Kunsang Yoon

Polyoxazoline: Chemistry, Properties, and Applications in Drug Delivery

Polyoxazoline polymers with methyl (PMOZ), ethyl (PEOZ), and propyl (PPOZ) side chains were prepared by the living cationic polymerization method and purified by ion-exchange chromatography. The following properties of polyoxazoline (POZ) were measured: apparent hydrodynamic radius by aqueous size-exclusion chromatography, relative lipophilicity by reverse-phase chromatography, and viscosity by cone-plate viscometry. The PEOZ polymers of different molecular weights were first functionalized and then conjugated to model biomolecules such as bovine serum albumin, catalase, ribonuclease, uricase, and insulin. The conjugates of catalase, uricase, and ribonuclease were tested for in vitro activity using substrate-specific reaction methods. The conjugates of insulin were tested for glucose lowering activity by injection to naïve Sprague-Dawley rats. The conjugates of BSA were injected into New Zealand white rabbits and serum samples were collected periodically and tested for antibodies to BSA. The safety of POZ was also determined by acute and chronic dosing to rats. The results showed that linear polymers of POZ with molecular weights of 1 to 40 kDa can easily be made with polydispersity values below 1.10. Chromatography results showed that PMOZ and PEOZ have a hydrodynamic volume slightly lower than PEG; PEOZ is more lipophilic than PMOZ and PEG; and PEOZ is significantly less viscous than PEG especially at the higher molecular weights. When PEOZ was attached to the enzymes catalase, ribonuclease, and uricase, the in vitro activity of the resultant bioconjugates depended on the extent of protein modification. POZ conjugates of insulin lowered blood glucose levels for a period of 8 h when compared to 2 h for insulin alone. PEOZ, like PEG, was also able to successfully attenuate the immunogenic properties of BSA. The POZ polymers (10 and 20 kDa) are safe when administered intravenously to rats, and the maximum tolerated dose (MTD) was greater than 2 g/kg. Blood counts, serum chemistry, organ weights, and the histopathology of key organs were normal. These results conclude that POZ has the desired drug delivery properties for a new biopolymer.

Rotigotine Polyoxazoline Conjugate SER-214 Provides Robust and Sustained Antiparkinsonian Benefit

Currently available dopaminergic drugs such as levodopa and dopamine (DA) receptor agonists impart considerable improvement in Parkinsons disease (PD) motor symptoms but often lead to significant motor complications including “wearing‐off” and dyskinesia. Such complications are believed to stem from the pulsatile nature of dopaminergic stimulation with these agents. Continuous dopaminergic drug delivery using polyoxazoline (POZ) polymer conjugation may improve motor symptoms, while avoiding development of side effects. The purposes of the current study are to characterize the in vitro and in vivo pharmacokinetics of POZ conjugation of a U.S. Food and Drug Administration (FDA)‐approved DA agonist, rotigotine, and to evaluate their effects in an established rat model of PD. After determination of release profiles of several POZ‐conjugated constructs (“fast”: SER‐212; “moderate”: SER‐213; and “slow”: SER‐214) using in vitro hydrolysis, normal male Sprague‐Dawley rats were used for determination of the pharmacokinetic profile of both acute and chronic exposure. Finally, a separate group of rats was rendered hemiparkinsonian using intracranial 6‐hydroxydopamine (6‐OHDA) infusions, treated acutely with POZ‐rotigotine, and assessed for rotational behavior and antiparkinsonian benefit using the cylinder test. POZ‐rotigotine formulations SER‐213 and SER‐214 led to substantial pharmacokinetic improvement compared to unconjugated rotigotine. In addition, SER‐214 led to antiparkinsonian effects in DA‐lesioned rats that persisted up to 5 days posttreatment. Repeated weekly dose administration of SER‐214 to normal rats for up to 12 weeks demonstrated highly reproducible pharmacokinetic profiles. The continuous dopaminergic stimulation profile afforded by SER‐214 could represent a significant advance in the treatment of PD, with potential to be a viable, once‐per‐week therapy for PD patients.