The detection of anti-erythropoietin antibodies in human serum and plasma. Part I. Validation of the protocol for a radioimmunoprecipitation assay

Rare cases of unexplained sudden severe anemia or red cell aplasia and resistance to recombinant human erythropoietin (rHuEPO) in patients with chronic renal failure (CRF) have been attributed to the development of anti-EPO antibodies. The development and validation of a radioimmunoprecipitation (RIP) assay to detect human anti-EPO antibodies in serum or plasma has been hampered by the lack of purified antibody to fully characterize and validate the assay. We have prepared an affinity-purified human antibody to EPO and used the antibody to characterize and validate a sensitive and reproducible RIP assay that can qualitatively measure anti-EPO antibody in serum or plasma samples. The lower limit of detection of the assay is 8 ng/ml of purified antibody. The threshold for detecting antibody is > or =0.9% cpm bound. The precision of the assay using purified antibody standards ranges from 5.8% to 15.3% and the precision of the assay using dilutions of the positive control ranges from 15.9% to 18.7%. EPO in the samples did not interfere with detection of the anti-EPO antibody except at high concentrations.     

Global coagulation assays in healthy controls: are there compensatory mechanisms within the coagulation system?

Journal of Thrombosis and Thrombolysis - Global coagulation assays (GCAs) may provide a more comprehensive individual hemostatic profiling. We aim to evaluate GCAs (thromboelastography, thrombin...     

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 Parkinson's 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.     

Bioanalytical Method Validation for Macromolecules in Support of Pharmacokinetic Studies

The development and validation of ligand binding assays used in the support of pharmacokinetic studies has been the focus of various workshops and publications in recent years, all in an effort to establish a guidance document for standardization of these bioanalytical methods. This summary report of the workshop from 2003 focuses on the issues discussed in presentations and notes points of discussion and areas of consensus among the participants.