Stacey A Henning

National Institutes of Health, Bethesda, MD, United States

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Publications (9)25.25 Total impact

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    ABSTRACT: There is a paucity of pharmacokinetic studies describing weight-based dosing of intravenous voriconazole in obese patients. In this case report, we describe the pharmacokinetics of intravenous voriconazole in an obese CYP2C19 homozygous poor metabolizer and review previously reported data regarding the use of intravenous voriconazole in obese patients. A 17-year-old obese Hispanic male patient (body mass index 35 kg/m ) received intravenous voriconazole for the treatment of suspected aspergillosis. After 2.5 days of voriconazole 4 mg/kg intravenously every 12 hours based on adjusted body weight, the voriconazole area under the serum concentration-time curve over the course of a single (12-hr) dosing interval and trough concentration were 86,100 ng · hr/ml and 6.2 µg/ml, respectively. Six days later, the voriconazole dosage was decreased. A trough concentration measured just before the dosage reduction (after 8.5 days of voriconazole 4 mg/kg intravenously every 12 hours based on adjusted body weight) remained elevated at 5.8 µg/ml. Genotyping revealed a CYP2C19 homozygous poor metabolizer (CYP2C19*2/*2). Voriconazole was subsequently discontinued due to QTc prolongation. These data and those from two recent publications suggest that voriconazole does not distribute extensively into human adipose tissue and that obese patients should be dosed on an adjusted body weight basis. If an obese patient dosed on total body weight is also a CYP2C19 poor metabolizer, serum voriconazole concentrations will be further elevated, potentially leading to drug-induced toxicity.
    Pharmacotherapy 03/2013; 33(3):e19-22. · 2.31 Impact Factor
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    ABSTRACT: Echinocandins induce a postantifungal effect and a paradoxical effect. The postantifungal effect is a concentration-dependent process that allows for sustained kill of Candida spp. after relatively brief exposures to a compound. The paradoxical effect is growth that occurs at high echinocandin concentrations above the MIC. Paradoxical growth varies in terms of media, species, strain and type of echinocandin. The study by Shields et al. evaluated the impact of a brief exposure of caspofungin on paradoxical growth and postantifungal effects in Candida albicans isolates. In the postantifungal effect experiments, prolonged concentration-dependent killing occurred. Maximum postantifungal effects occurred with caspofungin exposures of 5 or 15 min. A brief exposure of caspofungin eliminated the paradoxical growth that was observed in the time-kill experiments. The report by Shields et al. illustrates that short exposures to an echinocandin may lead to prolonged postantifungal effects and furthers our understanding of the paradoxical effect in C. albicans.
    Future Microbiology 05/2012; 7(5):565-9. · 4.02 Impact Factor
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    ABSTRACT: Triazole and imidazole antifungal agents inhibit metabolism of vincristine, leading to excess vinca alkaloid exposure and severe neurotoxicity. Recent reports of debilitating interactions between vincristine and itraconazole, as well as posaconazole, voriconazole and ketoconazole underscore the need to improve medical awareness of this adverse combination. We, therefore, undertook a comprehensive analysis of reports of adverse drug interactions (ADIs) with the combination of vincristine and azole antifungal agents, established a new classification, and provided a detailed summary of these toxicities. In patients who had sufficient data for analysis, 47 individuals were identified who had an ADI with the combination of vincristine and antifungal azoles. Median age was 8 years (1.3-68 years) with 33(70%) having a diagnosis of acute lymphoblastic leukaemia. Median time to ADI with vincristine was 9.5 days with itraconazole, 13.5 days posaconazole and 30 days voriconazole. The median number of vincristine doses preceding the ADI was 2 doses with itraconazole, 3 doses posaconazole and 2 doses voriconazole. The most common severe ADIs included gastrointestinal toxicity, peripheral neuropathy, hyponatremia/SIADH, autonomic neuropathy and seizures. Recovery from these ADIs occurred in 80.6% of patients. We recommend using alternative antifungal agents if possible in patients receiving vincristine to avoid this serious and potentially life-threatening drug interaction.
    Mycoses 11/2011; 55(4):290-7. · 1.28 Impact Factor
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    Mycoses 05/2011; 54(6):e877-9. · 1.28 Impact Factor
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    ABSTRACT: Candida empyema is a serious complication of disseminated candidiasis. However, little is known about the intrapleural pharmacokinetics of echinocandins. We report the penetration of anidulafungin into the pleural fluid of a patient with Candida tropicalis empyema. The anidulafungin ratio for the area under the concentration-time curve from 0 h to the last measurement between pleural fluid and serum values was only 0.125 (12.5%), with pleural fluid concentrations ranging between 0.67 and 0.88 μg/ml.
    Antimicrobial Agents and Chemotherapy 03/2011; 55(5):2478-80. · 4.57 Impact Factor
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    ABSTRACT: To report a case series of high-dose continuous infusion beta-lactam antibiotics for the treatment of resistant Pseudomonas aeruginosa infections. Continuous infusion ceftazidime or aztreonam was administered to achieve target drug concentrations at or above the minimum inhibitory concentration, when possible, in 3 patients with P. aeruginosa infections. The maximal calculated target drug concentration was 100 mg/L. In the first patient, with primary immunodeficiency, neutropenia, and aggressive cutaneous T-cell lymphoma/leukemia, continuous infusion ceftazidime (6.5-9.6 g/day) was used to successfully treat multidrug-resistant P. aeruginosa bacteremia. In the second patient, with leukocyte adhesion deficiency type 1, continuous infusion aztreonam (8.4 g/day) was used to successfully treat multidrug-resistant P. aeruginosa wound infections. In the third patient, with severe aplastic anemia, continuous infusion ceftazidime (7-16.8 g/day) was used to treat P. aeruginosa pneumonia and bacteremia. In each patient, bacteremia cleared, infected wounds healed, and pneumonia improved in response to continuous infusion ceftazidime or aztreonam. Treatment strategies for multidrug-resistant P. aeruginosa infections are limited. A novel treatment strategy, when no other options are available, is the continuous infusion of existing beta-lactam antibiotics to maximize their pharmacodynamic activity. High-dose continuous infusion ceftazidime or aztreonam was used for the successful treatment of resistant systemic P. aeruginosa infections in 3 chronically immunocompromised patients. Continuous infusion beta-lactam antibiotics are a potentially useful treatment strategy for resistant P. aeruginosa infections in immunocompromised patients.
    Annals of Pharmacotherapy 05/2010; 44(5):929-35. · 2.57 Impact Factor
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    ABSTRACT: We report the penetration of liposomal amphotericin B into the pleural fluid of a patient with pulmonary zygomycosis and empyema. The ratio of area under the concentration-versus-time curve in pleural fluid (AUC(pleural fluid)) to that in serum (AUC(serum)) for liposomal amphotericin B over 24 h was 9.4%, with pleural fluid concentrations of 2.12 to 4.91 microg/ml. Given the relatively low level of intrapleural penetration of liposomal amphotericin B, chest tube drainage may be warranted for successful treatment of zygomycotic empyema.
    Antimicrobial Agents and Chemotherapy 04/2010; 54(4):1633-5. · 4.57 Impact Factor
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    ABSTRACT: The physical compatibility of magnesium sulfate and sodium bicarbonate in a pharmacy-compounded hemofiltration solution was assessed. Two bicarbonate-buffered hemofiltration solutions (low- and high-magnesium formulations) were compounded in triplicate. The concentrations of magnesium (15 meq/L) and sodium bicarbonate (50 meq/L) in the high-magnesium formulation were chosen to be somewhat below the concentrations reported as being incompatible in a popular reference. The six hemofiltration bags were stored at 22-25 degrees C without protection from light for 48 hours. Physical compatibility was assessed by visual inspection and microscopy. The pH of the solutions was assayed 3-4 and 52-53 hours after compounding. Electrolyte and glucose concentrations of the solutions were assayed at 3-4 and 50-51 hours after preparation. No particulate matter was observed by visual or microscopic inspection in the compounded hemofiltration solutions at 48 hours. The mean +/- S.D. pH values of the low-magnesium solutions were 8.01 +/- 0.02 and 8.04 +/- 0.02 at 3-4 and 52-53 hours after compounding, respectively. The mean +/- S.D. pH values of the high-magnesium solutions were 7.96 +/- 0.02 and 7.98 +/- 0.01 at 3-4 and 52-53 hours after compounding, respectively. The electrolyte and glucose concentrations in the low- and high-magnesium solutions were similar 3-4 and 50-51 hours after preparation. Magnesium sulfate 1.5 meq/L and sodium bicarbonate 50 meq/L were physically compatible in a pharmacy-compounded hemofiltration solution for 48 hours when stored at 22-25 degrees C without protection from light.
    American journal of health-system pharmacy: AJHP: official journal of the American Society of Health-System Pharmacists 04/2010; 67(7):562-5. · 2.10 Impact Factor
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    ABSTRACT: To describe the rationale, principles, and dosage calculations for continuous-infusion beta-lactam antibiotics to treat multidrug-resistant bacteria in patients undergoing continuous venovenous hemofiltration (CVVH). A MEDLINE search (1968-November 2008) of the English-language literature was performed using the terms continuous infusion and Pseudomonas or Acinetobacter; hemofiltration or CVVH or hemodiafiltration or CVVHDF or continuous renal replacement therapy or pharmacokinetics; and terms describing different beta-lactam antibiotics. In vitro, in vivo, and human studies were evaluated that used continuous-infusion beta-lactam antibiotics to treat Pseudomonas aeruginosa and Acinetobacter baumannii infections. Studies were reviewed that described the pharmacokinetics of beta-lactam antibiotics during CVVH as well as other modalities of continuous renal replacement therapy. Continuous infusion of beta-lactam antibiotics, maintaining drug concentrations 4-5 times higher than the minimum inhibitory concentration, is a promising approach for managing infections caused by P. aeruginosa and A. baumannii. Safe yet effective continuous infusion therapy is made difficult by the occurrence of acute renal failure and the need for renal replacement therapy. Case series and pharmacokinetic properties indicate that several beta-lactam antimicrobials that have been studied for continuous infusion, such as cefepime, ceftazidime, piperacillin, ticarcillin, clavulanic acid, and tazobactam, are significantly cleared by hemofiltration. Methodology and formulas are provided that allow practitioners to calculate dosage regimens and reach target drug concentrations for continuous beta-lactam antibiotic infusions during CVVH based on a literature review, pharmacokinetic principles, and our experience at the National Institutes of Health Clinical Center. Continuous infusion of beta-lactam antibiotics may be a useful treatment strategy for multidrug-resistant gram-negative infections in the intensive care unit. Well-established pharmacokinetic and pharmacodynamic principles can be used to safely reach and maintain steady-state target concentrations of beta-lactam antibiotics in critical illness complicated by acute renal failure requiring CVVH.
    Annals of Pharmacotherapy 08/2009; 43(7):1324-37. · 2.57 Impact Factor

Publication Stats

41 Citations
25.25 Total Impact Points

Institutions

  • 2009–2013
    • National Institutes of Health
      • Pharmacy Department
      Bethesda, MD, United States
  • 2011
    • National Heart, Lung, and Blood Institute
      Maryland, United States
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States
  • 2010
    • Society of Critical Care Medicine
      Maryland, United States