Table 2.

Benefits and limitations of commonly accepted drug delivery systems

		Benefits	Limitations
	Encapsulation	1. flexible to tune physical properties (size, shape)	hydrophobic polymer: requires hydrophilic polymer to increase bioactivity of protein toxicity of solvent and stabilizers, emulsifiers, other additives high energy mechanical mixer or homogenizer needed high cost of particle production some sterilization methods require high temperature (glass transition temperature 40–60°C)
	Delivery	FDA approved biocompatible low level of immunogenicity and toxicity	sensitivity to pH water penetration leads to denaturation of protein drugs surface modification important for eluding immune system uptake in reticuloendothelial system (RES) system not mucoadhesive
	Release	rate of degradation dependent on crystallinity and polymer grafting selective release at high pH	acidic degradation products denature proteins
	Encapsulation	hydrophobicity and drug encapsulation tuned by glycolic and lactic acid content	solvent, stabilizers, emulsifiers, other additives toxicity concerns high energy mechanical mixing and homogenization low drug encapsulation capacity high cost of particle production sterilization thermal processing (glass transition temperature 40–60°C) not mucoadhesive initial burst release in acidic pH
	Delivery	mechanical stability	surface functionalized of PLGA particles will compromise mechanical strength sensitivity to pH
	Release	crystallinity tuned by copolymer composition	degradation products glycolic and lactic acids, decrease the bioactivity of protein drugs bulk erosion of polymer - entire volume, less controlled
	Encapsulation	chemical and thermal stability non-ionic surfactant as stabilizing agent, viscosity modifier excellent flow properties and high compressibility hydrophilic – higher encapsulation capacity	difficult to process as insoluble in most organic solvents and high viscosity soluble in water only when heated chemical/physical crosslinking required
	Delivery	biocompatible	low stability in aqueous media particle swelling not mucoadhesive
	Release	biodegradable	degradation product acidic, harmful for protein drugs less controlled release due to bulk erosion, swelling controlled release