Patent Application
20150050219
This invention relates to a solution of a perfluorocarbon with a dye, in particular intended for use in surgical methods for the treatment of the bodies of humans or animals.
In particular, this invention was prepared with reference to the sector of ophthalmic surgery and even more particularly that of vitreoretinal surgery. Therefore, hereinafter explicit reference will be made to said sector, without thereby excluding other applications.
In surgeries involving the retina, for example for the treatment of retinal detachment or retinal alterations, the vitreous humour must be removed (vitrectomy). Generally, three small incisions are made in the sclera of the eye, which allow access to the back chamber of the eye, where the vitreous humour is located. Surgical instruments can be inserted into the eye through the holes. To prevent the eye from losing its shape due to the resulting loss of pressure and to prevent secondary lesions, as the vitreous humour is sucked out, a substitute substance is inserted into the back chamber in its place, keeping the internal pressure constant.
In order to be able to then proceed with correct reattachment of the retina using a laser, the retina must be kept spread out and stationary in its physiological position. That result is normally guaranteed by the substance used to substitute the vitreous humour which acts as a temporary tamponade.
For many years now the prior art has involved the use of liquid perfluorocarbons as temporary tamponades for smoothing out and stabilising the retina during surgical manipulations.
Chemically, perfluorocarbons are completely synthetic compounds which contain only fluorine and carbon atoms. The main features of this class of chemical compounds are the fact that they are extremely inert chemically, biologically and physiologically. They are also not soluble in water or in lipophilic liquids, with which they instead form emulsions.
For example, WO 03/079927 proposes the use of fluorinated alkanes. However, the most widely used perfluorocarbons include perfluorodecalin, perfluorooctane (or n-perfluorooctane) and perfluorophenanthrene. Thanks to their low viscosity, these liquids can be infused directly on the end of the optic nerve using standard cannulas. In fact, thanks to their high density they sink towards the rear retina and slowly fill the vitreous cavity from the bottom up.
After the surgery and the consequent stabilisation of the retina, the perfluorocarbons are removed and are substituted with the conventional gaseous and liquid endo-tamponades.
Complete removal of the perfluorocarbons during this procedure is essential. Any residues of perfluorocarbons in the eye, and in particular in the back chamber, may in fact subsequently cause significant problems for the patient. First, they may cover the retina like a thin film, causing vision problems. Second, they may cause collateral effects such as inflammatory reactions.
However, the perfluorocarbons are transparent and colourless, which makes their complete removal extremely difficult.
To overcome that disadvantage, the idea of creating coloured yet still transparent tamponade liquids was developed. The aim was to make them easily identifiable by the surgeon (even small residual amounts).
However, due to the extreme inertness of perfluorocarbons, so far no dye substances have been identified which are able to colour them at least in a way that is stable and safe for patient health, as acknowledged in both patent application WO 2011/151079 and in the article by S. Rizzo, C. Belting, F. Genovesi-Ebert, N. Hagedorn, “Colored perfluorocarbon liquids as novel intraoperative tools”, Graefes Arch Clin Exp Ophthalmol on line, 2 December 2011 (DOI 10.1007/s00417-011-1874-7).
In an attempt to overcome that problem, both of the documents just referred to in fact proposed an alternative solution for making coloured tamponade liquids, which involves mixing a colourless perfluorocarbon (completely fluorinated alkane) with a coloured liquid consisting of a solution in which a dye (in itself not soluble directly in the colourless perfluorocarbon) is dissolved in a semi-fluorinated alkane. In particular, whilst the above-mentioned article describes the use of only anthraquinone blue as a dye, the patent application describes preferably the use of Sudan-class dyes.
Although the preparations produced in this way may on one hand have a density suitable for allowing their use as tamponades, and on the other hand a colour suitable for making them visible, it is still a solution that is not without disadvantages.
First, preparations of this type are mixtures of two substances rather than solutions, with the risk that even inside the eye they may separate into the two phases. It is easy to understand how the separation of the colourless perfluorocarbon would cause the same disadvantages as the tamponades commonly used today.
Second, production of these preparations is relatively complex because it requires first colouring of the semi-fluorinated alkanes and then their homogeneous mixing with the fluorinated alkanes.
Moreover, the fact that, as also indicated in the above-mentioned article by Rizzo et al., the semi-fluorinated alkanes have a density that is too low, puts limits on the maximum quantity of semi-fluorinated alkanes which can be used in the mixture.
A further major disadvantage is highlighted in the article by Rizzo et al., where it indicates that the preparation tends to release the dye when it is put in contact with silicone oil (until it even loses it completely in a relatively short time).
That means not only that the silicone oil may be contaminated when the two substances make contact during the surgery, but also that there is a real risk, if the preparation remains in the eye too long, that the dye may migrate (for the same reasons for which it migrates into the silicone oil) into the fatty parts of the tissues with which it makes contact. In fact, they are lipophilic dyes which can bind to the tissue to some degree, making it difficult to remove them.
In this context the technical purpose which forms the basis of this invention is to provide a coloured solution which overcomes the above-mentioned disadvantages.
In particular, the technical purpose of this invention is to provide a coloured solution which is biocompatible and which can be used as a retinal tamponade.
It is also the technical purpose of this invention to provide a coloured solution which is stable with respect to laser treatments of the type used for vitreoretinal surgery.
Furthermore, it is the technical purpose of this invention to provide a coloured solution which has a reduced risk of release of the dye compared with the prior art solutions.
The technical purpose specified and the aims indicated are substantially achieved by a coloured solution as described in the appended claims.
Further features and the advantages of this invention are more apparent in the detailed description below of several preferred, non-limiting embodiments of a coloured solution.
In general, according to a first aspect of this invention, the coloured solution comprises on one hand at least one perfluorocarbon which has the function of a solvent, and on the other hand a dye dissolved in the perfluorocarbon and selected from the family of fluorinated derivatives of phthalocyanines obtained by substituting one or more of the hydrogen H atoms of the phthalocyanine linked to the benzene rings with a fluorine atom or a fluorinated group, and it is intended for use in surgical methods for the treatment of the bodies of humans or animals.
According to a second aspect of this invention, the coloured solution comprises on one hand at least one perfluorocarbon selected from perfluorooctane (CAS No. 307-34-6), perfluorodecalin (CAS No. 306-94-5) and perfluorophenanthrene (CAS No. 306-91-2) and which has the function of a solvent, and on the other hand a dye dissolved in the perfluorocarbon and selected from the family of fluorinated derivatives of phthalocyanines obtained by substituting one or more of the hydrogen H atoms of the phthalocyanine linked to the benzene rings with a fluorine atom or a fluorinated group. This solution is intended for use both in surgical methods and for any other application for which it may be useful.
It should be noticed that the terms perfluorooctane, perfluorodecalin and perfluorophenanthrene in the context of this description and in the appended claims also include all synonyms commonly used which have the same CAS number.
According to all aspects of this invention, the dye is preferably selected from the family of fluorinated derivatives of metal phthalocyanines obtained by substituting one or more of the hydrogen H atoms of the phthalocyanine linked to the benzene rings with a fluorine atom or a fluorinated group.
Since the subject matter of this invention is a solution, it does not cover any mixtures of a perfluorocarbon and a fluorinated derivative of phthalocyanine of the type indicated above, which do not constitute a solution.
Therefore, the fluorinated derivatives of the phthalocyanines (metal or not) used in the context of this invention, that is to say, those obtained by substituting one or more of the hydrogen H atoms linked to the benzene rings with a fluorine atom or a fluorinated group, are defined by a formula:
where:
M may be absent or may be an ion or an atom or a group;
m, n, o and p are, independently of each other, an integer between 0 and 4, at least one of them not being zero;
RA, RB, RC and RD are, independently of each other, either a fluorine atom or a generic fluorinated group, advantageously perfluorinated, linked to one of the four external carbon atoms of the benzene ring to which it is connected. Moreover, for each benzene ring each RA, RB, RC and RD present in the formula (that is to say, if the related subscript item m, n, o and p is greater than 1) may be an atom or a group which is the same as or different to the others of the same benzene ring or of the other benzene rings.
In other words, the dye may have, at each of the four benzene rings of the phthalocyanine, one or more fluorine atoms or fluorinated groups, up to a maximum of four, which may either be the same as each other or different. Each of said atoms or groups is linked to one of the four carbon atoms of the benzene ring in place of the hydrogen H atom which would normally be present in an unmodified phthalocyanine.
Even more preferably, the dye belongs to the family of metalpoly(fluoroalkyl)phthalocyanines and advantageously to that of metalpoly(perfluoroalkyl)phthalocyanines. It should be noticed that these are dyes which are easily found on the market and whose synthesis has been known to experts in the field for many years, as indicated for example in patents U.S. Pat. No. 3,281,426 and U.S. Pat. No. 7,473,782. Consequently, they are not described in further detail herein.
Therefore, advantageously, in the preferred embodiment of this invention, the dye has a formula:
where:
M is at least one metal ion or one metal atom (which may be linked also to one or more atoms of other elements);
m, n, o and p are, independently of each other, an integer between 0 and 4, at least one of them not being zero;
each R, independently of the others present, represents a generic fluoroalkyl group, advantageously perfluoroalkyl, linked to one of the four external carbon atoms of the benzene ring to which it is connected. Moreover, for each benzene ring each R present in the formula (that is to say, if the related subscript item m, n, o and p is greater than 1) may represent a different fluoroalkyl or perfluoroalkyl group.
In other words, the dye may have, at each of the four benzene rings of the phthalocyanine, one or more fluoroalkyl or perfluoroalkyl groups, up to a maximum of four, which may either be the same as each other or different. Each of said groups is linked to one of the four carbon atoms of the benzene ring in place of the hydrogen atom which would normally be present in an unmodified phthalocyanine.
Advantageously, each fluoroalkyl or perfluoroalkyl group R comprises a number of carbon atoms which is between 3 and 16. In particular, each fluoroalkyl or perfluoroalkyl group R may be either linear and have the formula CF3(CF2)q-, where q is an integer between 2 and 15, or branched, or cyclical.
The metal part M of the molecule advantageously consists of an atom of an element selected from copper, cobalt and zinc, and is preferably copper.
In this case the formula (I) becomes respectively:
However, in a preferred embodiment the dye has the formula:
It should be noticed that in this dye each perfluoroalkyl group —(CF2)7CF3 may be linked to any one of the external carbon atoms of the benzene ring, in place of one of the four hydrogen H atoms present in the unmodified phthalocyanine.
However, in general, since the fluorinated derivatives of phthalocyanines considered by this invention may adopt various colours, the choice of colour may be made on each occasion depending on requirements for use.
With reference to the coloured solution as a whole, preferably the weight ratio of solute to solvent is between 0.0008% and 0.01%, and preferably between 0.005% and 0.01%.
However, in general the quantity of dye used will be selected in such a is way that the solution obtained with it has a colour which is sufficient but not excessive for the purpose for which it will be used.
In fact, advantageously, despite having a colour which makes it clearly visible, the coloured solution is substantially transparent. That means that during use the coloured solution must allow what is behind it to be seen. In particular, when used in a vitreoretinal surgical method, it must allow the structures of the eye, such as the retina, behind it to be seen.
For example, in a preferred composition of the coloured solution according to this invention, the solvent is selected from the following compounds: perfluorooctane with the formula
perfluorodecalin with the formula
and perfluorophenanthrene with the formula
whilst the dye is defined by the formula (V) and is present in a weight ratio of 0.008% to the solvent. In particular, with the solvent consisting of perfluorooctane (VI), the solution has an absorbance equal to 1,403 at a wavelength of 580 nm. Said solution also has a density of 1,756 kg/l at a temperature of 20° C. (substantially equal to that of perfluorooctane alone which, at 20° C., is equal to 1,755).
Regarding the physical properties of the coloured solution (such as density and viscosity), it should also be noticed that, also thanks to the small quantities of dye used in the preferred embodiments, advantageously they do not significantly deviate from those of the solvent alone.
In any case, the coloured solution is liquid at least in the temperature range between 0° C. and 50° C.
With reference to the surgical methods for which the coloured solution according to this invention is intended, in particular it is intended to be used in a vitreoretinal surgical method, and even more particularly as a retinal tamponade. In the latter case, during the vitreoretinal surgery the coloured solution according to this invention is injected into the back chamber and acts as a temporary tamponade for spreading out and stabilising the retina. However, advantageously, the coloured solution is removed when a predetermined period of time has elapsed after it was injected. During removal the dye present in the coloured solution provides a clear distinction between the coloured solution itself and the structures of the eye. Thanks to said distinction, it is easier to completely remove the coloured solution from the back chamber, and from the eye in general if there were any leaks during the surgery.
A second possible use of the coloured solution according to this invention is for identifying any residual vitreous humour during removal of the vitreous humour. In this case, the coloured solution is injected into the back chamber when the surgeon believes that he has removed all of the vitreous humour. In fact, thanks to the high density of the perfluorocarbons present in the solution, any residues of vitreous humour float on the coloured solution. At that point, the colour contrast obtained between any residues of vitreous humour and the coloured solution makes the former more visible.
Furthermore, the use of the coloured solution according to this invention makes the interface between the coloured solution and silicone oil clearly visible during the step of substituting the coloured solution with silicone oil (again in vitreoretinal surgeries).
An important aspect of the coloured solutions according to this invention, and in particular of those which use perfluorooctane, perfluorodecalin and perfluorophenanthrene as a solvent, is the fact that they have optimum biocompatibility and a substantial absence of release of the dye used.
Tests carried out by the Applicant demonstrated their stability even when subjected to laser treatment. In particular, the Applicant tested a sample of blue perfluorooctane in which the dye is defined by the formula (V), treating it in the following conditions:
instrument used: endolaser photocoagulation with a laser diode made and marketed by the company Iridex, Calif.;
power used: between 400 and 600 mw;
laser pulse duration: 9000 ms.
Before and after said treatment two NMR analyses were carried out which demonstrated that the laser treatment did not modify in any way the product tested.
It should be noticed that the test conditions selected are much more critical than those normally used in surgeries, where, generally speaking:
the power is between 150 and 250 mw;
the duration is between 200 and 500 ms.
It should also be noticed that the context of this invention also covers any concentrated solutions intended to be diluted by adding solvent before they are actually used.
Finally, both the concentrated solutions and the more dilute ones may also be used with the sole aim of facilitating the removal of a conventional fluorinated endo-tamponade at the end of the surgery. In fact, in that case, after using a conventional transparent perfluorinated liquid, the surgeon can inject the coloured solution at the end of the surgery. In fact, the coloured solution quickly mixes with the transparent perfluorinated liquid, colouring it and so making it easier to see.
This invention therefore brings important advantages.
First, thanks to this invention it was possible to prepare coloured solutions which are biocompatible, which can be used as retinal tamponades and which are stable even after laser treatment.
In particular, it was possible to prepare coloured solutions which use as a solvent only perfluorinated substances, unlike the prior art.
Moreover, the coloured solutions according to this invention have practically no risk of releasing the dye, unlike the prior art solutions.
Finally, it should be noticed that this invention is relatively easy to produce and that even the cost linked to implementing the invention is not very high.
The invention described above may be modified and adapted in several ways without thereby departing from the scope of the inventive concept.
Moreover, all details of the invention may be substituted with other technically equivalent elements and the materials used, as well as the shapes and dimensions of the various components, may vary according to requirements.
| Number | Date | Country | Kind |
|---|---|---|---|
| VR2012A000049 | Mar 2012 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2013/051951 | 3/12/2013 | WO | 00 |
