Patent Application
20210259981
The present invention relates to a composition for the topical treatment of inflammation and/or pain.
Whilst there have been many developments in pharmaceutical formulation, topically applied anti-inflammatories and analgesics still suffer from poor penetration and therefore poor efficacy. Increasing dosing levels in topical medicaments can often cause allergic reactions and is undesirable due to the increased cost of production associated with the higher dosing of the active pharmaceutical ingredient (API). Despite the issues posed by topically administering anti-inflammatories and analgesics, it still represents an ideal route for administration if only the penetration of the API can be improved so that it can be delivered to the muscles or joints of an individual suffering from inflammation or pain.
An object of the present invention is to address one or more of the above problems associated with the treatment and management of inflammation and/or pain. It is also an object of the present invention to provide an inflammation and/or pain treatment. It is additionally an object of the present invention to provide a treatment which allows for better penetration or delivery of anti-inflammatory and/or analgesic agents.
In accordance with a first aspect of the present invention, there is provided a polymer capable of forming nanoparticles and an anti-inflammatory and/or analgesic agent.
The polymer comprises a linear and/or branched or cyclic polymonoguanide/polyguanidine, polybiguanide, analogue or derivative thereof.
By forming nanoparticles from polymers and an anti-inflammatory and/or analgesic agent, the inventors have advantageously found that it is possible to enhance the delivery of the anti-inflammatory and/or analgesic agent into and through the stratum corneum.
It is preferred that the polymer comprises a linear and/or branched or cyclic polymonoguanide/polyguanidine, polybiguanide, analogue or derivative thereof. The linear and/or branched or cyclic polymonoguanide/polyguanidine, polybiguanide, analogue or derivative thereof may be according to the following formula 1a or formula 1b, with examples provided in tables A and B below:
wherein:
“n”, refers to number of repeating units in the polymer, and n can vary from 2 to 1000, for example from 2 or 5 to 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800 or 900;
G1 and G2 independently represent a cationic group comprising biguanide or guanidine, wherein L1 and L2 are directly joined to a Nitrogen atom of the guanide. Thus, the biguanide or guanidine groups are integral to the polymer backbone. The biguanide or guanidine groups are not side chain moieties in formula 1a.
Example of Cationic Groups:
In the present invention, L1 and L2 are the linking groups between the G1 and G2 cationic groups in the polymer. L1 and L2 can independently represent an aliphatic group containing C1-C140 carbon atoms, for example an alkyl group such as methylene, ethylene, propylene, C4, C5, C6, C7, C8, C9 or C10; C1-C10, -C20, -C30, -C40, -C50-C60, -C70, -C80, -C90, -C100, -C110, -C120, -C130 or -C140, alkyl; or L1 and L2 can (independently) be C1-C140 (for example C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10; C1-C10, -C20, -C30, -C40, -C50-C60, -C70, -C80, -C90, -C100, -C110, -C120, -C130 or -C140), cycloaliphatic, heterocyclic, aromatic, aryl, alkylaryl, arylalkyl, oxyalkylene radicals, or L1 and L2 can (independently) be a polyalkylene radical optionally interrupted by one or more, preferably one, oxygen, nitrogen or sulphur atoms, functional groups as well as saturated or unsaturated cyclic moiety. Examples of suitable L1 and L2 are groups are listed in table A.
L1, L2, G1 and G2 may have been modified using aliphatic, cycloaliphatic, heterocyclic, aryl, alkaryl, and oxyalkylene radicals.
N and G3 are preferably end groups. Typically the polymers of use in the invention have terminal amino (N) and cyanoguanidine (G3) or guanidine (G3) end groups. Such end groups may be modified (for example with 1,6-diaminohexane, 1,6 di(cyanoguanidino)hexane, 1,6-diguanidinohexane, 4-guanidinobutyric acid) by linkage to aliphatic, cycloaliphatic heterocyclic, heterocyclic, aryl, alkylaryl, arylalkyl, oxyalkylene radicals. In addition, end groups may be modified by linkage to receptor ligands, dextrans, cyclodextrins, fatty acids or fatty acid derivatives, cholesterol or cholesterol derivatives or polyethylene glycol (PEG). Optionally, the polymer can end with guanidine or biguanide or cyanoamine or amine or cyanoguanidine at N and G3 positions or cyanoamine at N and cyanoguanidine at G3 position or guanidine at N and Cyanoguanide at G3 positions or L1 amine at G3 and cyanoguanidine at N. G3 can be L1-amine, L2-cyanoguanidine or L2-guanidine. Depending on the number of polymerization (n) or polymer chain breakage and side reactions during synthesis, heterogeneous mixture of end groups can arise as described above as an example. Thus, the N and G3 groups can be interchanged/present as a heterogeneous mixture, as noted above. Alternatively N and G3 may be absent and the polymer may be cyclic, in which case the respective terminal L1 and G2 groups are linked directly to one another.
In formula 1 b, X can be either present or absent. L3, L4 and X are as noted above for “L1 or L2”. In Thus, L3 and L4 and X are the linking groups between the G4 and G5 cationic groups in the polymer. L3 and L4 and X can independently represent an aliphatic group containing C1-C140 carbon atoms, for example an alkyl group such as methylene, ethylene, propylene, C4, C5, C6, C7, C8, C9 or C10; C1-C10, -C20, -C30, -C40, -C50, -C60, -C70, -C80, -C90, -C100, -C110, -C120, -C130 or -C140, alkyl; or L3 and L4 and X can independently be C1-C140 (for example C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10, C1-C10, -C20, -C30, -C40, -C50, -C60, -C70, -C80, -C90, -C100, -C110, -C120, -C130 or -C140), cycloaliphatic, heterocyclic, aromatic, aryl, alkylaryl, arylalkyl, oxyalkylene radicals, or L3 and L4 and X can independently be a polyalkylene radical optionally interrupted by one or more, preferably one, oxygen, nitrogen or sulphur atoms, functional groups as well as saturated or unsaturated cyclic moiety. Examples of suitable L3 and L4 and X are groups are listed in table B.
“G4” and “G5” are cationic moieties and can be same or different. At least one of them is a biguanidine moiety or carbamoylguanidine, and the other moiety may be as above (biguanidine or carbamoylguanidine) or amine. For the avoidance of doubt, in formula 1b, cationic moiety G4 and G5 do not contain only single guanidine groups. For example, G4 and G5 typically do not contain single guanidine groups. Examples of such compounds are polyallylbiguanide, poly(allylbiguanidnio-co-allylamine), poly(allylcarbamoylguanidino-co-allylamine), polyvinylbiguanide, as listed in table B.
Example of polyallylbiguanide is as shown below:
In case of polyallylbigunidine L3 and L4 are identical, G4 and G5 are similar, thus polyallylbiguanide can be simplified as below.
Example of poly(allylcarbamoylguanidnio-co-allylamine) is as shown below
The polymers for use in the invention will generally have counter ions associated with them. Suitable counter ions include but are not limited to the following: halide (for example chloride), phosphate, lactate, phosphonate, sulfonate, amino carboxylate, carboxylate, hydroxy carboxylate, organophosphate, organophosphonate, organosulfornate and organosuflate.
Polymers for use in the invention can be either heterogeneous mixtures of polymers of different “n” number or homogenous fractions comprising specified “n” numbers purified by standard purification methods. As indicated above the polymers may also be cyclic and in addition may be branched.
Preferred numbers for “n” include 2-250, 2-100, 2-80 and 2-50.
CAS numbers for example compounds arising from formula 1a
The polymer used in the method of the invention may comprise linear, branched or dendrimeric molecules. The polymer may comprise a combination of linear, branched or dendrimeric molecules. The polymer may comprise one or any combination of molecules of Formula 1a or Formula 1b, for example as described above.
For example, the polymer can comprise one or more of polyhexamethylene biguanide (PHMB), polyhexamethylene monoguanide (PHMG), polyethylene biguanide (PEB), polytetramethylene biguanide (PTMB) or polyethylene hexamethylene biguanide (PEHMB). Some examples are listed in table A and B.
Thus, the polymer may comprise homogeneous or heterogeneous mixtures of one or more of polyhexamethylene biguanide (PHMB), polyhexamethylene monoguanide (PHMG), polyethylene biguanide (PEB), polytetramethylene biguanide (PTMB), polyethylene hexamethylene biguanide (PEHMB), polymethylene biguanides (PMB), poly(allylbiguanidnio-co-allylamine), poly(N-vinylbiguanide), polyallybiguanide.
Most preferred the polymer comprises polyhexamethylene biguanide (PHMB).
In one embodiment, the anti-inflammatory and/or analgesic agent comprises the same active pharmaceutical ingredient. It will be apparent to the skilled addressee that certain anti-inflammatory agents have been shown to also have analgesic properties. In other embodiments, the composition comprises a separate anti-inflammatory and a separate analgesic agent.
The anti-inflammatory agent may comprise a number of different types of anti-inflammatory agents, including steroidal anti-inflammatory agents (SAID) and non-steroidal anti-inflammatory agents. In certain embodiments, it is preferred that the anti-inflammatory agent comprises a non-steroidal anti-inflammatory (NSAID) agent. Such a NSAID may be selected from one or more of the following: Aspirin (Anacin, Ascriptin, Bayer, Bufferin, Ecotrin, Excedrin); Choline and magnesium salicylates (CMT, Tricosal, Trilisate); Choline salicylate (Arthropan); Celecoxib (Celebrex); Diclofenac potassium (Cataflam); Diclofenac sodium (Voltaren, Voltaren XR); Diclofenac sodium with misoprostol (Arthrotec); Diflunisal (Dolobid); Etodolac (Lodine, Lodine XL); Fenoprofen calcium (Nalfon); Flurbiprofen (Ansaid); Ibuprofen (Advil, Motrin, Motrin IB, Nuprin); Indomethacin (Indocin, Indocin SR); Ketoprofen (Actron, Orudis, Orudis KT, Oruvail); Magnesium salicylate (Arthritab, Bayer Select, Doan's Pills, Magan, Mobidin, Mobogesic); Meclofenamate sodium (Meclomen); Mefenamic acid (Ponstel); Meloxicam (Mobic); Nabumetone (Relafen); Naproxen (Naprosyn, Naprelan); Naproxen sodium (Aleve, Anaprox); Oxaprozin (Daypro); Piroxicam (Feldene); Rofecoxib (Vioxx); Salsalate (Amigesic, Anaflex 750, Disalcid, Marthritic, Mono-Gesic, Salflex, Salsitab); Sodium salicylate (various generics); Sulindac (Clinoril); Tolmetin sodium (Tolectin); and Valdecoxib (Bextra).
Preferably, the anti-inflammatory and/or analgesic agent comprises one or more selected from the following: Rapamycin, Tacrolimus, Ibuprofen, Ciclosporin, Diclofenac, Naproxen and related derivatives and salts thereof.
Most preferred the anti-inflammatory and/or analgesic agent Diclofenac and related derivatives and salts thereof. The Diclofenac may be in the form of Diclofenac potassium (Cataflam), Diclofenac sodium (Voltaren, Voltaren XR), or a Diclofenac salt in combination with another pharmaceutically active ingredient such as misoprostol (marketed under the Arthrotec brand).
If the anti-inflammatory and/or analgesic agent comprises Diclofenac and related derivatives and salts thereof, the average mean diameter may be in the approximate range of 50 to 250 nm. Preferably, the nanoparticles will have an average mean diameter in the range of 100 to 200 nm, more preferably the nanoparticles will have an average mean diameter in the range of 125 to 175 nm and most preferably an average mean diameter of about 150 nm and/or an average modal diameter of about 138 nm.
The nanoparticles may be formed with and/or in the presence of the anti-inflammatory and/or analgesic agent. Various methods may be used to form the nanoparticles and it is envisaged that the nanoparticles will be formed as a polymer and anti-inflammatory and/or analgesic agent complex. However, polymer nanoparticles may be independently formed and then incubated with anti-inflammatory and/or analgesic agent so that it is absorbed or attached to the nanoparticles. Alternatively, the nanoparticles may be formed during incubation with anti-inflammatory and/or analgesic agent.
It will be apparent to the skilled addressee that the composition may further comprise one or more of the following component: buffers, excipients, binders, oils, water, emulsifiers, glycerin, antioxidants, preservatives and fragrances or any additional components usually found in topical creams, gels, ointments sprays, powders, foams or mousses. Furthermore, the composition could be in a number of forms such as a paste or a suspension for use with a spraying device. Preferably, the composition is topical application.
The composition may be for use as a medicament. Such a medicament may comprise a topical medicament.
The composition may be for use in the treatment or management of inflammation and/or pain.
In a related aspect of the present invention, there is provided a composition for use in the treatment or management of inflammation and/or pain, the composition comprising a polymer capable of forming nanoparticles and an anti-inflammatory and/or analgesic agent.
In another related aspect of the present invention, there is provided a composition for the treatment or management of inflammation and/or pain, comprising a polymer capable of forming nanoparticles and an anti-inflammatory and/or analgesic agent.
Further related to the first aspect of the present invention, there is provided the use of a composition comprising a polymer capable of forming nanoparticles and an anti-inflammatory and/or analgesic agent, in the manufacture or preparation of a medicament for the treatment or management of inflammation and/or pain.
Such inflammation and/or pain may be muscular or skeletal. The composition may be for use in the treatment or management of trauma of the tendons, ligaments, muscles and joints, rheumatism, arthralgia or arthritis.
In accordance with another aspect of the present invention, there is provided use of polyhexamethylene biguanide (PHMB) to form one or more nanoparticles with, or associated with, an anti-inflammatory and/or analgesic agent in the preparation of a medicament.
The nanoparticles may be used as the delivery vehicle for the anti-inflammatory and/or analgesic agents to an affected area. The affected area may be a muscular or skeletal area. The inflammation and/or pain may comprise trauma of the tendons, ligaments, muscles and joints, rheumatism, arthralgia or arthritis.
In accordance with a further aspect of the present invention, there is provided a method of producing a composition for the treatment or management of inflammation and/or pain comprising mixing a polymer capable of forming nanoparticles with an anti-inflammatory and/or analgesic agent under conditions suitable to allow the formation of nanoparticles.
It is preferred that the method is used to produce a composition as herein above described.
In accordance with a further aspect of the present invention, there is provided a composition for use in the treatment or management of inflammation and/or pain, comprising nanoparticles or nanoparticle conjugates formed of PHMB and an anti-inflammatory and/or analgesic agent.
In a related first aspect of the present invention, there is provided the use nanoparticles or nanoparticle conjugates formed of PHMB and an anti-inflammatory and/or analgesic agent, for the manufacture or preparation of a medicament for the treatment or management of inflammation and/or pain.
PHMB (polyhexamethylene biguanide) is known as a safe and effective biocidal agent and is used as a sanitiser and preservative: U.S. Pat. Nos. 7,897,553, 4,758,595, US2008261841; US 20040009144. PHMB and related molecules are also found to be useful entry-promoting agents. It was surprisingly observed that PHMB (for example) itself enters a wide range of cells, including bacteria, fungi and mammalian cells. More surprisingly, PHMB (for example) is able to form nanoparticles with a wide range of molecules and deliver these molecules into such cells PCT/GB2012/052526. Finally the delivered molecules ranging from nucleic acids to small molecules were found to be functional inside cells. Moreover, work carried out with some natural product molecules such as retinoic acid and vitamin C have demonstrated an enhanced stabilizing effect on the natural products so they are less likely to break down when combined with PHMB.
Here we generally describe the invention of a formulation of anti-inflammatory and/or analgesic agents with PHMB which forms nanoparticles enabling penetration into and through the stratum corneum.
Embodiments of the present invention will now be described, by way of example only, with reference to the following experiments and accompanying figures, in which:
A program of work was chosen to screen a number of anti-inflammatories formulated with Nanocin® (Tecrea Ltd, UK) (polyhexamethylene biguanide (PHMB)) to determine which would be best to take forward as a therapeutic for the treatment and management of inflammation and/or pain. The active pharmaceutical ingredient (API)/Nanocin selection process was determined by the following program of work:
Topical skin application studies were also used to determine if formulating the API's enhances delivery of the API's into the skin.
Five anti-inflammatories of different classifications were chosen for the initial screening and are detailed in Table 1 below.
Solubilites of each compound in ethanol & water was determined and are shown in Table 2 below:
Celcoxib was then dropped from the program due to its insolubility, but Ibuprofen (a non-selective COX inhibitor, with better solubility in water and ethanol) was tested as a replacement.
As Diclofenac (D) was the most soluble, it was formulated first with Nanocin. A ratio of Diclofenac with Nanocin (D:N) was tested and showed change in particle size with the differing ratios. However, the polydispersity index (a measure of the variability of nanoparticle size in the mixture), as shown in
A 1:1 mg/ml ratio of Diclofenac and Nanocin in 20% ethanol produced an opaque solution, which initially was thought to be due to insolubility, but it also occurred with a 30% ethanol vehicle and water.
When the combined formulation was processed through the Nanosight LM10 (nanoparticle detecting machine), the sample was too bright to read, but upon flushing the sample out, there were signs of many nanoparticles. The formulation had to be diluted 1 in 100 to get a level of nanoparticles that could be scanned. Even at this dilution, the number of particles was measured in the billions/ml (see
The data from the LM10 and also the DLS showed that the mean particle size for this formulation is approximately 150 nm, and the mode (from the LM10) is 138 nm. Ata 1:100 dilution of the 1:1 mg/ml solution the number of particles was 7×109 particles/ml. The polydispersity index was described as good on the DLS. The population profile can be seen in
The formulation was also examined under scanning electron microscopy (SEM) by EM Support Systems Ltd, UK. First as a dry sample coated in gold and also using WET SEM.
The electron micrograph shown in
The WETSEM imaging of the nanoparticles was successfully completed and images were obtained.
Formulations with the Other API's
When the other API's were formulated with Nanocin at either a concentration of 0.33:1 mg/ml or 1:1 mg/ml (API:Nanocin) there was evidence of nanoparticles being formed in both.
Table 3 below shows the DLS data for 0.33:1 mg/ml API:Nanocin.
Table 4 below shows DLS data for 1:1 mg/ml API:Nanocin
The PDI's were high with Rapamycin and only the D:N formulation at 1:1 mg/mi gave a ‘good’ report with this but not at the 0.33:1 mg/ml.
To standardise conditions for the assay, a LPS dose (0-1 ug/ml) was investigated on TNF-α, IL-8 and IL-1α response, over a time period from 2, 4 and 24 hours. The results showed that IL-1α and IL-8 had their greatest expression after 24 hours, whereas TNF-a was an earlier responder between 2 and 4 hours, which is well known in the inflammatory cascade. As IL-8 and IL-1α both indicated a later stage in the inflammatory response and IL-8 showed a clearer response curve, IL-8 was progressed through into the screening process and IL-1α was discontinued.
API Dose Range on the Response with IL-8
A dose range of 0-30 ug/ml of each API was tested on the THP-1 cell assay (see
The API's were then tested with and without Nanocin formulation at a concentration of 30 ug/ml API and 100 ug/ml Nanocin. As previously shown Ibuprofen (I) had very little effect on reducing the IL-8 release, whereas the other API's did (
The results from
With the formulated samples and Nanocin alone the levels of IL-8 dropped nearly to zero (
The THP-1 cells are sensitive to the Nanocin concentration so a Nanocin dose was performed on the cells (
As shown in
Both cytokine measurements showed that Diclofenac alone and Nanocin alone reduced the LPS-stimulated inflammatory response. When formulated together, the levels of cytokine secreted was still considerably less than the LPS-stimulated response. The data suggests that Nanocin alone could have some anti-inflammatory action.
In vitro permeation studies were performed using porcine ear skin as described in greater detail in Example 2.
The experimental work involved applying various formulations to the skin in a Franz cell, leaving it for 24 hours as an infinite dose. Initial formulations were 1 mg/ml Nanocin and 300 ug/ml API in 20% ethanol. The same concentration of formulation were also used using FITC labelled Nanocin. Methods of detection was by: Franz Cell Method 1: Full OCT Embedding Method and Cryo-Sectioning; Franz Cell Method 2: Partial OCT Embedding and Cryo-Sectioning; Franz Cell Method 3: Partial OCT Embedding and Tape Stripping; and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) Fluorescence Microscopy.
In brief, at this concentration none of the API's were detectable in all the methods, apart from Diclofenac formulated with Nanocin, that had new secondary ions within the stratum corneum. It was hypothesised that the co-formulation of the diclofenac with the nanocin was causing substantive change in the ionisation pattern of the compound that resulted in a different fingerprint.
As diclofenac was showing signs of a signal it was decided to progress Tacrolimus as another class of anti-inflammatory agent, already used in skin remedies, ISAC was then provided with a higher dose of formulation as 1:1 mg/ml API: Nanocin to improve the signal in the ToF SIMS.
The ToF-SIMS analysis of the top 3 tape strips from 3 diclofenac and 3 diclofenac+nanocin appeared to suggest that the combination formulation induced permeation of the active ingredient into the top layers of the stratum corneum where the active alone does not.
Presented are distributions of CN— (marker for skin chemistry) and Cl—, NaCl2— and Na2Cl3— which were used as markers for the diclofenac (salt). These were used based on a peak search looking for variance between the two sample types and a control (blank).
The CN— marker is used to showcase the successful stripping of skin tissue, and the respective localisation of this tissue on the tape strip. While Cl— was seen to be somewhat ubiquitous and is to a limited extent associated with native skin chemistry, the NaCl2— and Na2Cl3— ion markers showed a strong variance compared to the control samples and do appear to correlate with the active ingredient. They are logical fragments of the salt structure of the compound.
Comparing the diclofenac+nanocin to the diclofenac alone samples it can be readily determined that there is a substantial, albeit heterogeneous presence of the NaCl2— and Na2Cl3— ions in tape strips 1-3 of all the former samples, but none of the latter. Cl— is present in all the tape strips from both sample series, but shows a marked increase in intensity in the combination formulation.
Plots of the ion intensity data from all the samples and then combined into their respective groups supports this assertion.
One example of the Diclofenac & nanocin results is shown in
Sample preparation by the partial embedding method appeared to provide better sample stability (left with underlying cartilage) and reduced the impact of the OCT on image analysis.
CN— and PO2- were used as markers for the skin chemistry, while Cl—, NaCl2- and Na2Cl3- were used as markers for the Diclofenac (salt).
Notably, the control samples show no evidence of these markers accumulated in the stratum corneum. The diclofenac alone samples showed a slight elevation in the intensity of these ions in the stratum corneum region, and in the epidermis in general. However the diclofenac+nanocin samples show significant elevations in the stratum corneum, presenting as inconsistent, heterogeneous spikes in intensity. These often correlate with suppression of the PO2- signal that helps confirm the localisation.
The aims of these experiments were to assess the ‘in-vitro’ permeation of selected active pharmaceutical ingredients (APIs) on porcine skin sections, with and without Nanocin as a permeation enhancer.
During the experiments, it was planned that a Franz cell protocol was to be developed to model the topical delivery and subsequent permeation of Rapamycin, Tacrolimus, Ibuprofen, Ciclosporin and Diclofenac APIs. These APIs were then topically applied to porcine skin both alone and co-formulated Nanocin. The skin sections recovered from the Franz cells were then to be cryo-blocked and subsequently cryo-sectioned to provide cross sectional slices of tissue. The sections were then be chemically imaged by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and fluorescence microscopy (FM) to localise the APIs and assess the extent to which they have permeated the skin sections. Secondary ion peaks representative of the APIs as pure materials were to be characterised in the initial phase of the project. These were to be used in the first instance to identify the API distributions. An (additional) FITC labelled nanocin variant was used to provide a fluorescence active permeation enhancer, which could then be detected by FM to determine permeation and tissue localisation of the range of formulations. The fluorescence work-up was performed in the first part of the project.
Porcine ears used for the Franz cell analysis were sourced from a local abattoir. The age of the pig slaughtered were between 4-6 months old. The ears were cleaned with deionised water and the outside skin was carefully removed from the underlying cartilage. The excised skin was then stored at −20° C. until use. All ears used for the permeation experiment were within 6 months after procurement.
Prior to setting up the Franz cells, the skin was defrosted by leaving it at room temperature and pressure. Excess hairs on the porcine skin were not trimmed in this instance (to promote capacity to identify follicular delivery). The skin sections were directly cut to smaller section sizes with a diameter of 3 cm to ensure that the skin could be mounted in between the donor and receptor chamber of the Franz diffusion cells.
The receptor chambers were filled with 3 ml of 10% ethanol in phosphate buffer saline (PBS). Upon assembling the Franz cells, the skin was allowed to equilibrate in a 37° C. water bath for 30 minutes. This was carried out to ensure the skin reaches physiological temperature, 32° C. The skin was then treated with desired API formulations.
After 23 hours, the excess formulation was removed from the skin and cleaned with 3% Teepol solution using a non-scratching sponge. The skin sections were then cut into 1 cm×1 cm squares (corresponding to the effective area of the treated skin site). This skin section was then cut into half so that it can fit into a base mold containing optimal cutting temperature (OCT) resin. The skin sections were placed upright so that when sectioned, vertical cross-sections are obtained. The base molds were placed on a cooled aluminium block in a liquid nitrogen bath to allow the OCT to set. The molds were then stored at −80° C. until cross-sectioned. Sequential cross sectioning was then performed using a Leica CM 3050 S cryostat to generate a number of cross sectional slices for image analysis.
The porcine skin was sourced and underwent pre-preparation in the same fashion as in method 1 above. The ears were cleaned with deionised water and then stored at −20° C. until use. All ears used for the permeation experiment were within 6 months of procurement. For this experimental set up, inside skin attached to cartilage was used to generate sections with enhanced stability.
Prior to setting up the Franz cells, the skin was defrosted by leaving it at room temperature and pressure. Excess hairs on the porcine skin were again not trimmed as per a standard protocol (to promote capacity to identify follicular delivery) and the skin excepts were cut to smaller sections with a diameter of 3 cm for mounting in between the donor and receptor chamber of the Franz diffusion cells. The receptor chambers were filled with 3 ml of 10% ethanol in phosphate buffer saline (PBS).
Upon assembling the Franz cells, the skin was allowed to equilibrate in a 37° C. water bath for 30 minutes. This was carried out to ensure the skin reaches physiological temperature, 32° C. The skin was then treated with selected formulation. After 23 hours excess formulation was removed from the skin and the section washed with 3% Teepol solution using a non-scratching sponge.
The skin sections were cut into a 1 cm×1 cm square (corresponding to the treated skin site area). This reduced skin section was then cut in half placed on a cooled aluminium block in a liquid nitrogen bath to freeze the skin solid. These frozen skin sections were then placed upright in a base mould partially filled with OCT, with the goal of ensuring the portion of skin for sectioning is not embedded in OCT.
The skin sections were then stored at −80° C. until cross-sectioned. Cryo-sectioning was performed using a Leica CM 3050 S cryostat to a thickness of 20 μm. Resultant sections were transferred onto glass microscope slides and progressed to imaging analysis.
Porcine skin was sourced and underwent standard preparation and Franz cell processing according to the same steps as laid out in method 1 (above) up to the removal of the samples from the Franz cells after treatment.
When the samples were cut down to 1 cm×1 cm following Franz cell extraction, they were subject to sequential tape stripping according to standardised protocol. Adhesive filmstrips were applied and removed successively to the treated skin area. The adhesive tape was pressed onto the skin using a roller to stretch the skin surface. 15 tape strip layers were collected for each sample prepared according to this method. Resultant tape strips were progressed to imaging analysis.
All ToF-SIMS sample section analysis was carried out on a ToF-SIMS IV instrument (ION-TOF GmbH., Münster, Germany) under ultra high vacuum conditions with operational parameters as below:
Sample sections for fluorescence microscopy were imaged using an inverted Nikon Eclipse T1 and QIMAGING optiMOS camera equipped with CoolLED pE-4000 fluorescence illumination, pE-100 bright field illumination and a Nikon plan Fluor 10×(0.30 NA) objective. Fluorescence was captured through excitation at 490 nm collecting emission at 410-500 (exposure time 50 μs), 500-550 (exposure time 200 μs), 550-650 (exposure time 200 μs) and 650-750 (exposure time 200 μs). Bright field was captured at an exposure time of 10 μs. All fluorescent and bright field images were corrected to a 12 bit image (0-4095).
The experimental plan at the outset of the project was to prepare and analyse:
1. API+Nanocin Cross Sections for ToF-SIMS
2. API Cross Sections for ToF-SIMS
3. API+FITC-Nanocin Cross Sections for FM
Ciclosporin+Nanocin Samples all failed with stratum corneum delamination. Ibuprofen+Nanocin samples all failed with stratum corneum delamination. Rapamycin+Nanocin (2 Samples successfully prepared) Illustrative data shown in
One sample was successfully prepared and 1 sample rejected for heavy contamination. The data is shown in
Two samples were successfully prepared and
The ToF-SIMS analysis of the API+nanocin cross section samples highlighted several key points:
The following experiments were used to maximise the analytical area the API/nanocin should be detectable and ensure lack of detection was not a threshold issue.
The ToF-SIMS analysis of the API-nanocin treated tape strip samples was consistent with the cross sectional data:
Two API (Diclofenac and Tacrolimus) FITC-nanocin samples were chosen to assess whether FM imaging would showcase any obvious permeation in contradiction to the ToF-SIMS data.
The data for API+FITC-Nanocin Tape Strip Analysis is shown in
The tape stripped samples provide a lateral view of the skin surface which should maximise the capacity to detect the actives (fluorophore) relative the cross sectional preparation.
The top 3 tape strip layers (TS) from the stacks collected were imaged by FM to assess whether permeation of the nanocin-API complex could be inferred and assessed by the localisation of the fluorophore.
The illustrative images above (TS1 and 2) and fluorescent intensity (FI) data collected suggested there was no significant different between intrinsic fluorescence seen on the control samples relative to the Tacrolimus and Diclofenac samples. The Diclofenac samples visually appeared to show more fluorescence on TS1 (top surface) but this was not identified as statistically significant by Fl.
This data supported the ToF-SIMS tape strip data that there was no evidence of the critical components (APIs/nanocin) permeating or residing on the skin surface.
As Diclofenac was the only active ingredient where some suggestion of permeation could be identified (cross sectional analysis) it was decided to focus solely on this API, with and without nanocin. It was also determined that an elevated concentration of the API in the formulation (1 mg/ml) would be used to increase detection efficacy.
Furthermore to address sample preparation issues and improve the structural integrity of the skin sections (avoid delamination) an adjusted preparation method was used. Skin sections still attached to underlying cartilage were used to provide enough support to enable a partial embedding technique to be used. This provided a physical structure that was more robust, and also had the added benefit of reducing analytical issues around OCT leaching and complicating of image interpretation.
These experiments investigated the following:
The ToF-SIMS analysis of the top 3 tape strips from 3 diclofenac and 3 diclofenac+nanocin appear to suggest that the combination formulation induced permeation of the active ingredient into the top layers of the stratum corneum where the active alone does not.
Presented are distributions of CN— (marker for skin chemistry) and Cl—, NaCl2— and Na2Cl3— which were used as markers for the diclofenac (salt). These were used based on a peak search looking for variance between the two sample types and a control (blank).
The CN— marker is sued to showcase the successful stripping of skin tissue, and the respective localisation of this tissue on the tape strip. While Cl— was seen to be somewhat ubiquitous and is to a limited extent associated with native skin chemistry, the NaCl2— and Na2Cl3— ion markers showed a strong variance compared to the control samples and do appear to correlate with the active ingredient. They are logical fragments of the salt structure of the compound.
Comparing the diclofenac+nanocin to the diclofenac alone samples it can be readily determined that there is a substantial, albeit heterogeneous presence of the NaCl2— and Na2Cl3— ions in tape strips 1-3 of all the former samples, but none of the latter. Cl— is present in all the tape strips from both sample series, but shows a marked increase in intensity in the combination formulation.
Plots of the ion intensity data from all the samples and then combined into their respective groups supports this assertion.
The ToF-SIMS cross sectional analysis comparing the 1 mg/ml Diclofenac and 1 mg/ml Diclofenac+Diclofenac+Nanocin could be seen to suggest that the nanocin formulation promoted (heterogeneously distributed) permeation into the stratum corneum, where there was reduced evidence of the same with the Diclofenac only formulation.
Sample preparation by the partial embedding method appeared to provide better sample stability (left with underlying cartilage) and reduced the impact of the OCT on image analysis.
CN— and PO2- were used as markers for the skin chemistry, while Cl—, NaCl2- and Na2Cl3- were used as markers for the Diclofenac (salt).
Notably, the control samples show no evidence of these markers accumulated in the stratum corneum. The diclofenac alone samples showed a slight elevation in the intensity of these ions in the stratum corneum region, and in the epidermis in general. However the diclofenac+nanocin samples show significant elevations in the stratum corneum, presenting as inconsistent, heterogeneous spikes in intensity. These often correlate with suppression of the PO2-signal that helps confirm the localisation.
The key findings where that there was no evidence of cyclosporine, ibuprofen, rapamycin or tacrolimus permeation with or without Nanocin, although it cannot be discounted that this was due to the sensitivity of the method to detect these APIs. There was some evidence of diclofenac permeation when co-formulated with nanocin by tape stripping analysis and ToF-SIMS imaging.
A full range of API treated skin samples were successfully generated by a Franz cell experimentation method. However subsequent sample progression to cross sectional slices proved to be inconsistent with several sample failures, most commonly attributed to stratum corneum inflammation and delamination. Initial data collected using the ToF-SIMS on the (non FITC labelled) nanocin-API formulation treated samples provided no evidence that neither the APIs nor nanocin could be detected using the ion markers identified. Experiments investigating API alone ToF-SIMS & API+FITC-Nanocin FM were not conducted and a method adjustment was initiated based on this data to carry out some lateral analysis of the skin surface via tape stripping to see whether the ion markers could be detected when looking over a larger expected surface area.
A more advanced data analysis of the secondary ion dataset for the cross sectional slices was also undertaken. This work highlighted that the Diclofenac-Nanocin sample sections showed some evidence of unique (relative to blank reference samples) secondary ion localisation to the stratum corneum. These markers (mass range 200-400 m/z) were not consistent with the reference markers listed from the reference work up. No such evidence was found for the other API systems. This suggested that the co-formulation of the Nanocin with the APIs was generating a unique ionisation matrix that resulted in different secondary ion structures to the APIs and the nanocin alone.
Fluorescent microscopy imaging of FITC-labelled nanocin-API treated samples presented no evidence of the fluorophore within the first 3 tape strip layers of the skin. An additional method change was initiated based on this data to exclusively focus on Diclofenac and use a variant on the sample preparation mechanism to improve sample stability. Higher concentrations (1 mg/ml) of the Diclofenac were formulated to ensure the limit of detection was been exceeded. A partial embedding protocol, on skin sections still attached to cartilage was used to good effect to improve sample viability under processing and remove the impact of OCT on image analysis and component leaching. Sample viability was improved, with reduced sample loss, and chemical imaging capacity was improved by removing the impact of the OCT chemistry. Both cross sectional slices and tape strips were prepared with Diclofenac (alone) and Diclofenac plus nanocin treated samples.
Tape stripping analysis of repeats of these two systems showed a difference in the localisation of the same ions identified in the ToF-SIMS cross sectional analysis but also a more pronounced other ion markers that logically correspond to the diclofenac structure. The tape strip data suggests heterogeneous permeation of the API in the nanocin formulated variant, with none in the API alone system. This was largely based on the use of ions relating the Diclofenac salt (Cl—, NaCl2—, Na2Cl3—). The cross sectional analysis supports this assertion, suggesting permeation of diclofenac (by the same markers listed above) when co-formulated with nanocin into the stratum corneum. The distribution of these ions in the stratum corneum is somewhat heterogeneous, with spikes in intensity localised to particular points.
Human skin studies confirmed the enhanced drug delivery of an NSAID (diclofenac) into healthy human skin (see
All samples were analysed for the presence of diclofenac by quantitative LC-MS using a Waters ACQUITY QDa mass detector (
At 24 hours, there was little detectable diclofenac in any of the receptor fluid samples showing that minimal drug had passed through the skin in this time. The only exception was for one of the diclofenac/polyhexanide samples where substantial amounts of the applied drug were found in the receptor fluid. However, this was due to leakage of the fluid past the skin disk in this one sample (
In comparison to the diclofenac alone treated disks, the diclofenac/polyhexanide treated samples demonstrated significantly enhanced drug delivery into the upper layers of the skin as demonstrated by higher drug concentrations from diclofenac/polyhexanide skin tape strips compared to diclofenac alone treated skin (
Following striping of the skin, tape strips were suspended in 5 ml of methanol to solubilize drug off the tape prior to analysis by LC-MS.
These results demonstrate clear, enhanced skin delivery of diclofenac into human skin following formulation of diclofenac with polyhexanide.
The forgoing embodiments are not intended to limit the scope of the protection afforded by the claims, but rather to describe examples of how the invention may be put into practice.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1810925.6 | Jul 2018 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2019/051889 | 7/3/2019 | WO | 00 |
