ABSTRACT
Novel phage-derived peptides are the first reported molecules specifically targeting human placental growth factor 1 (PlGF-1). Phage data enabled peptide modifications that decreased IC(50) values in PlGF-1/VEGFR-1 competition ELISA from 100 to 1 µM. Peptides exhibiting enhanced potency were bioconjugated to the CovX antibody scaffold 1 (CVX-2000), generating bivalent CovX-Bodies with 2 nM K(D) against PlGF-1. In vitro and in vivo peptide cleavage mapping studies enabled the identification of proteolytic hotspots that were subsequently chemically modified. These changes decreased IC(50) to 0.4 nM and increased compound stability from 5% remaining at 6 h after injection to 35% remaining at 24 h with a ß phase half-life of 75 h in mice. In cynomolgus monkey, a 78 h ß half-life was observed for lead compound 2. The pharmacological properties of 2 are currently being explored.
Subject(s)
Antibodies/chemistry , Peptides/chemistry , Pregnancy Proteins/metabolism , Amino Acid Sequence , Amino Acid Substitution , Animals , Binding, Competitive , Cross Reactions , Drug Stability , Enzyme-Linked Immunosorbent Assay , Humans , Macaca fascicularis , Male , Mice , Models, Molecular , Molecular Sequence Data , Peptide Library , Peptides/pharmacokinetics , Peptides/pharmacology , Placenta Growth Factor , Protein Binding , Structure-Activity Relationship , Vascular Endothelial Growth Factor Receptor-1/antagonists & inhibitorsABSTRACT
The goals of this study were to determine the solubility values of solid organic solutes in pure HFA-134a and in HFA-134a/ethanol cosolvent systems (0-20%, w/w), and to investigate the relationship between these solubilities and a solute's physico-chemical properties. A direct inject on-line HPLC method was used to determine the solubility of 21 solutes in HFA-134a/ethanol. The samples were allowed to equilibrate for at least 48 h. The filtered sample was injected directly on an analytical HPLC column through a manual injector interface, and analyzed at an appropriate solute wavelength via HPLC. The solutes display diverse physico-chemical properties and yielded solubility values that ranged over four orders of magnitude. In general, a linear-linear solubility relationship was observed as the fraction of ethanol increased. The effects on solubilization ranged from 1.3 to 99.4 times when 20% (w/w) ethanol was introduced, relative to pure HFA-134a. A regression equation utilizing a solute's hydrogen bonding potential resulted in a significant correlation to the slope obtained from a linear model for solubility in HFA-134a with 0-20% (w/w) ethanol, and may be useful for pre-formulation studies.
Subject(s)
Drug Carriers/chemistry , Ethanol/chemistry , Hydrocarbons, Fluorinated/chemistry , Metered Dose Inhalers , Chromatography, High Pressure Liquid , Drug Delivery Systems/instrumentation , Drug Delivery Systems/methods , Linear Models , SolubilityABSTRACT
The reformulation of pressurized metered dose inhalers with HFAs from CFCs has given rise to many solubility challenges. Compounds and excipients previously used in CFCs were observed to have significantly different solubility values in HFA-134a. In this investigation, the solubility values of 36 solid organic solutes in HFA-134a were determined. The set of compounds display diverse physico-chemical properties and yielded solubility values that ranged over 4 orders of magnitude. The experimental solubilities were compared to calculated values obtained from ideal solubility theory as well as from regular solution theory. While the theoretical models did not offer absolute solubility estimations, a clear correlation with the ideal solubility (melting point) was noted. Further consideration utilizing multiple linear regression models afforded correlations based on molecular properties. Regression models, containing melting point and log P (or molar volume) resulted in promising correlations having average absolute errors of 0.43 log units, or a factor of 2.69.
