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| Researchers | Drugs used | Surfactants | Co-surfactants | Other ingredients | Description and outcome of the study |
|
Gallarate et al., 1988; Gasco et al., 1989
[42, 43] | Timolol | Lecithin | 1-Butanol | Isopropyl myristate,
octanoic acid (OA), and distilled water | The topical administration of timolol as an ion-pair with octanoate was achieved by the use of an oil-in-water ME. The areas under the curve for timolol in aqueous humour after administration of the ME and the ion-pair solution were 3.5 and 4.2 times higher, respectively, than that observed after the administration of timolol alone |
|
Gallarate et al., 1993
[44] | Levobunolol
(LB) | Lecithin | 1-Butanol | Isopropyl myristate,
octanoic acid (OA), and distilled water | Aqueous and aqueous-PEG 200 solutions and o/w ME containing LB coupled to OA as lipophilic ion-pair were prepared and investigated
in vitro, in view of possible ophthalmic applications. Permeation studies in aqueous and in aqueous-PEG-200 solutions through the artificial membrane indicated a higher apparent lipophilicity of LB-OA with respect to the drug alone. The ME, which was isotonic and nonirritating to rabbit eyes, appears as a potentially interesting ophthalmic vehicle for LB |
|
| Haße and Kiepert, 1997 [45] | Pilocarpine nitrate | Macrogol-1500-glyceroltriricinoleate and lecithin | PEG 200,
Propylene glycol, | Isopropyl myristate,
distilled water | The authors developed o/w ME for ocular application of pilocarpine. Prolonged
in vitro
drug release was observed from ME. The miotic activity was measured on albino rabbits. For ophthalmological use, the miotic retarding effect of pilocarpine in ME turns out to be advantageous |
|
| Fialho and da Silva-Cunha, 2004 [24] | Dexamethasone | Cremophore EL | Propylene glycol | Isopropyl myristate,
benzalkonium chloride, and
distilled water | Developed MEs showed acceptable physicochemical properties and stability. The ocular irritation test suggested that the MEs did not provide any significant alteration to the eyelids, conjunctiva, cornea, and iris. This formulation showed greater penetration of dexamethasone in the anterior segment of the eye and also release of the drug for a longer time when compared with a conventional preparation. The area under the curve obtained for the ME system was more than twofold higher than that of the conventional preparation |
|
Alany et al., 2006
[23] | Pilocarpine hydrochloride | Sorbitan laurate, polysorbate 80 | Alkanol or alkandiol | Ethyl oleate,
water | w/o MEs capable of undergoing a phase-transition to lamellar liquid crystals or bicontinuous MEs upon aqueous dilution were formulated. Results showed only formulations having cosurfactants; all other ingredients were nonirritant to rabbit eyes. It was observed that cosurfactant irritation was dependent on its carbon chain length. Precorneal clearance studies revealed that the retention of colloidal and coarse dispersed systems was significantly greater than an aqueous solution with no significant difference between MEs |
|
| Lv et al., 2006; 2005 [25, 46] | Chloramphenicol | Tween 20 | Span 20 | Isopropyl myristate,
distilled water | Chloramphenicol was trapped into oil core or palisade layer of the o/w ME free of alcohols. Its stability was investigated by the high-performance liquid chromatography (HPLC) assays and H1-NMR in the accelerated experiments of 3 months. The stability of the chloramphenicol in the ME formulations was increased remarkably; the pseudoternary diagram of the ME is given in Figures 3 and 4 |
|
Chan et al., 2007
[47] | Pilocarpine hydrochloride | Polyoxyethylene sorbitan monooleate | Sorbitan monolaurate | Ethyl oleate,
water | ME-based phase transition systems were evaluated for ocular delivery of pilocarpine hydrochloride (model hydrophilic drug). These systems undergo phase change from ME to liquid crystalline (LC) and to coarse emulsion (EM) with a change in viscosity depending on water content (Figure 5). The miotic response and duration of action were greatest in case of ME and LC formulations indicating high ocular bioavailability (Figure 5) |
|
Baspinar et al., 2008
[48] | Everolimus | Poloxamer 184 | Propylene glycol | Triacetin, deionized and sterile water | In this study, ocular MEs bearing everolimus were prepared for preventing corneal-graft rejection. The permeation rate of the model drug everolimus through a freshly isolated pig cornea was determined
ex vivo. Authors concluded that prepared ME is a promising ocular formulation for preventing corneal-graft rejection |
|
Kesavan et al., 2013
[26] | Dexamethasone | Tween 80 | Propylene glycol | Isopropyl myristate,
chitosan, and
distilled water | The mucoadhesive chitosan-coated cationic MEs were prepared for treatment in condition of chronic uveitis. The average globule size was less than 200 nm with a positive surface charge. The developed microemulsion revealed stability for 3 months. The
in vivo
studies evidenced marked improved therapeutic effect of the incorporated steroid |
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