Do Clustering Monoclonal Antibody Solutions Really Have a Concentration Dependence of Viscosity?

AbstractProtein solution rheology data in the biophysics literature have incompletely identified factors that govern hydrodynamics. Whereas spontaneous protein adsorption at the air/water (A/W) interface increases the apparent viscosity of surfactant-free globular protein solutions, it is demonstrated here that irreversible clusters also increase system viscosity in the zero shear limit. Solution rheology measured with double gap geometry in a stress-controlled rheometer on a surfactant-free Immunoglobulin solution demonstrated that both irreversible clusters and the A/W interface increased the apparent low shear rate viscosity. Interfacial shear rheology data showed that the A/W interface yields, i.e., shows solid-like behavior. The A/W interface contribution was smaller, yet nonnegligible, in double gap compared to cone-plate geometry. Apparent nonmonotonic composition dependence of viscosity at low shear rates due to irreversible (nonequilibrium) clusters was resolved by filtration to recover a monotonically increasing viscosity-concentration curve, as expected. Although smaller equilibrium clusters also existed, their size and effective volume fraction were unaffected by filtration, rendering their contribution to viscosity invariant. Surfactant-free antibody systems containing clusters have complex hydrodynamic response, reflecting distinct bulk and interface-adsorbed protein as well as irreversible cluster contributions. Literature models for solution viscosity lack the appropriate physics to describe the bulk shear viscosity of unstable surfactant-free antibody solutions

Efficacy and safety of bilastine 20 mg compared with cetirizine 10 mg and placebo for the symptomatic treatment of seasonal allergic rhinitis: a randomized, double-blind, parallel-group study

Background Bilastine is a new non-sedative H-1 receptor antagonist, indicated for the treatment of allergic rhinitis (AR) (seasonal and perennial). Objective To assess and compare the efficacy and safety of bilastine 20 mg vs. cetirizine 10 mg and placebo in relieving the symptoms of seasonal allergic rhinitis (SAR). Methods Overall, 683 SAR patients, aged 12-70 years, were randomized to a double-blind treatment with bilastine 20 mg, cetirizine 10 mg or placebo, once daily for 14 days, in 61 centres across Europe. Patients recorded reflective (over the past 12 h) and instantaneous nasal (obstruction, rhinorrhoea, itching and sneezing) and non-nasal (ocular tearing, redness and itching) symptom scores (NSS and NNSS, respectively) twice daily, according to a pre-determined severity scale to provide reflective and instantaneous total symptom scores (TSS). The primary efficacy measure was the area under curve (AUC) of reflective TSS over 14 days of treatment (TSS-AUC(0-14 days)). Secondary efficacy measures included mean change from baseline in TSS, NSS and NNSS; discomfort caused by AR; and investigator's clinical global impression of the treatment. Safety was assessed according to adverse events (AEs), laboratory tests and electrocardiograms. Results The mean TSS-AUC(0-14 days) (score x day) was reduced in bilastine- and cetirizine-treated groups to a similar and significantly greater extent, compared with placebo (76.5, 72.3 and 100.6, respectively; P < 0.001). Similarly, bilastine and cetirizine were comparable and significantly superior to placebo for all secondary outcomes. While all treatments were well tolerated and the AE profiles of bilastine and placebo were similar, significantly fewer patients in the bilastine-treated group experienced somnolence (1.8%; P < 0.001) and fatigue (0.4%; P=0.02) than patients in the cetirizine-treated group (7.5% and 4.8%, respectively). Conclusions Bilastine 20 mg once daily was significantly superior to placebo and comparable to cetirizine 10 mg in relieving symptoms of SAR, although it demonstrated a significantly better AE profile than cetirizine