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The word "sustained release" is recognized to have existed in the medical and pharmaceutical literature for many decades. Oral drug delivery is the most preferred route for the various drug molecules among all other routes of drug delivery, because ease of administration which lead to better patient compliance. The goal of any drug delivery system is to supply a therapeutic quantity of drug to the suitable site in the body and then maintain the desired drug concentration A well designed controlled drug delivery system can overcome some of problems of conventional. therapy and enhance therapeutic efficacy of the given drug. There are different approaches in delivering therapeutic material to the goal site in sustained release fashion. One such approach is of the microspheres as carriers for drug. There are various departments of medicine like cancer, pulmonary, cardiology, radiology, gynecology, oncology and diabetes etc, number of drugs are used and they delivered by various types of drug delivery system. Among the sustained release of drugs has gained enormous attention due to its wide range of application and maximum time up to drug release. Moreover the microspheres are of micron size so they can easily fit into various micron size capillary beds. The main purpose of this review is to compile various types of sustained release microspheres, method of preparation, its application and also various parameters to evaluate their efficiency.

Objective: This work is aimed to formulate and evaluate alginate-chitosan microspheres of glipizide for the effective use in the treatment of diabetes.Methods: Sustained release (SR) microspheres were prepared by gentle mixing of polymers in water with the drug by agitation. The polymers used were sodium alginate and chitosan, which was extruded into 5% calcium chloride solution to produce microspheres by ionic gelation method.Results: Single unit dosage form of glipizide causes gastric irritation. When converted into the multiple unit dosage forms, it will release the drug evenly throughout the stomach causing suppression of irritation. The aim of the study was to formulate and evaluate alginate-chitosan microspheres, for SR of the chosen drug. The particle size of microspheres was in the range of 200-500 µ, maximum mucoadhesive property observed was 88.2±0.50% for formulation GCS7, maximum swelling index was 27.0% for GCS7, and the maximum entrapment was 89.1±0.28% for GCS6 formulation. It showed better in-vitro release between 80% and 90% for GCS1 and GCS2 formulation and in formulation GCS3, 50-60% reduction in plasma glucose level than conventional dosage forms when tested in-vivo. The work also aims to study various parameters affecting the behavior of microspheres in oral dosage form. Conclusion:Drugs with short half life that are absorbed from the gastrointestinal tract (GIT) are eliminated rapidly from the blood flow. To avoid this, the oral SR was developed as this formulation released the drug slowly into the GIT and maintained a stable drug concentration in the serum for a longer duration of time.

Aim: The aim of the present study was to develop and optimize the self-nanoemulsifying drug delivery system of α-pinene (ALP-SNEDDS) and to evaluate its in-vivo anti-Parkinson’s activity. Background: Different lipid-based drug delivery technologies have been researched to upgrade the bioavailability of such drug candidates and to expand their clinical adequacy upon oral administration. Self-emulsifying drug delivery system (SEDDS) have pulled in expanding interests and, specifically, self-nanoemulsifying drug delivery system (SNEDDS). Objective: The present work was an attempt in order to improve the bioavailability of the ALP via defining the role of self-nanoemulsifying formulations for its neuroprotective effect. Method: Miscibility of the ALP was estimated in various excipient components to select the optimized combination. Self-nanoemulsification, thermodynamic stability, effect of dilution on robustness, optical clarity, viscosity and conductivity tests were performed. The in-vivo anti-Parkinson’s activity of the ALP-SNEEDS formulations were done by using Pilocarpine antagonism induced Parkinsonism in rodents. Behavioural tests like tremulous jaw movements, body temperature, salivation and lacrimation are performed. Result: Two optimized formulation, composed of Anise oil, Tween 80 and Transcutol-HP of Oil: Smix ratio (4:6 and 3:7) were selected. The Smix ratio for both the formulation was 2:1. The particle size was found to consistent with the increase in dilution. The mean negative zeta potential of the formulations was found to be increased with increase in dilution. The TEM images of the formulations reveals spherical shape of the droplet. The in-vitro drug release profile was found to be significant as compared to plain ALP suspension. Conclusion: The results form in-vivo studies indicate that nanosizing and enhanced solubilisation of oral ALP-SNEDDS formulations significantly improved the behavioural activities as compared to plain ALP suspension.

Objective: The objective of this research work was to develop a transdermal drug delivery system containing atenolol with different ratios of hydrophilic and hydrophobic polymeric combinations, using solvent evaporation technique and to examine the effect of hydrophilicity and hydrophobicity of polymers on the physicochemical and drug release properties of transdermal patches.Methods: Solvent casting method has been used to formulate transdermal patches. Hydroxypropyl methylcellulose (HPMC), Polyvinylpyrrolidone (PVP), Ethylcellulose (EC) in different combination ratios were used as the polymer. Propylene glycol was used as a plasticizer. Permeation enhancers such as span 80 were used to enhance permeation through the skin. In vitro diffusion study was carried out by franz diffusion cell using egg membrane as a semi-permeable membrane for diffusion.Results: Result showed that the thickness of the all batch of patches varied from 0.32 to 0.39 mm with uniformity of thickness in each formulation. Formulations F1 to F3 had high moisture content varied from 2.07±0.09 to 2.56±0.15 and high moisture uptake value varied from 3.21±0.35 to 4.09±0.38, due to a higher concentration of hydrophilic polymers. Drug content of all batches was ranged between 85.92±1.32 to 95.71±1.42. Folding endurance values off all batches were more than 75. Formulation batches F1 to F3 showed higher cumulative drug release varied from 61.34% to 68.11% as compared to formulation batches F4 to F6.Conclusion: Higher proportion of hydrophilic polymer in the formulation of transdermal patches, gives higher percentage drug release from prepared patches. The finding of the study indicates that hydrophilicity and hydrophobicity of polymer effects the physicochemical and drug release properties of transdermal patches and an optimum proportion of hydrophilic and hydrophobic polymer is required for the preparation of effective transdermal patches.