A procedure for the efficient entrapment of drugs in dehydration-rehydration liposomes (DRVs)

Gregoriadis, Gregory; Silva, Helena da; Florence, Alexander T.

doi:10.1016/0378-5173(90)90148-w

Cited by 56 publications

(11 citation statements)

References 8 publications

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“…content (100 to 300 mmol/mL) in liposome also enhanced the EE (Shimizu and others 1993). Gregoriadis (1990) indicated that adequate addition of cholesterol to lecithin increases the arranging order and density of lipid bilayers, leading to an increase in thickness of liposome membranes. Moreover, the interactions such as hydrogen bonds between cholesterol and fatty acids increased the cohesiveness and mechanical strength of liposome bilayers, thus reducing the release of encapsulated materials (Gregoriadis and Davis 1979).…”

Section: Discussionmentioning

confidence: 99%

“…. be enclosed during the preparation of liposomes (Ostro and Cullis 1989;Gregoriadis 1990;Lasic 1998). Moreover, the increase in dehydration-rehydration cycles enhanced the rigidity of liposome bilayers as a result of the improved arrangement of bilayers, thus benefiting the EE of materials (Shimizu and others 1993).…”

Section: Effect Of Freeze Drying-rehydration Cycle On Ee Of Bsamentioning

confidence: 99%

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Properties of Liposomes Prepared with Various Lipids

Hsieh

Chen

Wang

et al. 2002

Journal of Food Science

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Use of several lipids as an alternative to cholesterol to prepare stable liposomes was tried. Liposome prepared at 1/0.25 lecithin/stearic acid ratio exhibited better (55%) encapsulation efficiency (EE) of bovine serum albumin (BSA) than that (41%) prepared at 1/0.25 lecithin/cholesterol ratio. Liposomes showed the minimal released percentage of encapsulated BSA at pH 6. Storage at -20°C caused serious damage to liposomes.Addition of a-tocopherol was effective in stabilizing liposomes. Liposomes, incorporated with a-amylase, prepared at 1/0.25 lecithin/cholesterol or stearic acid ratio were effective in protecting enzyme against acid (pH 2.8) and pepsin (15 mg/mL). Use of stearic acid, instead of cholesterol, would be feasible in preparing stable liposomes.

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Section: Discussionmentioning

confidence: 99%

Section: Effect Of Freeze Drying-rehydration Cycle On Ee Of Bsamentioning

confidence: 99%

Properties of Liposomes Prepared with Various Lipids

Hsieh

Chen

Wang

et al. 2002

Journal of Food Science

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“…The suspension was then freeze-dried overnight (Edwards freeze-dryer Modulayo equipped with an Edwards 8 two-stage vacuum pump). The powder was rehydrated with isotonic solution (0Á9%) by vortex, until a homogeneous suspension was obtained (Gregoriadis et al 1990). Empty liposomes were prepared in the same way except that isotonic phosphate buffer was used instead of drug solution.…”

Section: Liposome Preparationmentioning

confidence: 99%

Characterization and In-vivo Ocular Absorption of Liposome-encapsulated Acyclovir

Fresta

Panico

Bucolo

et al. 1999

Journal of Pharmacy and Pharmacology

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The potential of liposomes as an in-vivo ophthalmic drug delivery system for acyclovir was investigated. The drug-membrane interaction was evaluated by means of differential scanning calorimetry analysis. These experiments showed that acyclovir is able to interact with both positively and negatively charged membranes via electrostatic or hydrogen bonds. No interaction was observed with neutral membranes made up of dipalmitoylphosphatidylcholine. Different liposome preparation procedures were carried out to encapsulate acyclovir. The drug encapsulation mainly depends on the amount of water which the liposome system is able to entrap. In the case of multilamellar vesicles, charged systems showed the highest encapsulation efficiency. No particular difference in the encapsulation efficiency was observed for oligolamellar vesicles prepared with the reverse-phase evaporation technique. Oligolamellar liposomes showed the highest acyclovir encapsulation parameters and had release profiles similar to those of multilamellar liposomes. In-vivo experiments using male New Zealand albino rabbits were carried out to evaluate the aqueous humour concentration of acyclovir bioavailability. The most suitable ophthalmic drug delivery system was oligolamellar systems made up of dipalmitoylphosphatidylcholine-cholesterol-dimethyldioctadecyl glycerole bromide (7:4:1 molar ratio), which presented the highest encapsulation capacity and were able to deliver greater amounts of the drug into the aqueous humour than a saline acyclovir solution or a physical liposome/drug blend.

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“…How-Comparison ofS. mutans liposome vaccines 173 ever, investigations (11,12,32) have shown that trehalose and glycerol can effectively preserve small unilamellar liposomes, thus preventing fusion and aggregation of vesicle-s, which can occur with reconstitution of dried liposomes. It has also been proposed that the process of dehydration could more effectively associate antigens to the liposome membrane for the induction of immune responses (11,32).…”

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confidence: 99%

Properties of practical oral liposome‐Streptococcus mutans glucosyltransferase vaccines for effective induction of caries protection

Childers

Zhang

Harokopakis

et al. 1996

Oral Microbiology and Immunology

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Here we report the effectiveness of various liposome vaccines containing Streptococcus mutans glucosyltransferase (GTF) in protecting against dental caries after oral immunization. Rats were immunized by gastric intubation of the appropriate liposome vaccine at weaning and boosted 3 times. Rats were infected with S. mutans following initial immunization and fed cariogenic diet (Diet 305). Saliva and serum were collected during the study and assessed for antibody activity by enzyme-linked immunosorbent assay. Mandibles were removed on day 47 and assessed for S. mutans levels and then for caries. Animals immunized with sonicated, filtered and microemulsified GTF liposome preparations had decreased levels of dental caries compared with control animals given empty liposomes. Rats given dehydrated/rehydrated or purified liposomal GTF also had significantly less caries than control group (GTF alone). Because of economy, ease of preparation and efficiency in amount of antigen used, filtered, dehydrated/ rehydrated and purified liposomal GTF preparations are most practical for use in further assessing the efficacy of liposomal GTF in oral immunization.

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A procedure for the efficient entrapment of drugs in dehydration-rehydration liposomes (DRVs)

Cited by 56 publications

References 8 publications

Properties of Liposomes Prepared with Various Lipids

Properties of Liposomes Prepared with Various Lipids

Characterization and In-vivo Ocular Absorption of Liposome-encapsulated Acyclovir

Properties of practical oral liposome‐Streptococcus mutans glucosyltransferase vaccines for effective induction of caries protection

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