Development and characterization of a cyclodextrin-based delivery system for enhanced pharmacokinetic and safety profile of oseltamivir

Oseltamivir (OST) phosphate is a prodrug, metabolized by hepatic carboxylesterase to its active metabolite (oseltamivir carboxylate). OST is efficient in treatment of influenza, in both children and adults. The protein bonding of the prodrug and its active metabolite is low (42% and 3%, respectively). It has a short half-life 1–3 h but its active metabolite has a half-life of 6–10 h, permitting twice daily administration. The most common side effect is gastrointestinal disturbances that are usually nausea and vomiting and can be reduced when taken simultaneously with food. OST phosphate is a white powder with bitter taste and the marketed oral suspension uses sorbitol for masking it. Cross-linked cyclodextrin polymers are known for their ability to increase the dissolution rate, solubility, stability, and permeability of insoluble drugs and provide prolonged release. Therefore, they are promising drug delivery systems that could improve its pharmacokinetic properties and patient adherence. In this study we focused on developing a therapeutic system of OST using cyclodextrin polymer crosslinked with pyromellitic dianhydride (PMDA CD) to enhance its pharmacokinetic properties and to improve its compliance. PMDA CD polymer and PMDA CD polymer complex with OST were prepared. Physicochemical characterization by FTIR spectra, thermal analysis, DLS, SEM and EDX confirmed the existence of interaction between the two components. The prepared complex has a different pharmaceutical profile compared to OST, with higher stability and a controlled dissolution profile. Toxicity studies showed that the polymer complex has lower toxicity than OST, suggesting the protective effect of the polymer.