Liposome-Based Depot Injection Technologies

Silk-based biomaterials for sustained drug delivery

This study aimed to elaborate on all the aspects of multivesicular liposomes, including structure, function, topology, etc. Liposomes are a unique drug delivery system, in which both hydrophilic and hydrophobic drug molecules can be incorporated. Particularly, multivesicular liposomes have more advantages than other liposomes because of their unique structure. This study provides an overview of several works already performed by various researchers in this field. Numerous studies have reported on preparing and evaluating multivesicular liposomes for drug delivery applications. This study summarizes the process of formulating multivesicular liposomes and their application in drug delivery systems and provides details about how to resolve the problem of limited solubility and stability of biomolecules, along with controlled drug release kinetics, with the possibility of loading various drugs. There is no doubt that multivesicular liposome opens new avenues to develop novel drug delivery system for achieving the desired functional performances and expanding the applications in the drug delivery area.

Introduction Glaucoma is a group of progressive optic neuropathies resulting in irreversible blindness. It is associated with an elevation of intraocular pressure (>21 mm Hg) and optic nerve damage. Reduction of the intraocular pressure (IOP) through the administration of ocular hypotensive eye drops is one of the most common therapeutic strategies. Patient adherence to conventional eye drops remains a major obstacle in preventing glaucoma progression. Additional problems emerge from inadequate patient education as well as local and systemic side effects associated with adminstering ocular hypotensive drugs. Areas covered Sustained-release drug delivery systems for glaucoma treatment are classified into extraocular systems including wearable ocular surface devices or multi-use (immediate-release) eye formulations (such as aqueous solutions, gels; ocular inserts, contact lenses, periocular rings, or punctual plugs) and intraocular drug delivery systems (such as intraocular implants, and microspheres for supraciliary drug delivery). Expert opinion Sustained release platforms for the delivery of ocular hypotensive drugs (small molecules and biologics) may improve patient adherence and prevent vision loss. Such innovations will only be widely adopted when efficacy and safety has been established through large-scale trials. Sustained release drug delivery can improve glaucoma treatment adherence and reverse/prevent vision deterioration. It is expected that these approaches will improve clinical management and prognosis of glaucoma.

One of the challenges of ocular drug delivery systems is sustainable delivery of the intended drug to the posterior segment of the eye. Periocular routes of drug delivery are a promising method to bridge this challenge. The purpose of this study is to investigate the recent advances and potentials of subconjunctival route and its pros and cons in comparison with other ocular drug delivery routes. In this literature review, the comprehensive search of publications was performed in MEDLINE/PubMed indicating investigations on subconjunctival drug delivery systems using relevant keywords. Based on the resultant detailed criteria to choose an appropriate ocular drug delivery route, it is revealed that most of these routes are either highly invasive and/or provide low bioavailability of drug to the target tissue. Nevertheless, subconjunctival drug delivery could be considered as one of the less invasive and easily accessible routes for delivering various drugs to both anterior and posterior segments of the eye. However, most of such researches are at the stage of animal study in their pipelines. Periocular route of drug delivery is one of the most efficient routes for delivering the drugs to both anterior and posterior segments of the eye. Subconjunctival sustained drug delivery is highly effective and less invasive compared to other periocular routes. This makes subconjunctival implants and injections one of the most proper ways of treating various ranges of ocular diseases and disorders, e.g., diabetic retinopathy, dry eye syndrome, glaucoma, etc.

A lipid based depot (DepoFoam ® technology) for sustained release drug delivery

RSM optimized chitosan based composite hydrogel for sustained drug delivery applications

Development and characterization of multivesicular liposomes bearing serratiopeptidase for sustained delivery

The controlled release drug delivery preserves the efficient concentration of drug in blood and omits the side effect of it. Also, it provides more comfort and high quality of life for patients. Polymers, one of the common substrate of drug delivery systems, usually were used in nano-particle shape, that are one of the appropriate methods for controlled and efficient drug delivery. Among the methods for preparation of nano-particles, electrospray because of its simple control on the rate of deposition, size, and density of particles, low-cost equipment, fabrication in atmospheric condition and low temperature is a unique way.In this study, the theophylline(TF) was encapsulated in PVA by electrospray for controlled release drug delivery purposes. For determining the optimized particle, the first different molecular weights of PVA (23000, 72000 and 144000 gr/mol) were assessed by SEM pictures. Then different concentrations of PVA (5, 10, 13 and 15% w/v) were evaluated by SEM for the best homogenous particles. Afterward, the appropriate method for crosslinking of particles (glutaraldehyde for 24&48 h and oven in 130 oC) was determined. Finally, theophylline was added to the PVA solution and encapsulated by electro-spraying and morphology of particles was investigated by rhodamine staining and SEM.SEM results of the different molecular weight of electro-sprayed PVA particles were determined in the sample with 23000 g/mol (98% hydrolyzed) was the best one. For choosing of the optimized concentration of PVA, SEM, and rhodamine staining results showed that particles with 10% w/v PVA were the most homogenous ones. After encapsulation of 5% w/v TF in PVA, the morphology of particles after crosslinking was determined the oven in 130 oC and glutaraldehyde for 24h was the appropriate method for crosslinking of particles because of the stable and homogenous morphology of them. So PVA nano-particles have shown as appropriate and promising systems for sustained drug delivery.

Nano-crystalline cellulose: Preparation, modification and usage as sustained release drug delivery excipient for some non-steroidal anti-inflammatory drugs

The main objective of sustained release drug delivery system is to provide a steady state blood plasma level concentration which is non-toxic and therapeutically active for a longer period of time. Owing its increased patient compliance and prolonged release of action in delivering drugs several benefits can be contemplated in delivering of sustained release dosage form[1]. Among various route of drug delivery Sustained release drug delivery is most widely preferred as it’s less frequency of dosing and controls the release of drugs. Natural polymers are biodegradable and nontoxic in nature with reduced side effects. It is also eco-friendly and safe to be administered as compared to synthetic polymers. The current work was based on preparation of sustained release tablets of Propranolol Hydrochloride using natural polymers like Gum Acacia, Hibiscus Rosasinesis and Microcrystalline cellulose. Presently much attention is being paid for formulation of sustained release tablets that contains matrix system. Direct compression method was used for formulation of sustained release tablets of Propranolol Hydrochloride. The prepared tablets were evaluated for different pre-formulation studies and in vitro dissolution studies were performed using USP-III dissolution apparatus. Dissolution studies of different formulations were evaluated for 24 hours at 370C.

Objective: The study was carried out with an objective to achieve a potential sustained release oral drug delivery system of an antihypertensive drug, Perindopril which is a ACE inhibitor having half life of 2 hours. Perindopril is water soluble drug, so we can control or delay the release rate of drug by using release retarding polymers. This may also decrease the toxic side effects by preventing the high initial concentration in the blood.Method: Microcapsules were prepared by solvent evaporation technique using Eudragit L100 and Ethyl cellulose as a retarding agent to control the release rate and magnesium stearate as an inert dispersing carrier to decrease the interfacial tension between lipophilic and hydrophilic phase. Results: Prepared microcapsules were evaluated for the particle size, percentage yield, drug entrapment efficiency, flow property and in vitro drug release for 12 h. Results indicated that the percentage yield, mean particle size, drug entrapment efficiency and the micrometric properties of the microcapsules was influenced by various drug: polymer ratio. The release rate of microcapsules could be controlled as desired by adjusting the combination ratio of dispersing agents to retarding agents.Conclusion:Perindopril microcapsules can be successfully designed to develop sustained drug delivery, that reduces the dosing frequency and their by one can increase the patient compliance.

Gelation of the internal core of liposomes as a strategy for stabilization and modified drug delivery II. Theoretical analysis and modelling of in-vitro release experiments.

Fluocinolone acetonide sustained drug delivery device to treat severe uveitis

Temperature sensitive copolymer systems were previously studied using modified diffusion cells in vitro for intratympanic injection, and the PLGA-PEG-PLGA copolymer systems were found to provide sustained drug delivery for several days. The objectives of the present study were to assess the safety of PLGA-PEG-PLGA copolymers in intratympanic injection in guinea pigs in vivo and to determine the effects of additives glycerol and poloxamer in PLGA-PEGPLGA upon drug release in the diffusion cells in vitro for sustained inner ear drug delivery. In the experiments, the safety of PLGA-PEG-PLGA copolymers to inner ear was evaluated using auditory brainstem response (ABR). The effects of the additives upon drug release from PLGA-PEG-PLGA hydrogel were investigated in the modified Franz diffusion cells in vitro with cidofovir as the model drug. The phase transition temperatures of the PLGA-PEG-PLGA copolymers in the presence of the additives were also determined. In the ABR safety study, the PLGA-PEG-PLGA copolymer alone did not affect hearing when delivered at 0.05-mL dose but caused hearing loss after 0.1-mL injection. In the drug release study, the incorporation of the bioadhesive additive, poloxamer, in the PLGA-PEG-PLGA formulations was found to decrease the rate of drug release whereas the increase in the concentration of the humectant additive, glycerol, provided the opposite effect. In summary, the PLGA-PEG-PLGA copolymer did not show toxicity to the inner ear at the 0.05-mL dose and could provide sustained release that could be controlled by using the additives for inner ear applications.

Background: Medicine is a substance that through its chemical effects brings about changes in biological functions. The GRDDS delivery system is a sustained drug delivery system that can hold drugs back in the stomach for a longer time. The advantages of GRDDS include being able to increase bioavailability, increase the solubility of drugs that are poorly soluble in high pH, can control of therapeutic levels to reduce the occurrence of fluctuations, can extend the half-life so that the frequency of drug administration can be reduced.
 
 Objectives: This study aims to describe the types of GRDDS preparations. The variation is due to a combination of differences in mechanisms and technology.
 
 Method: The design in this study uses a systematic review of the review process that identifies, assesses, and interprets all findings on a research topic.
 
 Result: Floating systems can use expandable polymeric materials such as HPMC and chitosan. The floating mechanism begins with the contact of gastric juices with tablets which causes the polymer to hydrate to form a gel layer that can withstand CO2 gas formed due to the interaction of sodium bicarbonate with citric acid so that the tablets can expand and can float. The oral drug delivery route is the most preferred because it is easy to use. Absorption of oral drugs mostly occurs in the stomach and the intestines.
 
 Conclusion: Therefore, it is necessary to have a drug delivery system that can extend the contact time with the stomach, namely the Gastroretentive Drug Delivery System (GRDDS).