Table 5.
List of brief description of reported microparticles formulated by using various polymers by different methods.
| S. No. | Methods | Advantages | Disadvantages | Applications |
|---|---|---|---|---|
| 1. | Spray drying | 1. Process is rapid | 1. High temperature is required | This technique is rapid, fast. PLGA-microparticles loaded with thyrotropin releasing hormone was produced by Takada et al. (1995) |
| 2. Formation of porous microparticles | 2. Yield is very less due to the sticking of microparticles to the drying chamber | |||
| 3. Complete evaporation of organic solvent | 3. It can change the polymorphism of spray dried drugs | |||
| 4. Operation is feasible under aseptic conditions | 4. Cost effective | |||
| 5. Both hydrophobic and hydrophilic polymer can be used | 5. Highly viscous fluids cannot be spray dried | |||
| 6. Ideal for sterile product manufacturing | ||||
| 2. | Single Emulsion technique | 1. Simple method | 1. Chemical crosslinker is toxic and if added in excess, should be subjected to centrifugation, washing and separation, which makes it a lengthy process | This method is used to prepare microspheres containing protein and peptide drugs. Kawashima et al. (1999) prepared nanospheres by using single emulsion technique in which insulin solution was dissolved in organic solvent |
| 2. In expensive | ||||
| 3. | Double emulsification | 1. Controlled release | 1. Stability problem is the major disadvantage | Currently, a product named, leuprolide acetate (a luteinizing hormone-releasing hormone (LHRH) agonist was encapsulated in form of w/o/w by using PLGA (75/25) polymer having MW 14 K is in market |
| 2. Used for hydrophilic drugs, proteins, vaccines | 2. Coalescence | |||
| 4. | Solvent evaporation | 1. Suitable for microencapsulation of lipophilic drugs like peptide for sustained delivery | 1. Sometimes in w/o type of emulsions, removal of oil from final product is complicated | Preparation of drug containing Poly (dl-lactide) microparticles by solvent evaporation method |
| 2. Cost effective | ||||
| 3. Use of organic solvents like DCM which is toxic, and need its complete removal from final product | ||||
| 4. Sometimes, protein get denatured and formed aggregates | ||||
| 5. | Interfacial polymerization | 1. Fast, rapid | 1. Microcapsules formed by this method are fragile and difficult to handle | Watnasirichaikul et al. (2000), prepared insulin nanoparticles using this technique |
| 2. Much controlled approach | 2. Due to large w/o interface, enzymes or proteins get inactivated | |||
| 3. Efficient | 3. It’s hard to control the polymerization reaction | |||
| 4. Large no. of washing steps are required for the complete removal of monomers and other by products | ||||