Comparative pharmacokinetic, immunologic and hematologic studies on the anti-HIV-1/2 compounds aconitylated and succinylated HSA

Abstract

Charge modification by succinylation or cis-aconitylation of the terminal epsilon NH2 functions of the amino acid lysine in human serum albumin, resulted in polyanionic compounds with an anti-HIV-1 activity in the low nanomolar concentration range. After iv injections in rats of the negatively charged albumins (NCAs), a dose dependent elimination pattern was observed indicating a saturable eliminations pathway. The Michaelis-Menten parameters Vmax and K(m) were 62 +/- 8 micrograms.min-1.kg-1 and 16 +/- 4 micrograms.ml-1 (Clintr 3.9 +/- 1.1 ml.min-1.kg-1) and 74 +/- 6 micrograms.min-1.kg-1 and 11 +/- 2 micrograms.ml-1 (Clintr 6.7 +/- 1.2 ml.min-1.kg-1) for aconitylated-HSA (Aco-HSA) and succinylated-HSA (Suc-HSA) respectively, using 125I-labelled proteins. The volume of distribution (V) of both compounds was approximately 60 ml.kg-1. Coadministration of poly-inosinic acid and formaldehyde treated albumin showed a marked inhibition of blood clearance indicating that the compounds are mainly cleared from the bloodstream by scavenger receptors on liver and spleen endothelial cells and macrophages. The Michaelis-Menten constant K(m) was remarkably higher when the hydrophobic flurophore fluorescein was covalently linked to the protein, indicating that the affinity for the scavenger receptors is largely decreased by FiTC conjugation. The latter observation may have implications for the kinetic behavior of drug-carrier preparations if antiviral drugs like AZT or PMEA are linked to these intrinsic active carriers. In contrast to other polyanionic compounds like heparins and dextran sulfate, these NCAs did not exhibit acute toxicity and had no effect on blood coagulation. They neither had an effect on the lymphocyte proliferation. Studies on immunogenicity of the homologous derivatized albumins in rats did not show a significant response. The present pharmacokinetic and toxicologic data of Suc-HSA and Aco-HSA show that both compounds are interesting preparations for studies in SIV infected monkeys and AIDS patients.

Oligomeric Modeling and Electrostatic Analysis of the gp120 Envelope Glycoprotein of Human Immunodeficiency Virus

“…Since the primary interaction appears to be dependent on charge density rather than a particular structural motif (57), it seems unlikely that the specificity essential for effective therapeutic treatment is present. This does not bode well for drug development based on polyanions such as sulfated polysaccharides (2,24,35), carboxylated albumins (26,51), porphyrins (13,49), or DNA or RNA derivatives (31). Nevertheless, the unusual basicity observed for the CXCR4-using viruses may, in this particular case, permit anion-based intervention.…”

Tritium labeling of full‐length small interfering RNAs

“…Other labeling techniques such as fluorophores or direct coupling of the radio isotope 125 I have been used for labeling siRNAs. However, these labeling approaches may influence the pharmacokinetics and pharmacodynamics, as highlighted already for modified proteins (Swart et al …”

Metabolism Studies of Unformulated Internally [3H]-Labeled Short Interfering RNAs in Mice

“…Overall, drug candidates with attached pendant groups containing complexed isotopes are often assumed to not alter the reactivity or metabolism of the molecules. However, this labeling approach has previously been shown to influence the pharmacodynamic and pharmacokinetic behavior of large molecules, such as for proteins by Swart et al (1996). ABBREVIATIONS: ADME, absorption, distribution, metabolism, and excretion; ESI, electrospray ionization; HPLC, high-performance liquid chromatography; MRP4, multidrug resistance protein isoform 4; MS, mass spectrometry; QWBA, quantitative whole-body autoradiography; siRNA, short interfering RNA; SSB, Sjögren Syndrome antigen B; UHPLC, ultra high-performance liquid chromatography.…”

“…Studies using proteins have shown that labeling by 125 I affected the pharmacokinetics, compared with the molecule labeled with carbon-14 (Swart et al, 1996).…”