Differences Between Biologics and Small Molecule Drugs

Biologics and small molecule drugs differ biochemically and pharmacologically, therefore, formulation requirements are inherently different. Poor permeability and nonspecific enzyme degradation rule out oral administration for biologics. Commonly accepted routes of biologic administration are IV and subcutaneous. Potential alternative routes include nasal, buccal and transdermal. Several absorption-enhancing approaches have been attempted and will be discussed.

Biologics and small molecule drugs differ significantly in biochemistry, pharmacology and formulation. Pharmacological attributes include target specificity, therapeutic potency, biochemical attributes include membrane permeability and non-specific metabolism, and formulation attributes include pH, buffer, osmoticity, polymerization and interfacial adsorption. Each and every variable will be examined.

Poor oral absorption leaves IV and SC as the choice of administration. Several absorption- enhancing approaches including surfactant, nanoparticles, iontophoresis for transdermal delivery, and liposome for targeted delivery will be reviewed.