IntroductionPhospholipids (PLs) are the most commonly used lipid carriers in drug delivery. They are used in forming bilayered lipid membranes vesicles called liposomes along with incorporating cholesterol. PLs are considered as essential constituents for biosynthesis of the animal cell membraneliposomes as a vehicle are considered as one of the leading controlled release delivery systems available to deliver a wide variety of active agents as they can carry hydrophilic and hydrophobic compounds. However, the properties and applicability of liposomes as carriers are largely dependent on the physicochemical characteristics of the membrane.

Results

a- Mean particle size

PurposeThe purpose of this study was to develop vehicles of liposomes that are able to enclose high content water-soluble drug particles for a controlled release pulmonary delivery system.

The release profile of the drug through the system will be controlled to allow slow and sustained release at a predictable and reproducible rate (24 hours). Accordingly reducing frequency of aerosolization. Hence, this will help reduce the incidence of mortality and morbidity especially for patients suffering nocturnal asthma.

Material and MethodsVarious ratios of L-a- phosphatidylcholine phospholipid (PC) and cholesterol were prepared as the following 16:2, 16:4 and 16:8 using the lipid film hydration method.

Lipid Film Hydration method

1. Preparation of Lipid for HydrationThe lipids composition were dissolved and mixed in an organic solvent to assure a homogeneous mixture of lipids.

2. Hydration of the lipid filmDrug was dissolved in sufficient amounts of PBS at different concentrations 6mg, 3mg and 1mg per ml of PBS. The drug solution was then added to the dry lipid film at a temperature above the transition temperature -10oC for PC and vortexing to form multi lamellar vesicles (MLV’s) for 10 minutes at 10 rpm.

Investigation Of The Effect Of Liposomal Cholesterol Content

On Theophyll ine Drug Encapsulation Efficiency And Release Characterist ics

Aston Pharmacy School, Aston University, Birmingham, B4 7ET, UK

Lindsay Marshal Mandeep Marwah Deborah Lowry Mohammad AlyamiPhoto

Literature Cited

Ahmad, Z., Sharma, S. & Khuller, GK., 2005. Inhalable Alginate Nanoparticles as Antitubercular Drug Carriers against Experimental Tuberculosis. International Journal of Antimicrobial; 26(4), pp. 298 – 303.Akbarzadeh, A. ., 2013. Liposome: classification, preparation, and applications. Nanoscale research letters, 8(1), p.102.

b- Liposomes made of 12.5% cholesterol

c- Liposomes made of25% cholesterol

d- Liposomes made of 50 % cholesterol

E- Entrapment efficiency

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ConclusionImportantly, in the absence of cholesterol, the liposomes content leaked easily; but this could be largely inhibited by the inclusion of cholesterol. The entrapment studies revealed that the correlation between the amount of cholesterol added and percentage entrapment efficiency was proportional, theophylline loading increased from 7.7% and 9.3% to 29.4% when the amount of cholesterol was increased. The in vitro release data exhibited a fairly constant release of theophylline over 24 Hrs. Significantly, a high cholesterol content highlighted its capability of controlling drug release over extended periods of time releasing only 20% of theophylline after 7 hours, 16:4 released 65% at 10 hours, while 16:2 released 80% after 10 hrs. To conclude, the cholesterol is a substantial component of liposomes that helps improve liposome stability, enhances the loading of water-soluble compounds and provides sustained release of theophylline

f- In vitro release profile