ES2835399A1 - Procedure for obtaining a textile material carrying molecules of pharmacological interest and material thus obtained (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Procedure for obtaining a textile material carrying molecules of pharmacological interest and material thus obtained. The present invention describes a process for obtaining a textile material that contains drug molecules with analgesic and anti-inflammatory properties on the surface. It is a dry presentation that would allow a controlled topical desorption of the drug. The material obtained could be applied in the manufacture of bandages, gauze, dressings and clothing, for use, among others, in physiotherapy and / or veterinary treatments.

Description

DESCRIPTION

Procedure for obtaining a textile material carrying molecules of pharmacological interest and material thus obtained

Field of the invention

The present invention falls within the pharmaceutical area since the main objective of this invention is to obtain a textile material whose fibers have been coated with an anti-inflammatory substance that can be subsequently desorbed under natural conditions of pH and temperature.

For this, the possible interaction mechanisms responsible for the adsorption process of the drug on the fiber have been interpreted, considering the results of the electrokinetic and thermodynamic study carried out, in order to optimize the process by selecting the most suitable experimental conditions.

State of the art

Natural and synthetic polymers are among the most studied and used classes of materials today. We live with polymers on a daily basis, from clothing and footwear, kitchen utensils, parts of our vehicle, furniture to technological applications for example in biomedicine such as implants and biomaterials, among others. The interest of these materials is given by the wide range of physical properties that they present, which allows their performance in a large number of fields.

Fibers are a particular type of polymers that are susceptible to a multitude of applications if we take into account the adsorption processes that can be carried out on their surface.

Traditionally, the research group in which this study has been developed has focused its research on improving dyeing processes with the help of surfactants as enhancers of the bonds between the fiber and the final adsorbate. In recent years our effort has been directed mainly to the adsorption of drugs with applied interest in external topical use, analyzing both the adsorption and desorption conditions.

Let's see below a brief summary of the background on the state of the art proposed in this report.

1. Background (scientific articles)

to. Previous studies carried out by the research group.

i. Giménez-Martín, E., et al. "Adsorption of chlorhexidine onto cellulosic fibers." Cellulose 16.3 (2009): 467-479.

In this work, a study of the adsorption characteristics of the Chlorhexidine antiseptic on natural fibers is carried out, as well as its subsequent desorption under conditions similar to saline serum in order to be used topically as a disinfectant in both humans and animals.

ii. Giménez-Martín, E., et al. "Polyamide fibers covered with chlorhexidine:

Thermodynamic aspects. " Journal of Surface Engineered Materials and Advanced Technology 5.04 (2015): 190.

In this second study, an option for adsorption of the antiseptic Chlorhexidine is presented, this time on synthetic fibers such as polyamide through the binding of the antiseptic to a reactive dye that acts between the fiber and the compound, since directly the union between the polyamide and Chlorhexidine is not possible.

iii. Giménez-Martín, E., MA López-Andrade, and D. Campos. "Nylon fibers coated with diclofenac: adsorption properties." The Journal of The Textile Institute 110.4 (2019): 515-523.

In this work, the study of the optimal adsorption conditions of a non-steroidal anti-inflammatory drug, Diclofenac Sodium on polyamide fibers, as well as its possible desorption in distilled water, is proposed.

b. Previous studies not carried out by the research group.

The most relevant article that relates Nylon fibers to a non-steroidal anti-inflammatory is:

i. Labay, C., C. Canal, and MJ García-Celma. "Influence of corona plasma treatment on polypropylene and polyamide 6.6 on the release of a model drug." Plasma Chemistry and Plasma Processing 30.6 (2010): 885-896.

In this work, the state of the art that is presented is different since the fiber is previously subjected to a treatment with plasma in order to improve the controlled desorption of drugs. In this work the chosen fiber is Nylon and the anti-inflammatory used is ketoprofen and in our work the anti-inflammatory used is Dexketoprofen tromethanol.

Apart from the aforementioned article, there are other works in which fibers are related to controlled drug desorption but using different fibers and different drugs and different treatments of the drug fiber system. Among this can be cited

ii. McCarey, Bernard E., et al. "Corneal wound healing strength with topical antiinflammatory drugs." Cornea 14.3 (1995): 290-294.

In this work, the application of Nylon sutures in corneal incisions previously treated with diclofecac, prednisone and other corticosteroids, is studied.

iii. Ostad, SN, et al. "The blood pressure and dermal sensitivity effects of nylon hollow fiber releasing glycerin trinitrate in vivo." DARU Journal of Pharmaceutical Sciences 10.3 (2002): 125-129.

In this case, a hollow Nylon fiber is used for the controlled release of Glycerin Trinitrate used to lower blood pressure.

In the field of application of smart fibers to biomedicine there are numerous works in which studies of technological applications of biomaterials and fibers for the manufacture of implants, prostheses, tissues, etc. are combined. (Park, S., & Jayaraman, S., 2010), as well as drug applications from specific carriers such as fibers or molecules with the intention of producing a gradual local desorption of the drug. It is worth mentioning the work:

iv. Ten Breteler, MR, VA Nierstrasz, and MMCG Warmoeskerken.

"Textile slowrelease systems with medical applications." AUTEX research journal 2.4 (2002): 175-189.

In this work, a general review of the possibility of obtaining controlled desorption of drugs from fibers is made, proposing its advantages in contrast to other routes of drug administration.

Other works related to the controlled release of drugs from substrates can be, Dai, C., Wang, B., & Zhao, H., 2005; Liu, Z., et al., 2008; Dash et al., 2010; but in none of them is a textile fiber used as a support.

It should be noted that apart from the studies cited to date, we have not found studies on controlled desorption of anti-inflammatories and specifically Dexketoprofen from dry textile fibers, as is the case with the substrate used in this study in order to manufacture bandages, gauze or clothing.

2. Background (patent documents)

i. Document WO2016006996A1 of 01.14.2016, whose author is (LAWR-I) VICTOR LAWRENCE AJV describes a skin therapeutic tape to reduce pain and irritation that has a flexible tissue-based tape, an adhesive layer and a non-steroidal anti-inflammatory. The difference between this patent and our proposal is the fact that our invention does not have an adhesive.

ii. Document US9192625B1 of 11/24/2015 and authors OSHI MANGALA [IN]; PURWAR ROLI [IN]; UDAKHE JAYANT SUBHASH [IN]; SREEDEVI RAJAGOPALAN describes the incorporation of antibacterial agents in fibers, filaments and films through nanoclays that serve as a vehicle for agents such as chlorhexidine. This work seems to be based on the study that we published in 2009 on the adsorption of chlorhexidine on cellulose fibers, although an intermediate substance, nanoclays, is incorporated in this presentation.

3. State of the art of the present report

All these works cited above, both those developed and published by our research group and those published by other groups, are aimed at studying the physical-chemical properties and optimizing the adsorption process on a suitable adsorbent and the subsequent controlled desorption of a drug.

The work carried out by our group includes the optimization of the processes from the treatment of the fiber in different conditions, pH, temperature and ionic strength, and / or depending on the case, with an agent previously that will act as a union between the fiber and the final product, such is the case of the adsorption of Chlorhexidine on polyamide previously treated.

In the state of the art carried out in our laboratory, the fiber does not undergo any process or previous treatment as Labay and collaborators do in the publication "Influence of corona plasma treatment on polypropylene and polyamide 6.6 on the release of a model drug." Plasma Chemistry and Plasma Processing 30.6 (2010): 885-896.

This has the consequence that the treatment of the fiber, in addition to being simpler and faster, is much cheaper since it is only initially washed to guarantee that the reactive groups are not covered by substances derived from the manufacturing process.

The work routine that is proposed as state of the art is obviously not new, since it is the sequence of experiments carried out in most of the studies of adsorption of compounds on fibers.

However, it should be noted that the application of these techniques to the study of the adsorption and desorption of drugs in aqueous solution on textile fiber flock has not been used previously or, at least, it is not shown in the literature reviewed to date. .

One of our fundamental objectives is to use a simple experimentation method in which the fiber must not undergo previous treatments, proposing a solution at the applied level, based on speed and economy to obtain the final product.

In the research work carried out, the focus is on the application of textile fibers in the field of biotechnology as a possible route of topical delivery of drugs, specifically an anti-inflammatory such as Dexketoprofen Tromethanol, DXK.

The optimization of the adsorbed quantity and therefore the subsequent obtaining of a higher yield in desorption, requires a correct electrokinetic and thermodynamic characterization of the solid-liquid interface. These phenomena depend on the type of surface as well as the free energy involved in the process. However, the study and characterization of these properties can be a difficult job given that both the structure of the adsorbate and that of the adsorbent change according to the working conditions (temperature, pH ...), which must be kept under control at all times.

Desorption is the reverse process, in which the adsorbate detaches from the adsorbent by interacting more strongly with a different solvent. In previous works published in the magazine "The Journal of the Textile Institute" the desorption of Diclofenac Sodium is carried carried out only with distilled water while in the current proposal, taking into account that it is intended to achieve the topical application of an anti-inflammatory through its desorption from the fiber in the form of gauze or bandage, it has been used as a solvent for the saline desorption to study whether the anti-inflammatory compound would be released on contact with the skin under irrigation conditions or, for example, sweating.

Previous studies have analyzed the adsorption of an antiseptic, Chlorhexidine Digluconate, with a high degree of application, mainly in dentistry, both on cellulose fibers (Giménez-Martín et al., 2009), and on polyamide fibers (Giménez -Martín et al., 2015). In a subsequent study, the adsorption of an anti-inflammatory drug, Diclofenac Sodium, on polyamide fibers was analyzed (Giménez-Martín, 2018).

The main differences with respect to this previous work could be encompassed in five fundamental aspects:

a) Regarding the pH of the treatment:

i) With DXK, the fiber must be treated at an acidic pH, pH 3. If the treatment is carried out at a higher pH, no adsorption is observed.

ii) With DCF the adsorption is zero at very acidic pH. The pH of the treatment must be greater than 5.6

b) Regarding the type of adsorption isotherm:

i) With DXK the adsorption isotherms in the concentration conditions of the treatment do not reach saturation. The adsorption isotherms conform to the FREUNDLICH theoretical model that predicts multilayer adsorption without reaching saturation. This makes it easier to control the specific concentration of adsorbed compound because the fiber allows a wide concentration range to be adsorbed, which makes it easier to obtain a greater range of possible treatment in a subsequent desorption phase.

ii) With DCF the adsorption isotherms under the concentration conditions of the treatment if they reach saturation. The adsorption isotherms conform to the theoretical model of LANGMUIR that predicts a monolayer adsorption, reaching saturation of the adsorbent.

c) Regarding the influence of temperature:

i) With DXK, the influence of temperature in the adsorption process is very low, with practically no increase in adsorption with increasing temperature. This would allow significant savings in energy consumption, of great value in a hypothetical production process at an industrial level.

ii) With DCF, the influence of temperature in the adsorption process is notable, with an increase in adsorption with increasing temperature.

d) Regarding the reaction kinetics:

i) With DXK the adsorption process is very fast and in a few minutes the fiber adsorbs the maximum concentration of the treatment, for an initial concentration of 25 mg / L and 250 ml of solution and 1 g of fiber the value of the mean adsorption time It is less than 3 minutes at a temperature of 323 K, 75% of the compound is adsorbed in solution.

ii) With DCF the adsorption process is much slower, the mean adsorption time being around 43 minutes in the case of the most favorable temperature, 323K.

e) Regarding the desorption process:

i) With DXK the desorption is achieved by means of a NaCl solution similar to physiological serum. What provides interesting possibilities in applications in contact with the skin, either in conditions of controlled irrigation or sweating.

ii) With DCF the desorption is carried out with distilled water.

In view of the fact that this line of research in the case of adsorption studies with Chlorhexidine and Sodium Digluconate allowed obtaining positive results of scientific interest, as shown by the fact that they have been published in prestigious journals (two of them of the first quartile ), we continue with similar experiments, applying the same technique to the adsorption of Dexketoprofen Trometatol also on polyamide fibers, observing the differences indicated in the previous paragraph. Thus, the work developed to obtain this invention has focused on the study of adsorption of the anti-inflammatory Dexketoprofen Tromethanol on polyamide fibers, and its subsequent desorption in physiological serum under normal conditions of pH and temperature.

The best known route of administration of Dexketoprofen is orally, although it is also presented in injectable solution or topically in gel form. However, there is currently no presentation in which the drug is administered directly from textile materials through its use in gauze, bandages and even garments, so that the drug can be desorbed in the affected area when in contact with the skin, helping to treat inflammations and achieving a rapid analgesic effect.

Obtaining the polyamide / Dexketoprofen product, PA6.6 / DXK, aims to combine the benefits of a bandage, gauze, even clothing, with those of a drug widely used in the treatment of pain such as Dexketoprofen, with high anti-inflammatory power and pain reliever. The objective is to be able to apply the compound topically from the tissue in contact with the skin. The foregoing, on the one hand, provides the benefits of topically isolating or protecting an area with gauze, compresses, bandages and other tissues and, on the other, provides a local topical treatment with the drug.

The advantages of having a tissue with a controlled amount of the drug adsorbed on the surface could be classified into two groups taking into account two fundamental aspects, namely:

I. Benefits derived from the presentation of the drug

a) As it is a dry presentation, the product does not need special packaging.

b) Likewise, it does not require special storage, for example cold, since the product is directly attached to the fiber without the need for a fluid excipient.

c) The application of the drug by means of a gauze, facilitates the isolation of the area and avoids contamination due to friction with clothing or with the outside.

d) The amount of drug provided by a unit of fiber, measured in mg of Dexketoprofen / g of dry fiber, is perfectly controlled.

II. Benefits derived from the desorption of the drug topically in the area of application

a) Due to the previous point (Id), the dose corresponding to each topical application through a gauze of a certain weight is perfectly controlled, thus avoiding the risks of applications through cream or gel in amounts not corresponding to the treatment.

b) Topical and controlled desorption of the product occurs under physiological conditions of pH and temperature.

As for the process of manufacturing polyamide fibers with known amounts of Dexketoprofen Tromethanol, previously adsorbed, it is simple and low cost. Treatment of the fiber with solutions of known drug concentration at acidic pH makes it possible to obtain an adsorption close to 65% of the drug on the fiber.

Furthermore, the fact that the temperature factor only slightly influences the process results in the low manufacturing cost of the product and obviously leads to less environmental pollution.

The interaction polyamide fiber, Dexketoprofen molecule follows the Freundlich adsorption model. This fact facilitates two fundamental situations:

• In the first place, it indicates an interaction of a physical nature, which will later facilitate the desorption process, which is the stage that governs the objective of this work.

• Secondly, the fact that the fiber does not reach a saturation at a high concentration of treatment is indicative of a multilayer adsorption, which allows increasing the drug concentration per unit of fiber and therefore obtaining a treatment range with different concentrations depending on its subsequent application.

The adsorption process is fast, reaching saturation at a treatment temperature of 323K in an approximate time of 50 minutes. This fact makes it possible to manufacture a large quantity of treated fiber in a short time.

Desorption experiments at natural pH in a NaCl solution (0.9% w / v) similar to physiological saline, in the current phase of experimentation have resulted in a desorption of approximately 15% of the product in the first 180 minutes . This data must be optimized to obtain higher yields.

Notwithstanding the foregoing, the presentation of polyamide / Dexketoprofen, PA6.6 / DXK, has not yet been tested on skin. In our opinion, it is very possible that the positive interaction between the reactive carbonyl and carboxylic groups of the Dexketoprofen molecule, and the amino groups on the skin surface, results in the adsorbed molecules in a suitable medium such as physiological serum. on the fiber they pass to the skin in a higher concentration than that observed in the desorption experiments.

The product detailed in the present invention has been developed on a laboratory scale and is part of a group of experiments in which different textile substrates have been used as carriers of molecules of pharmacological interest.

Bibliography

• Dai, C., Wang, B., & Zhao, H. (2005). Microencapsulation peptide and protein drugs delivery system. Colloids and Surfaces B: Biointerfaces, 41 (2-3), 117-120. Dash, S., Murthy, PN, Nath, L., & Chowdhury, P. (2010). Kinetic modeling on drug release from controlled drug delivery systems. Acta Pol Pharm, 67 (3), 217-23.

• Giménez-Martín, E., López-Andrade, MA, & Campos, D. (2018). Nylon fibers coated with diclofenac: adsorption properties. The Journal of The Textile Institute, 1-9.

• Giménez-Martín, E., López-Andrade, M., Moleón-Baca, JA, López, MA, & Ontiveros-Ortega, A. (2015). Polyamide Fibers Covered with Chlorhexidine: Thermodynamic Aspects. Journal of Surface Engineered Materials and Advanced Technology, 5 (04), 190.

• Giménez-Martín, E., López-Andrade, M., Ontiveros-Ortega, A., & Espinosa-Jiménez, M. (2009). Adsorption of chlorhexidine onto cellulosic fibers. Cellulose, 16 (3), 467-479.

• Labay, C., C. Canal, and MJ García-Celma. "Influence of corona plasma treatment on polypropylene and polyamide 6.6 on the release of a model drug." Plasma Chemistry and Plasma Processing 30.6 (2010): 885-896.

• Liu, Z., Robinson, JT, Sun, X., & Dai, H. (2008). PEGylated nanographene oxide for delivery of water-insoluble cancer drugs. Journal of the American Chemical Society, 130 (33), 10876-10877.

• McCarey, Bernard E., et al. "Corneal wound healing strength with topical antiinflammatory drugs. " Cornea 14.3 (1995): 290-294.

• MR ten Breteler, VA Nierstrasz and MMCG Warmoeskerken (2002). Textile slowrelease systems with medical applications. Autex Research Journal, .2 (4), 175-189

• Ostad, SN, et al. "The blood pressure and dermal sensitivity effects of nylon hollow fiber releasing glycerin trinitrate in vivo." DARU Journal of Pharmaceutical Sciences 10.3 (2002): 125-129.

• Park, S., & Jayaraman, S. (2010). Smart textile-based wearable biomedical systems:

a transition plan for research to reality. IEEE transactions on information technology in biomedicine, 14 (1), 86-92.

Brief description of the invention

The present invention shows a product with the ability to adsorb molecules of pharmacological interest, specifically Dexketoprofen Tromethanol, DXK, for the treatment of processes that cause pain or inflammation, both in humans and in animals.

The active ingredient used is Dexketoprofen, whose generic name is Dexketoprofen Tromethanol and is the tromethamine salt of S - (+) - 2- (3-bonzoylphenyl) propionic acid, it is an analgesic, anti-inflammatory and antipyretic drug belonging to the family of the non-steroidal anti-inflammatory drugs (NSAIDs) derived from propionic acid. It is indicated in the symptomatic treatment of acute moderate to severe pain. It is administered primarily orally in capsule form and parentally as ampoules or as a gel for topical use.

On the other hand, the use of various fibers of artificial and synthetic origin such as viscose and rayon or polyester, polyamide, acrylic fibers, elastomers, etc., for the use of material with pharmacological applications such as gauze, bandages dressings is increasingly widespread. This is so due to its technical properties, among which it is worth highlighting its great absorption capacity (more or less twice that of cotton), great resistance to frequent washing, resistance to high temperatures, up to 95 ° C, which makes them extremely hygienic. Microfiber fabrics do not deform, have a high insulating power and attract dirt and moisture, retaining them, thus preventing them from entering the interior. These characteristics provide many advantages that make their application increasingly common and in many cases replace fibers of natural origin such as cellulose and cotton.

The result of the procedure presented in this report is to combine the benefits of the use of a synthetic fiber such as polyamide for medical or even veterinary purposes (dressings, gauze, bandages) with the benefits that a controlled topical desorption of the anti-inflammatory can provide. Dexketoprofen.

The presentation will then be a dry textile material bearing a known concentration of Dexketoprofen with the ability to desorb in contact with the skin of the subject to be treated, under normal conditions of pH and temperature.

The invention has involved the selection of the suitable adsorbent substrate to favor the greater adsorption of the compound, as well as the study of the experimental conditions that allow optimizing the process.

Therefore, in a first aspect of the invention, it refers to a process for obtaining a material with the capacity to carry molecules of pharmacological interest that comprises the following steps:

a) First, the fibers are totally immersed in an aqueous solution of Dexketoprofen under controlled conditions of concentration, between 5 and 15 mg / L, and pH 3.

b) They are then placed in a thermostatted bath with gentle agitation for 48 hours, sufficient time to reach adsorption equilibrium. The temperature of the bath will vary in the different experiments between 283 and 313K.

c) After said time, the amount of compound adsorbed on the fiber for each initial concentration of treatment is determined spectrophotometrically, from the concentration read in the supernatant, in this way the performance of the process is determined for each concentration and temperature.

d) The fibrous plug is removed from the solution and completely dried in an oven at a temperature of 50 ° C.

e) The dry caps are stored in hermetically closed plastic bottles protected from light and moisture.

In another aspect, the present invention relates to the use of the textile material obtained in the manufacture of bandages, sanitary towels and clothing.

In another aspect, the present invention relates to the use of the textile material obtained in the treatment of painful and anti-inflammatory processes in humans.

In another aspect, the present invention refers to the use of the textile material obtained in the treatment of painful and anti-inflammatory processes in animals.

Detailed description of the invention

The product detailed in the present invention has been developed on a laboratory scale and is part of a group of experiments in which different textile substrates have been used as carriers of molecules of pharmacological interest.

The specific steps followed to obtain the invention have been the following:

First phase: fiber selection

A 1 g pellet of different fibers is used that are immersed in a fixed concentration DXK solution, 25 mg / L (adequate concentration to easily follow its value by spectrophotometric measurements), and at three different treatment pHs. Taking into account that the pH of the solution is 5.45, a more acidic and a basic pH are selected. This first phase is carried out at room temperature.

We measure the concentration of the supernatant at regular intervals of time and observe that there is only adsorption on the polyamide fiber and that this value doubles if the pH is more acidic.

Second phase: determination of the preferred conditions of the adsorption process. Analysis of the interactions involved in the process

Once the fiber has been selected, an adsorption study is carried out, varying the pH in a range of 0.2 units until the optimum is set, which turns out to be pH 3.

The influence of the ionic strength is determined with NaCl solutions of different concentrations, observing that the greatest adsorption takes place in an aqueous medium.

From here, the influence of the treatment concentration is evaluated by first analyzing the evolution of the zeta potential value of the fiber as a function of the treatment concentration.

The fact that the absolute value of this parameter changes sign from its initially positive value of 20 mV for PA6.6 at pH 3 and without DXK treatment, to negative values with a maximum of -25 mV for a concentration of 5 mg / L from which it remains practically constant, -17 mV, at increasing DXK treatment concentrations, is indicative of the presence of the anionic compound on the fiber. The zeta potential is analyzed with an Electrokinetic Analyzer, EKA, Anton Paar KG.

Once it is verified that there is adsorption at any concentration, the influence of temperature is analyzed through studies of adsorption isotherms as well as the influence of this parameter on the reaction time through kinetic studies.

Increasing adsorption is observed at higher concentration without observing a saturation at any of the analyzed temperatures. Furthermore, the influence of temperature is practically negligible in the amount adsorbed, as can be seen in figure 1. The yield obtained in the process is approximately 65%. This data is subject to improvement.

When analyzing the adsorption kinetic data, figure 3, which we have presented in table 1, it can be seen that the process is faster at higher temperatures. Based on this data we have selected as optimal conditions of the treatment in the range studied, pH 3, and temperature 323K.

The adsorption treatments are carried out following the following scheme:

1. Fibrous plugs of 1g are immersed in 100 ml of aqueous solution of different concentration in the range of 5 to 25 mg / L and at a fixed pH of 3 units. This treatment is carried out at different temperatures that vary between 283-323 K. All the adsorption experiments are carried out in hermetically sealed Pyrex flasks.

2. The samples are placed in a thermostatted bath with continuous agitation (WMB Memmbert) for 48 h.

3. Subsequently, the supernatant is removed and the fibrous plugs are dried in an oven at 50 ° C.

4. The concentration adsorbed on the fiber is determined from the measurement of the concentration of the supernatant which spectrophotometrically values a 260 nm wavelength using an Agilent Cary 60 UV-Vis spectrophotometer.

5. Finally, they are stored in individual bottles covered to avoid possible contamination.

The product obtained is a textile material that has Dexketoprofen molecules adsorbed on the surface in a proportion that varies according to the concentration of the treatment. The percentage of compound adsorbed on the fiber apparently does not depend on the concentration of the initial treatment or on the temperature, remaining in all cases in the range of 60 to 65%.

The studies carried out to know the characteristics that govern this adsorption process of Dexketoprofen on polyamide fiber are detailed below. The results of the amount of DXK adsorbed by the fiber are shown in the adsorption isotherms (figure 1), which is the representation of the amount of DXK adsorbed by the fiber against the concentration in solution at equilibrium, carried out at different temperatures and at pH 3. It is observed that the amount adsorbed by the fiber increases with the concentration of the solution without reaching saturation. This indicates that the adsorption is likely to be multilayer. The influence of temperature is positive but not very noticeable, the amount adsorbed at 323K and 313K being very similar but slightly higher. We speak of adsorption practically independent of temperature, although, as mentioned before, it has a positive influence if we compare it with a lower temperature such as 283K.

As can be seen in Figures 1 and 2, the results of the adsorption isotherms conform to the Freundlich model since the correlation coefficient is very close to 1. This fact reinforces the trend that had been observed in Figure 1 and is that the adsorption is possibly multilayer, which is why no saturation has been observed. We are facing a physical type adsorption (physisorption), therefore, apparently a chemical bond is not formed between the adsorbate and the adsorbent, but there is a weaker interaction.

After the adsorption study, a kinetic study of the process is carried out. The kinetics are then carried out manually: it is measured every 0.5 minutes for 32 minutes, then every 1 minute until 60 minutes and every 2 minutes until minute 90 from which, until minute 200 is measured every 5 minutes. The results are presented in Figure 3.

The data of the adsorption kinetics at different temperatures in Figure 3 have been adjusted to the theoretical models of pseudo-first and pseudo-second order. Although in both cases the correlation coefficients are high, the fact that the qe, theoretical mod and the qe, experimental exp for the pseudo-second order model are very similar predicts that the adsorption should be described according to this model (YS Ho and G. Mckay, 1999). Similar results have been observed working with graphene (Giménez-Martin, 2018).

At this point, the kinetic constants corresponding to the pseudo-second order adsorption kinetic model are calculated. Said constants are the final concentration in equilibrium, both theoretical and experimental, qe, mod; qe, exp, the kinetic reaction constant, k2 , and the mean reaction time, t 1/2. The results obtained at the different temperatures of the test are shown in the following table.

Table 1. Kinetic constants calculated from pseudo-second order kinetics.

We present this table because one of the most relevant results of the experimentation is that although the temperature of the treatment has a slight influence on the amount adsorbed, it is very relevant when analyzing the time it takes for the fiber to reach adsorption equilibrium. Thus, increasing the temperature greatly increases the speed of the process.

An aspect that brings special relevance to the invention that we present here is the possibility of desorption under natural conditions of pH and temperature of the adsorbed compound. For this, the desorption kinetics of the fiber previously treated with a solution of 50 mg / L of DXK at 323K and pH 3 is carried out for 48 hours, where the fiber adsorbs a quantity of DXK in the equilibrium of 6.5 mg / g. Subsequently, the desorption kinetics is carried out in physiological serum at room temperature, 298 K and pH 5.9, natural from the solution.

In figure 5 it is observed that there is an amount of desorbed DXK, that is, the drug is being attracted to the new solvent, NaCl (0.9% (w / v)), and it is observed that the amount desorbed increases progressively over time, that is, it desorbs little by little without reaching a constant value. In the 180 minutes that the experiment lasts, approximately 15% of the amount of DXK present in the stopper is desorbed. It is possible that the first layer of adsorbent is more attracted to the surface of the PA 6.6. and what is desorbed are the upper layers that remain together with less attraction. In future work we intend to optimize and improve this process.

Finally, figures 7 and 8 show the conglomerates of particles that corroborate the multilayer adsorption justified by a physical mechanism, predominantly electrostatic and acid-base interactions. This interaction is the one that is easily reversed in desorption processes with Sodium Chloride.

Brief description of the figures

Fig. 1 shows the adsorption isotherms at different temperatures, as a function of the initial concentration of the treatment.

Fig. 2 shows the linear fit of the Freundlich isotherm.

Fig. 3 shows the adsorption kinetics at different temperatures.

Fig. 4 shows the pseudo-second order kinetics fit.

Fig. 5 shows the desorption isotherm.

Fig. 6 SEM clean polyamide. Image obtained by Scanning Electron Microscopy, before submitting it to the procedure.

Fig. 7 SEM Polyamide treated with DXK. Image obtained by Scanning Electron Microscopy after subjecting the polyamide to the procedure, in which the coating of the fiber with DXK particles is evidenced.

Fig. 8 SEM Polyamide treated with enlarged DXK.

Claims (11)

1. Procedure for the elaboration of a textile material carrying molecules of pharmacological interest that comprises the following steps: a) Immerse the polymeric fibers in an aqueous solution of known concentration of Dexketoprofen. b) Keep at constant temperature and stirring for 48h. c) Remove the supernatant and dry the fibers. 2. Process according to claim 1 characterized in that the polymeric fiber is polyamide. 3. Process according to claim 1 characterized in that the solution comprises a Dexketoprofen content between 5-25 mg / L. 4. Process according to any of the preceding claims, characterized in that the dissolution is carried out at a pH between 3. 5. Process according to any of the preceding claims, characterized in that the temperature of the solution is kept constant between 283-323 K. 6. Textile material obtained by the procedure defined in any of claims 1 to 5. 7. Textile material obtained, characterized in that it presents on the surface an amount of Dexketoprofen between 50-85% of the concentration of the initial solution. 8. Use of the textile material according to any of claims 6-7 in bandages, gauze and dressings. 9. Use of the textile material according to any of claims 6-7 in clothing. 10. Use of the textile material according to any of claims 6-7 in analgesic and anti-inflammatory treatments in humans. 11. Use of the textile material according to any of claims 6-7 in treatments analgesics and anti-inflammatories in animals.