چکیده (انگلیسی):

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 reversephase
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 9 neutral
9 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°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.