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57. Abacavir pharmacokinetics in African children living with HIV: A pooled analysis describing the effects of age, malnutrition and common concomitant medications.

Author

Tikiso, Tjokosela, McIlleron, Helen, Burger, David, Gibb, Diana, Rabie, Helena, Lee, Janice, Lallemant, Marc, Cotton, Mark F., Archary, Moherndran, Hennig, Stefanie, and Denti, Paolo

Subjects
HIV-positive children, MALNUTRITION, ABACAVIR, ARM circumference, AFRICANS, MYCOBACTERIUM tuberculosis, PHARMACOKINETICS, DRUGS
Abstract

Aims: Abacavir is part of WHO‐recommended regimens to treat HIV in children under 15 years of age. In a pooled analysis across four studies, we describe abacavir population pharmacokinetics to investigate the influence of age, concomitant medications, malnutrition and formulation. Methods: A total of 230 HIV‐infected African children were included, with median (range) age of 2.1 (0.1–12.8) years and weight of 9.8 (2.5–30.0) kg. The population pharmacokinetics of abacavir was described using nonlinear mixed‐effects modelling. Results: Abacavir pharmacokinetics was best described by a two‐compartment model with first‐order elimination, and absorption described by transit compartments. Clearance was predicted around 54% of its mature value at birth and 90% at 10 months. The estimated typical clearance at steady state was 10.7 L/h in a child weighing 9.8 kg co‐treated with lopinavir/ritonavir, and was 12% higher in children receiving efavirenz. During coadministration of rifampicin‐based antituberculosis treatment and super‐boosted lopinavir in a 1:1 ratio with ritonavir, abacavir exposure decreased by 29.4%. Malnourished children living with HIV had higher abacavir exposure initially, but this effect waned with nutritional rehabilitation. An additional 18.4% reduction in clearance after the first abacavir dose was described, suggesting induction of clearance with time on lopinavir/ritonavir‐based therapy. Finally, absorption of the fixed dose combination tablet was 24% slower than the abacavir liquid formulation. Conclusion: In this pooled analysis we found that children on lopinavir/ritonavir or efavirenz had similar abacavir exposures, while concomitant TB treatment and super‐boosted lopinavir gave significantly reduced abacavir concentrations. [ABSTRACT FROM AUTHOR]

Published
2022
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60. Aspergillus and progression of lung disease in children with cystic fibrosis

Author

Harun, Sabariah Noor, Wainwright, Claire E., Grimwood, Keith, Hennig, Stefanie, Australasian Cystic Fibrosis Bronchoalveolar Lavage (ACFBAL) study group, Moodie, Marjory, Harun, Sabariah Noor, Wainwright, Claire E., Grimwood, Keith, Hennig, Stefanie, Australasian Cystic Fibrosis Bronchoalveolar Lavage (ACFBAL) study group, and Moodie, Marjory

Published
2019

71. Methadone for the management of pain in advanced cancer

Author

Haywood, Alison, Norris, Ross, Khan, Sohil, Hardy, Janet, Hennig, Stefanie, George, Rani, Haywood, Alison, Norris, Ross, Khan, Sohil, Hardy, Janet, Hennig, Stefanie, and George, Rani

Abstract

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Pharmacy and Pharmac, Griffith Health, Most patients at advanced stages of cancer experience moderate to severe pain [1, 2]. Despite increased research and attempts on estimation and management, pain continues to be a predominant symptom in patients with cancer [1]. In general, cancer pain is treated with pharmacological agents, specifically using opioids alone or in combination with adjuvant analgesics [3]. Methadone is administered to patients with cancer pain not responsive to morphine or other strong opioids when intractable opioid adverse effects appear [4]. The inherent properties of methadone, including high oral bioavailability, rapid onset of analgesic effect, long half-life resulting in infrequent dosing regimens, lack of active metabolites, low rate of induction of tolerance, low cost, and perceived benefit in difficult pain control scenarios such as neuropathic pain, facilitates its use in in the management of pain in profoundly ill patients [5, 6]. Methadone is also considered as the first strong opioid analgesic in patients with renal impairment [4]. However, in clinical practice the use of methadone is highly restricted due to the narrow therapeutic window between efficacy and toxicity accompanied with large inter- and intra-individual variability in response [2]. Understanding the pharmacokinetics (PK) and pharmacodynamics (PD) of methadone could help determine appropriate opioid selection for individual patients with advanced cancer. In clinical practice, methadone is administered as a racemic mixture of l-and d-methadone and the analgesic properties are mostly attributed to the l-enantiomer. Clinical studies have also indicated the disposition of methadone to be enantioselective [7-9]. Evaluation of the PK profile of the methadone enantiomers requires accurate quantitation of each enantiomer. The use of saliva as a surrogate to plasma samples has been evidenced by strong correlations reported for analgesics such as paracetamol [10] and hydromorphone [11], with mixed results for methadon

Published
2017

72. Feedback quizzes enhanced academic performance and the student experience in two pharmacokinetics courses

Author

Hennig, Stefanie, Bond, Jacqueline, Staatz, Christine, Singleton, Judith A., Leung, Debbie, Hennig, Stefanie, Bond, Jacqueline, Staatz, Christine, Singleton, Judith A., and Leung, Debbie

Abstract

Background Pharmacy students do not typically enjoy studying pharmacokinetics because of its mathematical nature and perceived lack of relevance to clinical practice. To improve teaching at our institution, quizzes were introduced into an intermediate and advanced course in this discipline in 2013 and 2014 respectively. Aims To retrospectively evaluate the impact of two different approaches, of introducing ‘feedback quizzes’ to enhance teaching of clinical pharmacokinetics, on the experiences and academic performance of undergraduate pharmacy students. Methods Formative paper-based quizzes were introduced into tutorials in the intermediate course and summative online quizzes were introduced into the advanced course. Academic performance (based on student marks) and student experience data (based on the proportion of students who agreed or strongly agreed with statements in an institutional evaluation survey) were compared pre- and post-curricular change using a Mann–Whitney–Wilcoxon test and Test of Equal Proportions, respectively. Results Statistically significant increases in academic performance were noted in both courses; from 75.0 to 77.0% (p = 0.033) for the median weighted mark in the intermediate course, and from 77.8 to 85.7% (p =0.002) for the median mark in the pharmacokinetic component of the final exam in the advanced course. A non-significant trend towards increased overall course satisfaction was seen in both courses compared with the previous cohort (intermediate 87% vs 78% (p=0.3), advanced 63% vs 50%, (p=0.35)). Conclusion Our study demonstrated that quizzes, whether formative or summative, administered in-class or outside class, can enhance learning and lead to modest improvements in students’ satisfaction of pharmacokinetics courses.

Published
2017

77. eradication therapy and risk of acquiring in young children with cystic fibrosis.

Author

Harun, Sabariah Noor, Holford, Nicholas H. G., Grimwood, Keith, Wainwright, Claire E., Hennig, Stefanie, and Australasian Cystic Fibrosis Bronchoalveolar Lavage (ACFBAL) study group

Subjects
ACHROMOBACTER, CYSTIC fibrosis in children, PSEUDOMONAS aeruginosa, ASPERGILLUS, CYSTIC fibrosis transmembrane conductance regulator
Abstract

Background: While Aspergillus detection rates in adults, adolescents and older children with cystic fibrosis (CF) have increased, the risk of acquiring this fungal pathogen in young children is unknown.Aim: To determine the risk and explanatory factors of acquiring Aspergillus in children with CF by age 5 years.Methods: Cross-sectional analysis of clinical, bronchoalveolar lavage and treatment data from the Australasian Cystic Fibrosis Bronchoalveolar Lavage study was used to identify predictive factors for detecting Aspergillus at age 5 years. A parametric repeated time-to-event model quantitatively described the risk and factors associated with acquiring Aspergillus and Pseudomonas aeruginosa from birth until age 5 years.Results: Cross-sectional analysis found that the number of P. aeruginosa eradication courses increased the odds of detecting Aspergillus at age 5 years (OR 1.61, 95% CI 1.23 to 2.12). The median (IQR) age for the first P. aeruginosa positive culture was 2.38 (1.32-3.79) years and 3.69 (1.68-4.74) years for the first Aspergillus positive culture. The risk of P. aeruginosa and Aspergillus events changes with time after the first year of study entry. It also decreases for P. aeruginosa after completing P. aeruginosa eradication (HR 0.15, 95% CI 0.00 to 0.79), but increases for Aspergillus events (HR 2.75, 95% CI 1.45 to 5.41). The risk of acquiring both types of events increases after having had a previous event.Conclusion: In young children with CF, completing P. aeruginosa eradication therapy and previous Aspergillus events are associated with increased risk of acquiring Aspergillus. [ABSTRACT FROM AUTHOR]

Published
2019
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78. Das efferente System und seine frequenzspezifische Modulation des cochleären Verstärkers bei der Fledermaus carollia perspicillata

Author

Hennig, Stefanie

Subjects
ddc:570
Abstract

Die Funktion der äußeren Haarsinneszellen geht weit über die normale Rezeptoreigenschaft der Kategorie Mechanorezeptor hinaus. Äußere Haarzellen mit ihrer reichhaltigen efferenten Innervierung sind nicht nur für die sensorische Aufnahme mechanischer Bewegung zuständig, sondern ermöglichen aufgrund ihrer motorischen Funktionen die mechanische Verstärkung der Wanderwelle in der Cochlea. Äußere Haarzellen sind eine maßgebliche Komponente des ´cochleären Verstärkers` und ihr Ausfall führt zur Schwerhörigkeit. Beiprodukte des cochleä-ren Verstärkers sind otoakustische Emissionen, deren Messung Aufschluss über aktive mechanische Prozesse im Innenohr gibt. Die äußeren Haarsinneszellen bilden Synapsen mit dem olivo-cochleären efferenten System, welches im Zentrum der vorliegenden Untersuchung steht. Es vermittelt den Einfluss des Zentralnervensystems auf das Corti-Organ des Innenohrs. Über die akustische Reizung des olivo-cochleären Reflexbogens ist man in der Lage, das efferente System zu aktivieren und gleichzeitig die Antworteigenschaften der Cochlea zu verändern. Efferente Modulationen des cochleären Verstärkers können sich z. B. in einer Veränderung des Emissionspegels bemerk-bar machen. Die Fledermausspezies Carollia perspicillata ist aufgrund ihres Echoortungs-systems mit einem sehr sensitiven und hochauflösenden Hörvermögen ausgestattet und eignet sich hervorragend als Modelltier in der Hörforschung, insbesondere auch deshalb, da oto-akustische Emissionen sehr gut messbar sind. Das efferente System von C. perspicillata wurde in dieser Untersuchung durch akustische Stimulation der kontralateralen Cochlea angeregt. Die Stimuli, die nicht nur in ihrem Pegel sondern auch in ihrer Bandbreite und in der Mittelfrequenz in Relation zu den ipsilateralen Stimulusfrequenzen variierten, beeinflussten dabei die Generierung der otoakustischen Emis-sionen (DPOAE, engl: distortion product otoacoustic emissions) im ipsilateralen Ohr: akustische Stimulation der kontralateralen Cochlea bewirkte zuverlässig eine Änderung der DPOAE- Amplitude im kontralateralen Ohr. Vor allem eine Suppression des cochleären Verstärkers in Form von DPOAE-Pegelverminderungen wurde beobachtet. Die supprimieren-den Effekte erreichten trotz leiser bis moderater kontralateraler Rauschpegel (bis maximal 54 dB SPL) Werte von bis zu 14, 17.1 und 13.9 dB SPL (bei f2 = 20, 40 und 60 kHz und effek-tivstem kontralateralen Rauschstimulus) und waren damit deutlich größer als in vorangegang-enen Studien an anderen Spezies. Die DPOAE-Pegelverminderungen waren positiv mit dem x Pegel der kontralateralen akustischen Stimulation, ebenso wie seiner Bandbreite und der Mittelfrequenzen in Relation zu den ipsilateralen Stimulusfrequenzen korreliert. Es gab keinen absoluten Frequenzbereich, in dem die efferenten Effekte am größten gewesen wären. Vielmehr traten maximale Effekte immer durch etwas oberhalb der ipsilateralen Stimulusfre-quenzen gelegene kontralaterale Rauschstimuli auf. Die Effekte waren auch abhängig von der Bandbreite des kontralateralen Rauschstimulus und maximal bei einer relativen Bandbreite von 1.5 Oktaven. Die Verschiebung des efferenten Effekts hin zu hohen Frequenzen und die Bandbreitenabhängigkeit sind vereinbar mit den anatomischen Eigenschaften der Projektio-nen der medialen olivo-cochleären Efferenzen in der Säugetiercochlea. Kontralaterale akusti-sche Reizung bewirkte auch eine Verschiebung der Wachstumsfunktionen der 2f1-f2 -DPOAE in einen unsensitiven Bereich und außerdem eine Verformung der Wachstumsfunktion. Bei-des könnte durch Beeinträchtigung des cochleären Verstärkers verursacht sein. Eine Beteili-gung des Mittelohrmuskels an den Effekten kann nahezu ausgeschlossen werden und die beobachteten Effekte sind höchstwahrscheinlich dem olivo-cochleären System zuzuschreiben. Funktionell ist denkbar, dass bei C. perspicillata das mediale olivo-cochleäre System im Kontext einer Frequenzverschärfung bei der cochleären Verstärkung der Basilarmembranbe-wegung aktiv wird. Aus diesem Grund wurden ipsilateral sogenannte DPOAE-Suppressions- Abstimmkurven gemessen, welche die mechanische Abstimmschärfe im Innenohr beschrei-ben. Während und nach kontralateraler Reizung kam es zu Veränderungen der Abstimmkur-ven. Signifikante Effekte konnten allerdings nicht festgestellt werden, da die Veränderungen der Suppressions-Abstimmkurven variabel und schlecht kategorisierbar war. Die vorliegenden Ergebnisse unterstützen weit verbreitete Hypothesen zur Funktion der medialen olivo-cochleären Effernzen in Bezug auf mechanische Suppression, Verbesserung des cochleären Signal-Rauschverhältnisses und einer generellen frequenzspezifischen Wirkung.

Published
2014

86. Evaluation of Tobramycin Exposure Predictions in Three Bayesian Forecasting Programmes Compared with Current Clinical Practice in Children and Adults with Cystic Fibrosis.

Author

Burgard, Marc, Sandaradura, Indy, van Hal, Sebastiaan J., Stacey, Sonya, and Hennig, Stefanie

Subjects
CYSTIC fibrosis in children, TOBRAMYCIN, WILCOXON signed-rank test, DISEASES in adults, DRUG dosage, THERAPEUTICS
Abstract

Background and Objectives: Bayesian forecasting (BF) methods for tobramycin dose individualisation has not seen widespread clinical adoption, despite being endorsed by clinical practice guidelines. Several freeware and commercial programmes using BF methods are available to support personalised dosing. This study evaluated exposure estimates, dose recommendations, and predictive performance compared with current clinical practice.Methods: Data from 105 patients (50 adults and 55 children) with cystic fibrosis who received intravenous tobramycin treatment and had paired concentration-time measurements were analysed using (1) log-linear regression analysis, and (2) three BF programmes: TDMx, InsightRX, and DoseMe. Exposure estimates and dose recommendations were compared using the Wilcoxon signed-rank test and Bland-Altman analysis. Predictive performance of BF programmes was compared based on bias and imprecision.Results: Median estimated tobramycin exposure with current clinical practice was significantly lower (87.8 vs. 92.5, 94.0 and 90.3 mg h l-1; p ≤ 0.01), hence median subsequent dose recommendations were significantly higher (10.1 vs. 9.4, 9.4 and 9.2 mg kg-1; p ≤ 0.01) compared with BF programmes. Furthermore, median relative dose-adjustment differences were higher in adults (> 10%) compared with children (4.4-7.8%), and differences in individual dose recommendations were > 20% on 19.1-27.4% of occasions. BF programmes showed low bias (< 7%) and imprecision (< 20%), and none of the programmes made consistently significantly different recommendations compared with each other.Conclusions: On average, the predictions made by the BF programmes were similar, however substantial individual differences were observed for some patients. This suggests the need for detailed investigations of true tobramycin exposure. [ABSTRACT FROM AUTHOR]

Published
2018
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89. Pseudomonas aeruginosaeradication therapy and risk of acquiring Aspergillusin young children with cystic fibrosis

Author

Harun, Sabariah Noor, Holford, Nicholas H G, Grimwood, Keith, Wainwright, Claire E, and Hennig, Stefanie

Abstract

BackgroundWhile Aspergillusdetection rates in adults, adolescents and older children with cystic fibrosis (CF) have increased, the risk of acquiring this fungal pathogen in young children is unknown.AimTo determine the risk and explanatory factors of acquiring Aspergillusin children with CF by age 5 years.MethodsCross-sectional analysis of clinical, bronchoalveolar lavage and treatment data from the Australasian Cystic Fibrosis Bronchoalveolar Lavage study was used to identify predictive factors for detecting Aspergillusat age 5 years. A parametric repeated time-to-event model quantitatively described the risk and factors associated with acquiring Aspergillusand Pseudomonas aeruginosafrom birth until age 5 years.ResultsCross-sectional analysis found that the number of P. aeruginosaeradication courses increased the odds of detecting Aspergillusat age 5 years (OR 1.61, 95% CI 1.23 to 2.12). The median (IQR) age for the first P. aeruginosapositive culture was 2.38 (1.32–3.79) years and 3.69 (1.68–4.74) years for the first Aspergilluspositive culture. The risk of P. aeruginosaand Aspergillusevents changes with time after the first year of study entry. It also decreases for P. aeruginosaafter completing P. aeruginosaeradication (HR 0.15, 95% CI 0.00 to 0.79), but increases for Aspergillusevents (HR 2.75, 95% CI 1.45 to 5.41). The risk of acquiring both types of events increases after having had a previous event.ConclusionIn young children with CF, completing P. aeruginosaeradication therapy and previous Aspergillusevents are associated with increased risk of acquiring Aspergillus.

Published
2019
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90. Aspergillusand progression of lung disease in children with cystic fibrosis

Author

Harun, Sabariah Noor, Wainwright, Claire E, Grimwood, Keith, and Hennig, Stefanie

Abstract

BackgroundThe impact of Aspergilluson lung disease in young children with cystic fibrosis is uncertain.AimsTo determine if positive respiratory cultures of Aspergillusspecies are associated with: (1) increased structural lung injury at age 5 years; (2) accelerated lung function decline between ages 5 years and 14 years and (3) to identify explanatory variables.MethodsA cross-sectional analysis of association between Aspergilluspositive bronchoalveolar lavage (BAL) cultures and chest high-resolution CT (HRCT) scan findings at age 5 years in subjects from the Australasian Cystic Fibrosis Bronchoalveolar Lavage (ACFBAL) study was performed. A non-linear mixed-effects disease progression model was developed using FEV1% predicted measurements at age 5 years from the ACFBAL study and at ages 6–14 years for these subjects from the Australian Cystic Fibrosis Data Registry.ResultsPositive AspergillusBAL cultures at age 5 years were significantly associated with increased HRCT scores for air trapping (OR 5.53, 95% CI 2.35 to 10.82). However, positive Aspergilluscultures were not associated with either FEV1% predicted at age 5 years or FEV1% predicted by age following adjustment for body mass index z-score and hospitalisation secondary to pulmonary exacerbations. Lung function demonstrated a non-linear decline in this population.ConclusionIn children with cystic fibrosis, positive AspergillusBAL cultures at age 5 years were associated contemporaneously with air trapping but not bronchiectasis. However, no association was observed between positive AspergillusBAL cultures on FEV1% predicted at age 5 years or with lung function decline between ages 5 years and 14 years.

Published
2019
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97. Phenytoin loading doses in adult critical care patients: does current practice achieve adequate drug levels?

Author

Putt, Michael, Udy, Andrew, Jarrett, Paul, Martin, J., Hennig, Stefanie, Salmon, N., Lipman, Jeffrey, Roberts, Jason, Putt, Michael, Udy, Andrew, Jarrett, Paul, Martin, J., Hennig, Stefanie, Salmon, N., Lipman, Jeffrey, and Roberts, Jason

Abstract

Phenytoin is regularly employed in the critically ill for prophylaxis against or treatment of seizure disorders. No prior studies have examined current dosing practices in an Australasian intensive care unit (ICU) setting. The aims of this study were to: a) describe the adequacy of contemporary dosing in respect to free and total serum phenytoin concentrations; b) identify factors associated with therapeutic drug concentrations; and c) examine the accuracy of predictive equations that estimate free concentrations in this setting. All patients receiving a loading dose of phenytoin in a tertiary-level ICU were eligible for enrolment; 53 patients were enrolled in the study. Serum samples to determine free and total phenytoin concentrations (measured by high performance liquid chromatography) were then drawn prior to the following dose. Free concentrations below the recommended target (<1 mg/l) were considered as suboptimal. The most common indication for phenytoin loading was traumatic brain injury (49%) and the mean administered dose was 14.5 (3.66) mg/kg. Twenty-six patients (49%) had suboptimal trough free concentrations, although this subgroup was significantly heavier and therefore received a lower per kilogram dose (12.8 [3.1] vs 16.3 [3.4] mg/kg, P=0.001). In multivariate analysis, larger weight adjusted doses (P=0.018), higher albumin concentration (P=0.034) and receiving phenytoin for an indication other than seizure (P=0.035), were associated with a greater likelihood of adequate concentrations. In conclusion, phenytoin dosing remains complex in critically ill patients, although lower per kilogram loading doses are strongly associated with free concentrations below the desired target.

Published
2013

98. A systematic review of treatment outcomes with weight-based dosing of chemotherapy in obese adult patients with acute leukemia or lymphoma.

Author

Mapp, Sally, Sandhu, Geeta, Carrington, Christine, and Hennig, Stefanie

Subjects
CANCER chemotherapy, OVERWEIGHT persons, LYMPHOMAS, LEUKEMIA, SURVIVAL analysis (Biometry), DISEASES
Abstract

The article focuses on a study regarding weight-based dosing of chemotherapy treatment for obese adult patients with lymphoma or leukemia. Topics discussed include reduction of weight-based chemotherapy in case of obese hematology and oncology patients due to excess of toxicity and altered pharmacokinetics in the population, decreased chances of survival in obese cohort, and requirement of broader chemotherapy protocols for assessment of weight-based dosing treatment.

Published
2016
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