US 2015O190359A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0190359 A1 Venkatraman et al. (43) Pub. Date: Jul. 9, 2015 (54) STABLE LIPOSOMAL FORMULATIONS FOR Publication Classification OCULAR DRUG DELVERY (51) Int. Cl. (71) Applicants:Nanyang Technological University, A63L/216 (2006.01) Singapore (SG); Singapore Health A 6LX 9/27 (2006.01) Services Pte Ltd., Bowyer Block (SG) (52) U.S. Cl. CPC ............... A61 K3I/216 (2013.01); A61K 9/127 (72) Inventors: Subramanian Venkatraman, Singapore (2013.01) (SG); Jayaganesh V. Natarajan, Singapore (SG); Tina Howden, (57) ABSTRACT Singapore (SG); Freddy Boey, Singapore (SG) A stable liposomal formulation for ocular delivery. The for mulation contains a liposome that includes at least one lipid (21) Appl. No.: 14/149,159 bilayer containing a phosphatidylcholine, and a prostaglan din F, encapsulated in the liposome. Also provided is a (22) Filed: Jan. 7, 2014 method for treating an ocular disorder with the formulation. Patent Application Publication Jul. 9, 2015 Sheet 1 of 3 US 2015/O190359 A1 Cumulative release data of iataroprast from i ni is liposames into 40 in PBS pH 7.4 i:38 say F.G. Patent Application Publication Jul. 9, 2015 Sheet 2 of 3 US 2015/O190359 A1 8 8 Patent Application Publication Jul. 9, 2015 Sheet 3 of 3 US 2015/O190359 A1 baseline basise hassissa 2 a as a 4 Essy 2 & 28 Afeek 6 weeks week week. days or weeks F.G. 3 US 2015/O 190359 A1 Jul. 9, 2015 STABLE LIPOSOMAL FORMULATIONS FOR be apparent from the description and from the claims. All OCULAR DRUG DELVERY references cited herein are hereby incorporated by reference in their entirety. BACKGROUND BRIEF DESCRIPTION OF THE DRAWINGS 0001 Intraocular pressure (IOP) in the eye is maintained by a continuous flow of aqueous humor produced by the 0010. The description below refers to the accompanying ciliary body. Excess fluid flows out of the eye through the drawings, of which: trabecular meshwork. If the outflow is blocked, aqueous 0011 FIG. 1 is a plot of cumulative release of latanoprost humor builds up inside the eye leading to increased IOP and from a palmitoyl oleoyl phosphatidylcholine (POPC) lipo ocular hypertension. The ocular hypertension can damage the Some versus time; optic nerve, resulting in an optic neuropathy and irreversibly 0012 FIG. 2a is a plot of the percentage of the starting impaired vision. This condition, known as glaucoma, affects amount of latanoprost remaining in liposomes versus time for more than 60 million people worldwide and is the second egg phosphatidyl choline (PC)-containing liposomes and leading cause of blindness. Increased IOP is the key modifi POPC-containing liposomes; able risk factor for glaucoma. 0013 FIG. 2b is a plot of liposome size versus time of 0002 Conventional treatments for ocular hypertensive storage at 4°C.; and and glaucoma patients include ocular Surgery and topical eye 0014 FIG. 3 is a plot of intraocular pressure versus days drop instillation. These treatment modalities have drawbacks. after a single Subconjunctival injection of latanoprost encap For example, not all patients are candidates for ocular Sur sulated in a POPC-containing liposome gery. Additionally, although topical eye drops are generally considered to be effective, patients long-term compliance DETAILED DESCRIPTION with instillation schedules is a major issue. Ocular hyperten 0015. As mentioned above, a stable liposomal formulation sion and glaucoma cannot be well controlled if patients do not for ocular delivery is provided. The formulation includes a adhere to the proper topical eye drop instillation schedule. liposome containing at least one lipid bilayer that includes a 0003 Topical eye drops contain drugs for controlling IOP phosphatidylcholine. In an embodiment, the liposome is a which typically act by reducing fluid production by the eye, unilamellar vesicle. In a preferred embodiment, the phos increasing fluid outflow, or by both mechanisms. Prostaglan phatidyl choline is palmitoyl oleoyl phosphatidyl choline din analogues, e.g., latanoprost, are potent drugs which can (POPC). reduce IOP by increasing aqueous outflow through the uveo 0016. The formulation also contains a prostaglandin F, Scleral pathway. encapsulated in the liposome. The prostaglandin F, can be 0004 Typically, only 5% of free drug applied to the cor latanoprost, bimatoprost, travoprost, or carboprost. In a pre neal epithelium via eye drops successfully penetrates through ferred embodiment, the prostaglandin F is latanoprost. the cornea. As a result, the amount of drug reaching the 0017. The mole ratio of prostaglandin F, to POPC can be aqueous humor often falls below the therapeutically effective 0.01:1 to 0.5:1. In an embodiment, the mole ratio is 0.01:1 to concentration. This necessitates repeated administration. 0.35:1. In a preferred embodiment, the stable liposomal for Additionally, a Substantial portion of the drug can enter the mulation includes latanoprost and POPC at a mole ratio of circulation via the conjunctival sac, causing undesirable sys 0.01:1 to 0.175:1. Additionally, the liposome can be formu temic side effects. lated to include between 2 and 25 wt % of the prostaglandin F2c. 0005. As an alternative to topical eye drops, subconjunc 0018. The liposome can have a diameter of less than 2 Lum. tival injection of a Sustained release IOP-reducing drug can be In an embodiment, the diameter of the liposome is 100 nm to used to deliver drugs directly to the site of action. Such a 300 nm, e.g., 100 nm, 150 nm, 200 nm, 250 nm, and 300 nm. delivery modality solves the problems of patient non-compli In a preferred embodiment, the diameter is 100 nm. These ance with instillation schedules and inefficient drug transport nano-sized drug-loaded liposomes can release the prostaglan across the cornea. din F, slowly over time. 0006. The need exists for a stable drug formulation for 0019. In an embodiment, the liposomal formulation Subconjunctival injection requiring a minimal frequency of described above can be a pre-constituted, ready-to-inject administration for long-term stable control of IOP aqueous formulation for Sub-conjunctival injection. 0020. Also within the scope of the invention is a method SUMMARY for treating an ocular disorder that relies on administering the liposomal formulation described above. The ocular disorder 0007 To address the need for an improved treatment for can be ocular hypertension or glaucoma. Preferably, the dis intraocular pressure (IOP), a stable liposomal formulation for order is glaucoma. In an embodiment, the liposomal formu ocular delivery is provided. The formulation includes a lipo lation is administered by Subconjunctival injection. Some containing at least one lipid bilayer that includes a 0021 Administering the liposomal formulation described phosphatidylcholine. The formulation also contains a pros above can significantly reduce IOPat one hour post injection. taglandin Fencapsulated in the liposome. Additionally, the More specifically, administering the liposomal formulation liposome has a diameter of less than 2 Jum. results in a reduction in IOP of at least 30% (e.g., 30%, 40%, 0008 Also provided is a method for treating an ocular and 50%) compared to the pretreatment IOP. Advanta disorder by administering the formulation described above. geously, the IOP remains reduced for as long as 4-6 months 0009. The details of one or more embodiments of the following a single injection. invention are set forth in the drawings and description below. 0022. As mentioned above, the injected liposomal formu Other features, objects, and advantages of the invention will lation can slowly release the prostaglandin F, e.g., latano US 2015/O 190359 A1 Jul. 9, 2015 prost, over several months. For example, 50% of the initial latanoprost:POPC mole ratio of 0.175:1 was used to prepare amount of drug in the liposomes can be released within 10 the drug-loaded LUVs. Latanoprost-loaded POPC LUVs days after injection of the formulation into the eye. Prefer were sterile filtered at room temperature using a 0.2 um ably, 65% of the drug is released within 28 days of injection. syringe filter and stored at 4° C. until analyzed. A similar Chronic topical application of anti-glaucoma drugs often method was used to prepare latanoprost-loaded egg PC lipo induces ocular surface disease. The slow-release feature of SOS. the liposomal formulation obviates the need for daily appli cations of these drugs, thereby reducing or eliminating the Example 3 concomitant side effects. 0023 Typically, drugs which are not stable are lyophilized Characterization of Drug Loaded POPC Liposomes or frozen at a temperature of -20°C. or lower to prevent loss 0028 Drug Release studies were performed by dialysing of activity over time. Notably, lyophilizing or freezing sus latanoprost-loaded POPCliposomes prepared as described in tained release formulations of drug-loaded liposomes can EXAMPLE 1 above against PBSata pH of 7.4 and measuring adversely affect the drug release profile, resulting in an unpre by HPLC the amount of latanoprost released. The results are dictable variability in the drug effectiveness. shown in FIG.1. Over a 28 day period, approximately 65% of 0024 Advantageously, the liposomal formulation is stable the latanoprost was released from the latanoprost-loaded for extended periods of time. For example, the formulation POPC liposomes in a time-dependent manner. can be stored at 4°C. for up to 6 months (e.g., 1, 2, 3, 4, 5, and 0029. The physical characteristics of the latanoprost 6 months) without aggregation of the liposomes or loss of loaded POPC liposomes were determined essentially as drug from them. Thus, the liposomal formulation can be described in Venkatraman et al., International Application stored in a vial at 4°C. for extended periods and then can be Publication No. 2012/021107, the content of which is incor directly injected straight from the vial.