KA-104, a new multitargeted anticonvulsant with potent antinociceptive activity in preclinical models.

OBJECTIVE: The main objective of the present work was to assess the utility of KA-104 as potential therapy for drug-resistant seizures and neuropathic pain, and to characterize its druglike properties in a series of absorption, distribution, metabolism, excretion and toxicity (ADME-Tox) studies. We also aimed to establish its mechanism of action in electrophysiological studies. METHODS: The activity of KA-104 against drug-resistant seizures was tested in the mouse 6-Hz (44-mA) model, whereas the antinociceptive activity was assessed with the capsaicin- and oxaliplatin-induced pain models in mice. The patch-clamp technique was used to study the influence of KA-104 on fast voltage-gated sodium currents in rat prefrontal cortex pyramidal neurons. The pharmacokinetic profile was determined after intraperitoneal (ip) injection in mice. The in vitro ADME-Tox properties were studied by applying routine testing procedures. RESULTS: KA-104 was effective in the 6-Hz (44-mA) model (median effective dose [ED50 ] = 73.2 mg/kg) and revealed high efficacy in capsaicin-induced neurogenic pain as well as in oxaliplatin-induced neuropathic pain in mice. Patch-clamp technique showed that KA-104 reversibly inhibits voltage-gated sodium currents. KA-104 was rapidly absorbed after the ip injection and showed relatively good penetration through the blood-brain barrier. This molecule was also characterized by high passive permeability, moderate influence on CYP2C9, and negligible hepatotoxicity on HepG2 cells. SIGNIFICANCE: The results reported herein indicate that KA-104 is a new wide-spectrum multitargeted anticonvulsant with favorable in vitro ADME-Tox properties. Importantly, this compound may also prove to become an interesting and hopefully more effective therapeutic option for treatment of neuropathic pain.

Comparison of Effects of Anti-thrombin Aptamers HD1 and HD22 on Aggregation of Human Platelets, Thrombin Generation, Fibrin Formation, and Thrombus Formation Under Flow Conditions.

HD1 and HD22 are two of the most-studied aptamers binding to thrombin exosite I and exosite, respectively. To complete of their pharmacological profiles, the effects of HD1 and HD22 on thrombin-, ristocetin-, and collagen-induced human platelet aggregation, on thrombin generation and fibrin formation in human plasma, as well as on thrombus formation in human whole blood under flow conditions were assessed. The dissociation constants for HD1 and HD22 complexes with thrombin in simulated plasma ionic buffer were also evaluated. HD1 was more potent than HD22 in terms of inhibiting thrombin-induced platelet aggregation in platelet-rich plasma (PRP; 0.05-3 µM) and in washed platelets (WPs; 0.005-3 µM): approximately 8.31% (±6.99% SD) and 89.53% (±11.38% SD) for HD1 (0.5 µM) and HD22 (0.5 µM), respectively. Neither HD1 nor HD22 (3 µM) did influence platelets aggregation induced by collagen. Both of them inhibited ristocetin-induced aggregation in PRP. Surprisingly, HD1 and HD22 aptamers (3 µM) potentiated ristocetin-induced platelet aggregation in WP. HD1 reduced thrombin generation in a concentration-dependent manner [ETP at 3 µM: 1677.53 ± 55.77 (nM⋅min) vs. control 2271.71 ± 423.66 (nM⋅min)], inhibited fibrin formation (lag time at 3 µM: 33.70 min ± 8.01 min vs. control 7.91 min ± 0.91 min) and reduced thrombus formation under flow conditions [AUC30 at 3 µM: 758.30 ± 344.23 (kPa⋅min) vs. control 1553.84 ± 118.03 (kPa⋅min)]. HD22 (3 µM) also delayed thrombin generation but increased the thrombin peak. HD22 (3 µM) shortened the lag time of fibrin generation (5.40 min ± 0.26 min vs. control 7.58 min ± 1.14 min) but did not modify thrombus formation (3, 15 µM). K d values for the HD1 complex with thrombin was higher (257.8 ± 15.0 nM) than the K d for HD22 (97.6 ± 2.2 nM). In conclusion, HD1 but not HD22 represents a potent anti-thrombotic agent, confirming the major role of exosite I in the action of thrombin. HD22 aptamer blocking exosite II displays weaker anti-platelet and anti-coagulant activity, with surprising activating effects on thrombin and fibrin generation most likely induced by HD22-induced allosteric changes in thrombin dynamic structure.

Effects of structural modification of the daunosamine moiety of anthracycline antibiotics on pKa values determined by capillary zone electrophoresis.

The thermodynamic acid dissociation constants (pKa1 and pKa2) of 16 anthracycline antibiotics, including doxorubicin (DOX) and daunorubicin (DAU), their epimers, epidoxorubicin (EDOX) and epidaunorubicin (EDAU), as well as novel anthracycline derivatives containing piperidine (FPIP), morpholine (FMOR) and hexamethylenoimine (FHEX) rings in the formamidine group of the daunosamine moiety were determined by analysis of the dependence between measured electrophoretic mobility and the pH of the buffer using the capillary zone electrophoresis method. The results obtained confirmed the ampholytic character of anthracyclines with at least two ionization states. The determined values were in the range of 8.36-9.28 and 9.38-11.48 for pKa1 and pKa2 arising from ionization of amino and phenolic groups, respectively. Structural modifications in the daunosamine moiety of the studied anthracyclines affected their pharmacological properties, such as antiproliferative activity.