 and 10-13 (test of cure), for bacterial presence and improvement/resolution of the signs/symptoms of acute bacterial maxillary sinusitis. They completed SNOT-16 and Activity Impairment Assessment questionnaires daily, before receiving moxifloxacin, until day 10. RESULTS: In both the bacteriologically and clinically evaluable populations, over 85% of patients showed clinical improvement by day 2, rising to over 96% by day 4. Pretherapy, according to the SNOT-16 questionnaire, almost all of the bacteriologically evaluable patients reported facial pain/pressure but this proportion had fallen to below 50% by day 4. In the bacteriologically evaluable population, 32/42 (76%) patients reported an improvement in facial pain/pressure from the pretherapy visit to day 4. Of patients showing improvement, 50% improved from 'moderate-to-severe facial pain' at pretherapy to 'no problem' at day 4. At day 4, 45-50% of patients reported impairment of normal activities, compared with 79-88% pretherapy. CONCLUSIONS: Moxifloxacin rapidly improves the signs and symptoms of acute bacterial maxillary sinusitis and results in clinical cure in most patients. Responses to the SNOT-16 questionnaire accurately reflected clinical assessments, indicating that when fully validated the SNOT-16 questionnaire may be a valuable tool for the assessment of patient outcomes in ABS.

Complicated urinary tract infections treated with extended-release ciprofloxacin with emphasis on Pseudomonas aeruginosa.

This report focuses on the role of Pseudomonas aeruginosa in complicated urinary tract infections in a prospective, open-label, multicenter study designed to evaluate the safety and efficacy of extended-release ciprofloxacin (ciprofloxacin XR) 1000 mg once daily for 7-14 days for the treatment of complicated urinary tract infections. A total of 204 patients were valid for intention-to-treat analysis, of whom 130 were included in the clinical efficacy population. In the 56 microbiologically valid patients the bacteriological eradication rate was 82.1% and the clinical cure rate was 94.6%. Patients with P. aeruginosa infections valid for microbiological efficacy (n = 7) had 100% bacteriological eradication and clinical cure rates. In the intention-to-treat population, the bacteriological and clinical cure rates were 42.1% (51/121) and 55.9% (114/204), respectively. These rates were 58.3% and 75.0% respectively, for patients with P. aeruginosa infections. To achieve the desired 10 patients with P. aeruginosa for analysis, these data were pooled with data from a previous study. Treatment failure correlated with pre-therapy P. aeruginosa isolates being resistant to ciprofloxacin. On exploratory multivariate regression analysis, presence of neurogenic bladder, urinary retention owing to benign prostatic hypertrophy, prior urinary tract infection, and ischemic heart disease predicted P. aeruginosa infection.

Cell fusion induced by herpes simplex virus glycoproteins gB, gD, and gH-gL requires a gD receptor but not necessarily heparan sulfate.

To characterize cellular factors required for herpes simplex virus type 1 (HSV-1)-induced cell fusion, we used an efficient and quantitative assay relying on expression of HSV-1 glycoproteins in transfected cells. We showed the following: (1) Cell fusion depended not only on expression of four viral glycoproteins (gB, gD, and gH-gL), as previously shown, but also on expression of cell surface entry receptors specific for gD. (2) Cell fusion required expression of all four glycoproteins in the same cell. (3) Heparan sulfate was not required for cell fusion. (4) Coexpression of receptor with the four glycoproteins in the same cell reduced fusion activity, indicating that interaction of gD and receptor can limit polykaryocyte formation. Overall, the viral and cellular determinants of HSV-1-induced cell fusion are similar to those for viral entry, except that HSV-1 entry is significantly enhanced by binding of virus to cell surface heparan sulfate.

Human herpesvirus-8 glycoprotein B interacts with Epstein-Barr virus (EBV) glycoprotein 110 but fails to complement the infectivity of EBV mutants.

To characterize human herpesvirus 8 (HHV-8) gB, the open reading frame was PCR amplified from the HHV-8-infected cell line BCBL-1 and cloned into an expression vector. To facilitate detection of expressed HHV-8 gB, the cytoplasmic tail of the glycoprotein was tagged with the influenza hemagglutinin (HA) epitope. Expression of tagged HHV-8 gB (gB-HA), as well as the untagged form, was readily detected in CHO-K1 cells and several lymphoblastoid cell lines (LCLs). HHV-8 gB-HA was sensitive to endoglycosidase H treatment, and immunofluorescence revealed that HHV-8 gB-HA was detectable in the perinuclear region of CHO-K1 cells. These observations suggest that HHV-8 gB is not processed in the Golgi and localizes to the endoplasmic reticulum or nuclear membrane. Because both HHV-8 and EBV are gamma-herpesviruses, the ability of HHV-8 gB to interact with and functionally complement EBV gp110 was examined. HHV-8 gB-HA and EBV gp110 co-immunoprecipitated, indicating formation of hetero-oligomers. However, HHV-8 gB-HA and HHV-8 gB failed to restore the infectivity of gp110-negative EBV mutants. These findings indicate that although HHV-8 gB and EBV gp110 have similar patterns of intracellular localization and can interact, there is not sufficient functional homology to allow efficient complementation.

Partial resistance to gD-mediated interference conferred by mutations affecting herpes simplex virus type 1 gC and gK.

Cells expressing herpes simplex virus (HSV) gD can be resistant to HSV entry as a result of gD-mediated interference. HSV strains differ in sensitivity to this interference, which blocks viral penetration but not binding. Previous studies have shown that mutations or variations in virion-associated gD can confer resistance to gD-mediated interference. Here we show that HSV-1 mutants selected for enhanced ability to bind and penetrate in the presence of inhibitory concentrations of heparin were partially resistant to gD-mediated interference. The resistance was largely due to the presence of two mutations: one in gC (the major heparin-binding glycoprotein) resulting in the absence of gC expression and the other in gK resulting in a syncytial phenotype. The results imply that heparin selected for mutants with altered postbinding requirements for entry. Resistance to gD-mediated interference conferred by mutations affecting gC and gK has not been previously described.

Modified entry and syncytium formation by herpes simplex virus type 1 mutants selected for resistance to heparin inhibition.

Herpes simplex virus type 1 (HSV-1) mutants were selected by passage of HSV-1 (KOS) in HEp-2 cells such that binding and penetration occurred in the presence of heparin. Analysis of selected uncloned virus pools revealed that approximately 95% of virus formed syncytia and greater than 58% were gC-negative. Plaque-purified gC-negative syncytial mutants were more resistant than HSV-1 (KOS) to heparin inhibition, as was an engineered nonsyncytial recombinant deleted for gC, delta gC6. Thus, absence of gC was sufficient to explain the enrichment for gC-negative mutants. The syncytial phenotype of most mutants mapped to a mutation in gK. Transfer of this mutation to HSV-1 (KOS) resulted in a recombinant that induced fusion of Vero cells but not HEp-2 cells and was more sensitive to heparin inhibition of entry, revealing a previously undescribed phenotype of mutations in gK. Engineered gC-negative virus containing the gK syncytial mutation induced fusion of both cell lines and was as resistant to heparin inhibition as was delta gC6. Because deletion of gC reduces infectivity of HSV-1 in the absence of heparin, mutations in gC combined with the syncytial mutation could have provided a selective advantage. Thus, absence of gC reduced heparin inhibition of binding and penetration while the combination of the gC and gK mutations enhanced spread through the HEp-2 cell monolayer by cell fusion. Because extreme selective pressure was required to favor these mutations and such mutations are rare in clinical isolates, the wild-type forms of gC and gK must provide for optimal viral replication and propagation in cell culture as well as in vivo, despite the view that gC is dispensable in cultured cells.

Adverse reactions to dapsone in persons infected with human immunodeficiency virus.

Dapsone is used in prophylaxis for and treatment of Pneumocystis carinii pneumonia. We present a case of Stevens-Johnson syndrome that was likely induced by administration of dapsone. A review of charts at the HIV Treatment Center of Northwestern University (Chicago) revealed that 40.3% of patients treated with trimethoprim-sulfamethoxazole could not tolerate the medication, while 25.2% of those treated with dapsone were intolerant of the drug. We also found a higher rate of adverse reactions to dapsone among patients with prior intolerance to trimethoprim-sulfamethoxazole than among patients without such a history; however, the difference was not significant.

Risk of developing cytomegalovirus retinitis in persons infected with the human immunodeficiency virus.

This study examines the risk of developing cytomegalovirus (CMV) retinitis as a function of the duration and degree of CD4+ lymphocyte depletion. A retrospective analysis of 135 persons infected with the human immunodeficiency virus (HIV) was performed. Kaplan-Meier estimates for the percentage of patients developing CMV retinitis during the 27-month study period were calculated. Twenty-six patients were diagnosed as having CMV retinitis. In 14 of these patients, T cell phenotyping was done within the 3 months preceding diagnosis. The mean CD4+ lymphocyte count for these patients was 15.6 cells/mm3 (range, 2-33/mm3). At 27 months, the percentage of patients developing CMV retinitis with baseline CD4+ lymphocyte counts of 0-50, 51-100, and 101-250 cells/mm3 was 41.9%, 26.3%, and 14.7%, respectively (log-rank test, p = 0.003). The odds ratio for developing CMV retinitis for those with baseline CD4+ lymphocyte counts of 0-50 cells/mm3 compared with those with CD4+ lymphocyte counts of 101-250 cells/mm3 was 4.62 (p = 0.002). Twenty-four patients had CD4+ lymphocyte counts of < or = 50 cells/mm3 for an average of 13.1 months prior to diagnosis. Twenty-two patients had an acquired immune deficiency syndrome (AIDS)-defining illness diagnosed for an average of 18.0 months prior to the onset of retinitis. CMV retinitis is most likely to develop in patients with AIDS when the CD4+ lymphocyte count is < or = 50 cells/mm3.