Accelerated Stability Assessment Program to Predict Long-term Stability of Drugs: Application to Ascorbic Acid and to a Cyclic Hexapeptide.

During pharmaceutical development, the stability of the product is assessed during long-term study. If any stability issues are discovered at this point of the process, it will result in re-formulation and important loss of time and cost. Therefore, important efforts are made in order to select the most stable product. Nevertheless, predicting the stability of the developed product at early stage of the development is challenging. Accelerated stability assessment program (ASAP), based on modified Arrhenius equation and isoconversion approach, appears as an interesting tool allowing to evaluate stability and shelf-life of pharmaceutical product in a short period of time. Nevertheless, few studies using these approaches are published in the literature, and the majority concern small drug molecules. Here, this approach was applied on a small drug molecule, ascorbic acid (AA), and on a cyclic hexapeptide named cFEE. AA and cFEE have been exposed to various temperatures for a maximum of 3 weeks, and then analyzed by capillary electrophoresis coupled to UV detection (CZE-UV) for AA or LC-MS for cFEE. The level of major degradation products was used to build ASAP models and predict the stability of both compounds. Comparison between predicted and long-term data were found accurate for both compounds undergoing two different degradation pathways (oxidation and hydrolysis), confirming the real interest of accelerated predicting stability approach for consistent determination of long-term stability shelf-life of pharmaceutical products.

Elimination of three doses of gentamicin over three consecutive days using a polyacrylonitrile-derived filter: An in vitro assessment.

INTRODUCTION: Adsorption of gentamicin in a polyacrylonitrile filter was previously evidenced in a session lasting 6 h using the NeckEpur model. We extended the study over three consecutive days to mimic the 72-h life span of a filter. METHODS: Prismaflex® monitor and ST150® filter were used in the continuous diafiltration (CDF) mode at a 2.5 L/h flowrate. The daily session started with a 6-h session of CDF. Thereafter, the 5-L central compartment was changed using a bag free of gentamicin to assess gentamicin release over the following 18 h. Experiments were repeated on Day 2 and stopped at the end of the 6-h session of CDF on Day 3. The experiment was performed in duplicate. RESULTS: At a 2.5 L/h diafiltration flowrate, the mean daily clearances of gentamicin were 5.5, 4.0, and 3.3 L/h, respectively. The mean diafiltration and adsorption ratios in the daily elimination of gentamicin were 32/68%, 58/42%, and 88/12%, respectively. During days 1 and 2, the mean amount of gentamicin released from the ST150® filter were 14 and 34 mg, respectively. CONCLUSION: The pharmacokinetics of gentamicin over 3 days is strongly altered by adsorption in the same filter with a progressive decrease of elimination by adsorption, suggesting saturation of the filter. One limitation of our study results from the mode of administration using a bolus dose instead of an infusion over 30 min. Adsorption adds a clearance to those of diafiltration. The time-dependency of gentamicin clearance precludes using a constant dosage regimen over the filter's life span.

Alteration of the pharmacokinetics of aminoglycosides by adsorption in a filter during continuous renal replacement therapy. An in vitro assessment.

OBJECTIVES: Filters used in continuous renal replacement therapy (CRRT) induce elimination by filtration, dialysis, and adsorption. The worldwide used ST150® filter adsorbs cytokines. However, adsorption is a non-specific process which might alter the pharmacokinetics of drugs. Pharmacodynamic/pharmacokinetic relationship of aminoglycosides evidences the importance of the peak concentration at the first dose. We hypothesize an in vitro study may clarify the routes of elimination of aminoglycosides using the ST150® filter. METHODS: Prismaflex® and the STX150® filter, Baxter-Gambro were used. The diafiltration mode combined flowrates of dialysis and filtration at 2.5/1.5L/h, respectively, over 6h. One ionic solute was used in the different compartments. Pharmacokinetic analyses were performed using the NeckEpur® software. RESULTS: Percentages of gentamicin, tobramycin, and amikacin eliminated from the central compartment were 97±1, 95±3, and 94±6, %, respectively. The clearances were 8.4±2.3, 5.4±5, and 4.2±0.4L/h, respectively. The contributions of dialysis, filtration, and adsorption for gentamicin, tobramycin, and amikacin were 34.3±2.1, 0±0, and 67.7±2.1; 51.1±1.6, 6.3±3.1, and 46.3±2.0, and 37.8±6.3, 46.3±2.0, and 16.0±5.7%, respectively. Among physico-chemical properties, the rate of adsorption linearly and inversely correlated with the polar surface area of aminoglycosides (Y=-0.44X+161.7; R2=0.9993). DISCUSSION: Using the ST150® filter, dialysis, filtration, and adsorption play a role depending on the chemical structure of aminoglycosides. In the diafiltration mode, elimination of gentamicin and tobramycin by filtration is not detected or weak, respectively. Adsorption should be considered as a potential adverse effect of CRRT. Polar surface area of drugs is a physico-chemical parameter which should be considered regarding adsorption of drugs in filters. The risk needs to be systematically assessed.

Elimination of fluconazole during continuous renal replacement therapy. An in vitro assessment.

INTRODUCTION: Continuous renal replacement therapy (CRRT) efficiently eliminates fluconazole. However, the routes of elimination were not clarified. Adsorption of fluconazole by filters is a pending question. We studied the elimination of fluconazole in a model mimicking a session of CRRT in humans using the NeckEpur® model. Two filters were studied. METHODS: The AV1000®-polysulfone filter with the Multifiltrate Pro. Fresenius and the ST150®-polyacrylonitrile filter with the Prismaflex. Baxter-Gambro were studied. Continuous filtration used a flowrate of 2.5 L/h in post-dilution only. Session were made in duplicate. Routes of elimination were assessed using the NeckEpur® model. RESULTS: The mean measured initial fluconazole concentration (mean ± SD) for the four sessions in the central compartment (CC) was 14.9 ± 0.2 mg/L. The amount eliminated from the CC at the end of 6 h-session at a 2.5 L/h filtration flowrate for the AV1000®-polysulfone and the ST150®-polyacrylonitrile filters were 90%-93% and 96%-94%, respectively; the clearances from the central compartment (CC) were 2.5-2.6 and 2.4-2.3 L/h, respectively. The means of the instantaneous sieving coefficient were 0.94%-0.91% and 0.99%-0.91%, respectively. The percentages of the amount eliminated from the CC by filtration/adsorption were 100/0%-95/5% and 100/0%-100/0%, respectively. CONCLUSION: Neither the ST150®-polyacrylonitrile nor the AV1000®-polysulfone filters result in any significant adsorption of fluconazole.

Are we correctly treating invasive candidiasis under continuous renal replacement therapy with echinocandins? Preliminary in vitro assessment.

There is major concern regarding the pharmacokinetics of drugs under continuous renal replacement therapy (CRRT), including anti-infectious agents and more especially antifungal agents. From a regulatory viewpoint, only dialysis and filtration are considered meanwhile there is growing evidence that adsorption may also significantly alter the pharmacokinetics of anti-infectious agents. Adsorption results from a complex drug-filter interaction and might be considered an unexpected adverse effect induced by CRRT. Measurement of total plasma concentrations instead of the unbound, free, active concentrations in in vitro as well as in clinical studies hides this major adverse effect, which may jeopardise the therapeutic effect and even result in treatment failure. Noteworthy, minimal inhibitory concentrations (MIC) of anti-infectious agents are performed using solid and liquid medium without proteins testing only the antimicrobial activity of the free fraction of drugs. In a new in vitro model using crystalloid solution instead of blood, we report data supporting the assumption that the assessment of the disposition of the free fraction of caspofungin and micafungin unveils adverse effects of ST150® filter, which might eventually result in non-detectable drug concentrations and treatment failure. From a technical viewpoint, we conclude the measurement of the free fraction of drugs that largely bound to plasma proteins, including caspofungin and micafungin, should be considered instead of total plasma concentrations to assess all effects induced by filters used in CRRT.

Pre-clinical assessment of the Lovo device for dimethyl sulfoxide removal and cell concentration in thawed hematopoietic progenitor cell grafts.

BACKGROUND: Cryopreserved hematopoietic progenitor cell (HPC) grafts are widely infused to patients with malignant and nonmalignant conditions. Despite reduction of immediate side effects linked to dimethyl sulfoxide (DMSO), cell debris-containing grafts and comparable hematopoietic engraftment between washed and unwashed cryopreserved products, bedside infusion of thawed HPC grafts is still preferred. Introduction of automated devices is important for standardization and consistency of graft manipulation. Additionally, these techniques are likely to be useful for the delivery of innovative cell-based medicinal products that are currently under development. METHODS: In this study, we evaluated three consecutive versions of the Lovo device (Fresenius Kabi) for automated washing of thawed HPC products. A total of 42 HPC products intended for destruction were used. Measured outcomes included viable CD34+ cell recovery, viability, total processing time and post-washing stability. RESULTS: Preliminary data using the prototype Lovo 0.0 to process a single HPC unit showed better recovery and viability of CD34+ cells using a two-cycle than a three-cycle wash, with >95% DMSO elimination. The Lovo 1.0 performed equally well. When simultaneously processing two HPC units, the upgraded Lovo 2.0 device demonstrated comparable CD34+ recovery, DMSO elimination efficiencies and time-saving capacity. Furthermore, washed cell products were stable for 4 hours at room temperature. DISCUSSION: Lovo device satisfies clinically relevant issues: ability to efficiently wash two HPC units simultaneously and compatibility with transport to nearby transplantation centers.

What would PCR assessment change in the management of fevers in a malaria endemic area? A school-based study in Benin in children with and without fever.

BACKGROUND: A recent school-based study in Benin showed that applying a policy of anti-malarial prescriptions restricted to parasitologically-confirmed cases on the management of fever is safe and feasible. Additional PCR data were analysed in order to touch patho-physiological issues, such as the usefulness of PCR in the management of malaria in an endemic area or the triggering of a malaria attack in children with submicroscopic malaria. METHODS: PCR data were prospectively collected in the setting of an exposed (with fever)/non exposed (without fever) study design. All children had a negative malaria rapid diagnostic test (RDT) at baseline, were followed up to day 14 and did not receive drugs with anti-malarial activity. The index group was defined by children with fever at baseline and the control group by children without fever at baseline. Children with submicroscopic malaria in these two groups were defined by a positive PCR at baseline. RESULTS: PCR was positive in 66 (27%) children of the index group and in 104 (44%) children of the control group respectively. The only significant factor positively related to PCR positivity at baseline was the clinical status (control group). When definition of malaria attacks included PCR results, no difference of malaria incidence was observed between the index and control groups, neither in the whole cohort, nor in children with submicroscopic malaria. The rate of undiagnosed malaria at baseline was estimated to 3.7% at baseline in the index group. CONCLUSIONS: Treating all children with fever and a positive PCR would have led to a significant increase of anti-malarial consumption, with few benefits in terms of clinical events. Non malarial fevers do not or do not frequently trigger malaria attacks in children with submicroscopic malaria.