Ophthalmic product

Ophthalmic product comprising nanocapsules, process for preparing it and application of the nanocapsules. The present invention relates to an ophthalmic product comprising nanocapsules, characterized by a central core of lipid nature surrounded by a polymeric membrane capable of adhering to biological tissues. The present invention also relates to its preparation and to the application of the nanocapsules for ophthalmic use.

The present invention relates to a novel product intended for ophthalmic 
use. 
Eye diseases are generally treated by instilling one or more drops of 
collyrium on the cornea at the level of the lower eyelid. The majority of 
collyria are in the form of an aqueous solution containing the active 
principle in dissolved form. The cornea proper is covered by a lipophilic 
multi-layer epithelium having the function of a barrier for foreign bodies 
such as collyria so that during administration the collyria mix with the 
lachrymal fluid which permanently covers the eye and are very rapidly 
eliminated towards the nasal fossae. It is thought that the time during 
which the collyria act does not exceed one to two minutes and that only 
10% of the quantity of active principle instilled exerts a therapeutic 
action. 
Collyria in the form of an aqueous solution are thus not entirely 
satisfactory and have to be administered several times a day to exert a 
minimal therapeutic effect. 
Various contrivances of galenic formulation have been envisaged to increase 
the fraction of medicament penetrating the eye: increasing the viscosity 
of the solutions, manufacturing optionally biodegradable inserts placed 
between the eye and the eyelid, the wearing of contact lenses, etc. All 
these systems have enabled the therapeutic effect of the medicoments to be 
increased, but none of them has yet replaced aqueous collyria because of 
blurring of vision and the uncomfortable sensation brought about by these 
systems in patients. 
The present invention enables the problems mentioned above to be solved. In 
fact, the present invention relates to a novel ophthalmic product 
comprising nanocapsules and enabling the intraocular penetration of the 
medicoments to be increased considerably, in an unexpected manner. Within 
the context of the present invention, the term "ophthalmic product" 
designates not only a collyrium, namely products intended to be deposited 
on the outside of the eye at the level of the eyelids, but also products 
intended to be administered in the interior of the eye, namely in 
particular below the sclerotic conjunctiva or even in the vitreous humour. 
Advantageously, it has been possible to carry out such internal 
administration by means of appropriate syringes with the ophthalmic 
products of the present invention. The said ophthalmic products may 
furthermore be injected not directly into the eye but into the peri-ocular 
region (injections intended for the palpebral-oculo-orbital region, ocular 
surroundings and paths of visual projection and conduction). 
The invention is further illustrated below by reference to the following 
drawings, the purpose of which is not to limit the scope of the invention

Preferably, in accordance with the present invention, the nanocapsules are 
vesicular structures formed by a central core of oily or lipid nature 
surrounded by a fine polymeric membrane capable of adhering to biological 
tissues. These nanocapsules have a diameter of betxveen 100 and 5000 nm, 
preferably between 200 and 500 nm. The nanocapsules of the present 
invention may enable cosmetics intended for ophthalmic use to be produced, 
such as products enabling the colour of the iris to be modified. The 
nanocapsules of the present invention may also carry markers (gamma 
emitters), tracers or colouring agents, in particular intended to display 
the condition of the haemato-ocular barriers. 
However, according to the present invention the said nanocapsules are 
preferably intended to carry one or more medicinal active principles. This 
will in particular be for the treatment of the most conunon eye diseases, 
such as intraocular hypertension or glaucoma, inflaminations, allergies or 
infections. It is for this reason that the active principle is preferably 
chosen from anti-hypertensive agents such as betaxolol (ALCON 
Laboratories, Ft. Worth, Texas, USA) or carteolol (OTSUKA Laboratory, 
Japan), anti-inflammatory agents such as indomethacin, anti-allergic 
agents or antibiotics such as tetracyclines. The ophthalmic products of 
the present invention also enable dry-eye syndrome to be treated, either 
by carrying a substance intended to stimulate the formation of artificial 
tears or by themselves creating a medium providing a substitute for 
insufficient tears. 
Furthermore, it is known that those suffering from AIDS or other viral 
diseases very frequently become blind, in a manner which is inescapable, 
because of the inadequacy of conventional collyria. It is f or this reason 
that in accordance with the present invention the active principle carried 
by the nanocapsules is preferably chosen from the anti-viral agents: these 
are in particular acyclovir or iododeoxy uridine; and the ocular effects 
of viral diseases can thus be effectively checked. It goes without saying 
that in accordance with the present invention a plurality of active 
principles can be used in combination in the said nanocapsules. In fact, 
all molecules, whether of lipophilic or hydrophilic nature, can be 
incorporated in the nanocapsules of the present invention. This 
constitutes a considerable additional advantage, since it is known that 
certain active principles necessary however for the prevention or cure of 
particular eye diseases cannot, because of their lipophilic nature, be 
incorporated in conventional collyria. 
This advantage results from the conventional process for preparing the 
nanocapsules, as appears for example in EP 274 961, and in the following 
steps: 
(a) the active principle or principles are dissolved in their non-ionized 
form in a lipophilic solvent, such as an oil; 
(b) the product obtained from step (a) is mixed with an organic solvent in 
which a polymer has previously been dissolved; 
(c) the product obtained from step (b) is added to an aqueous solution 
containing a surfactant agent, with stirring; 
(d) the organic solvent and where appropriate some of the water are 
evaporated from the product obtained from step (c) in order to obtain the 
desired concentration of active principle. 
Preferably, in accordance with the present invention, before step (a), the 
salt of the active, principle is converted to the non-ionized form of the 
said active principle. This conversion may be carried out in conventional 
manner but, preferably, in accordance with the present invention the 
active principle is dissolved in distilled water, the pH of this aqueous 
phase is adjusted to pKa-2 if the active principle is an acid or pKa+2 
where the active principle is a base; the active principle then passes 
into the non-ionized form, precipitates and can be extracted by means of 
an appropriate solvent. 
In the course of step (a), there is preferably used as the lipophilic 
solvent Mygliol 812.RTM.. The polymer used in step (b) of the process of 
the present invention is preferably polyepsiloncaprolactone, but other 
appropriate polymers may be used (polyacrylic derivatives, etc.). Finally, 
various surfactants may be used in the course of step (c); one may for 
example make use of Pluronic F68.RTM.. 
The result of the said preparation process is that the ophthalmic products 
of the present invention supply the active principle in its non-ionized 
form, insoluble in water and thus insoluble in a conventional collyrium. 
Furthermore, the fact that the active principle is dissolved in an oil 
allows it to be protected from the action of the lachrymal fluid which 
could re-ionize it and thus cause it to lose its lipophilic nature. This 
non-ionized form is advantageously retained by the lipophilic epithelium 
to reach the aqueous stroma. Once in the said stroma, the active principle 
can take up its hydrophilic form again. In fact, at the pH of the stroma 
(approximately 7) the active principle takes up its ionized form again and 
again becomes soluble in aqueous medium, allowing it to diffuse across the 
stroma. The aqueous stroma constitutes approximately 9/10 of the thickness 
of the cornea and ends in a unilayer endothelium which is very permeable 
to all substances and can thus easily be crossed by the ionized active 
principle. 
The results obtained following the experiments carried out with the 
ophthalmic products of the present invention are surprising: for a 
considerably increased therapeutic effect which lasts longer in time, the 
quantities of active principle used are approximately at most a fifth of 
that of commercially available collyria. At the same time, a decrease in 
the undesirable side effects is observed. 
Consequently, thanks to the ophthalmic products of the present invention, 
it will be possible to: 
decrease the number of instillations or injections at the time of treating 
patients 
use certain active principles in non-toxic doses, such as atenolol. 
The present invention also relates to the application of nanocapsules for 
preparing ophthalmic products, namely on the one hand products intended 
for tonical ocular or peri-ocular use, such as collyria, and on the other 
hand products intended for systemic ocular or peri-ocular administration. 
In fact, in accordance with the present invention it is possible to make 
use of all the means of administration used in ophthalmology, such as 
sub-conjunctival or intra-vitreous administration. Thus, shadowgraph 
studies carried out during an intra-vitreous administration of the 
nanocapsules of the present invention show that the said capsules remain 
in the vitreous humour for at least 48 to 72 hours. Given that currently 
at least two intra-vitreous administrations per day are required to treat 
someone suffering from AIDS, one can imagine the scope of progress enabled 
by the ophthalmic products of the present invention, since the number of 
intra-vitreous injections required is considerably reduced. 
The present invention is illustrated by the following non-restrictive 
examples. 
EXAMPLE 1: Process for preparing the ophthalmic products of the present 
invention. 
1- 1 Case with betaxolol 
The active principle is dissolved in water. 
Then, the pH of this aqueous phase is adjusted to (pKa+2) with NaOH 1N. 
The active principle takes on the non-ionized form and precipitates. 
The active principle is then extracted in a chloroform phase. 
Finally, after separation by decanting, the chloroform phase is dried and 
the active principle crystallizes. 
0.005 g of non-ionized betaxolol are dissolved in 0.5 ml of lipophilic 
excipient (Mygliol 812.RTM.). 
0.125 g of non-ionized betaxolol are dissolved in 0.5 ml of lipophilic 
excipient (Mygliol 812.RTM.). 
Then, the Mygliol 812.RTM. containing the betaxolol is mixed with the 
acetone containing the polycaprolactone, with stirring (300 rpm). 
The acetone containing the polycaprolactone, the Mygliol 812.RTM., and the 
betaxolol is then added with magnetic stirring (500 rpm) to 50 ml of 
water at pH 7 containing 0.125 g of surfactant (Pluronic F 66.RTM.). 
Homogenization is carried out for 5 minutes. Then the suspension formed is 
evaporated in vacuo until a final volume of 5 ml is reached. 
______________________________________ 
Polycaprolactone 2.5 g % 
Pluronic F 68 .RTM. 2.5 g % 
Mygliol 812 .RTM. 10 ml 
Non-ionized betaxolol 0.1 g % 
______________________________________ 
The pH is readjusted to 7 if necessary by NAOH 0. 1N and 0.01 g of 
preservative (benzalkonium chloride) is added. 
1-2 Case with carteolol 
The active principle is dissolved in water. 
Then, the pH of this aqueous phase is adjusted to (pKa+2) with NAOH 1N. 
The active principle takes on the non-ionized form and precipitates. 
The active principle is then extracted in a chloroform phase. 
Finally, after separation by decanting, the chloroform phase is dried and 
the active principle crystallizes. 
0.01 g of non-ionized carteolol are dissolved in 0.5 ml of lipophilic 
excipient (Tio5.RTM. oil). 
0.125 g of polyepsiloncaprolactone are dissolved in 20 ml of organic 
solvent (acetone) by ultrasound action for 5 minutes. 
The oil containing the carteolol is mixed with the acetone containing the 
polycaprolactone, with stirring (300 rpm). 
Then, the acetone containing the polycaprolactone, the oil and the 
carteolol is added with magnetic stirring (500 rpm) to 50 ml of water (pH 
7) containing 0.125 g of surfactant (Pluronic F 68.RTM.). 
Homogenization is carried out for 5 minutes. Finally, the suspension formed 
is evaporated in vacuo until a final volume of 5 ml is reached. The 
following concentrations result: 
______________________________________ 
Polycaprolactone 2.5 g % 
Pluronic F 68 .RTM. 2.5 g % 
Tio5 .RTM. 10 ml 
Non-ionized carteolol 0.2 g % 
______________________________________ 
The pH is readjusted to 7 if necessary with NAOH 0. 1N and 0.01 g of 
preservative (benzalkonium chloride) is added. 
1-3 Case with indium oxinate (radioactive product provided by the C.E.A. 
(French Atomic Energy Commission), Saclay, France) 
1 ml of indium oxinate solution is mixed with 1 ml of Tio5.RTM. oil; the 
mixture is stirred for 15 minutes. 
The mixture is centrifuged at 3000 rpm for 5 minutes. 
0. 5 ml of Tio5.RTM. oil are then sampled and mixed by magnetic stirring 
(300 rpm) with 20 ml of organic solvent (acetone) containing 0.125 g of 
polycaprolactone previously dissolved by the action of ultrasound for 5 
minutes. 
Then, the acetone containing the polycaprolactone, the oil and the indium 
oxinate is added with magnetic stirring (500 rpm) to 50 ml of water at pH 
7 containing 0.125 g of surfactant (Pluronic F 68.RTM.). 
Homogenization is carried out for 5 minutes. Finally, the suspension formed 
is evaporated in vacuo until a final volume of 5 ml is reached. 
EXAMPLE 2: Tests in vivo on rabbits. 
These tests were carried out with the aid of two beta-blockers used in the 
treatment of intraocular hypertension or glaucoma. In order to reduce the 
intraocular hypertension, these molecules have to penetrate the eyeball. 
The penetration of the medicament into the eye, after instillation at the 
level of the conjunctival sac, is a direct function of the time it remains 
in contact with the eye. This contact time is very small with the collyria 
currently commercially available. When the same product is incorporated in 
the ophthalmic product of the present invention, it remains in contact 
with the eye for much longer. This increase in the time of local residence 
is demonstrated by gamma-shadowgraph studies and by measuring the 
therapeutic effect. 
2-1 Therapeutic effect 
The therapeutic effect is measured directly in the rabbit which was given 
glaucoma (by injecting chymotrypsin into the eye) with the aid of an 
aplanatic ionometer. The two active principles tested are currently used 
in the treatment of glaucoma. These are: betaxolol (Betoptic.RTM., Alcon 
Laboratories, Kaysersberg, France) and carteolol (Carteol.RTM., 
Chauvin-Blache Laboratories, France). The results obtained are shown in 
the FIGS. (1 and 2). These FIGURES show the chronological evolution of 
intraocular pressure after instillation of the commercial collyrium 
containing either 0.5% betaxolol or 1% carteolol and the ophthalmic 
products of the present invention containing either 0.1% betaxolol or 0.2% 
carteolol. 
With a concentration only one fifth as strong of active principle by 
comparison with the two commercially available collyria, the ophthalmic 
products of the present invention increase significantly (test of t, 
p&lt;0.01) and for an extended period the decrease in intraocular pressure. 
Moreover, the use of a lower concentration of active principle in the 
ophthalmic products of the present invention allows a reduction in the 
undesirable side effects encountered when 90% of the product passes into 
general circulation (cardiac, respiratory and neurological effects of 
current collyria). 
2-2 Study of secondary cardiovascular effects 
In order to demonstrate the secondary cardiovascular effects following 
instillation of the beta-blocker collyria, the cardiovascular system of 
the rabbit is stimulated by a single administration of a dose of 
isoprenaline (2.5 ;.mu.g/kg) . The result of this administration is an 
increase in the heart rate and a decrease in arterial pressure. After 
instillation of the commercially available collyrium (Carteol.RTM. 1%), 
the same injection of isoprenaline no longer modifies the heart rate and 
increases the arterial pressure. This leads to beta-blocking of the 
general cardiovascular system and may be the cause of the side effects 
such as severe cardiac disorders and subsequently cerebro-vascular 
illnesses. Under the same conditions, the instillation of the ophthalmic 
products of the present invention containing carteolol at a dose of only a 
fifth (0.2%) significantly reduces beta-blocking in the general 
cardiovascular system while having a therapeutic action superior to that 
of the commercially available collyrium. Thus, the incidence of 
undesirable illnesses is reduced to a very considerable extent. These 
results are shown in diagrammatic form in FIG. 3. 
2- 3 Gamma-shadowgraph study 
The ophthalmic products of the present invention are marked with the aid of 
a gamma emitter, indium oxinate, and monitored by a gamma camera after 
instillation into the eye of the rabbit. At the same time, the indium 
solution simulating the collyrium (control) is instilled in the other eye 
and monitored by the same camera. The results obtained show that after 5 
minutes there is no more than 40% of initial radioactivity in the eye 
receiving the indium solution, while at the end of 20 minutes 80% of the 
radioactivity administered at the outset is still present in front of the 
eye receiving the ophthalmic products of the present invention. 
In conclusion, the ophthalmic products of the present invention allow the 
contact time of a medicament in the eye to be extended and to deliver the 
active principle in the non-ionized form, which penetrates across the 
cornea better. They thus significantly improve its efficacity. The use of 
polymers already used in other sectors of health care and considered as 
biocompatible provides a basic guarantee of the absence of toxicity of the 
nanocapsules. On the other hand, their tolerance in the rabbit was 
satisfactory. In time, all the active principles used in ophthalmology 
(antibiotics, anti-viral agents, anti-inflammatory agents, etc. ) are 
capable of being incorporated into the ophthalmic products of the present 
invention and of thus greatly increasing their efficacity, as well as 
their duration of action, and consequently greatly reducing their side 
effects.