Eye drops made of aloe are a sterile, aqueous extract of fresh leaves of Aloe arborescens Mill., containing necessary additives and
neomycin sulphate. The aim of the studies was to establish the technology of
eye drops containing biologically active aloe substances and those containing both chemical constituents of aloe and
neomycin sulphate. Within the studies, the formulary content and the way of preparing
eye drops were determined, criteria were defined and methods of qualitative assessment of drops were proposed. On the basis of the proposed analytical methods, the physicochemical and microbiological stability of the
eye drops stored at a temperature of 20-25 degrees C was studied. As the criteria of qualitative assessment of the
eye drops, the following analyses were considered:
sterility, appearance of the
eye drops (clarity), pH, osmotic pressure, density, viscosity, TLC analysis, content of
aloenin and
aloin, studies of anti-microbial activity of
neomycin in the drops, and preservative efficiency of
thiomersal in the
eye drops. The studies showed that the additives such as:
sodium chloride,
benzalkonium chloride,
chlorhexidine diacetate and digluconate, phenylmercuric
borate and Nipagins M and P could not be used to prepare the
eye drops because they were involved in
pharmaceutical interactions with chemical constituents of aloe in the
eye drops. The
eye drops containing: aqueous extract of fresh leaves of aloe,
boric acid,
thiomersal,
sodium pyrosulphite,
disodium EDTA, beta-
phenylethyl alcohol and
neomycin sulphate, both freshly prepared and after two years of storage, met the requirements of the Polish Pharmacopoeia (PPh V) mentioned in the monograph Guttae ophthalmicae. They were sterile, clear, their osmotic pressure approximated the osmotic pressure of lacrimal fluid and they were characterized by appropriate pH.
Aloenin in the drops was much more stable than
aloin.
Neomycin after two years of storage retained almost 98% of its starting antimicrobial activity which allows the conclusion that the biologically active aloe substances did not decrease the stability of
neomycin in the drops. The preservation assay showed that
thiomersal, both in the freshly prepared drops and after two years of storage, maintained antimicrobial activity, which was in accordance with PPh V.