Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/33—Heterocyclic compounds
  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/495—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with two or more nitrogen atoms as the only ring heteroatoms, e.g. piperazine or tetrazines
  • A61K31/496—Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P27/00—Drugs for disorders of the senses
  • A61P27/02—Ophthalmic agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P41/00—Drugs used in surgical methods, e.g. surgery adjuvants for preventing adhesion or for vitreum substitution

Definitions

• the present invention concerns the use of pirenoxine for the protection of the corneal tissues in photokeratectomy interventions. More particularly, the invention concerns the use of pirenoxine and salts thereof as agents able to inhibit within the cornea the oxidative phenomena determined by reactive oxygen species (or ROS, reactive oxygen species) which are produced in the tissues following the laser irradiation.
• ROS reactive oxygen species
• the ophthalmic surgery and particularly the refractive one, which aims to modify the eye refractive power in order to correct not negligible visual defects makes use of various, less or more consolidated or in evolution techniques, some examples of which are radial keratectomy, epikeratofachia and keratomileusis.
• laser particularly solid state laser, (like neodymium:yttrium-aluminium-garnet laser, known as Nd:YAG), and, above all, excimer laser, is remarkably increased.
• Excimer laser is a pulse laser which, due to the decay of excited noble gas dimers (excimers obtained from gas mixtures of halogen and noble gases), are able to emit large amounts of energy in form of radiation within the range of far ultraviolet (UV-C), in the form of pulse trains having predetermined duration, frequency and fluence. Any photon emitted during the irradiation has enough energy to break the intramolecular bonds of the exposed material, in such a way that the irradiated molecules are "broken” in small volatile fragments which are expulsed at supersonic speed embodying a process known as "photodecomposition".
• UV-C far ultraviolet
• an argon-fluorine laser emitting radiation with a wavelength of 193 nm, which is suitable to carry out highly precise interventions with an optimal control on the penetration depth and a minimal thermal or mechanical damage effect on adjacent to exposed tissues.
• the excimer laser does not emit energy concentrated in a focal point but it has a radius with a large cross section which, going through suitable slits, is directed to strike large surface cornea zones with an accurate control of the shape and sizes of the exposed zones.
• the emitted energy is almost totally adsorbed by a surface layer within a thickness of few microns and results, by means of evaporation, in ablation at every pulse of cornea layers little more thicker than molecular, with a reproducibility not attainable by other techniques.
• the excimer laser is widely used for corneal refractive remodelling in techniques known as photorefractive keratectomy or PRK and LASIK (laser intrastromal keratomileusis), for the correction of various ametropias among which the most diffused is myopia.
• PRK and LASIK laser intrastromal keratomileusis
• the latter is a defect determined by a cornea curvature higher than required by the length of ocular bulb, so that light rays from outside are refracted in a such way that, before to reach the retina, they converge in a focal point.
• the use of excimer laser provides that layers of corneal tissue, the thickness of which is increasing toward the centre, be ablated reducing therefore the curvature of the cornea.
• the technique is used for the correction of hypermetropia, wherein, on the contrary, the modification to be obtained is an increase of the cornea curvature
• the amount of ablated tissue within the periphery of the exposed zone is more important than in the centre.
• the depth of the ablation can be asymmetric, depending on the meridian to be "flatted".
• the restorative process after the photoablation is not without drawbacks which are less or more transitory and boring or dis-enabling for the patient, among which, for example, there are corneal cicatricial problems, generation of under-epithelial opacities called "haze", which determine a reduction of visual efficiency resulting from "light scattering" phenomenon (light diffusion) and, in some circumstances, a reduction of refractive values as result of operation. It appears to be not debatable by those skilled in the field that at least partially such effects result from the formation of free radicals and, generally, reactive oxygen species, which was detected as side effect of UV irradiation and temperature increase occurring in the involved tissues.
• ROS reactive oxygen species
• the activity of these species exerts, within the organism, on various cellular components, among which there are a large number of structural proteins and enzymes, DNA, RNA and, above all, the membrane lipids.
• the lipid peroxidation is the most known mechanism by which ROS exert their degenerative activity on the cellular structures damaging polyunsaturated fatty acids (PUFA) contained in the cytoplasmic membranes, often as phospholipid esters.
• PUFA polyunsaturated fatty acids
• lipid peroxide radical ROO » which, being a so strong oxidant to attack another PUFA, starts the propagation step of the reaction.
• a lipid hydroperoxide radical, ROOH; and, correspondingly, another lipid peroxide radical ROO » are formed. Therefore the above described main branch of the reaction occurs by means of radical chain attacks to the membrane lipids which are thus transformed step by step in the corresponding hydroperoxides till to the chain termination by means of a free radical.
• the object of the present invention is to provide the corneal tissues involved in UV irradiation, both before and soon after the treatment, with an agent suitable to perform a protective activity against the cellular damage triggered by the reactive oxygen species and to scavenge the action thereof.
• the suggested agent must be effective to oppose the lipid peroxidation in the corneal cellular tissues.
• Pirenoxine or 1-hydroxy-5-oxo-5H-pyrido-[3,2a]-phenoxazin-3- carboxylic acid (also called pirfenossone) is a known compound having the following formula:
• cataracts used in ophthalmology, usually in the form of sodium salt thereof, for the treatment of the cataract.
• the latter is an abnormal progressive condition of the eye crystalline lens characterized by an increasing loss of transparency.
• the cataracts more often result from degenerative modifications, often occurring after 50 year age, while more rarely they can result from traumas or poison exposure. Initially the vision is hazy, then the brilliant lights dazzle diffusely and distortion and double vision can develop. At the end, if the cataract is not treated, anopia occurs.
• the cataracts can be treated by the ophthalmic topic administration of pirenoxine in the form of collyrium.
• pirenoxine can be advantageously used for the protection of the corneal tissues during excimer laser treatments because it is active in inhibiting the lipid peroxidation in the corneal cellular tissues.
• pirenoxine 1- hydroxy-5-oxo-5H-pyrido-[3,2a]-phenoxazin-3-carboxylic acid (pirenoxine) or a pharmaceutically acceptable salt thereof for the production of a topic ophthalmic drug suitable for the protection of the corneal tissues in photokeratectomy interventions.
• the suggested drug is designed as inhibitor of the ROS activity (reactive oxygen species) at level of corneal tissues and, particularly as inhibitor of the lipid peroxidation at level of said tissues.
• Use of pirenoxine as pre- and post-operation protective agent finds application in any photokeratectomy treatment, being further presumable a wider use in those treatments which presently are more diffused, i.e. corneal photoablation by means excimer laser, both refractive and therapeutic and, in the first case by means of both PRK and LASIK technique.
• the ophthalmic preparations of the present invention preferably contain the active principle, i.e. pirenoxine or a pharmaceutically acceptable salt thereof, in amount from 0,0001 % to 0,01 weight %, expressed as free acid. More conveniently said medicaments contain from 0,001 % to 0,005 weight % of pirenoxine, expressed as free acid, the optimum concentration being the same as that presently used for the therapy of the cataract, i.e. 0,005 weight %. Most conveniently said pirenoxine is in the form of the sodium salt.
• the preparation according to the invention can be administered, in order to obtain the desired effect of ROS inhibition, at a dosage of one-two drops twice or three times a day, preferably two drops three times a day, beginning at least one or two days before the operation and continuing, after the operation, over at least one or two days.
• the dosage and posology can be widely variable without impairing the whole protective effect against ROSs exerted by the product.
• the ophthalmic topic drug containing pirenoxine or a salt thereof can be, generally, in the same forms as prepared or proposable for the use of the same active principle for the therapy of the cataract or ophthalmic inflammation, as described in the above mentioned European patent publication EP-A-0885612.
• the product can be in the form of aqueous solution or suspension for collyrium or in the form of emulsion, ointment, gel or cream.
• the product is administered as aqueous ophthalmic solution.
• pirenoxine is normally formulated, in the already used medicaments for the treatment of the cataract, as a two component preparation wherein a first component comprises freeze-dried pirenoxine and the second component comprises an eye acceptable aqueous carrier or diluent.
• the two components are reconstituted before the use and the thus obtained solution can be generally stored at ambient temperature for about two weeks without degradation.
• the compositions containing pirenoxine or a salt thereof according to the invention can be formulated according to the known art, for example according to the teachings suggested by "Remington's Pharmaceutical Sciences Handbook", hack Publ. Co., U.S.A.
• agents for the regulation of tonicity should be added whereby the solution has a suitable osmolarity value.
• Any one of the products usually used in the art can be used, as, for example, sodium chloride, potassium chloride, mannitol, dextrose, boric acid, propylene glycol.
• the preparation can also comprise acids or bases as agents for the regulation of pH and/or buffers, as, for example, monosodium phosphate - disodium phosphate, sodium borate - boric acid or sodium succinate - succinic acid systems.
• the pH should be between 4,5 and 8,5.
• composition should also comprise preservatives and antimicrobial agents, as benzalkonium chloride, sodium merthiolate or thimerosal, mehyl-, ethyl- and propyl-paraben, chlorobutanol, as well as chelating or sequestering agents as edetates or EDTA. If the product is packaged in unit dose containers the presence of preservatives can be avoided but, when multiple dose containers are used, for example vials for collyrium containing from 5 to 15 ml, the presence of the preservatives is necessary.
• preservatives and antimicrobial agents as benzalkonium chloride, sodium merthiolate or thimerosal, mehyl-, ethyl- and propyl-paraben, chlorobutanol, as well as chelating or sequestering agents as edetates or EDTA.
• the ophthalmic preparation can comprise further optional ingredients, as thickening agents, anti-oxidants, stabilizers, surface active agents, ecc.
• the composition of an already commercially available product designed for the treatment of the cataract is described below.
• the formulation can be suitable also for the use of the product as cornea protective agent against free radicals and ROS.
• figure 2 shows the in vitro fluorescence formation of lipidic soluble substances in UV312 irradiated (80 mJ/cm 2 ) epithelial corneal cells after incubation in presence and in absence of 10 "5 M pirenoxine. The results are mean of 3 experiments; figure 3 shows the ex vivo effects of pirenoxine instillations (60 ⁇ l every hour for 8 hours over 2 days) in the rabbit eyes on conjugated diene formation in the corneas in vitro submitted to iron-induced lipid peroxidation. Each bar ⁇ S.E.M.
• the dry powder component of the product has the following composition, wherein the amounts are given for the reconstitution in a 7 ml solution: sodium pirenoxine 0.376 mg (equivalent to 0.350 mg of pirenoxine) taurine 34,34 mg
• the aqueous solvent has the following composition: polyvinyl alcohol 98 mg succinic acid 2,31 mg sodium succinate .6 H 2 O 89,215 mg sodium chloride 34,3 mg benzalkonium chloride 0,175 mg sodium edetate 0,89 mg deionized water q.b to 7 ml
• said formulation contains PVA as thickening agent.
• the pH of the solvent component is 6.
• the formulation is prepared by firstly mixing and dissolving in water all the ingredients except benzalkonium chloride. After the complete dissolution of all the products benzalkonium chloride is added under continued stirring and the mixture is sterilized by filtration. The pH of the reconstituted product is 6-6.3. Activity tests as inhibitor of the lipid-peroxidation
• the experimental procedure for the evaluation of the inhibiting action against the lipid-peroxidation exerted by pirenoxine in cornea epithelial and endothelial cells made use of Fe(lll)-ascorbic acid system to induce the peroxidative phenomenon.
• the oxidative attack on membrane lipids was confirmed by the spectrophotometric determinations of both the conjugated dienes and fluorescent lipid-soluble substances which, as known, are generated by the oxidative degradation of lipid molecules.
• Used experimental procedure included the following steps: a) abstraction of the cornea from the eye of male pigmented rabbits suitably selected and prepared for the study; b) incubation of the latter in 100 ⁇ M phosphate buffer, pH 7,5, in the presence of 1000 U collagenase and 5 ⁇ M CaCI 2 for 20 hours at 37°C; c) centrifugation at 35000 rpm at 0°C for 10 minutes and washings of the sediment with phosphate buffer; d) homogenization of the cellular sediment in 1 ml of buffer, pH 7,4 (10 % w/v); e) incubation of a suitable homogenate aliquot with 10 ⁇ M FeC and ascorbic acid in phosphate buffer, pH 7,4, at 27°C for 30 minutes in presence and in absence of 10 "5 M pirenoxine; f) extraction of the lipid- soluble substances using chloroform/methanol mixture (2:1 v/v).
• Each value ⁇ SEM represents the mean value of at least 3 (x2) determinations
• SIRC epithelial corneal cells
• Each value ⁇ SEM represents the mean of at least 3 (x2) determinations * : p ⁇ 0,05
• the values reported in table 3 indicate that pirenoxine, administered topically in the rabbit eyes, reaches in the cornea such a concentration to in vitro contrast the lipid-peroxidizing action of ROS, in fact the formation of conjugated dienes in corneas of eyes (right) subjected to 0,005 % pirenoxine instillation was lower than that present in eyes (left) treated only by saline.

Landscapes

• Health & Medical Sciences (AREA)
• Veterinary Medicine (AREA)
• Pharmacology & Pharmacy (AREA)
• Public Health (AREA)
• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Medicinal Chemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Epidemiology (AREA)
• Surgery (AREA)
• Ophthalmology & Optometry (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

Family

ID=11406570

Family Applications (1)

Country Status (10)

Cited By (1)

Families Citing this family (17)

Family Cites Families (4)

• 1999
  • 1999-03-17 IT IT1999RM000166A patent/IT1305306B1/it active
• 2000
  • 2000-03-13 US US09/936,597 patent/US6610686B1/en not_active Expired - Lifetime
  • 2000-03-13 PT PT00911259T patent/PT1173255E/pt unknown
  • 2000-03-13 WO PCT/IT2000/000081 patent/WO2000054757A2/en not_active Ceased
  • 2000-03-13 DE DE60032594T patent/DE60032594T2/de not_active Expired - Lifetime
  • 2000-03-13 AT AT00911259T patent/ATE349244T1/de active
  • 2000-03-13 ES ES00911259T patent/ES2277831T3/es not_active Expired - Lifetime
  • 2000-03-13 JP JP2000604833A patent/JP5167499B2/ja not_active Expired - Fee Related
  • 2000-03-13 AU AU33241/00A patent/AU3324100A/en not_active Abandoned
  • 2000-03-13 EP EP00911259A patent/EP1173255B1/en not_active Expired - Lifetime

Also Published As

Similar Documents

Legal Events