Thermosensitive in situ liposomal gels loaded with antimicrobial agent for oral care in critically ill patients

Aim: A novel thermosensitive in situ gel loaded with meropenem (MP) liposomes was designed to improve retention in the oral cavity as a prophylactic measure to prevent ventilator-acquired pneumonia in critically ill patients. Methodology & results: Meropenem liposomes were incorporated into poloxamer 407 gels and gamma irradiated. Mean size of liposome was 247 nm, polydispersity index < 0.3 and zeta potential >-25 mV; properties remained unaltered even post sterilization. Permeation study revealed that 75.26% and 34% of MPs were released from MP in situ gel and MP in situ liposomal gel, respectively. The relation between viscosity (cp) and shear rate (1/s) indicate that in situ gels exhibited non-Newtonian behavior at 37°C. The study using Pseudomonas aeruginosa confirmed the antimicrobial activity of meropenem. Conclusion: Prolonged in situ residence, because of rapid gelation process enables an easy administration of meropenem as liposomal suspension in critically ill patients.

ENCAPSULATION OF ANTITUMOR COPPER COMPLEX INTO LIPOSOMES

To encapsulate a new copper coordination compound drug for triple-negative breast cancer treatment we have developed a new approach. The obtained liposomal suspension is stable up to 2 weeks; successful complex loading is confirmed spectrophotometrically and can be quantified by HPLC.

Preparation and Characterization of Freeze-dried Liposomes Loaded with Amphotericin B

Background: Amphotericin B (AmB) is a drug of choice in the therapy of systemic fungal infection because of its board-spectrum antifungal activity. However, its conventional formulation has many side effects such as acute and chronic nephrotoxicity. Liposomes have been developed to reduce the drug’s toxicity. However, they had to meet strict stability criteria. In general, liposomes can be freeze-dried to inhibit liposomes infusion, phospholipids degradation during storage. Liposomal size usually increases after freeze-drying because of being influenced by many factors in freezing, lyophilizing and rehydration processes. Therefore, cryoprotectants are used to stabilize liposomal vesicles during freeze-drying process. </P><P> Objective: In the present study, we developed AmB liposomal suspension and lyophilized liposomes loaded with AmB, evaluated the effect of different cryoprotectants on the characterization of freeze-dried AmB liposomes. </P><P> Methods: In this study, AmB liposomes were prepared from hydrogenated soy phosphatidylcholine, distearoylphosphatidylglycerol and cholesterol by thin lipid film hydration method using different hydrate mediums likely: Glucose solution, citrate buffer, phosphate buffer. High-pressure homogenization and extrusion methods were used to reducing vesicles size. Dynamic light scattering was used to characterize liposomal size, and size distribution. HPLC method was used to assay drug and determine entrapment efficiency. Liposomal suspension was lyophilized with different cryoprotectants: Sucrose, mannitol, lactose, trehalose and glycerol. Differential scanning calorimetry was used to study lyophilized cake. </P><P> Results: We found that liposomal suspension with hydration medium10 mM citrate buffer pH 5.5 had a small average size (<100nm) and narrow distribution (PDI <0.2). Sucrose and trehalose stabilized vesicles size during freezing process, and lyophilized liposomes with sucrose and trehalose had an elegant appearance, yellow, compact cake. DSC study showed that sucrose and trehalose in lyophilized cake were amorphous. The cake was rehydrated within 10 seconds to form liposomal suspension, in which vesicles size was less than 140 nm. </P><P> Conclusion: We have developed successfully AmB liposomal suspension and lyophilized liposomes loaded with AmB. Sucrose and trehalose can be used as cryoprotectants in the freeze-drying and reconstitution process.

Spray dried proliposomes of Rosmarinus officinalis polyphenols: a quality by design approach

Harnessing the benefits of rosemary polyphenols is limited by variability in their physicochemical properties. These limitations may be overcome by encapsulation in systems possessing hydro-lipophilic centers thereby accommodating molecules of different polarities. Proliposomes offer a viable option in this regards, being particles which form liposomal suspension in water. Lyophilized extracts of rosemary was encapsulated in hydrogenatedsoyphosphatidylcholine/cholesterol by solvent replacement method. Spray dried proliposomes were obtained with lactose as carrier. Using Central Composite Design, the effects of lipid, extract and carrier concentrations on response variables including bioactive content and retention, moisture content characteristics, recuperation and redispersibility were evaluated by statistical analysis. Keywords: Polyphenols; antioxidant; proliposomes; spray drying