Pharmacokinetic and Pharmacodynamic Analyses To Determine the Optimal Fixed Dosing Regimen of Iclaprim for Treatment of Patients with Serious Infections Caused by Gram-Positive Pathogens.

Iclaprim is a bacterial dihydrofolate reductase inhibitor that is currently being evaluated in two phase 3 trials for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI). Prior animal infection model studies suggest that the pharmacokinetic/pharmacodynamic (PK/PD) drivers for efficacy are area under the concentration-time curve from 0 to 24 h at steady state (AUC0-24ss), AUC/MIC, and time above the MIC during the dosing interval (T > MIC), while QTc prolongation was associated with the maximal concentration at steady state (Cmaxss) in a thorough QTc phase 1 study. Using PK data collected from 470 patients from the previously conducted phase 3 complicated skin and skin structure infection (cSSSI) trials, population PK modeling and Monte Carlo simulation (MCS) were used to identify a fixed iclaprim dosage regimen for the ongoing phase 3 ABSSSI studies that maximizes AUC0-24ss, AUC/MIC, and T > MIC while minimizing the probability of a Cmaxss of ≥800 ng/ml relative to the values for the previously employed cSSSI regimen of 0.8 mg/kg of body weight infused intravenously over 0.5 h every 12 h. The MCS analyses indicated that administration of 80 mg as a 2-h infusion every 12 h provides 28%, 28%, and 32% increases in AUC0-24ss, AUC/MIC, and T > MIC, respectively, compared to values for the 0.8-mg/kg cSSSI regimen, while decreasing the probability of a Cmaxss of ≥800 ng/ml, by 9%. Based on PK/PD analyses, 80 mg iclaprim administered over 2 h every 12 h was selected as the dosing scheme for subsequent phase 3 clinical trials.

Four-Factor Prothrombin Complex Concentrate for Coagulopathy Reversal in Patients With Liver Disease.

A 4-factor prothrombin complex concentrate (4F-PCC, Kcentra®) was recently approved in the United States for the reversal of vitamin K antagonist-associated major bleeding, but it is often used to reverse coagulopathy in patients with liver disease (LD). This single-center, retrospective study analyzed the efficacy and safety of 4F-PCC administered in patients with and without LD. Prothrombin time/International Normalized Ratio (PT/INR) reversal with 4F-PCC was attempted in 85 patients; LD was documented in 31 patients. Coagulopathy reversal and hemostasis with 4F-PCC were inferior in patients with LD compared to patients without LD. Coagulopathy reversal, defined as INR = 1.5 after 4F-PCC administration, was achieved in 6 (19.4%) LD patients, compared to 44 (81.5%) non-LD patients ( p < 0.01). Hemostasis was achieved in 6 LD patients (19.4%) compared to 23 non-LD patients (42.6%) ( p = 0.03). Thromboembolic events occurred in 1 LD patient (3.2%) and 8 non-LD patients (14.8%) ( p = 0.15). Mortality was 51.6% in LD patients and 18.5% in non-LD patients ( p < 0.01). These observations suggest that the efficacy of 4F-PCC is suboptimal to correct coagulopathy and hemostasis in patients with LD, who have high rates of in-hospital mortality due to sequelae of LD. The incidence of thromboembolic events appeared comparable, suggesting that 4F-PCC does not cause undue thromboembolism in LD patients. In conclusion, 4F-PCC appears to be safe in LD patients when administered judiciously; however, further studies are necessary to optimize its use and elucidate its hemostatic potential in this patient population.

Plasma Levels of Advanced Glycation End Products Are Related to the Clinical Presentation and Angiographic Severity of Symptomatic Lower Extremity Peripheral Arterial Disease.

Evidence implicates a role of advanced glycation end products (AGEs) in the development of atherosclerosis. The present study examined the relationship between plasma levels of AGEs and the clinical and angiographic characteristics of patients with symptomatic peripheral arterial disease (PAD). A total of 40 consecutive patients with symptomatic lower extremity PAD undergoing invasive evaluation were enrolled. Clinical history, angiographic data, and plasma levels of total AGE (tAGE), N'-carboxymethyllysine (CML), and high-sensitivity C-reactive protein were obtained. In multivariate analyses, there were independent relationships noted between tAGE levels and the presence of critical limb ischemia (CLI) (r (2) = 0.195, p = 0.003), Rutherford stage (r (2) = 0.351, p < 0.001), and the average below the knee (BTK) score (r (2) = 0.119, p = 0.006). Presence of CLI (r (2) = 0.154, p = 0.012) and the Rutherford stage (r (2) = 0.194, p = 0.003) were associated with CML levels. We demonstrate a relationship between tAGE and the symptom profile of patients with PAD and an association between tAGE and infrapopliteal angiographic disease severity. Both tAGE and CML levels were related to the presence of CLI. These data suggest that AGE levels may reflect the severity of PAD and may be of importance in CLI.

High-fidelity simulation training in advanced resuscitation for pharmacy residents.

OBJECTIVE: To assess the impact of high-fidelity patient simulation on pharmacy resident knowledge, confidence, and competency with advanced resuscitation algorithms and interventions. DESIGN: An overview of the institutional cardiopulmonary arrest algorithm and a review of pertinent medications and calculations were presented to postgraduate year 1 (PGY1) pharmacy residents, followed by participation in 3 simulated clinical scenarios using a high-fidelity mannequin. ASSESSMENT: An improvement of pharmacy resident knowledge, confidence, and competency with advanced resuscitation skills was observed. In addition, pharmacy residents demonstrated high performance levels with skills requiring advanced competency and proactive interactions with the cardiac arrest team. CONCLUSION: Incorporating high-fidelity patient simulation into an advanced resuscitation training program can help pharmacy residents achieve competency through the active learning of practical skills.

Plerixafor as first- and second-line strategies for autologous stem cell mobilization in patients with non-Hodgkin's lymphoma or multiple myeloma.

STUDY OBJECTIVE: To describe the institutional experience of plerixafor plus filgrastim as the initial peripheral blood stem cell (PBSC) mobilization (first-line strategy) and as rescue therapy after failure with filgrastim plus cyclophosphamide (second-line strategy). DESIGN: Retrospective medical record review. SETTING: Academic medical center. PATIENTS: Thirty-three patients (median age 62 yrs) who received plerixafor between January 2008 and December 2009. MEASUREMENTS AND MAIN RESULTS: We collected data on total CD34(+) cell yield and number of apheresis sessions in both first-line and second-line plerixafor recipients. Mobilization with plerixafor plus filgrastim resulted in a median yield of 8.95 × 10(6) and 2.45 × 10(6) CD34(+) cells/kg in patients with multiple myeloma or non-Hodgkin's lymphoma, respectively. As rescue mobilization, plerixafor plus filgrastim successfully mobilized CD34(+) cells in 16 (84%) of 19 patients. When comparing first-line plerixafor plus filgrastim therapy with second-line therapy, we found an increase in CD34(+) yield and 1 less apheresis day in patients with multiple myeloma, but no difference in patients with non-Hodgkin's lymphoma. CONCLUSION: A regimen of plerixafor plus filgrastim successfully mobilized CD34(+) cells in a median of 1 apheresis day for patients with multiple myeloma and 2 apheresis days for patients with non-Hodgkin's lymphoma, including patients who failed initial filgrastim plus cyclophosphamide mobilization. Plerixafor plus filgrastim could be a viable first-line option in patients with multiple myeloma, as it improved CD34(+) cell yield and decreased number of apheresis days compared with second-line plerixafor plus filgrastim therapy, whereas it was comparable to second-line therapy in patients with non-Hodgkin's lymphoma.

Inclusion of a CRF01_AE HIV envelope protein boost with a DNA/MVA prime-boost vaccine: Impact on humoral and cellular immunogenicity and viral load reduction after SHIV-E challenge.

The current study assessed the immunogenicity and protective efficacy of various prime-boost vaccine regimens in rhesus macaques using combinations of recombinant DNA (rDNA), recombinant MVA (rMVA), and subunit gp140 protein. The rDNA and rMVA vectors were constructed to express Env from HIV-1 subtype CRF01_AE and Gag-Pol from CRF01_AE or SIVmac 239. One of the rMVAs, MVA/CMDR, has been recently tested in humans. Immunizations were administered at months 0 and 1 (prime) and months 3 and 6 (boost). After priming, HIV env-specific serum IgG was detected in monkeys receiving gp140 alone or rMVA but not in those receiving rDNA. Titers were enhanced in these groups after boosting either with gp140 alone or with rMVA plus gp140. The groups that received the rDNA prime developed env-specific IgG after boosting with rMVA with or without gp140. HIV Env-specific serum IgG binding antibodies were elicited more frequently and of higher titer, and breadth of neutralizing antibodies was increased with the inclusion of the subunit Env boost. T cell responses were measured by tetramer binding to Gag p11c in Mamu-A*01 macaques, and by IFN-γ ELISPOT assay to SIV-Gag. T cell responses were induced after vaccination with the highest responses seen in macaques immunized with rDNA and rMVA. Macaques were challenged intravenously with a novel SHIV-E virus (SIVmac239 Gag-Pol with an HIV-1 subtype E-Env CAR402). Post challenge with SHIV-E, antibody titers were boosted in all groups and peaked at 4 weeks. Robust T cell responses were seen in all groups post challenge and in macaques immunized with rDNA and rMVA a clear boosting of responses was seen. A greater than two-log drop in RNA copies/ml at peak viremia and earlier set point was achieved in macaques primed with rDNA, and boosted with rMVA/SHIV-AE plus gp140. Post challenge viremia in macaques immunized with other regimens was not significantly different to that of controls. These results demonstrate that a gp140 subunit and inclusion of SIV Gag-Pol may be critical for control of SHIV post challenge.

Breast milk hydrocodone and hydromorphone levels in mothers using hydrocodone for postpartum pain.

OBJECTIVE: To estimate the extent of passage of hydrocodone and its active metabolite, hydromorphone, into breast milk. METHODS: This is a pharmacokinetic study of 30 postpartum women receiving hydrocodone bitartrate for postpartum pain in the inpatient setting. Mothers donated timed breast milk samples for the analysis of hydrocodone and hydromorphone. RESULTS: Fully breastfed neonates received 1.6% (range 0.2%-9%) of the maternal weight-adjusted hydrocodone bitartrate dosage. When combined with hydromorphone, the total median opiate dosage from breast milk is 0.7% of a therapeutic dosage for older infants. Most mothers excreted little to no hydromorphone into breast milk. CONCLUSION: Standard postpartum dosages of hydrocodone bitartrate appear to be acceptable to use in women nursing newborns. Prolonged use of high dosages is not advisable.

Hydrocodone excretion into breast milk: the first two reported cases.

Hydrocodone is a narcotic that is widely used, often in nursing mothers. Although case reports suggest that hydrocodone in breast milk sometimes may be problematic for the breastfed infant, no reports exist on the amount of its excretion into breast milk. Two mothers who were taking an acetaminophen and hydrocodone combination product donated pumped milk for analysis of hydrocodone. Their infants received an estimated 3.1% and 3.7% of the maternal weight-adjusted dosage, but the absolute hydrocodone dosages were 8.58 microg/kg per day and 3.07 microg/kg per day because of the differences in the dosages ingested by their mothers. Moderate dosages of hydrocodone appear acceptable during breastfeeding, but more data are needed to determine the maximum safe dosage for nursing mothers. Neonates and preterm infants may be more susceptible than older infants to adverse effects of hydrocodone and its metabolites in breast milk.

Inhibition of pentagastrin-stimulated gastric acid secretion by pantoprazole and omeprazole in healthy adults.

Our objective was to compare the onset and duration of a single dose of pantoprazole or omeprazole on maximally stimulated gastric acid secretion. This double-blind, randomized, placebo-controlled study involved 36 healthy adults and utilized continuous pentagastrin infusion to stimulate acid secretion after administration of pantoprazole, 40 mg, omeprazole, 20 mg, or placebo. Gastric aspirates were collected over 24 hr and analyzed for volume, pH, and hydrogen ion concentration, and gastric acid outputs (GAO) were calculated. Comparison between GAO and intragastric pH was performed. Pantoprazole resulted in significantly greater inhibition of GAO than omeprazole. Mean cumulative 24-hr GAO was 164 +/- 130 mEq for pantoprazole versus 283 +/- 159 mEq for omeprazole (P = 0.031). Pantoprazole patients reached and maintained GAO levels below the 10-mEq/hr threshold at 5.7 hr, whereas omeprazole patients never reached this threshold. We conclude that pantoprazole significantly suppressed gastric acid secretion compared to omeprazole. Comparisons between pH and GAO showed that GAO was a more appropriate measure of gastric acid secretion than intragastric pH.

Pharmacokinetics of UH and LMWH are similar with respect to antithrombin activity.

BACKGROUND: The ability to administer low molecular weight heparins (LMWH) subcutaneously without laboratory monitoring contributes to their popularity for the treatment of thrombotic disorders. Subcutaneous unfractionated heparin, although less expensive, is deemed to require routine laboratory monitoring on the basis of more variability in drug effect compared to LMWH. However, the more predictable pharmacokinetic profiles of low molecular weight heparins are largely based on anti-Xa activity, while antithrombin activity may be at least as important to their mechanisms of action. METHODS: We performed a clinical pharmacokinetic trial to compare the variability in peak antithrombin effect between subcutaneous unfractionated heparin and various LMWHs, all given in recommended weight-adjusted treatment doses. Sixty-one patients enrolled in a warfarin clinic were randomized to receive one of four different weight-adjusted subcutaneous heparin doses: unfractionated heparin, 250 units/kg (n=15); tinzaparin, 175 units/kg (n=15); dalteparin, 200 units/kg (n=15); or enoxaparin, 1 mg/kg (n=16). The areas under the curves of antithrombin levels during the first 3 h after administration were determined for each patient, and the coefficients of variation (CV) and 95% confidence intervals of the AUCs were compared among the treatment groups. RESULTS: There was no statistically significant difference in the coefficients of variation of antithrombin effect between unfractionated heparin (52.8, 95% CI: 32.6-72.9) and enoxaparin (56.5, 95% CI: 35.7-77.4) or dalteparin (43.5, 95% CI 25.4-61.6). Tinzaparin had statistically significant decrease in coefficients of variation (21.6, 95% CI: 12.2-30.9) relative to unfractionated heparin, dalteparin and enoxaparin. CONCLUSIONS: LMWHs, as a class of drugs, are no more predictable in antithrombin effect after subcutaneous injection than unfractionated heparin. There were considerable differences among LMWHs in the observed variability of antithrombin effects, with tinzaparin being somewhat more predictable than the other drugs tested.

Population pharmacokinetics III: design, analysis, and application of population pharmacokinetic Studies.

OBJECTIVE: To present a framework within which population pharmacokinetic (PPK) studies should be designed and analyzed and discuss the application of developed PPK models. METHODS: Information on PPK was retrieved from a MEDLINE search (1979-December 2003) of the literature and a bibliographic evaluation of review articles and books. This information is used in conjunction with experience to explain the design and analysis of PPK studies. Also, examples are included to demonstrate the usefulness of PPK. SYNTHESIS: A great deal of thought must be given to the design and analysis of PPK studies (ie, development of PPK models). Models are of 2 primary types--descriptive and predictive--and the process applied to these models is necessarily different. An approach that ensures model applicability is presented. CONCLUSIONS: PPK models have great utility, and the applications are many. They are very different from single-subject pharmacokinetic models and therefore require different approaches to model estimation.

Model appropriateness and population pharmacokinetic modeling.

The purpose of this study was to define model appropriateness, identifying the individual elements thereof, and to set out a framework within which model appropriateness could be determined for population pharmacokinetic (PPK) models. Model appropriateness was defined by stating the problem to be solved, with the intended use of the model being the pivotal event. The elements of model appropriateness were identified with the type of model (descriptive vs. predictive) determining which elements of model appropriateness need to be executed. An example is presented to show how model appropriateness is determined for the optimal application of PPK models. It was determined that PPK models are developed to solve problems. Model appropriateness depends on identifying the problem, as well as stating the intended use of the model, and requires evaluation of the model for goodness of fit, reliability, and stability if intended for descriptive purposes; for predictive models, validation would be an additional requirement. Descriptive models are used to explain variability in the pharmacokinetics (PK) of a drug, while predictive models are developed to extrapolate beyond the immediate study population. For those models used for predictive purposes, strong assumptions are made about the relationship to the underlying population from which the data were collected. As an example of determining model appropriateness, a PPK model for 5-fluorocytosine was developed, using NONMEM, version IV. The model was evaluated and validated by the process of percentile bootstrapping. From the PPK model, the range of expected serum concentrations based on two widely used dosing methods (Sanford and the University of California at San Diego [UCSD]) was simulated (Pharsight Trial Designer software). These results indicated that the UCSD method performed well and has the advantage of recommending convenient dosing intervals. In conclusion, considering and applying the principles of model appropriateness to PPK models will result in models that can be applied for their intended use with confidence. Model appropriateness was efficiently established and determined to address the problem of comparing competing dosing strategies.

Among 46 near full length HIV type 1 genome sequences from Rakai District, Uganda, subtype D and AD recombinants predominate.

The impact of HIV-1 genetic diversity on candidate vaccines is uncertain. To minimize genetic diversity in the evaluation of HIV-1 vaccines, vaccine products must be matched to the predominant subtype in a vaccine cohort. To that end, full genome sequencing was used to detect and characterize HIV-1 subtypes and recombinant strains from individuals in Rakai District, Uganda. DNA extracted from peripheral blood mononuclear cells (PMBC) was PCR amplified using primers in the long terminal repeats (LTRs) to generate nearly full length genomes. Amplicons were directly sequenced with dye terminators and automated sequencers. Sequences were phylogenetically analyzed and recombinants were detected and mapped with distance scan and bootscan. Among 46 sequences, 54% were subtype D, 15% were subtype A, and 30% were recombinant. All recombinants were individually unique, and most combined subtypes A and D. Subtype D comprised more than 70% of all the HIV-1 genomes in Rakai when both pure subtypes and recombinants were considered. Candidate vaccines based on HIV-1 subtype D would be appropriate for evaluation in Rakai District, Uganda.