TABLE 1

Comparison of features of small-molecule drugs, biotherapeutic proteins, and multimolecular DDS

Small MoleculesProteinsDDSs
Size<5 kDa10–300 kDaAbove 1000 kDa
<1 nm1–10 nm10–1000 nm
AdvantagesStabilityMultifunctional
UtilityPrecisionHigh drug load
Low costCatalytic powerControlled release
Quality controlNatural activityRegulation of PK/BD
High purityTargetingDelivery of nucleic acids
Routes of administrationTargeting
ChallengesHigh costAs for proteins
Off-target effectsParenteral routesRES overload
Limited efficacyImmunologic issuesHost defense reactions
Limited mechanismsPrecise delivery neededBiologic barriers