Alan L. Myers

Physical and chemical stability of high-dose ifosfamide and mesna for prolonged 14-day continuous infusion.

Purpose Ifosfamide plus mesna have been used recently in a high-dose regimen that allows this chemotherapy to be given to outpatients with less toxicity over 14 days using a portable pump. However, there is a need for published stability information. The aim of this study was to investigate the physicochemical stability of ifosfamide with mesna in normal saline at room temperature over a prolonged period of 14 days. Methods Infusion solutions of 1:1 ifosfamide and mesna at final concentrations of 10, 20 and 30 mg/mL were prepared with 0.9% sodium chloride in PVC bags. Solutions were stored at room temperature. Concentrations of ifosfamide and mesna were measured at 0 and 1, 3, 7 and 14 days using a stability-indicating reversed phase high-performance liquid chromatography (HPLC) assay with ultraviolet detection. Results Ifosfamide and mesna were both physicochemically stable (>94%) for 14 days in all tested infusion solutions (10, 20 and 30 mg/mL). Conclusions Our stability data indicate that ifosfamide and mesna (1:1) combination can be administered as a prolonged continuous infusion with portable pump in an outpatient setting without replacement of the infusion bag. We suggest 20 mg/mL as a reasonable concentration for infusion rates of about 2-4 cc/hr over prolonged periods of time.

Regulation of Gene Expression in Brain Tissues of Rats Repeatedly Treated by the Highly Abused Opioid Agonist, Oxycodone: Microarray Profiling and Gene Mapping Analysis

Although oxycodone is the most often used opioid agonist, it remains one of the most understudied drugs. We used microarray analysis to better understand the global changes in gene expression in brain tissues of rats repeatedly treated with oxycodone. Many genes were significantly regulated by oxycodone (e.g., Fkbp5, Per2, Rt1.Dα, Slc16a1, and Abcg2). Validation of the microarray data by quantitative real-time-polymerase chain reaction (Q-PCR) indicated that there was a strong significant correlation (r = 0.979, p < 0.0000001) between the Q-PCR and the microarray data. Using MetaCore (a computational platform), many biological processes were identified [e.g., organic anion transport (p = 7.251 × 10−4) and regulation of immune response (p = 5.090 × 10−4)]. Among the regulated genes, Abcg2 mRNA was up-regulated by 2.1-fold, which was further confirmed by immunoblotting (1.8-fold up-regulation). Testing the Abcg2 affinity status of oxycodone using an Abcg2 ATPase assay suggests that oxycodone behaves as an Abcg2 substrate only at higher concentrations (≥500 μM). Furthermore, brain uptake studies demonstrated that oxycodone-induced Abcg2 up-regulation resulted in a significant (p < 0.05) decrease (∼2-fold) in brain/plasma ratios of mitoxantrone. These results highlight markers/mediators of neuronal responses and identify regulatory pathways involved in the pharmacological action of oxycodone. These results also identify genes that potentially modulate tolerance, dependence, immune response, and drug-drug interactions. Finally, our findings suggest that oxycodone-induced up-regulation of Abcg2 enhanced the efflux of the Abcg2 substrate, mitoxantrone, limiting its brain accumulation and resulting in an undesirable drug-drug interaction. Extrapolating these results to other Abcg2 substrates (e.g., daunorubicin and doxorubicin) indicates that the brain uptake of these agents may be affected if they are administered concomitantly with oxycodone.

High-dose gemcitabine, busulfan, and melphalan for autologous stem-cell transplant in patients with relapsed or refractory myeloma: a phase 2 trial and matched-pair comparison with melphalan

BACKGROUND High-dose melphalan is of little benefit as a regimen for patients with relapsed or refractory myeloma undergoing an autologous stem-cell transplant (ASCT). The poor performance of single-agent melphalan in this setting prompted us to study a new high-dose combination of infused gemcitabine, busulfan, and melphalan. METHODS We did a phase 2 trial at the University of Texas MD Anderson Cancer Center (Houston, TX, USA). We enrolled patients with primary refractory or relapsed myeloma who had received treatment with bortezomib, an immunomodulatory drug, or both, or who were receiving a salvage ASCT. Gemcitabine was infused at 1875 mg/m2 for 3 h for 2 days, followed by busulfan (target area under the curve 4000 μmol/L per min per day for 4 days) and melphalan (60 mg/m2 per day for 2 days). The primary endpoint of this trial was to establish the proportion of patients with measurable disease at ASCT receiving gemcitabine, busulfan, and melphalan who achieved stringent complete remission in accordance with the International Myeloma Working Group criteria. We then retrospectively compared the patients in this study with all other concurrent patients at the MD Anderson Cancer Center who were eligible for this trial but declined to participate or had no financial coverage for ASCT in a clinical trial and instead received melphalan at 200 mg/m2 intravenously over 30 min on 1 day, followed by ASCT (control group). To compare survival outcomes, we used a statistical algorithm to select a subset of patients from this control cohort who were matched in a 1-2:1 ratio with the patients in the gemcitabine, busulfan, and melphalan group by sex, age, disease status, refractory to both proteasome inhibitors and immunomodulatory imide drugs, time from diagnosis to ASCT, and cytogenetic risk. All analyses were per protocol. This is the final analysis of the clinical trial, which is registered at ClinicalTrials.gov, number NCT01237951. FINDINGS Between Nov 30, 2010, and Dec 11, 2013, we enrolled 74 patients into the gemcitabine, busulfan, and melphalan trial. In these patients, median age was 58 years (IQR 51-62), median number of previous lines of therapy was two (2-5), 38 patients had high-risk cytogenetics, 17 were unresponsive to all previous treatments, and 32 were receiving a salvage ASCT. We identified 184 patients for the concurrent control cohort. The study patients and the concurrent controls received similar post-ASCT maintenance. Among patients with measurable disease at ASCT, 16 of 65 patients (24·6%, 95% CI 14·2-35·0) in the gemcitabine, busulfan, and melphalan group had stringent complete remission compared with 22 of 174 patients (12·6%, 10·1-15·1) in the concurrent control group (p=0·040). Median follow-up time was 36 months (IQR 30-46) in the patients receiving gemcitabine, busulfan, and melphalan and 34 months (25-53) in the matched control subset (n=111). With respect to the secondary survival endpoints, the gemcitabine, busulfan, and melphalan cohort had significantly longer median progression-free survival than the matched control cohort (15·1 months [95% CI 8·7-22·1] vs 9·3 months [8·0-10·7]) with a significantly reduced risk of progression or death (HR 0·55, 95% CI 0·38-0·81, log-rank p=0·030), as well as significantly longer median overall survival (37·5 months [26-not reached] vs 23·0 months [16·6-30·5]) and a lower risk of death (HR 0·60, 0·34-0·84, log-rank p=0·0092). For only the patients treated with gemcitabine, busulfan, and melphalan, grade 3 or worse adverse events included grade 3 mucositis (12 patients), grade 3 dermatitis (five patients), grade 3 aminotransferase elevation (seven patients), grade 3 diarrhoea (two patients), and three treatment-related deaths. One death was cardiac sudden death and two were due to sepsis. INTERPRETATION Gemcitabine, busulfan, and melphalan is a comparatively safe and active regimen for ASCT in patients with refractory or relapsed myeloma. Better outcomes were achieved in patients who received this regimen than in a concurrent matched cohort receiving melphalan, although this will need to be confirmed in a prospective, randomised trial. FUNDING Otsuka Pharmaceutical Development & Commercialization and US National Cancer Institute.BACKGROUND High-dose melphalan is of limited benefit as autologous stem-cell transplantation (ASCT) regimen for relapsed/refractory myeloma. Its poor results in this setting prompted us to study a new high-dose combination of infusional gemcitabine/busulfan/melphalan (Gem/Bu/Mel). METHODS We conducted a phase 2 trial of Gem/Bu/Mel in patients with primary refractory or relapsed disease after bortezomib and/or an immunomodulatory drug (IMiD), or receiving a salvage ASCT. Gemcitabine (1,875 mg/m2 over 3 hours × 2 days) was followed by busulfan (target AUC 4,000/day × 4 days) and melphalan (60 mg/m2/day × 2 days). The primary endpoint of this trial was to determine the stringent complete remission (sCR) rate of Gem/Bu/Mel in this population. We then retrospectively compared the study patients with all other concurrent patients eligible for this trial who, instead, received melphalan at 200 mg/m2 IV at our center. For survival outcomes, we used a statistical algorithm to select a subset from the control cohort that matched with the Gem/Bu/Mel patients by gender, age, disease status, double refractoriness to proteasome inhibitors/IMIDs, duration from diagnosis to transplant and cytogenetic risk, in a 1–2:1 ratio. All analyses are per protocol. This is the final analysis of the clinical trial. Trial registered at NCI.gov (NCT01237951). FINDINGS We enrolled 74 patients on the Gem/Bu/Mel trial, median age 58 (interquartile range [IQR], 11), median 2 prior therapy lines (IQR, 3), 38 high-risk cytogenetics, 17 unresponsive to all prior treatments, and 33 receiving a salvage ASCT. Toxicities of Gem/Bu/Mel included grade 3 mucositis (N=12), grade 3 dermatitis (N=5), grade 3 transaminase elevation (N=7), grade 3 diarrhea (N=2), grade 5 sudden death (N=1) and grade 5 sepsis (N=2). The study patients and the 184 concurrent controls received similar post-ASCT maintenance. Gem/Bu/Mel resulted in more sCR (24.6% v 12.6%, P=0.040), similar overall responses (73.8% v 74.1%, P=0.77) and similar transplant-related mortality (4.0% v 3.8%, P=0.90). The median follow-up times for the Gem/Bu/Mel patients and the matched subset (N=111) were 36 months (IQR, 15.2) and 34 months (IQR, 27), respectively. Gem/Bu/Mel resulted in improved progression-free survival (median 15.1 v 9.3 months, P=0.0030; hazard ratio=0.60; P=0.021) and overall survival (median 37.5 v 23 months, P=0.0092; hazard ratio=0.65, P=0.0087). INTERPRETATION Gem/Bu/Mel is a safe and active ASCT regimen for refractory/relapsed myeloma, with better outcomes than a concurrent matched cohort receiving melphalan. Funding Supported by a grant from Otsuka Pharmaceutical Development & Commercialization Inc. and NCI Grant P30 CA016672.

Stability study of carboplatin infusion solutions in 0.9% sodium chloride in polyvinyl chloride bags

Background and purpose Carboplatin is a platinum-containing compound with efficacy against various malignancies. The physico-chemical stability of carboplatin in dextrose 5% water (D5W) has been thoroughly studied; however, there is a paucity of stability data in clinically relevant 0.9% sodium chloride infusion solutions. The manufacturer’s limited stability data in sodium chloride solutions hampers the flexibility of carboplatin usage in oncology patients. Hence, the purpose of this study is to determine the physical and chemical stability of carboplatin–sodium chloride intravenous solutions under different storage conditions. Methods The physico-chemical stability of 0.5 mg/mL, 2.0 mg/mL, and 4.0 mg/mL carboplatin–sodium chloride solutions prepared in polyvinyl chloride bags was determined following storage at room temperature under ambient fluorescent light and under refrigeration in the dark. Concentrations of carboplatin were measured at predetermined time points up to seven days using a stability-indicating high-performance liquid chromatography method. Results All tested solutions were found physically stable for at least seven days. The greatest chemical stability was observed under refrigerated storage conditions. At 4℃, all tested solutions were found chemically stable for at least seven days, with nominal losses of ≤6%. Following storage at room temperature exposed to normal fluorescent light, the chemical stability of 0.5 mg/mL, 2.0 mg/mL, and 4.0 mg/mL solutions was three days, five days, and seven days, respectively. Conclusion The extended physico-chemical stability of carboplatin prepared in sodium chloride reported herein permits advance preparation of these admixtures, facilitating pharmacy utility and operations. Since no antibacterial preservative is contained within these carboplatin solutions, we recommend storage, when prepared under specified aseptic conditions, no greater than 24 h at room temperature or three days under refrigeration.

Double epigenetic modulation of high-dose chemotherapy with azacitidine and vorinostat for patients with refractory or poor-risk relapsed lymphoma

More active high‐dose chemotherapy (HDC) regimens are needed for refractory lymphomas. The authors previously combined infusional gemcitabine with busulfan and melphalan (Gem/Bu/Mel) pursuing DNA damage repair inhibition. Subsequently, they combined Gem/Bu/Mel with vorinostat, which facilitates chemotherapy access to DNA. The resulting regimen was safe and synergistic. However, vorinostat induced DNA methyltransferase up‐regulation, which could be preclinically abrogated by azacitidine, increasing tumor‐cell kill. Those observations led to a clinical combination of azacitidine with vorinostat/Gem/Bu/Mel.

Induction of Xenobiotic Receptors, Transporters and Drug Metabolizing Enzymes by Oxycodone

Perturbations of the expression of transporters and drug-metabolizing enzymes (DMEs) by opioids can be the locus of deleterious drug-drug interactions (DDIs). Many transporters and DMEs are regulated by xenobiotic receptors [XRs; e.g., pregnane X receptor (PXR), constitutive androstane receptor (CAR), and Aryl hydrocarbon receptor (AhR)]; however, there is a paucity of information regarding the influence of opioids on XRs. The objective of this study was to determine the influence of oxycodone administration (15 mg/kg intraperitoneally twice daily for 8 days) on liver expression of XRs, transporters, and DMEs in rats. Microarray, quantitative real-time polymerase chain reaction and immunoblotting analyses were used to identify significantly regulated genes. Three XRs (e.g., PXR, CAR, and AhR), 27 transporters (e.g., ABCB1 and SLC22A8), and 19 DMEs (e.g., CYP2B2 and CYP3A1) were regulated (P < 0.05) with fold changes ranging from −46.3 to 17.1. Using MetaCore (computational platform), we identified a unique gene-network of transporters and DMEs assembled around PXR, CAR, and AhR. Therefore, a series of transactivation/translocation assays were conducted to determine whether the observed changes of transporters/DMEs are mediated by direct activation of PXR, CAR, or AhR by oxycodone or its major metabolites (noroxycodone and oxymorphone). Neither oxycodone nor its metabolites activated PXR, CAR, or AhR. Taken together, these findings identify a signature hepatic gene-network associated with repeated oxycodone administration in rats and demonstrate that oxycodone alters the expression of many transporters and DMEs (without direct activation of PXR, CAR, and AhR), which could lead to undesirable DDIs after coadministration of substrates of these transporters/DMEs with oxycodone.

Physical and chemical stability of proflavine contrast agent solutions for early detection of oral cancer

Background and purpose Proflavine hemisulfate solution is a fluorescence contrast agent to visualize cell nuclei using high-resolution optical imaging devices such as the high-resolution microendoscope. These devices provide real-time imaging to distinguish between normal versus neoplastic tissue. These images could be helpful for early screening of oral cancer and its precursors and to determine accurate margins of malignant tissue for ablative surgery. Extemporaneous preparation of proflavine solution for these diagnostic procedures requires preparation in batches and long-term storage to improve compounding efficiency in the pharmacy. However, there is a paucity of long-term stability data for proflavine contrast solutions. Methods The physical and chemical stability of 0.01% (10 mg/100 ml) proflavine hemisulfate solutions prepared in sterile water was determined following storage at refrigeration (4–8℃) and room temperature (23℃). Concentrations of proflavine were measured at predetermined time points up to 12 months using a validated stability-indicating high-performance liquid chromatography method. Results Proflavine solutions stored under refrigeration were physically and chemically stable for at least 12 months with concentrations ranging from 95% to 105% compared to initial concentration. However, in solutions stored at room temperature increased turbidity and particulates were observed in some of the tested vials at 9 months and 12 months with peak particle count reaching 17-fold increase compared to baseline. Solutions stored at room temperature were chemically stable up to six months (94–105%). Conclusion Proflavine solutions at concentration of 0.01% were chemically and physically stable for at least 12 months under refrigeration. The solution was chemically stable for six months when stored at room temperature. We recommend long-term storage of proflavine solutions under refrigeration prior to diagnostic procedure.

Evaluation of Active Hexose Correlated Compound (Ahcc) on Phase IiDrug Metabolism Pathways and the Implications for Supplement-DrugInteractions

Background: The evaluation of active hexose correlated compound (AHCC) on hepatic metabolism mediateddrug interaction is critical in current clinical setting as there is little published information on the potential effect on drug efficacy and safety. The primary objective of this study was to evaluate the potential phase II hepatic metabolism pathways associated with the metabolism of AHCC and to determine potential drug/AHCC interactions. Methods: Four primary hepatic metabolism phase II pathways were evaluated: glutathione S-transferase (GST), quinone oxidoreductase (QOR), catechol-O-methyltransferases (COMT) and uridine diphosphate (UDP)- glucuronosyltransferase (UGT). Pooled human liver microsomes and human liver S9 fractions were utilized to evaluate QOR and UGT metabolism inhibition assays. The pool human liver S9 fractions were used to assess GST activity. Cryopreserved inducible human liver hepatocytes were used to evaluate potential induction of UGT and COMT metabolism. All experiments were carried out in triplicate. Results: Data demonstrated that AHCC is not an inhibitor of GST or UGT pathways, but may be a potential inhibitor of QOR pathway. Evaluation of induction of the phase II pathways demonstrated that AHCC showed potential induction of the UGT 1A3 and 1A6 pathways. There was no induction of the COMT pathway. Conclusion: Historically, drug interaction studies have only focused on Phase I metabolism pathways, so currently there is very limited information regarding the phase II metabolism of most commonly used medications. In conclusion, additional studies are warranted to determine potential of any phase II hepatic interactions with AHCC when administered with other medications or supplement that are substrates of these pathways.

Physical and chemical stability of reconstituted and diluted dexrazoxane infusion solutions

Background and purpose Dexrazoxane is used clinically to prevent anthracycline-associated cardiotoxicity. Hydrolysis of dexrazoxane prior to reaching the cardiac membranes severely hampers its mode of action; therefore, degradation during the preparation and administration of intravenous dexrazoxane admixtures demands special attention. Moreover, the ongoing national shortage of one dexrazoxane formulation in the United States has forced pharmacies to dispense other commercially available dexrazoxane products. However, the manufacturers’ limited stability data restrict the flexibility of dexrazoxane usage in clinical practice. The aims of this study are to determine the physical and chemical stability of reconstituted and diluted solutions of two commercially available dexrazoxane formulations. Methods The stability of two dexrazoxane products, brand and generic name, in reconstituted and intravenous solutions stored at room temperature without light protection in polyvinyl chloride bags was determined. The concentrations of dexrazoxane were measured at predetermined time points up to 24 h using a validated reversed phase high-performance liquid chromatography with ultraviolet detection assay. Results Brand (B-) and generic (G-) dexrazoxane products, reconstituted in either sterile water or 0.167 M sodium lactate (final concentration of 10 mg/mL), were found stable for at least to 8 h. Infusion solutions of B-dexrazoxane, prepared according to each manufacturer’s directions, were stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. Infusion solutions of G-dexrazoxane, prepared in either 5% dextrose or 0.9% sodium chloride following the manufacturer’s guidelines, were also stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. All tested solutions were found physically stable up to 24 h at room temperature. Conclusion The stability of dexrazoxane infusion solutions reported herein permits advance preparation of dexrazoxane intravenous admixtures, facilitating pharmacy workflow and clinical operations. However, due to the potential risks of fluid overload when these intravenous solutions are administered to patients, caution is advised to ensure patient safety.

Clarifying busulfan metabolism and drug interactions to support new therapeutic drug monitoring strategies: a comprehensive review

ABSTRACT Introduction: Busulfan (Bu) is an alkylating agent with a limited therapeutic margin and exhibits inter-patient variability in pharmacokinetics (PK). Despite decades of use, mechanisms of Bu PK-based drug-drug interactions (DDIs), as well as the negative downstream effects of these DDIs, have not been fully characterized. Areas covered: This article provides an overview of Bu PK, with a primary focus on how known and potentially unknown drug metabolism pathways influence Bu-associated DDIs. In addition, pharmacogenomics of Bu chemotherapy and Bu-related DDIs observed in the stem cell transplant clinic (SCT) are summarized. Finally the increasing importance of Bu therapeutic drug monitoring is highlighted. Expert opinion: Mechanistic studies of Bu metabolism have shown that in addition to GST isoenzymes, other oxidative enzymes (CYP, FMO) and ABC/MDR drug transporters likely contribute to the overall clearance of Bu. Despite many insights, results from clinical studies, especially in polypharmacy settings and between pediatric and adult patients, remain conflicting. Further basic science and clinical investigative efforts are required to fully understand the key factors determining Bu PK characteristics and its effects on complications after SCT. Improved TDM strategies are promising components to further investigate, for instance DDI mechanisms and patient outcomes, in the highly complex SCT treatment setting.