Leveraging the Exploratory and Predictive Capabilities of Design of Experiments in Development of Intraarticular Injection of Imatinib Mesylate Containing Lipospheres.

An intraarticular, liposphere-based, formulation of Imatinib mesylate for weekly administration was developed. Lipospheres were prepared using double emulsion technique using dierucoyl phosphatidylcholine, 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt), cholesterol, and tricaprylin as lipid phase in dichloromethane in a four-step process. Primary emulsion, formed using a high-pressure homogenizer, was diluted using a secondary aqueous phase in an Inline mixer to form the liposomal dispersion. Nitrogen flushing was done to remove dichloromethane, and the dispersion was finally centrifuged and adjusted for potency. The amount of cholesterol and triglyceride was taken as formulation variables, and speed of homogenization was used as a process variable in the Box-Behnken design while particle size, % drug entrapment, and drug release at the end of 4 h and 5 days were taken as response variables. Multivariate data analysis grouped the variables in two latent variable sets, one based on the speed and the other on the composition of lipospheres. Multiple linear regression analysis was used to generate mathematical model for each response. Constraints were put on the values of responses, as per the requirements of the final product, and the "freedom to operate" design space was located using an overlay plot. The center point batch sufficed all the set criteria, and Monte Carlo simulations on the factor variables indicated a defect rate of 5%. The center point batch was characterized for viscosity, osmolality, pH, drug release, and lipocrit value. The dispersion was charged in a prefilled syringe and studied for stability. The product was found to be stable at 2-8°C over a period of 6 months.

Brain Targeting of Quetiapine Fumarate via Intranasal Delivery of Loaded Lipospheres: Fabrication, In-Vitro Evaluation, Optimization, and In-Vivo Assessment.

A liposphere system for intranasal delivery of quetiapine fumarate (QTF) was created to assess the potential for enhanced drug delivery. We investigated the effects of particle size, entrapment effectiveness, poly dispersibility index, and pluronic incorporation percentage on these variables. The optimal formula was examined using a TEM, and investigations into DSC, XRD, and FTIR were made. Optimized liposphere formulation in vitro dissolution investigation with a mean diameter of 294.4 ± 18.2 nm revealed about 80% drug release in 6 h. The intranasal injection of QTF-loaded lipospheres showed a shorter Tmax compared to that of intranasal and oral suspension, per the findings of an in vivo tissue distribution investigation in Wistar mice. Lipospheres were able to achieve higher drug transport efficiency (DTE %) and direct nose-to-brain drug transfer (DTP %). A potentially effective method for delivering QTF to specific brain regions is the liposphere system.

Promises of Lipid-based Drug Delivery Systems in the Management of Breast Cancer.

Breast cancer is one of the leading types among the common non-cutaneous malignancies in women. All the curative methods available for its treatment are minimal due to their toxicity issues and dose-related side effects. Various evolving nanotechnology techniques displayed the opportunity to target breast cancer. One such delivery system is lipid-based drug delivery systems (LDDS). This concept is constrained only for the laboratory scale should be shifted to the industrial level targeting the nanomedicine with clinical benefits. This work tried to portray the advancements in the LDDS along with the lipid-based excipients, advantages, disadvantages and applications. It even helped in highlighting the recently developed lipid-based nanocarriers for breast cancer management.

Precisely Fabricated Sulpiride-Loaded Nanolipospheres with Ameliorated Oral Bioavailability and Antidepressant Activity.

BACKGROUND: Sulpiride (SUL), is a selective antidopaminergic drug that had extensive biological activities. However, its sparingly aqueous solubility and limited gastrointestinal permeability lead to scanty oral bioavailability which hinders its clinical efficacy. OBJECTIVE: SUL-loaded lipospheres (SUL-LPS) were designed to serve as an oral biocompatible nanovector for improving SUL permeability as well as conquering its low oral absorption and then in turn enhancing its antidepressant action. METHODS: SUL-LPS were fabricated via two processing techniques namely, melt emulsification and solvent evaporation. The impact of different lipid cores, phospholipid shells together with various surfactant concentrations and types on the lipospheres properties were screened. Detailed physicochemical elucidations were performed followed by ex vivo permeation appraisal using the non-everted intestine model. The pharmacokinetic parameters of SUL-LPS, free SUL and marketed product were assessed following oral administration to healthy rats. Reserpine-induced depression rat model was used to assess the antidepressant action of SUL-LPS on which full behavioural and biochemical analysis was conducted. Safety attributes of nanoencapsulated SUL on the brain and other internal organs were evaluated. RESULTS: The optimum LPS revealed an excellent nanosize with a narrow PdI, negative zeta potential and acceptable entrapment efficiency of 68.62 nm, 0.242, -30.4 mV and 84.12%, respectively. SUL-LPS showed a sustained release pattern and 2.1-fold enhancement in the intestinal permeation parameters with low mucin interaction. Oral pharmacokinetic appraisal exhibited that LPS provided 3.4-fold improvement in SUL oral bioavailability together with long-circulating properties, relative to the free drug. Pharmacodynamic study confirmed the superior antidepressant action of SUL-LPS as evident by 1.6 and 1.25-fold elevation in the serotonin and dopamine expressions, respectively. Meanwhile, nanotoxicological appraisal proved the biocompatibility of SUL-LPS upon repetitive oral administration. CONCLUSION: Rationally designed lipospheres hold promising in vitro and in vivo characteristics for efficient delivery of SUL with high oral bioavailability, antidepressant activity together with a good safety profile.

Comparison of the effects of ultrasound in a repetitive mode and acoustically active lipospheres in the presence of doxorubicin on breast adenocarcinoma.

PURPOSE: We want to compare the synergistic effect of low-intensity, dual-frequency (dual) ultrasound (US), applied in a repetitive sonication mode, and acoustically active lipospheres (AALs) containing doxorubicin (DOX) in a murine model (Balb/C). SUBJECTS AND METHODS: The tumor-bearing mice were divided into nine groups, namely two untreated groups (control and sham), and seven experimental groups, including treated with dual-frequency US (150 kHzcontinuous + 1MHzpulse), triple exposure (3×30min) dual-frequency US, DOX (2 mg/kg intravenous), DOX in combination with single exposure (30 min) to dual-frequency US (drug + dual), DOX in combination with triple (3 × 30 min) exposure to dual-frequency US (drug + dual [REP]), AALs containing the drug-loaded (AAL), and a group receiving AAL in combination with single exposure (30 min) dual-frequency US (AAL + dual), respectively. RESULTS: The effectiveness of DOX on tumor growth was enhanced by a factor of three when combined with the triple exposures of dual US (drug + dual [REP]). This combination protocol further increased the times needed for each tumor to 2 and 7 times its initial volume, respectively by 94% and 36% compared to the drug group. During the 30 days, following the treatment of tumors, the relative volume of tumors in AAL group was 118% less than that of the drug group. The survival rate of the groups treated with drug and AAL + dual was increased by 78.7% and 167% compared with sham, respectively. CONCLUSION: Although as a short treatment, a major improvement in treatment was observed by (drug + dual [REP]) compared with other treatments, the AAL + dual treatment compared with (drug + dual [REP]) showed an increase in the survival rates, hence more preferable over long periods.

Lipospheres for Simultaneous Controlled Release and Improved Pharmacokinetic Profiles of Saxagliptin-Enalapril: Formulation, Optimization, and Comparative In Vitro-In Vivo Evaluation.

The current study aims at formulating and optimizing lipospheres (LS) by the Box-Behnken design (BBD) from safe biodegradable carnauba wax (CW) to co-administer saxagliptin (SG) and enalapril (EP) for co-existing chronic hypertensive diabetes in order to overcome inadequacies of conventional modes of drug administration. Optimized liposphere formulation (OLF) was selected by a numerical optimization procedure and a comparative in vivo pharmacokinetic study of OLF and commercial brands was also performed. Discrete, free-flowing, spherical, smooth-surface LS having a size range of 5-10 µm and zeta potential of - 20 to - 30 mV were successfully formulated. Compatibility studies by FTIR and DSC proved the lack of interaction of components while XRD suggested the transformation of crystalline drugs to amorphous form. Outcomes of dependent optimizing variables like percentage yield (30-90%), EP-release (32-92%), and SG-release (28-95%) followed a polynomial quadratic model. Pharmacokinetics studies indicated a significantly lower Cmax of EP (125.22 ± 6.32) and SG (75.63 ± 3.85) and higher mean Tmax values (9.4 h for EP and 10.73 h for SG) from OLF in comparison with reference brands of EP (257.54 ± 8.23 ng/mL) and SG (393.66 ± 2.97 ng/mL). Additionally, a potential rise in half-life and MRT of SG and EP was achieved reaching approximately 2- to 3-fold higher than noted for reference brands. Importantly, the enhanced Tmax and AUC0-24 specified the achievement of enhanced bioavailability of both drugs from LS. Consequently, such an innovative approach could not only control drug release in both in vitro and in vivo analyses but also maintain plasma drug concentration for a longer time without maximizing Cmax leading towards effective management of chronic illnesses.

Cabazitaxel and thymoquinone co-loaded lipospheres as a synergistic combination for breast cancer.

Cabazitaxel as microtubule inhibitor and thymoquinone as HDAC inhibitor affects the important genes like p53, STAT3, Bax, BCL-2, p21 and down regulation of NF-κB are reported for potential activity against breast tumors. However, poor aqueous solubility and permeability hinders the delivery of these drugs to target site. To address the delivery challenges cabazitaxel and thymoquinone co-loaded lipospheres were developed. Lipospheres are the lipid based self-assemblies of particle size below 150 nm were prepared with more than 90% entrapment efficiency for both the drugs. In vitro drug release studies revealed there was a sustained diffusion controlled drug release from liposphere matrix leading to decrease in particle size with increase in zeta potential. Cytotoxicity studies on MCF-7 and MDA-MB-231 cells demonstrated cabazitaxel and thymoquinone as synergistic combination for the treatment of breast cancer which was proved by CompuSyn software. Enhanced efficacy of developed lipospheres can be due to rapid cellular internalization which was observed in confocal laser scanning microscopy. Drastic changes in cancer cell morphology such as nuclear fragmentation were observed upon treatment with these lipospheres in comparison to combination solution as observed in fluorescent imaging which are the hall marks of apoptosis. Cell cycle analysis and apoptosis studies confirmed the increased Sub G1 phase arrest as well as cell death due to apoptosis. Thus, as per observed results, it can be concluded that cabazitaxel and thymoquinone co-loaded lipospheres are the efficient delivery vehicles in management of breast cancer.

Liposphere mediated topical delivery of thymoquinone in the treatment of psoriasis.

Thymoquinone (TMQ) is reported with good anti-psoriatic activity; however, the hydrophobicity, poor aqueous solubility, light and pH sensitive nature of TMQ hinder its delivery to target site. To address these delivery challenges of TMQ, lipospheres were explored. The topical use of lipospheres offers an effective mean of penetration along with stability and scalability. TMQ lipospheres of particle size below 70 nm were prepared and evaluated. These lipospheres resulted in deeper skin penetration, slow release and skin compatibility. Anti-inflammatory and anti-psoriatic potential of lipospheres was determined using in vitro cell lines and imiquimod induced psoriatic plaque model. Cell lines studies indicated reduction in the level of nitric oxide and IL-2, IL-6, IL-1ß, TNF-α, whereas in vivo results indicated improvement in the phenotypic, histopathological features and reduced level of IL-17 and TNF-α in psoriatic skin. These results suggest the potential of TMQ lipospheres in the management of psoriasis.

Bio-shielding In Situ Forming Gels (BSIFG) Loaded With Lipospheres for Depot Injection of Quetiapine Fumarate: In Vitro and In Vivo Evaluation.

Quetiapine fumarate (QF), an anti-schizophrenic drug, suffers from rapid elimination and poor bioavailability due to extensive first-pass effect. Intramuscularly (IM) injected lipospheres were designed to enhance the drug's bioavailability and extend its release. A central composite design was applied to optimize the liposphere preparation by a melt dispersion technique using Compritol® 888 ATO or glyceryl tristearate as lipid component and polyvinyl alcohol as surfactant. Lipospheres were evaluated for their particle size, entrapment efficiency, and in vitro release. The optimized QF lipospheres were prepared using a Compritol® 888 ATO fraction of 18.88% in the drug/lipid mixture under a stirring rate of 3979 rpm. The optimized lipospheres were loaded into a thermoresponsive in situ forming gel (TRIFG) and a liquid crystalline in situ forming gel (LCIFG) to prevent in vivo degradation by lipases. The loaded gels were re-evaluated for their in vitro release and injectability. Bioavailability of QF from liposphere suspension and bio-shielding in situ gels loaded with QF lipospheres were assessed in rabbits compared to drug suspension. Results revealed that the AUC0-72 obtained from the liposphere-loaded TRIFG was ∼3-fold higher than that obtained from the aqueous drug suspension indicating the bio-shielding effect of Poloxamer® 407 gel to inhibit the biodegradation of the lipospheres prolonging the residence of the drug in the muscle for higher absorption. Our results propose that bio-shielding in situ Poloxamer® 407 gels loaded with lipospheres is promising for the development of IM depot injection of drugs having extensive first-pass metabolism and rapid elimination.

In Vitro-In Vivo Evaluation of Novel Co-spray Dried Rifampicin Phospholipid Lipospheres for Oral Delivery.

The objective of this study comprises of developing novel co-spray dried rifampicin phospholipid lipospheres (SDRPL) to investigate its influence on rifampicin solubility and oral bioavailability. Solid-state techniques were employed to characterize the liposphere formulation. SDRPL solubility was determined in distilled water. BACTEC 460TB System was employed to evaluate SDRPL antimycobacterial activity. The oral bioavailability of the lipospheres was evaluated in Sprague Dawley rats. Lipospheres exhibited amorphous, smooth spherical morphology with a significant increase (p < 0.001) in solubility of SDRPL (2:1), 350.9 ± 23 versus 105.1 ± 12 µg/ml and SDRPL (1:1) 306.4 ± 20 versus 105.1 ± 12 µg/ml in comparison to rifampicin (RMP). SDRPL exhibited enhanced activity against Mycobacterium tuberculosis, H37Rv strain, with over twofolds less minimum inhibitory concentration (MIC) than the free drug. Lipospheres exhibited higher peak plasma concentration (109.92 ± 25 versus 54.31 ± 18 µg/ml), faster T max (two versus four hours), and enhanced area under the curve (AUC0-∞) (406.92 ± 18 versus 147.72 ± 15 µg h/L) in comparison to pure RMP. Thus, SDRPL represents a promising carrier system exhibiting enhanced antimycobacterial activity and oral bioavailability of rifampicin.

Tacrolimus and curcumin co-loaded liposphere gel: Synergistic combination towards management of psoriasis.

Psoriasis is an autoimmune skin disorder characterized by hyper proliferation and poor differentiation of keratinocytes. It significantly affects patient's quality of life. This study reports the anti-psoriatic efficacy of tacrolimus and curcumin loaded liposphere gel formulation. Poor solubility, poor skin penetration and erratic absorption are some problems associated with the topical delivery of these drugs. To overcome these problems, lipospheres containing combination of tacrolimus and curcumin was prepared with a particle size of nearly 50nm and incorporated into a gel for topical application. Liposphere gel showed slow release of both the drugs and shear thinning behaviour that is desirable property of topical formulation. Further, dermal distribution study using dye loaded formulation suggested penetration of dye into skin layers. The therapeutic efficacy of tacrolimus and curcumin loaded liposphere gel was assessed on imiquimod induced psoriatic plaque model, and the level of expression of psoriatic biochemical markers was evaluated using enzyme-linked immunosorbent assay. Results indicated improvement in the phenotypic and histopathological features of psoriatic skin treated with tacrolimus and curcumin loaded liposphere gel. There was reduction in the level of TNF-α, IL-17 and IL-22 compared to imiquimod group. These results corroborate the premise that liposphere gel containing combination of tacrolimus and curcumin can be an effective strategy for the treatment of psoriasis.

Potential of aerosolized rifampicin lipospheres for modulation of pulmonary pharmacokinetics and bio-distribution.

The aim of the present study was to establish the potential of rifampicin loaded phospholipid lipospheres carrier for pulmonary application. Lipospheres were prepared with rifampicin and phospholipid in the ratio of 1:1 using spray drying method. Further, lipospheres were evaluated for flow properties and surface area measurement. The formulated lipospheres were evaluated in vitro for aerodynamic characterization and in vivo for lung pharmacokinetics and biodistribution studies in Sprague Dawley rats. Powder flow properties finding suggested the free flowing nature of the lipospheres. In-vitro aerosol performance study indicated more than 80±5% of the emitted dose (ED) and 77.61±3% fine particles fraction (FPF). Mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were found to be 2.72±0.13 µm and 3.28±0.12, respectively. In-vitro aerosol performance study revealed the higher deposition at 3, 4 and 5 stages which simulates the trachea-primary bronchus, secondary and terminal bronchus of the human lung, respectively. The drug concentration from nebulized lipospheres in the non-targeted tissues was lesser than from rifampicin-aqueous solution. The pulmonary pharmacokinetic study demonstrated improved bioavailability, longer residence of drug in the lung and targeting factor of 8.03 for lipospheres as compared to rifampicin-aqueous solution. Thus, the results of the study demonstrated the potential of rifampicin lipospheres formulation would be of use as an alternative to existing oral therapy.

Evaluation of dika wax-soybean oil-based artesunate-loaded lipospheres: in vitro-in vivo correlation studies.

OBJECTIVES: To formulate and evaluate artesunate-loaded lipospheres and study the in vitro-in vivo correlations (IV-IVC). MATERIALS AND METHODS: Lipospheres were formulated by melt homogenisation using structured lipid matrices consisting of (1:3 and 1:6) soybean oil and dika wax and were characterised in vitro and in vivo. RESULTS: The small angle X-ray diffraction (SAXD) results of the lipid matrices showed prominent reflection at 2θ = 2.49°, d = 3.55 Å while, wide angle X-ray diffraction (WAXD) showed prominent reflection at 2θ = 20.83°, d = 0.42 Å. Lipospheres had maximum encapsulation efficiency of 80%, showed no significant decrease in pH with time (p < 0.05), and had sustained release properties. The ratio of the area under the curve (AUC) of the lipospheres and the tablets gave bioavailability enhancement factor of 2.108. CONCLUSION: Artesunate-loaded lipospheres could be used orally or parenterally once daily, for the treatment of malaria.

PLGA-lipid liposphere as a promising platform for oral delivery of proteins.

The main challenge in the oral delivery of protein drugs is to enhance their oral bioavailability. Herein, we report the uniform-sized liposphere prepared by premix membrane emulsification combined with W1/O/W2 double-emulsion method as a potential oral carrier for proteins. The protein-loaded liposphere was composed of a hydrophobic poly (D, L-lactide-co-glycolide) (PLGA) core and the lipid molecules self-assembled at the interface of W1/O and O/W2. During the preparation, the protein structure was effectively maintained. Compared with PLGA microsphere, the liposphere achieved a higher loading capacity (LC, 20.18%), entrapment efficiency (EE, 90.82%) and a lower initial burst (24.73%). Importantly, the lipospheres also showed high transcytotic efficiency with human microfold cell (M cell) model, leading to a potential enhancement of intestinal absorption. This result, together with the above studies supported that the PLGA-lipid liposphere could be a promising platform for enhancing the proteins oral bioavailability.

Analgesic and Micromeritic evaluations of SRMS-based oral Lipospheres of Diclofenac Potassium.

The objective of our work was to study the micromeritic properties of lyophilized diclofenac potassium-loaded lipospheres and to evaluate in vivo, the analgesic properties of diclofenac potassium in the lipospheres in addition to other in vitro properties. Solidified reverse micellar solutions were prepared by fusion using 1:1, 2:1, and 1:2% w/w of Phospholipon(®) 90H and Softisan(®) 154. Diclofenac potassium (1, 3, and 5% w/w) was incorporated into the solidified reverse micellar solutions. Solidified reverse micellar solutions-based lipospheres were formulated by melt homogenization techniques using Ultra-Turrax homogenizer, and thereafter lyophilized to obtain water-free lipospheres. The lipospheres were characterized in terms of particle size and morphology, stability, thermal analysis, drug content, encapsulation efficiency, and loading capacity. The flow properties of the lipospheres were studied using both direct and indirect methods of assessing flow. The analgesic properties of the lipospheres were studied using the hot plate method. Results obtained showed that the yield of diclofenac potassium-loaded lipospheres was high and the particle size ranged from 0.61±0.07 to 2.55±0.04 µm. The lipospheres had high encapsulation efficiency of 95%, which was affected by the amount of drug loaded, while the loading capacity increased with the increase in drug loading. Diclofenac potassium-loaded lipospheres exhibited poor flow. The formulations exhibited good analgesic effect compared with the reference and had 84 to 86% drug release at 13 h. The lipospheres based on solidified reverse micellar solutions could be used for oral delivery of diclofenac potassium.

Design, physicochemical characterization, and optimization of organic solution advanced spray-dried inhalable dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine poly(ethylene glycol) (DPPE-PEG) microparticles and nanoparticles for targeted respiratory nanomedicine delivery as dry powder inhalation aerosols.

Novel advanced spray-dried and co-spray-dried inhalable lung surfactant-mimic phospholipid and poly(ethylene glycol) (PEG)ylated lipopolymers as microparticulate/nanoparticulate dry powders of biodegradable biocompatible lipopolymers were rationally formulated via an organic solution advanced spray-drying process in closed mode using various phospholipid formulations and rationally chosen spray-drying pump rates. Ratios of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine PEG (DPPE-PEG) with varying PEG lengths were mixed in a dilute methanol solution. Scanning electron microscopy images showed the smooth, spherical particle morphology of the inhalable particles. The size of the particles was statistically analyzed using the scanning electron micrographs and SigmaScan® software and were determined to be 600 nm to 1.2 µm in diameter, which is optimal for deep-lung alveolar penetration. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) were performed to analyze solid-state transitions and long-range molecular order, respectively, and allowed for the confirmation of the presence of phospholipid bilayers in the solid state of the particles. The residual water content of the particles was very low, as quantified analytically via Karl Fischer titration. The composition of the particles was confirmed using attenuated total-reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and confocal Raman microscopy (CRM), and chemical imaging confirmed the chemical homogeneity of the particles. The dry powder aerosol dispersion properties were evaluated using the Next Generation Impactor™ (NGI™) coupled with the HandiHaler® dry powder inhaler device, where the mass median aerodynamic diameter from 2.6 to 4.3 µm with excellent aerosol dispersion performance, as exemplified by high values of emitted dose, fine particle fraction, and respirable fraction. Overall, it was determined that the pump rates defined in the spray-drying process had a significant effect on the solid-state particle properties and that a higher pump rate produced the most optimal system. Advanced dry powder inhalers of inhalable lipopolymers for targeted dry powder inhalation delivery were successfully achieved.

Phospholipon 90H (P90H)-based PEGylated microscopic lipospheres delivery system for gentamicin: an antibiotic evaluation.

OBJECTIVE: To formulate gentamicin liposphere by solvent-melting method using lipids and polyethylene glycol 4 000 (PEG-4 000) for oral administration. METHODS: Gentamicin lipospheres were prepared by melt-emulsification using 30% w/w Phospholipon® 90H in Beeswax as the lipid matrix containing PEG-4 000. These lipospheres were characterized by evaluating on encapsulation efficiency, loading capacity, change in pH and the release profile. Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Salmonella paratyphii and Staphylococcus aureus using the agar diffusion method. RESULTS: Photomicrographs revealed spherical particles within a micrometer range with minimal growth after 1 month. The release of gentamicin in vitro varied widely with the PEG-4 000 contents. Moreover, significant (P>0.05) amount of gentamicin was released in vivo from the formulation. The encapsulation and loading capacity were all high, indicating the ability of the lipids to take up the drug. The antimicrobial activities were very high especially against Pseudomonas compare to other test organisms. This strongly suggested that the formulation retain its bioactive characteristics. CONCLUSIONS: This study strongly suggest that the issue of gentamicin stability and poor absorption in oral formulation could be adequately addressed by tactical engineering of lipid drug delivery systems such as lipospheres.

Phospholipon 90H (P90H)-based PEGylated microscopic lipospheres delivery system for gentamicin: an antibiotic evaluation

<p><b>OBJECTIVE</b>To formulate gentamicin liposphere by solvent-melting method using lipids and polyethylene glycol 4 000 (PEG-4 000) for oral administration.</p><p><b>METHODS</b>Gentamicin lipospheres were prepared by melt-emulsification using 30% w/w Phospholipon® 90H in Beeswax as the lipid matrix containing PEG-4 000. These lipospheres were characterized by evaluating on encapsulation efficiency, loading capacity, change in pH and the release profile. Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Salmonella paratyphii and Staphylococcus aureus using the agar diffusion method.</p><p><b>RESULTS</b>Photomicrographs revealed spherical particles within a micrometer range with minimal growth after 1 month. The release of gentamicin in vitro varied widely with the PEG-4 000 contents. Moreover, significant (P>0.05) amount of gentamicin was released in vivo from the formulation. The encapsulation and loading capacity were all high, indicating the ability of the lipids to take up the drug. The antimicrobial activities were very high especially against Pseudomonas compare to other test organisms. This strongly suggested that the formulation retain its bioactive characteristics.</p><p><b>CONCLUSIONS</b>This study strongly suggest that the issue of gentamicin stability and poor absorption in oral formulation could be adequately addressed by tactical engineering of lipid drug delivery systems such as lipospheres.</p>

Phospholipon 90H (P90H)-based PEGylated microscopic lipospheres delivery system for gentamicin：an antibiotic evaluation

Objective: To formulate gentamicin liposphere by solvent-melting method using lipids and polyethylene glycol 4 000 (PEG-4 000) for oral administration. Methods: Gentamicin lipospheres were prepared by melt-emulsification using 30% w/w Phospholipon? 90H in Beeswax as the lipid matrix containing PEG-4 000. These lipospheres were characterized by evaluating on encapsulation efficiency, loading capacity, change in pH and the release profile. Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Salmonella paratyphii and Staphylococcus aureus using the agar diffusion method. Results:Photomicrographs revealed spherical particles within a micrometer range with minimal growth after 1 month. The release of gentamicin in vitro varied widely with the PEG-4 000 contents. Moreover, significant (P>0.05) amount of gentamicin was released in vivo from the formulation. The encapsulation and loading capacity were all high, indicating the ability of the lipids to take up the drug. The antimicrobial activities were very high especially against Pseudomonas compare to other test organisms. This strongly suggested that the formulation retain its bioactive characteristics. Conclusions: This study strongly suggest that the issue of gentamicin stability and poor absorption in oral formulation could be adequately addressed by tactical engineering of lipid drug delivery systems such as lipospheres.