©
`
`©
`
`Europâisches P a t e n t a m t
`European Patent Office
`Office européen des brevets
`
`© Publication number:
`
`0 0 3 7 0 4 3
`
`B 1
`
`EUROPEAN PATENT SPECIFICATION
`
`(45) Dateof publication of patent spécification: 21.11.84
`© Application number: 81102132.8
`® Date of filing: 20.03.81
`
`© Intel.3: A 61 K9/06, A 61 K 37/02,
`A 61 K 45/06 / / ( A 6 1 K 3 7 / 0 2 ,
`31/70, 31/505, 31/305, 31/045)
`
`(54) Stabiiised ophthalmic formulation.
`
`© Priority: 21.03.80 GB 8009589
`
`® Dateof publication of application:
`07.10.81 Bulletin 81/40
`
`© Publication of the grant of the patent:
`21.11.84 Bulletin 84/47
`
`© Designated Contracting States:
`BECH DE FRGB Ll LU NLSE
`
`© Proprietor: THE WELLCOME FOUNDATION
`LIMITED
`183-193 Euston Road
`London NW1 2BP (GB)
`
`© Inventor: Marsden, Peter Hugh
`24 Shepherds Lane
`Dartford Kent (GB)
`Inventor: Reader, Michael John
`31 St. Johns Way Borstal
`Rochester Kent (GB)
`
`74) Représentative: Berg, Wilhelm, Dr. et al
`Patentanwâlte Dr. Berg Dipl.-lng. Stapf Dipl.-lng.
`Schwabe Dr. Dr. Sandmair Postfach 86 02 45
`Stuntzstrasse 16
`D-8000 Munchen 86 (DE)
`
`© Références cited:
`FR-A-2255 909
`GB-A-1 340 518
`US-A-2 703 777
`UNLISTED DRUGS, vol. 2, February 1977.
`Chatham, New York, US
`CHEMICAL ABSTRACTS, vol. 55, nr. 21,
`October 16, 1961, abstract 21480b Columbus,
`Ohio, US MICHAEL IANNARONE: "Ophthalmic
`solutions in pharmacy"
`
`Références cited:
`UNLISTED DRUGS, vol. 26, October 1974,
`Chatham, New York, US
`Martindale: The Extra Pharmacopoeia
`The Pharmaceutical Codex (1979)
`Note: Withm nine months from the publication of the mention of the grant of the European patent, any person may
`give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall
`be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been
`paid. (Art. 99(1) European patent convention).
`Courier Press, Leamington Spa, England.
`
`MYLAN INST. EXHIBIT 1081 PAGE 1
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`MYLAN INST. EXHIBIT 1081 PAGE 1
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`

`

`The present invention relates to isotonic liquid pharmaceutical formulations, particularly to
`isotonic aqueous opthalmic formulations comprising trimethoprim and polymyxim, a vehicle therefore,
`a mercury-containing preservative and an isotonic agent.
`- Thiomersal, sodium ethylmercurithiosalicylate, is an effective antifungal and antibacterial agent
`widely used as a preservative in pharmaceutical formulations, particularly liquid formulations such as
`ophthalmic solutions. It has long been recognised that Thiomersal decomposes in aqueous media but
`as its biological, i.e. preservative, action is not impaired thereby such decomposition has not, in the
`past, been of great concern. However, in more recent times the requirements of regulatory authorities
`have become more stringent and in order that a product may be marketed it is essential to meet these
`new criteria. Amongst these criteria are those that the product and its ingredients be shown to be non-
`toxic in man and should be stable on storage under normal conditions. The toxicity of any
`decomposition products may be unknown or only poorly characterised. The stability of ingredients
`which may potentially give rise to toxic breakdown products is of particular importance in this respect,
`and amongst such ingredients are mercury-containing preservatives such as Thiomersal.
`Liquid pharmaceutical formulations frequently contain isotonic agents to ensure that the
`formulation is isotonic with blood serum or lachrymal secretions. Whilst such formulations may be
`presented in a non-isotonic form it is generally preferred to render such formulations isotonic in order to
`avoid patient discomfort, biological damage to the patient or ineffective treatment. Thus, for example,
`non-isotonic ophthalmic formulations cause substantial stinging of the eye resulting not only in patient
`discomfort but in loss of the active ingredients from the site of action through watering of the eye and
`thus ineffective treatment.
`The most commonly employed isotonic agents are ionic agents, in particular sodium chloride. For
`example, from F R - A - 2 255 909 an isotonic ophthalmic formulation is known containing trimetho-
`prim, polymyxin and a mercury-containing preservative like Thiomersal as well as sodium chloride as
`isotonic agent. However, ionic isotonic agents such as sodium chloride cause rapid decomposition of
`mercury-containing preservatives such as Thiomersal. The degree of decomposition is such that there is
`frequently none of the original preservative remaining a matter of days after the formulation is
`prepared, whereas the shelf-life of such formulations is measured in terms of years.
`We have now surprisingly found, however, that if, for certain liquid formulations a non-ionic
`polyhydroxy compound is employed as an isotonic agent, then the decomposition of mercury-
`containing preservatives such as Thiomersal is substantially arrested, being comparable to that in
`simple aqueous media.
`The invention accordingly provides an isotonic liquid pharmaceutical formulation, particularly an
`isotonic aqueous ophthalmic formulation comprising trimethoprim and polymyxin as the active
`ingredients, a vehicle therefor, a mercury-containing preservative and, as an isotonic agent, a non-ionic
`polyhydroxy compound.
`The liquid formulations will be either wholly or partly aqueous in which case the non-aqueous part
`will be any organic solvent(s) conventionally used in such liquid formulations. The formulation will
`normally be a solution but other liquid formulations are within the scope of the invention. The invention
`injectable, otic and especially ophthalmic formulations containing
`is particularly applicable to
`trimethoprim and polymyxin.
`Any suitable mercury-containing preservative may be employed, for example those described in
`United States Patent No. 1,672,615. The preferred preservative is Thiomersal, sodium ethylmercuri-
`thiosalicylate. Other preservatives include phenyl mercuric nitrate and phenyl mercuric acetate. The
`preservative should be present in an effective amount which will normally be in the range of 0.1 to
`0.0001% w/v, preferably less than 0.01% w/v, particularly about 0.005% w/v.
`Any non-ionic polyhydroxy containing compound (i.e. any non-ionic compound containing two or
`more hydroxy groups) and which is acceptable as an isotonic agent may be employed. To be acceptable
`as an isotonic agent, the compound will render a solution isotonic at a concentration of 10% w/v or
`less, preferably 5% w/v or less, will not be deleterious to the formulation and will not be deleterious or
`irritating to the recipient thereof. Suitable isotonic agents for use in the invention include carbohydrate
`compounds, particularly monomeric compounds such as dextrose, lactose, mannitol and sucrose and,
`low molecular weight
`preferably, polyhydric alcohols, such as propylene glycol, glycerol and
`polyethylene glycols (PEGs). By low molecular weight is meant a molecular weight of less than about
`750.
`Reference herein to the formulations being isotonic means for formulations being isotonic with
`the biological fluid with which the formulation will come into contact. The present invention is
`particularly concerned with ophthalmic formulations and hence the formulations will be isotonic with
`lachrymal secretions. Thus an isotonic solution will have an osmotic pressure of from about 270 to 320
`milliosmoles per kilogram of water (mosm/kg H20), in particular about 2 8 0 - 3 0 0 mosm/kg H20,
`especially about 290 mosm/kg H20.
`The isotonic agent is preferably not readily metabilised by micro-organisms. In addition it is
`preferred that the isotonic agent is not a nutrient for microorganisms. Thus the preferred isotonic agents
`
`MYLAN INST. EXHIBIT 1081 PAGE 2
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`MYLAN INST. EXHIBIT 1081 PAGE 2
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`

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`are polyhydric alcohols, particularly those identified above which in some cases themselves possess
`antimicrobial activity. The preferred isotonic agent is propylene glycol which renders conventional
`ophthalmic solutions isotonic with lachrymal secretions at a concentration of about 2.0% w/v.
`The present invention is applicable to any isotonic liquid pharmaceutical formulation containing
`trimethoprim and polymyxin for example intravenous injections and otic formulations, especially when
`presented in a multiple dose form. However, it is particularly useful or ophthalmic formulations, such as
`eyedrops, which are desirably isotonic and in which a preservative is essential as the formulation is
`generally provided in a multiple dosage form and once opened cannot be maintained in a sterile
`condition.
`The trimethoprim and polymyxin may be present in any form in which they are conventionally
`present in such formulations. In particular they may be present as acid addition salts such as sulphates.
`The ratio and amounts of trimethoprim to polymyxin may also be that conventionally used in such
`formulations i.e. from about 0.01 to 1 g trimethoprim per 1 Mega Units polymyxin, in particular about
`0.1 g trimethoprim per 1 Mega Units polymyxin. The formulations conveniently contain about 1 g/litre
`of trimethoprim and 10 Mega Units/litre of polymyxin.
`The formulations of the present invention may be prepared by any method known in the art of
`pharmacy for the preparation of such formulations, all of which involve the admixture of the active
`ingredients with the liquid vehicle.
`The present invention will now be illustrated by the following examples.
`Example 1
`Effect of Sodium Chloride on the Stability of Thiomersal in Aqueous Solution
`Thiomersal was stored as 0.1 % (w/v), 0.01 % (w/v) and 0.001 % (w/v) solutions in water and 0.8%
`(w/v) Saline solution at 5°, 25° and 50°C for up to 15 days. The amount of Thiomersal remaining was
`assayed by high performance liquid chromatography (HPLC) after 8 and 15 days.
`HPLC was carried out using a Cecil CE 210 pump with a 250 mm, 4 mm i.d. stainless steel
`column packed with Spherisorb 10 ODS using a mixture of methanol-water-phosphoric acid 60:50:1
`as eluent at a flow rate of 2.6 ml min-1 and a pressure of 12.5 MPa (1800 psig); injection volume 25 ul
`loop and operating at ambient temperature; detection by a Cecil CE 212 variable wavelength u.v.
`detector at 222 nm.
`The results are shown in Table 1.
`
`MYLAN INST. EXHIBIT 1081 PAGE 3
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`MYLAN INST. EXHIBIT 1081 PAGE 3
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`

`

`The results show that there was slight decomposition of the thiomersal in aqueous solution but that
`this was substantial in the presence of sodium chloride.
`Example 2
`Comparative effect of Isotonic Agents on Thiomersal Stability in Ophthalmic Formulations
`A series of eye drop formulations containing Thiomersal (0.001% w/v) in water, trimethoprim
`sulphate and polymyxin sulphate (as active ingredients) and an isotonic agent were prepared. The
`formulations were identical with that described in Example 3 with the exception that the isotonic
`agents were a indicated in Table 2 below. In one case no isotonic agent was incorporated to provide a
`control. The amount of each isotonic agent was sufficient to render the formulations isotonic with
`lachrymatory secretions. The formulations were stored at 25°C for up to six weeks and the Thiomersal
`content determined as described in Example 1 after 3 days and 1,3 and 6 weeks.
`The results are shown in Table 2.
`
`The results show that the ionic isotonic agents showed a substantial loss of Thiomersal after six
`weeks (15-20%) whereas for the polyhydroxy compounds required by the invention losses were
`negligible when compared to control.
`
`MYLAN INST. EXHIBIT 1081 PAGE 4
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`MYLAN INST. EXHIBIT 1081 PAGE 4
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`

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`Example 4
`Stability of Thiomersal in Ophthalmic Formulation of the invention
`Batches of the ophthalmic formulation of Example 3 were stored at 25°C for 1 year and then
`assayed for Thiomersal content.
`The results are shown in Table 3.
`
`1. An isotonic liquid pharmaceutical formulation comprising trimethoprim and polymyxin, a
`vehicle therefor, a mercury-containing preservative and an isotonic agent characterised in that the
`isotonic agent comprises a non-ionic polyhydroxy compound.
`2. A formulation as claimed in claim 1, in which the formulation is an ophthalmic solution.
`3. A formulation as claimed in claim 1 or claim 2 wherein the isotonic agent is selected from
`dextrose, lactose, mannitol, sucrose, propylene glycol, glycerol and polyethylene glycols having a
`molecular weight of less than about 750.
`4. A formulation as claimed in any one of claims 1 to 3 wherein the osmotic pressure of the
`formulation is from 270 to 320 mosm/kg H20.
`5. A formulation as claimed in any one of claims 1 to 4 wherein the osmotic pressure of the
`formulation is from 280 to 300 mosm/kg H20.
`6. A formulation as claimed in any one of claims 1 to 5 wherein the mercury-containing
`preservative is sodium ethylmercurithiosalicylate.
`7. An aqueous isotonic ophthalmic formulation comprising trimethoprim (0.1 g), polymyxin B
`sulphate (1,1 Mega Units), sodium ethylmercurithiosalicylate (0.005 g) and propylene glycol (2.100 g)
`per 100 ml of formulation.
`8. An isotonic liquid ophthalmic formulation comprising the following ingredients per 100 ml of
`_
`final product:
`_
`
`1. Isotonische flüssige pharmazeutische Formulierung, enthaltend Trimethoprim und Polymyxin,
`einen Träger dafür, ein quecksilberhaltiges Konservierungsmittel und ein isotonisches Mittel, dadurch
`gekennzeichnet, daß das isotonische Mittel eine nicht-ionische Polyhydroxyverbindung enthält.
`2. Formulierung nach Anspruch 1, worin die Formulierung eine ophthalmische Lösung ist.
`
`MYLAN INST. EXHIBIT 1081 PAGE 5
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`MYLAN INST. EXHIBIT 1081 PAGE 5
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`

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`3. Formulierung nach Anspruch 1 oder Anspruch 2, worin das isotonische Mittel unter Dextrose,
`Lactose, Mannit, Sucrose, Propylenglykol, Glycerin und Polyethylenglykolen mit einem Molekularge-
`wicht von weniger als etwa 750 ausgewählt ist.
`4. Formulierung nach einem der Ansprüche 1 bis 3, worin der osmotische Druck der Formulierung
`von 270 bis 320 mosm/kg H20 beträgt.
`5. Formulierung nach einem der Ansprüche 1 bis 4, worin der osmotische Druck der Formulierung
`280 bis 300 mosm/kg H20 beträgt.
`6. Formulierung nach einem der Ansprüche 1 bis 5, worin das quecksilberhaltige Konservierungs-
`mittel Natriumethylquecksilberthiosalicylat ist.
`7. Wässrige isotonische ophthalmische Formulierung, welche Trimethoprim (0,1 g), Polymyxin B-
`Sulfat (1,1 Mega-Einheiten), Natriumethylquecksilberthiosalicylat (0,005 g) und Propylenglykol (2,100
`g) pro 100 ml Formulierung enthält.
`8. Isotonische flüssige ophthalmische Formulierung, welche die folgenden Bestandteile pro 100
`ml des Endproduktes enthält:
`
`1. Formulation pharmaceutique
`isotonique comprenant du trimethoprim et de
`la
`liquide
`polymyxine, un véhicule pour ceux-ci, un agent de conservation contenant du mercure et un agent
`isotonique, caractérisée en ce que l'agent isotonique comprend un composé polyhydroxylé non ionique.
`2. Formulation suivant la revendication 1, qui est une solution ophtalmique.
`3. Formulation suivant la revendication 1 ou 2, dans laquelle l'agent isotonique est choisi parmi le
`dextrose, le lactose, le mannitol, le saccharose, le propylèneglycol, le glycérol et les polyéthylène-
`glycols d'un poids moléculaire inférieur à environ 750.
`4. Formulation suivant l'une quelconque des revendications 1 à 3, dans laquelle la pression
`osmotique de la formulation est de 270 à 320 mosm/kg HzO.
`5. Formulation suivant l'une quelconque des revendications 1 à 4, dans laquelle la pression
`osmotique de la formulation est de 280 à 300 mosm/kg H20.
`6. Formulation suivant l'une quelconque des revendications 1 à 5, dans laquelle l'agent de
`conservation contenant du mercure est l'éthylmercurithiosalicylate de sodium.
`7. Formulation ophtalmique isotonique aqueuse comprenant du triméthoprim (0,1 g), du sulfate
`de polymyxine B (1,1 méga-unité), de l'éthylmercurithiosalicylate de sodium (0,005 g) et du propylène-
`glycol (2,100 g) pour 100 ml de formulation.
`8. Formulation ophtalmique liquide isotonique comprenant les constituants suivants pour 100 ml
`de produit final:
`
`MYLAN INST. EXHIBIT 1081 PAGE 6
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`MYLAN INST. EXHIBIT 1081 PAGE 6
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`

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`O O37 O43.
`
`Triméthoprim
`
`0,1009
`
`Sulfate de polymyxine B
`
`1,1 méga-unité
`
`Ethylmercurithiosalicylate de sodium
`
`0,005 9
`
`Solution d'acide sulfurique 0,1 M
`
`Propyléneglycol
`
`1,722 ml
`
`2,100 g
`
`Solution d’acide sulfurique 0,1 M
`ou
`
`solution d'hydroxyde de sodium 0,2 M
`
`} q.s. pourpH 5,0—5,2
`
`Eau pour injections
`
`pour 100 ml
`
`10
`
`75
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`50
`
`65
`
`MYLAN INST. EXHIBIT 1081 PAGE 7
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`MYLAN INST. EXHIBIT 1081 PAGE 7
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`MYLAN INST. EXHIBIT 1081 PAGE 7
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`