Factors Affecting the in Vitro Release of Recombinant Human Interferon-γ (rhIFN-γ) from PLGA Microspheres

Typical methods used in cancer treatment, including chemotherapy, are debilitating because of the various adverse side effects experienced by cancer patients. The free drug injected into the patient at given doses affects both healthy and cancerous cells. Therefore, novel methods are being researched to ensure the selectivity of the treatment. The purpose of this study is to test the release of a model fluorescent drug, calcein, from echogenic stealth liposomes, triggered by lowfrequency pulsed ultrasound. Several experimental parameters related to the ultrasound (US) and the investigated liposomes were varied in order to examine their effect on the acoustic release. Upon analysis of experimental results, the study concluded that release can be maximized by optimizing the sonication frequency, power density, and US pulse duration. When a non-isothermal chamber is used to conduct the experiments, it is important to have longer ‘Off’ than ‘On’ US periods in order to avoid overheating the liposomes. Applying such pulsation pattern can also be utilized to achieve slower release rates, which safely meet the desired drug levels at the end of the session. Our study also concluded that optimizing the liposome concentration is vital to delivering desired drug doses. Additionally, the type of lipids used in the synthesis should be carefully selected to produce stable yet acoustically sensitive liposomes capable of releasing at desired rates.

Download Full-text

Effect of tricaprin on the physical characteristics and in vitro release of etoposide from PLGA microspheres

Biomaterials ◽

10.1016/s0142-9612(02)00053-4 ◽

2002 ◽

Vol 23 (16) ◽

pp. 3465-3471 ◽

Cited By ~ 19

Author(s):

Matthew J Schaefer ◽

Jagdish Singh

Keyword(s):

In Vitro Release ◽

Physical Characteristics ◽

Plga Microspheres ◽

Vitro Release

Download Full-text

Study of factors affecting the in vitro release of diclofenac sodium from hypromelose-based gels

ScienceRise Pharmaceutical Science ◽

10.15587/2519-4852.2021.243040 ◽

2021 ◽

pp. 12-31

Author(s):

Elena Bezuglaya ◽

Hanna Ivashchenko ◽

Nikolay Lyapunov ◽

Igor Zinchenko ◽

Anna Liapunova ◽

...

Keyword(s):

Apparent Viscosity ◽

Flow Behavior ◽

Diclofenac Sodium ◽

In Vitro Release ◽

Newtonian Liquid ◽

Resonance Spectroscopy ◽

Spin Probes ◽

Factors Affecting ◽

Vitro Release

The aim of our study was to identify factors affecting the in vitro release of diclofenac sodium (DS) from hypromellose-based gels (HPMC). Materials and methods. Gels with HPMC and liquids without HPMC were studied by viscosity-rotating viscometer method and spin probe electron paramagnetic resonance spectroscopy. Rheograms were used to determine the flow behavior and the apparent viscosity, and the EPR spectra were used to determine the rotational correlation time (τ–1) of the dissolved spin probes. The in vitro release tests were performed using vertical diffusion cells according to a validated procedure. The assay of DS and isopropyl alcohol (IPA) in the receptor medium was performed by high performance liquid chromatography (HPLC) and gas chromatography (GC) according to validated procedures, and the water content was determined using semi-micro method. Results. The apparent viscosity of the gels increased with increasing HPMC content and depended on the HPMC grade. The high apparent viscosity of the gels did not affect the values of τ–1 of the dissolved spin probes. In viscous gels and Newtonian fluids, the composition of which corresponded to the dispersion medium of gels, the values of τ–1 were identical and were in the range of rapid rotation, which is a prerequisite for similar and rapid release of the dissolved substances from gels and liquids. It was shown that the HPMC-based gel and Newtonian liquid without HPMC in terms of in vitro release parameters DS and IPA were equivalent. During in vitro testing the release of dissolved DS increased with increasing its concentration in the gel and depended on the dispersed state of DS. When the content of IPA was changed from 45.0 % to 22.5 %, the water absorption by the gel and the release of IPA decreased, and the release of DS increased, which was due to the decrease in the solubility of DS in the gel. Conclusions. HPMC, which provided high apparent viscosity of the gels, did not affect the value of τ–1 of the dissolved spin probes and the in vitro release of DS from the gels. The gel and Newtonian liquid were equivalent in terms of in vitro release of DS and IPA. The release of DS altered proportionally with the concentration of DS and depended on its dispersed state. As the content of IPA decreased, the release of IPA decreased, but the release of DS increased because of the decrease in the solubility of the DS in the gel

Download Full-text