Liposomes as an ocular delivery system for acetazolamide: In vitro and in vivo studies

Abstract

The purpose of this study was to formulate topically effective controlled release ophthalmic acetazolamide liposomal formulations. Reverse-phase evaporation and lipid film hydration methods were used for the preparation of reverse-phase evaporation (REVs) and multilamellar (MLVs) acetazolamide liposomes consisting of egg phosphatidylcholine (PC) and cholesterol (CH) in the molar ratios of (7:2), (7:4), (7:6), and (7:7) with or without stearylamine (SA) or dicetyl phosphate (DP) as positive and negative charge inducers, respectively. The prepared liposomes were evaluated for their entrapment efficiency and in vitro release. Multilamellar liposomes entrapped greater amounts of drug than REVs liposomes. Drug loading was increased by increasing CH content as well as by inclusion of SA. Drug release rate showed an order of negatively charged > neutral > positively charged liposomes, which is the reverse of the data of drug loading efficiency. Physical stability study indicated that approximately 89%, 77%, and 69% of acetazolamide was retained in positive, negative, and neutral MLVs liposomal formulations up to a period of 3 months at 4 degrees C. The intraocular pressure (IOP)-lowering activity of selected acetazolamide liposomal formulations was determined and compared with that of plain liposomes and acetazolamide solution. Multilamellar acetazolamide liposomes revealed more prolonged effect than REVs liposomes. The positively charged and neutral liposomes exhibited greater lowering in IOP and a more prolonged effect than the negatively charged ones. The positive multilamellar liposomes composed of PC:CH:SA (7:4:1) molar ratio showed the maximal response, which reached a value of -7.8 +/- 1.04 mmHg after 3 hours of topical administration.

Proniosomal gel-mediated transdermal delivery of bromocriptine:in vitroandex vivoevaluation

“…This confirms the formation of the double layer structure of the vesicle, as reported previously. [32] No peak of BCT was observed in the drug-loaded formulation, indicating the amorphous nature of the drug. No major difference was observed in the thermograms of drug-free and drug-loaded proniosomes.…”

Herbal liposome for the topical delivery of ketoconazole for the effective treatment of seborrheic dermatitis

“…Rollback was prevented using clamp. The cap was removed and gel extruded until the pressure was degenerated (Panigrahi et al 2006;Srisombat et al 2005;Dave et al 2010;Hathout et al 2007). …”

Nanomedicine for glaucoma: liposomes provide sustained release of latanoprost in the eye

“…7 Liposomal encapsulation protects drug molecules from enzymatic hydrolysis in the physiological environment while in circulation, and thus increases stability. Previous studies on topical application of liposomes demonstrated poor penetration into the eye, [8][9][10][11] however, while studies on subconjunctival injections on other IOP-lowering drugs showed limited sustainability. 9,11,12 Furthermore, it is not clearly understood whether drug-loaded liposomes in the subconjunctiva behave like a depot system or actually undergo circulation and endocytosis.…”

“…Previous studies on topical application of liposomes demonstrated poor penetration into the eye, [8][9][10][11] however, while studies on subconjunctival injections on other IOP-lowering drugs showed limited sustainability. 9,11,12 Furthermore, it is not clearly understood whether drug-loaded liposomes in the subconjunctiva behave like a depot system or actually undergo circulation and endocytosis. 12 The design of carriers for sustained delivery in the eye necessitates the use of a formulation that has the required optical clarity with sufficient drug loading efficiency for administration.…”