Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
1999-11-12
2002-06-11
Gitomer, Ralph (Department: 1623)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
C514S054000, C514S839000, C514S912000, C514S944000, C536S123100, C536S124000, C536S128000
Reexamination Certificate
active
06403609
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the use of adjuvants in topical ophthalmic compositions. In particular, the present invention relates to pharmaceutical compositions comprising galactomannan polymers in combination with borates, and methods for the controlled administration of pharmaceutically active agents to patients, wherein the compositions are administered as liquids which thicken to form gels upon instillation into the eye. The transition from liquid to gel is primarily due to the change in pH and ionic strength.
Topical ophthalmic compositions have taken the form of liquids, ointments, gels and inserts. Liquid compositions for drop-wise instillation of pharmaceutically active agents to the eve provide for easy administration, but they do not always provide for an accurate dosage amount, as portions of the liquid are often blinked away during administration or drained down the punctum into the nasal passage. Ointments and gels, which usually reside in the eye longer than a liquid and therefore provide for more accurate administration, often interfere with a patient's vision. Ocular inserts, both bioerodible and non-bioerodible, are also available and allow for less frequent administration of drug. These inserts, however, require complex and detailed preparation and are frequently uncomfortable to the wearer. An additional problem with non-bioerodible inserts is that they must be removed after use.
U.S. Pat. No. 4,136,173 (Pramoda, et al.) discloses the use of therapeutic compositions containing xanthan gum and locust bean gum which are administered in liquid form and gel upon instillation. This reference describes a mechanism for transition from liquid to gel involving pH change. pH sensitive gels such as carbomers, xanthan, gellan, and those described above, need to be formulated at or below the pKa of their acidic groups (typically at a pH of about 2 to 5). Compositions formulated at low pH, however, are irritating to the eye.
The use of locust bean gum to form a gel vehicle for ophthalmic drug delivery is described in U.S. Pat. No. 4,136,177 (Lin, et al.). However, the gels described by Lin, et al. are formed at the time of manufacture, rather than upon application to the eye.
U.S. Pat. No. 4,861,760 (Mazuel, et al.) discloses ophthalmic compositions containing gellan gum which are administered to the eye as non-gelled liquids and gel upon instillation due to a change in ionic strength. These systems do not involve the use of small cross-linking molecules, but instead provide gel characteristics due to self cross-linking during ionic condition changes.
Gels involving the cross-linking of polysaccharides wit h borates are disclosed for use as well fracturing fluids in U.S. Pat. No. 5,082,579 (Dawson), U.S. Pat. No. 5,145,590 (Dawson), and U.S. Pat. No. 5,160,643 (Dawson). These patents describe the use of borates and polysaccharides for industrial oil well excavation.
The ophthalmic use of current gelling liquid systems have a number of drawbacks. For example, natural polymers such as xanthan gum have the disadvantage of lot to lot variability due to variations in source and/or limited manufacturing controls during processing. These variabilities cause significant undesirable changes in the properties of the compound, such as variable gelling characteristics. Thermogelling systems such as polyethylene oxide/polypropylene oxide block copolymers (“PEO/PPO”) lose water in order to form gels, and consequently result in turbid gels. Polyvinyl alcohol (“PVA”)-borate combination gelling systems need to be formulated at low pH, and therefore, can cause ocular irritation upon instillation. Other gelling systems have viscosity, rehydration and cloud point instability problems associated with autoclaving.
Polyvinyl alcohol crosslinking with borates have been disclosed in U.S. Pat. No. 4,255,415 (Sukhbir et al.). These compositions are pre-formed gels, and are therefore hard to dispense. WIPO Publication No. WO 94/10976 (Goldenberg et al.) discloses a low pH PVA-borate delivery system that does go through liquid/gel transition. This system has the disadvantage, however, of limited gelling effects, and only at certain concentrations of PVA depending on the molecular weight of the PVA utilized. Furthermore, since the crosslinking cites are unlimited with this system, strong local gelation upon addition of base has limited its manufacturing, and therefore, polyvinyl pyrrolidone presumably has been included in these compositions to overcome the shortcoming. The novel gelling system of the present invention does not have the above limitation.
SUMMARY OF THE INVENTION
The present invention is directed to topical ophthalmic compositions comprising galactomannan polymers and borate compounds which provide controlled administration of a drug to the eye. The invention is based on a new gelling system which comprises a galactomannan polysaccharide and a borate crosslinker which forms a gel upon increases in pH and ionic strength. In this novel system, bisdiol borates crosslink with the cis diol groups of the sugar moieties of the polysaccharide. The compositions are administered as liquids or partially gelled liquids (hereinafter “liquids”) which thicken to form gels upon instillation into the eye. Alternatively, the compositions may not contain a pharmaceutically active agent, and can be administered to the eye for lubrication or to supplement tears in the treatment of, for example, dry eye.
The present invention galactomannan-borate gelling system has several advantages over other gelling systems. One advantage is that the compositions of the present invention are clear solutions and the resultant gel is also crystal clear. While other systems may become opaque or cloudy upon instillation, the crystal clear gel of the present invention provides greater clarity of vision to the treated eye. The present invention compositions may be formulated at slightly acidic to neutral pH and require only a minor pH change to activate gelation (i.e., about 0.5 to 1.0 pH unit). This feature minimizes possible irritation of the eye resulting from acidic exposure, such as may result with other pH sensitive systems which require a pH change of about 2.4 to about 4.4 pH units (i.e., are formulated with a pH of about 3-5). Galactomannan polymers are also heat stable and show no cloud point even during autoclaving conditions. As such, viscosity and rehydration problems resulting from batch scale up, such as exist with PVA and carbomer polymer systems, are not present with the galactomannan polymer containing compositions of the present invention.
Galactomannan polysaccharides are non-ionic and, in combination with borates at acidic to neutral pH, are also essentially non-ionic. Thus, the polymer system is completely compatible with anionic, neutral and cationic drugs. Furthermore, the preservative efficacy of the preservatives are not compromised by the presence of the polymer. Typically, the efficacy of benzalkonium chloride or other cationic preservatives are compromised with anionic polymers such as gellan and carageenan, and excess preservative may therefore be needed in those systems. Increases in preservative concentration may also increase irritation and toxicity of the composition.
The galactomannan-borate gelling system of the present invention has other advantages. Galactomannan polymers have a relatively low molecular weight and are therefore easy to manufacture and scale up. Galactomannan polymers are also readily available and have been used in food and personal care products such that the polymers are considered to be safe. Furthermore, control or manipulation of the gelling characteristics of the galactomannan-borate gelling compositions of the present invention is relatively simple as compared with prior art systems. The gelling properties of other single polymer systems, such as ionomers, e.g., gellan and carageenans, and thermogels, e.g., poloxamines and poloxamers, are typically related to the molecular weight and the number of functional groups of the polyme
Alcon Manufacturing Ltd.
Brown Gregg C.
Gitomer Ralph
Khare Devesh
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