Characterization of Complex Drug Formulations Using Cryogenic Scanning Electron Microscopy (Cryo-SEM).

The physicochemical properties of complex drug formulations, including liposomes, suspensions, and emulsions, are important for understanding drug release mechanisms, quality control, and regulatory assessment. It is ideal to characterize these complex drug formulations in their native hydrated state. This article describes the characterization of complex drug formulations in a frozen-hydrated state using cryogenic scanning electron microscopy (cryo-SEM).

Pharmacokinetics and Toxicity Evaluation of a PLGA and Chitosan-Based Micro-Implant for Sustained Release of Methotrexate in Rabbit Vitreous.

The present research investigates the pharmacokinetics and toxicity of a chitosan (CS) and poly(lactic-co-glycolic) acid (PLGA)-based methotrexate (MTX) intravitreal micro-implant in normal rabbit eyes. PLGA and CS-based micro-implants containing 400 µg of MTX were surgically inserted in the vitreous of twenty-four New Zealand rabbits using minimally invasive procedures. The PLGA-coated CS-MTX micro-implant and the placebo micro-implant were inserted in the right eye and in the left eye, respectively, of each rabbit.

Non-invasive evaluation of toxicity in vitreoretinal domain following insertion of sustained release methotrexate micro-implant.

Purpose: To evaluate the safety and toxicity profile of a chitosan (CS) and poly(lactic-co-glycolic) acid (PLGA)-based sustained release methotrexate (MTX) intravitreal micro-implant in normal rabbit eyes using non-invasive testing that included electroretinography (ERG), ultrasound biomicroscopy (US), slit-lamp biomicroscopy (SLB), funduscopy, and intraocular pressure (IOP).

Methods: PLGA-coated CS-based micro-implants containing 400 μg of MTX and placebo (without drug) micro-implants were surgically-implanted in the vitreous of the right and the left eyes, respectively, in each of the thirty New Zealand rabbits. ERG, US, SLB, funduscopy, and IOP were assessed in both eyes at pre-determined time points (days: 1, 3, 7, 14, 28 and 56).

Coexistence of oil droplets and lipid vesicles in propofol drug products.

Propofol is intravenously administered oil-in-water emulsion stabilized by egg lecithin phospholipids indicated for the induction and maintenance of general anesthesia or sedation. It is generally assumed to be structurally homogenous as characterized by commonly used dynamic light scattering technique and laser diffraction. However, the excessive amount of egg lecithin phospholipids added to the propofol formulation may, presumably, give rise to additional formation of lipid vesicles (i.

Probing the mechanism of bupivacaine drug release from multivesicular liposomes.

The mechanism of drug release from complex dosage forms, such as multivesicular liposomes (MVLs), is complex and oftentimes sensitive to the release environment. This challenges the design and development of an appropriate in vitro release test (IVRT) method. In this study, a commercial bupivacaine MVL product was selected as a model product and an IVRT method was developed using a modified USP 2 apparatus in conjunction with reverse-dialysis membranes.

Improved design and characterization of PLGA/PLA-coated Chitosan based micro-implants for controlled release of hydrophilic drugs.

Repetitive intravitreal injections of Methotrexate (MTX), a hydrophilic chemotherapeutic drug, are currently used to treat selected vitreoretinal (VR) diseases, such as intraocular lymphoma. To avoid complications associated with the rapid release of MTX from the injections, a Polylactic acid (PLA) and Chitosan (CS)-based MTX micro-implant prototype was fabricated in an earlier study, which showed a sustained therapeutic release rate of 0.2-2.

Noninvasive Electroretinography Assessment of Intravitreal Sustained-Release Methotrexate Microimplants in Rabbit Eyes.

Purpose: The purpose of this study is to noninvasively evaluate the safety and toxicity of a chitosan (CS) and polylactic acid (PLA)-based sustained-release methotrexate (MTX) intravitreal microimplant in normal rabbit eyes using electroretinography (ERG).

Methods: PLA-coated CS-based microimplants containing 400 μg of MTX and placebo microimplants (without drug) were surgically implanted in the vitreous of the right and the left eyes, respectively, in each of the 8 New Zealand rabbits using minimally invasive technique. At each predetermined time points (days 5, 12, 19, and 33), ERG was conducted on 2 rabbits to evaluate the safety of the microimplants administered in each eye.

Ultrasonographical assessment of implanted biodegradable device for long-term slow release of methotrexate into the vitreous.

Our group has developed a biodegradable drug delivery device (micro-implant) for long-term slow intraocular release of methotrexate (MTX) that can be implanted in the peripheral vitreous. The purpose of this study was to assess the position of the implanted devices and the status of the adjacent vitreous and peripheral retina over time using B-scan ocular ultrasonography (US). In each of the eight New Zealand rabbits used in this study, a chitosan (CS) and poly-lactic acid (PLA)-based micro-implant containing approximately 400 μg of MTX and a placebo micro-implant without MTX were inserted into the peripheral vitreous of the right and left eyes, respective, employing minimally invasive surgery.

Biodegradable chitosan and polylactic acid-based intraocular micro-implant for sustained release of methotrexate into vitreous: analysis of pharmacokinetics and toxicity in rabbit eyes.

Purpose: The purpose of this study was to evaluate the pharmacokinetics and toxicity of a chitosan (CS) and polylactic acid (PLA) based methotrexate (MTX) intravitreal micro-implant in an animal model using rabbit eyes.

Methods: CS- and PLA-based micro-implants containing 400 μg of MTX were fabricated using lyophilization and dip-coating techniques. The micro-implants were surgically implanted in the vitreous of eight New Zealand rabbits employing minimally invasive technique.

Development of chitosan and polylactic acid based methotrexate intravitreal micro-implants to treat primary intraocular lymphoma: an in vitro study.

Primary intraocular lymphoma (PIOL) is an uncommon but clinically and pathologically distinct form of non-Hodgkin's lymphoma. It provides a therapeutic challenge because of its diverse clinical presentations and variable clinical course. Currently available treatments for PIOL include intravenous multiple drug chemotherapy, external beam radiation therapy, and intravitreal methotrexate (MTX) injection.