STABILIZATION OF SELENITE IN A NUTRITIONAL SOLUTION BY DISSOLVED OXYGEN

Abstract

The invention relates to a medical product for preventing or correcting selenium deficiency in a patient comprising a solution provided in a flexible container comprising at least one selenium compound in the form of Se (IV), which is preferably selected from the group consisting of sodium selenite, selenous acid and selenium dioxide, characterized in that the solution comprises dissolved oxygen (DO), preferably 0.5 ppm to 8 ppm DO.

Claims

1. A medical product for preventing or correcting selenium deficiency in a patient comprising a solution provided in a flexible container comprising at least one selenium compound in the form of Se(IV), which is preferably selected from the group consisting of sodium selenite, selenous acid and selenium dioxide, characterized in that the solution comprises from 0.5 ppm to 8 ppm dissolved oxygen (DO).

2. The medical product according to claim 1, wherein the DO stabilizes the selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in the solution for at least three months when stored at a temperature between 1 and 50° C.

3. The medical product according to claim 1, wherein the DO stabilizes the selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in the solution for at least 6 months, preferably 12 months, more preferably 18 months, most preferably 24 months at a temperature of from about 18° C. to 25° C.

4. The medical product according to claim 1, wherein the solution is a sterilized solution.

5. The medical product claim 1, wherein the concentration of DO in the solution is equal or above 0.5 ppm, more preferably equal or above 1 ppm, throughout shelf life of the medical product.

6. The medical product according to claim 1, wherein the concentration of DO in the solution at the time of sterilization is at least 6 ppm.

7. The medical product according to claim 1, wherein the flexible bag or chamber additionally comprises a headspace with a gas composition comprising oxygen.

8. The medical product according to claim 1, wherein the solution comprises sodium selenite.

9. The medical product according to claim 1, wherein the solution has an acidic pH, preferably in the range of from 1 to 4, more preferably from 2 to 3.5, more preferably from about 2.5 to 3.2.

10. The medical product according to claim 1, wherein the solution comprises an acid, preferably an organic acid selected from the group comprising malic acid, tartaric acid, citric acid, maleic acid, fumaric acid, more preferably malic acid, wherein the concentration of the organic acid is preferably in the range of from 100 mM to 400 mM, preferably from 190 mM to 220 mM, and more preferably about 200 mM.

11. The medical product according to claim 1, wherein the solution comprises malic acid.

12. The medical product according to claim 1, wherein the solution does not comprise macronutrients selected from the group comprising carbohydrates, proteins and lipids, and wherein preferably the solution does not comprise any other nutrients.

13. The medical product according to claim 1, wherein the solution comprises at least one additional trace element, preferably selected from the group comprising zinc, iron, copper, manganese, chromium, iodine, fluoride and molybdenum, preferably zinc, iron, manganese and/or copper.

14. The medical product according to claim 1, wherein the solution is administered parenterally.

15. The medical product according to claim 1, wherein the solution comprises at least one selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in an amount corresponding to 10-200 μg, preferably 40-100 μg, more preferably about 70 μg of selenium.

16. A medical product for preventing or correcting selenium deficiency in a patient according to claim 1, wherein the solution is contained in one chamber of a multi chamber container having at least two, at least three, at least four, at least five or at least six chambers.

17. The medical product according to claim 16, wherein the container comprises at least a first chamber containing a carbohydrate formulation, a second chamber containing an amino acid formulation, a third chamber containing a lipid formulation, optionally comprises electrolytes and/or vitamins in at least the first, second and/or third chamber, and wherein at least one chamber comprises at least one selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in the presence of from 0.5 ppm to 8 ppm oxygen.

18. The medical product according to claim 16, wherein the solution comprising at least one selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in the presence of from 0.5 ppm to 8 ppm dissolved oxygen (DO) is present in a fourth chamber.

19. The medical product according to claim 16, wherein the solution comprises sodium selenite.

20. A method of preparing a medical product for preventing or correcting selenium deficiency in a patient according to any one of the preceding claims, wherein the solution is prepared by the steps comprising a. dissolving at least one selenium compound in the form of Se(IV), which is preferably selected from sodium selenite, selenous acid and/or selenium dioxide, in a liquid medium, preferably water for injection, to produce a solution, with a concentration of selenium between 0.28 and 28 mg/L, b. optionally further dissolving, alone or together with the selenium compound in the form of Se(IV), an acid, preferably an organic acid selected from the group comprising malic acid, tartaric acid, citric acid, maleic acid and fumaric acid, and/or at least one additional trace element selected from the group comprising zinc, iron, copper, manganese, chromium, iodine, fluoride and molybdenum, c. adjusting the solution to a concentration of dissolved oxygen of from 0.5 ppm to 8 ppm, d. sterilizing the solution, preferably by heat sterilization.

21. A sterilized solution for parenteral administration comprising at least one selenium compound in the form of Se(IV), which is preferably selected from the group comprising sodium selenite, selenous acid and selenium dioxide, for use in preventing or correcting selenium deficiency in a patient, characterized in that the solution comprises dissolved oxygen (DO).

Description

FIGURES

[0167] The invention is further described by the following figures. These are not intended to limit the scope of the invention but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

[0168] Description of the Figures:

[0169] FIG. 1: pH/redox diagram illustrating the transformation/reduction of SeO.sub.3 into volatile species in a media totally free of oxygen.

[0170] FIG. 2: Fitted line plot showing a 80% fit between Se dosage and log oxygen content (ppm).

[0171] FIG. 3: Variation of DO over time in bag made of oxygen semipermeable (EU2-S) and oxygen impermeable (EU2-F) films.

[0172] FIG. 4: Analysis of influence of (A) an oxygen semi-permeable bag material and (B) an oxygen-impermeable bag material on selenite stability.

[0173] FIG. 5: Analysis of the influence of headspace and port tube on DO in combination with an oxygen-impermeable bag.

EXAMPLES

[0174] The invention is further described by the following examples. These are not intended to limit the scope of the invention but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

Example 1: Lab-Scale Manufacturing of a Selenium Containing Solution for Parenteral Nutrition or Administration

[0175] For preparing a selenium containing solution according to the invention the required amount of organic acid is dissolved in water for injection and the pH of the solution is adjusted to the target pH ±0.5 with NaOH or HCl, as needed. In a next step the selenium as sodium selenite, selenium dioxide or selenous acid is introduced into the solution and stirred or agitated until complete dissolution.

[0176] Afterwards, the pH is again controlled and, if needed, finally adjusted to the target pH ±0.2 with NaOH or HCl. Oxygen can then be introduced either by exposing the solution to the atmosphere under stirring or agitation, followed by measuring the DO and flushing the solution with nitrogen if the DO is too high and needs to be adjusted to lower values, flushing with nitrogen is stopped, accordingly, when the target oxygen concentration is reached.

[0177] Alternatively, the solution is initially flushed with nitrogen to remove essentially all of the dissolved oxygen and oxygen is then added e.g. by stirring the solution or by bubbling oxygen into the solution under constant measurement until the desired amount of oxygen is dissolved. Once the desired DO has been achieved, the solution is filled into a container under constant control of the DO and then closed/sealed. The solution can then undergo terminal heat sterilization. Besides, the remaining gas headspace present in the bag after filling can be totally removed, partially removed or replaced by oxygen or nitrogen in define amount to reach the target level of DO.

Example 2: Lab-Scale Manufacturing of a Multi Trace Element Solution for Parenteral Nutrition or Administration Containing Selenium

[0178] For preparing a multi trace element selenium containing solution for parenteral nutrition/administration the required amount of organic acid is dissolved in water for injection and the pH of the solution is adjusted to the target pH ±0.5 with NaOH or HCl, as needed. In a next step the required amount of each trace element weighed in and added to the solution under constant stirring or agitation until complete dissolution. If, for certain trace elements, the required quantity is too low for weighing in the required amount, an intermediate concentrated solution can be previously prepared. A given volume of this intermediate solution will then be added to the final solution to reach the target concentration. Afterwards, the pH is again controlled and, if needed, finally adjusted to the target pH ±0.2 with NaOH or HCl. Oxygen can then be introduced either by exposing the solution to the atmosphere under stirring or agitation, followed by measuring the DO and flushing the solution with nitrogen if the DO is too high and needs to be adjusted to lower values, flushing with nitrogen is stopped, accordingly, when the target oxygen concentration is reached.

[0179] Alternatively, the solution is initially flushed with nitrogen to remove essentially all of the dissolved oxygen and oxygen is then added e.g. by stirring the solution or by bubbling oxygen into the solution under constant measurement until the desired amount of oxygen is dissolved. Once the desired DO has been achieved, the solution is filled into a container under constant control of the DO and then closed/sealed. The solution can then undergo terminal heat sterilization. Besides, the remaining gas headspace present in the bag after filling can be totally removed, partially removed or replaced by oxygen or nitrogen in define amount to reach the target level of DO.

Example 3: Methods for Determining the DO Concentration

[0180] As mentioned in the description of the invention, various methods can be used to determine the DO content of a given solution. Generally, electrochemical or optical sensors are used for determining the DO concentration according to the invention. A preferred method comprises using a fiber-optic oxygen meter such as MICROX TX3, which is a single-channel, temperature-compensated oxygen meter with fiber-optic trace oxygen microsensors based on a glass fiber (e.g. 140 μm). The optical oxygen microsensors (also called optodes) do not consume oxygen, their signal does not depend of the flow rate of the sample, the diameter of the microsensor tip is e.g. <50 μm, they measure oxygen in both liquid and gas phase and they have an on-line temperature compensation of the oxygen content. For data visualization during measurements, the oxygen meter is connected to a LCD & Data-Logger Unit.

[0181] The oxygen measure and adjustment are based on an equilibrium between exposure to nitrogen and oxygen containing gases during the mixing and filling steps of the process. An acute and regular monitoring of the solution DO throughout these process steps allows to control the oxygen level within the final container. Besides, the headspace of the bag can be filled with a specific volume of nitrogen or oxygen to reach the final targeted level of DO.

Example 4: Evaluation of Various Factors on the Stability of Selenite

[0182] A full factorial DoE was designed to evaluate the impact of five factors on the stability of Selenite:

[0183] Container material: an interaction between Selenite and plastic bags material was previously highlighted. To evaluate this factor a neutral material i.e. glass bottles was used as a comparison to plastic bags.

[0184] pH of the solution: all previous studies were conducted at pH<3.5 to ensure stability of Fe. A comparison with a native pH >7 obtained by simple dilution of Selenite into MilliQ water allowed to evaluate the impact of this parameter.

[0185] Sterilization: the terminal heat sterilization conducted on samples may initiate degradative chemical reactions by heat exposure. Unsterilized VS sterilized samples were compared regarding Selenite stability to assess the impact of this process step.

[0186] Storage temperature: accelerated stability studies are classically conducted at 40° C. However, selenite might be sensitive to it and a comparison with samples stored at 5° C. was conducted.

[0187] Dissolved oxygen content: oxygen is involved in many redox reactions most of the time deleterious for macro and micronutrients (particularly vitamins). To assess the impact of this parameter on Selenite stability, solutions of Selenite were flushed either with oxygen (up to saturation at about 8 ppm) or with nitrogen (DO <0.5 ppm).

[0188] All combinations of factors were produced and stored under appropriate conditions for 6 months. They were then submitted to several tests to evaluate the impact of each factor on several responses.

[0189] The following readouts were performed in order to assess the impact of the factors listed above:

[0190] Se assay to evaluate the degradation of Selenium.

[0191] Visual inspection of the samples to detect any precipitate, particles or discoloration.

[0192] pH measurement to evaluate the evolution of sample pH after 6 months storage.

[0193] Dissolved oxygen measurement to evaluate the evolution of the dissolved oxygen after 6 months of storage.

[0194] Redox potential measurement as Selenite is engaged into different Se redox couples the information on redox potential of the solution might help to understand the stability of this element.

[0195] For almost all responses studied, a same group of samples presented a different behavior than the rest of them. Observations are detailed in Table 3 below.

TABLE-US-00003 TABLE 3 Assessment of the different readouts visual inspection, pH, Dissolved oxygen, delta redox potential and Se assay for samples flushed with nitrogen and stored in plastic bags versus other samples (i.e. all samples flushed with oxygen + samples flushed with nitrogen and stored in glass bottles). Response Samples flushed with Other samples Nitrogen and stored in i.e. all samples flushed plastic bags with oxygen + samples flushed with nitrogen and stored in glass bottles Visual No particles nor Particles dust like in the inspection discoloration but strong glass bottles. egg-smell at the opening Nothing detected in plastic of the overpouch bags samples pH No significant variation No significant variation of pH after 6 months of pH after 6 months storage storage Dissolved About 0 ppm of oxygen All samples present oxygen detected after 6 months significant content of oxygen (>1.5 ppm) even samples in glass bottles flushed with nitrogen during manufacturing Delta redox Significant decrease of No significant variation potential redox potential during during the 5 minutes the 5 minutes measure measure or slight increase (up to −400 mV) witness of a neutral or witness of a oxydative behavour reductive reaction Se assay Significant degradation of No significant degradation Se (i.e. more than 10% of Se (i.e. +/−10% degradation after 6 months) variation after 6 months)

[0196] These observations allowed to conclude that in samples flushed with nitrogen and stored in oxygen-permeable plastic bags the degradation of selenium observed is most probably due to a reduction of Selenite SeO.sub.3 in H.sub.2Se/HSe—, a volatile form of Se known to present a bad smell similar to sulfuric gas. The pH/redox diagram presented in FIG. 1 illustrates the transformation of SeO.sub.3 in these volatile species in a medium totally free of oxygen.

Example 5: Impact of DO on Selenium Stability

[0197] The impact of oxygen seems of major importance in the stability of Selenite. Indeed, the few amounts of oxygen that penetrates into the solution initially flushed with nitrogen but stored in glass bottles certainly blocked the reduction reaction and allowed to maintain the stability of SeO.sub.3. To confirm this hypothesis, a regression test was performed between Se assay results and log(dissolved oxygen results). Only sterilized samples stored at 40° C. were considered as the sterilization and storage at high temperature seem to both increase the Se degradation. Indeed, most reaction kinetics are accelerated by heat explaining that samples not sterilized and kept at 5° C. for 6 months do not present a degradation as important as for samples sterilized and stored at 40° C.

[0198] The fitted line plot presented in FIG. 2 shows a 80% fit between Se dosage and log oxygen content. Considering a ±5% analytical variability and the few samples used for this regression test it can be considered as significantly representative. Dissolved oxygen content is so the most impacting parameter and CQA in the stability of Selenium. As shown by FIG. 2, low oxygen amounts of around 0.5 ppm can be sufficient to ensure the stability of Selenite in solution, no saturation would be required.

[0199] The presence of oxygen promotes selenite stability. To ensure that it is not deleterious to another TE the stability of a mix of the 9 TE of interest (i.e. Zn, Cu, Cr, Mo, Mn, Fe, I, F & Se) was evaluated at pH 2.2 with 200 mM of malic acid (to ensure Iodide stability) and stored in a glass bottle (so containing about 3 ppm of dissolved oxygen). The solution was heat sterilized and stored 6 months at 40° C. or 5° C. (T6M 40° C. and T6M 5° C., respectively). Recovered concentrations of the respective trace elements after 6 months at the two temperatures are summarized in the Table 4.

TABLE-US-00004 TABLE 4 Initial (theoretical) concentration of the respective TE and the concentrations recovered after 6 months at 5° C. or 40° C. and corresponding percentage of the recovered TE are indicated. Theoretical concentration T6 M 5° C. T6 M 40° C. TE μg/L μg/L % μg/L % Zn 203561 158347 77.8% 171822 84.4% Cu 12057 9784 81.1% 10504 87.1% Mn 2204 1838 83.4% 1949 88.4% F 39959 NA .sup. 94% NA .sup. 88% I 4029 3167 78.6% 3401 84.4% Se 2806 2446 87.2% 2461 87.7% Mo 817 653 79.9% 707 86.6% Cr 396 306 77.3% 329 83.1% Fe 40116 31842 79.4% 34190 85.2%

[0200] For all TE recoveries are around 80-90% at both temperatures. An excessive dilution might explain this lower than expected recoveries, but it is known that at 5° C. samples should be stable and so it can be considered as a reference. Comparison of the two samples shows that none of the TE was degraded significantly after 6 months storage at 40° C. It confirms the hypothesis that selenite stable in the presence of few ppm of dissolved oxygen. This presence of oxygen is not deleterious for the stability of the other TE.

[0201] It can be attested that oxygen introduction would not be a problem in manufacturing. For example, instead of flushing the solution with nitrogen as it was done so far, it should be kept under ambient air allowing a sufficient amount of oxygen to be dissolved into the solution. This oxygen content could be monitored at any time as an in-process control. During filling, sterilization and storage steps, the dissolved oxygen could be maintained in the solution by using a bag material impermeable to oxygen. Such materials do neither allow any oxygen entering the bag nor being removed out of the bag (even in contact with an oxygen absorber). This way the oxygen would remain entrapped within the TE solution and avoid Se degradation all along the shelf life of the product.

Example 6: Tests Performed with Oxygen Semi-Permeable and Oxygen Impermeable Barrier Films

[0202] Tests have been performed with two different films, an oxygen semipermeable-film (EU2-S) and an oxygen impermeable film (EU2-F).

[0203] The semi-permeable film is a co-extruded film having the following structure: PP|Tie|PA|Tie|PP/SEBS/LLDPE. Therein, “PP” refers to polypropylene, “PA” refers to polyamide, “SEBS” refers to styrene-ethylene-butylene-styrene block copolymer, and “LLDPE” refers to linear low-density polyethylene. “Tie” refers to special adhesive polymers or “tie resins” which are typically polyethylene copolymers of polar and nonpolar repeat units and with or without functional reactive groups, which are used to improve adhesion between the main layers of the multi-layer film. The oxygen barrier of the film is provided by the polyamide layer (˜50 cc/m.sup.2/day). Corresponding films have been described, for example, in US20100247935A1. The semipermeable film allows some oxygen to pass.

[0204] The oxygen-impermeable film is made from a coextruded polyolefinic material laminated to a polyester with a deposit of silicon oxide to provide an oxygen barrier, i.e. the oxygen barrier provided by PET-SiOx is <1 cc/m.sup.2/day.

[0205] In the tests described in Examples 6 and 7, 1 dd/25 ml of sodium selenite was present at a pH of 3.0±0.2. 100 mM malic acid was present as well in a 50 ml mono-bag having one port-tube, wherein the bag was either made of semi-permeable or oxygen-impermeable material as described above.

[0206] After mixing, the respective solution was flushed with nitrogen to arrive at a DO of below 0.5 ppm. A headspace of 10 ml ambient air was left in said 50 ml bag. After filling the oxygen was allowed to reach saturation (about 8 ppm, see FIG. 3). The respective container was sealed and wrapped in an oxygen impermeable aluminum overpouch to which an oxygen absorber was added. The respective container was then submitted to moist heat sterilization. The following results were observed:

[0207] As shown in FIG. 4, it was found that selenite, in the EU-2S batch (semi-permeable), fell below 80% recovery after about 5 months (FIG. 4A). It can be concluded that oxygen is drawn from the solution because of the oxygen absorber present on the outer pouch and the presence of a semi-permeable primary film which allows oxygen to pass. In the EU2-F bag (oxygen-impermeable), this did not happen because of the oxygen barrier film (FIG. 4B). Selenite was retained and stayed above the threshold of 80% recovery. So, an oxygen barrier film is advantageous to ensure stability of the selenite containing solution.

[0208] Importantly, as shown in FIG. 3, the DO fell from saturation to essentially 0 ppm DO in both cases even though this process was faster in case of the EU2S semi-permeable film and the effect of the oxygen absorber.

[0209] Accordingly, the DO content decreased even though an oxygen barrier film was used. It was found that some components in the solution, including, for example, other trace elements or malic acid, seem to consume the DO, even though it is no longer lost by permeating through the film. The presence of malic acid, for example, was found to have an influence on the DO consumption in such scenario. Without wanting to be bound by theory, it is assumed, that the redox potential in the solution favors the consumption of (reaction with) oxygen.

[0210] Importantly, as long as the DO concentration does not decrease below 0.5 ppm, the selenite remains stable and can be recovered with a rate of above 80% over 5 months. This is achieved by having a DO, at the time of filling, of above 6 ppm, preferably between 6-8 ppm (essentially up to saturation).

Example 7: Relevance of Headspace

[0211] In this example, Milli-Q water was used that was kept at ambient air and was, accordingly, saturated with oxygen. The solution volume used was 15 ml.

[0212] As shown in FIG. 5A, it was found that without headspace, even when the oxygen impermeable film was used, DO content rapidly fell below the threshold of 0.5 ppm (in contrast to the above setup, where headspace was included). It could thus be shown that the headspace filled with ambient air provides for an “oxygen stock” which replaces oxygen that is lost from the container due to the presence of a port tube. Oxygen from the headspace slowly gets dissolved in the solution until equilibrium is reached. Accordingly, the DO can be kept above 0.5 ppm over time if a headspace is present. Without headspace (filled grey circles), the selenite cannot be stabilized due to DO loss over time.

[0213] Accordingly, the port tube is another aspect which may contribute to DO loss, as the port tube must be sealed between the film layers and this portion of the seal is difficult to make completely oxygen tight. Accordingly, it is advantageous to improve the oxygen tightness of the port tube used in a setting as described herein, or, where possible, to completely remove the port tube, if possible. In FIG. 5A, it becomes obvious that without headspace and without port tube (open black circles) the DO is higher over time compared to a port tube being present (closed grey circle), and that a headspace of 5 ml, for example, cannot fully compensate the loss over the port tube (open black triangle). Preferably, there is a headspace and no port tube, if possible, for stabilizing a selenite comprising solution in an oxygen barrier bag. In such setting, the DO can basically be maintained (filled grey triangle).

[0214] FIG. 5B focuses on the volume of the headspace. As can be seen and as discussed above, a headspace is required for maintaining required DO levels in compositions where oxygen present in the solution at the time of filling is consumed by components present in the solution (DO is consumed by redox reaction in the solution, see open black circles, dashed line)or otherwise lost from the container. 2 ml headspace per 25 ml container/chamber volume or 15 ml solution is not fully sufficient either (black triangles). With 6 ml headspace the threshold of 0.5 ppm can about be met even if a port tube is present (grey square, continues line) and is fully sufficient if a port tube is absent (grey square, dashed line). Best results are obtained with a headspace of 10 ml per 15 ml solution of the chamber/container (filled grey circles, continuous line), even if port tube is present (filled grey circles, dashed line).