https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29956 Thu 17 Feb 2022 09:29:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39890 Thu 14 Jul 2022 14:21:17 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30308 2 or mg/kg basis and subsequent occurrence of dosing error or concern for underdosing. The ‘simple and safe’ strategy of a single dose of tyrosine kinase inhibitor for cancer has thus been widely adopted. However, the benefits purported to exist in the clinical trials do not appear to be borne out in clinical practice, particularly in solid tumours. In order to investigate whether pharmacokinetic variability is a contributor to the variable outcomes, pharmacokinetic targets to enable individualisation of tyrosine kinase inhibitor administration are now emerging. Evidence suggests there is not a clear relationship of a single dose to maximum plasma concentration (C_max), steady-state trough concentration (C_trough) or area under the curve (AUC). Furthermore, a significant number of questions remain related to the specific timing and frequency of sample collection required to achieve optimal outcomes. This article reviews the wide variability in the literature on this topic, specifically the different pharmacokinetic targets of the same drug for different cancers, for different states of cancer, and changing pharmacokinetic parameters over a treatment interval in cancer. It appears the optimal sampling times to enable appropriate dose recommendations across patients and diseases may vary, and are not always trough concentrations at steady state. Importantly, the need to be pragmatic in a clinical setting is paramount. Lastly, international collaborations to increase sample size are highly recommended to ensure enough patients are sampled to be sure of a clinical benefit from this concentration-directed methodology.]]> Sat 24 Mar 2018 07:31:48 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49507 Fri 19 May 2023 16:35:01 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:42242 90% of patients exhibiting concentrations within the defined target range throughout the entire treatment course. Additional work to formally establish target therapeutic concentrations is required; however, this study provides a valuable first step in determining optimal ribavirin treatment regimens for paramyxovirus infections in the lung transplant population.]]> Fri 19 Aug 2022 11:56:24 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40009 n = 61) were analysed using non-linear mixed modelling. Covariate analysis was performed to investigate the impact of standard and novel patient characteristics of carboplatin pharmacokinetics. A Monte Carlo simulation of 100,000 representative NSCLC patients evaluated the ability of the Calvert formula and novel dosing strategies to achieve the targeted therapeutic range. The associations between systemic inflammation and chemotherapy drug utilisation (cycles received, relative dose intensity (RDI) and second-line uptake) and clinical endpoints were also investigated in the pharmacokinetic cohort, and two independent cohorts of people with advanced NSCLC from the Chemotherapy Dosing in Cancer-Related Inflammation (CDCRI) database that were administered carboplatin–paclitaxel (n  = 37) or carboplatin–gemcitabine (n  = 358). Results: In all cohorts, 25–53% of people had elevated systemic inflammation (NLR > 5 or PLR > 300). In the pharmacokinetic cohort, no patients achieved the desired therapeutic target of carboplatin. Carboplatin exposure was related to renal function, as estimated using the Cockcroft–Gault formula, albumin and inflammation (NLR). In the pharmacokinetic cohort, increasing carboplatin area under the curve (AUC) correlated with greater reductions in red blood cells and haemoglobin. In this cohort, the average measured AUC of partial responders was 2.4 mg·min/mL. Also in the pharmacokinetic cohort, only 12% of people with an NLR > 5 received four or more cycles of chemotherapy, compared with 62% of patients with an NLR ≤ 5 (p < 0.001). For people in the CDCRI cohort receiving carboplatin–gemcitabine, those with an NLR > 5 also received less cycles (four or more cycles, 41% vs. 60%; p < 0.01) as well as less second-line chemotherapy (46% vs. 60%; p = 0.02) compared with patients without inflammation. People in the pharmacokinetic cohort with an NLR > 5 had 12 months less median survival compared with people with an NLR ≤ 5 (6.5 vs. 18 months; p = 0.08). Similarly, overall survival was significantly shortened in people in the CDCRI cohort receiving carboplatin–gemcitabine with an NLR > 5 compared with those with an NLR ≤ 5 (7 vs. 12 months; p < 0.001), and Cox regression analysis showed a 1.5-fold (1.3–2.1; p < 0.001) increased hazard of death associated with the increased systemic inflammation. Simulations of the newly developed model-based and Calvert dosing assessed the ability to reach this study’s proposed actual target AUC of 2.2–2.6 mg·min/mL. These showed current Calvert dosing was predicted to result in substantial overexposure in patients with high systemic inflammation. The newly developed model showed equivalent levels of carboplatin therapeutic target achievement across the spectrum of inflammation observed in the lung cancer population. Conclusion: An alternate model-based dosing strategy for carboplatin was developed and is predicted to result in consistent drug exposure across the population and improve attainment of therapeutic targets. Further studies of this new model are warranted in people with advanced NSCLC.]]> Fri 15 Jul 2022 11:35:17 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49423 100) was determined from simulations for four previously proposed treatment regimens: (i) 400 mg once daily, (ii) an 800 mg loading dose followed by 400 mg once daily, (iii) 400 mg twice daily, and (iv) a 12 mg/kg loading dose followed by 6 mg/kg once daily. The effect of body weight (40, 70, 120 kg) and renal function (continuous renal replacement therapy (CRRT); 20, 60, 120, 180 mL/min creatinine clearance) on PTA was assessed. Results: Early (0–48 h) fluconazole target attainment for infections with a minimum inhibitory concentration (MIC) of 2 mg/L was highly variable. PTA was highest with an 800 mg loading dose for underweight (40 kg) patients and with a 12 mg/kg loading dose for the remainder. End-of-treatment PTA was highest with the 400 mg twice daily maintenance dosing for patients who were under- or normal weight and 6 mg/kg maintenance dosing for overweight (120 kg) patients. None of the fluconazole regimens reliably attained early targets for MICs of ≥4 mg/L. Conclusion: Current fluconazole dosing regimens do not achieve adequate early target attainment in critically ill adults, particularly in those who are overweight, have higher creatinine clearance, or are undergoing CRRT. Current fluconazole dosing strategies are generally inadequate to treat organisms with an MIC of ≥4 mg/L.]]> Fri 12 May 2023 15:09:13 AEST ]]>