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Rivastigmine is an acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) inhibitor drug approved by the US Food and Drug Administration (FDA) for the treatment of mild to moderate dementia of Alzheimer's type. However, its first-pass metabolism and gastrointestinal side effects negatively affect the tolerability and efficacy of oral therapy. These adverse effects could be avoided with the use of a sustained -release formulation as an intramuscular (IM) administration system. The objective of this work was to develop polylactic co-glycolic acid (PLGA) microparticles for the sustained release of rivastigmine and to evaluate its stability during storage, tissue tolerance, in vitro release, and in vivo pharmacokinetics after its IM administration. The microparticles were made by the solvent evaporation emulsion method. A series of formulation parameters (the type of polymer used, the amount of polymer used, the initial amount of rivastigmine, and the volume of PVA 0.1% w/v) were studied to achieve an encapsulation efficiency (EE) and a rivastigmine load of 54.8 ± 0.9% and 3.3 ± 0.1%, respectively. The microparticles, whose size was 56.1 ± 2.8 μm, had a spherical shape and a smooth surface. FT-IR analysis showed that there is no chemical interaction between rivastigmine and the polymer. PLGA microparticles maintain rivastigmine retained and stable under normal (5 ± 3 °C) and accelerated storage (25 ± 2 °C and 60 ± 5 % RH) conditions for at least 6 months. The microparticles behaved as a sustained release system both in vitro and in vivo compared to non-encapsulated rivastigmine. The IM administration of the formulation in rats did not produce significant tissue damage. However, it is necessary to reproduce the experiments with multiple doses to rule out a negative effect in terms of tolerability in chronic treatment. To the best of our knowledge, this study is the only one that has obtained the sustained release of rivastigmine from PLGA microparticles after IM administration in an in vivo model. [Display omitted] [ABSTRACT FROM AUTHOR]

Schizophrenia is a neurodevelopmental disorder which is expressed in the form of disturbed behaviour and abnormal mental functions. Patient's non-adherence to the medicine is the main cause of failure of drug therapy and increases incidence of relapses. Thus, for successful management of disease long acting parenteral formulations were developed. Aripiprazole was encapsulated in biocompatible polycaprolactone microsphere by o/w emulsion solvent-evaporation method in order to achieve sustained release of the drug for several weeks after single subcutaneous administration. They were optimised on the basis of various parameters such as physical appearance, particle size (49.4 μm–387.1 μm), encapsulation efficiency (70%–95%), percentage yield (33%–75%) and drug loading (25.9%–47.5%). The surface topography and sphericity of the microspheres was determined by scanning electron microscopy which revealed that the microspheres formed were spherical and non-porous in nature. The in vitro releases from the selected formulations were found to be 87% and 95% respectively after 45 days of dissolution. In vivo efficacy of optimised formulation showed significantly (p < 0.05) amelioration of various positive, negative and cognitive symptoms associated with schizophrenia and oxidative stress markers in ketamine-induced schizophrenia model in rats for 30 days. [ABSTRACT FROM AUTHOR]