The Glycogen Synthase Kinase-3ß Inhibitor LSN 2105786 Promotes Zebrafish Fin Regeneration.

The Wnt pathway has been shown to regulate bone homeostasis and to influence some bone disease states. We utilized a zebrafish model system to study the effects of a synthetic, orally bioavailable glycogen synthase kinase-3ß (GSK3ß) inhibitor LSN 2105786, which activates Wnt signaling during bone healing and embryogenesis. GSK3ß inhibitor treatment was used to phenocopy GSK3ß morpholino oligonucleotide (MO) knockdown in zebrafish embryos. Human and zebrafish synthetic mRNA injection were similarly effective at rescue of GSK3ß MO knockdown. During caudal fin regeneration, bony rays are the first structure to differentiate in zebrafish fins, providing a useful model to study bone healing. Caudal fin regeneration experiments were conducted using various concentrations of a GSK3ß inhibitor, examining duration and concentration dependence on regenerative outgrowth. Experiments revealed continuous low concentration (4-5 nM) treatment to be more effective at increasing regeneration than intermittent dosing. Higher concentrations inhibited fin growth, perhaps by excessive stimulation of differentiation programs. Increased Wnt responsive gene expression and differentiation were observed in response to GSK3b inhibitor treatment. Activating Wnt signaling also increased cell proliferation and osteoblast differentiation in fin regenerates. Together, these data indicate that bone healing in zebrafish fin regeneration was improved by activating Wnt signaling using GSK3b inhibitor treatment. In addition, caudal fin regeneration is useful to evaluate dose-dependent pharmacological efficacy in bone healing, various dosing regimens and possible toxicological effects of compounds.

Pharmacokinetic and screening studies of the interaction between mononuclear phagocyte system and nanoparticle formulations and colloid forming drugs.

Studies have shown that nanoparticles (NPs) are cleared through the mononuclear phagocyte system (MPS). Pharmacokinetic studies of Doxil, DaunoXome, micellar doxorubicin (SP1049C) and small molecule (SM) doxorubicin were performed in SCID mice, Sprague-Dawley rats, and beagle dogs. An ex vivo MPS profiling platform was used to evaluate the interaction between the same agents, as well as colloid-forming and non-colloid forming SM drugs. In all species, the systemic clearance was highest for SP1049C and lowest for Doxil. With the exception of dog blood, the MPS screening results of mouse and rat blood showed that the greatest reduction in phagocytosis occurred after the ex vivo addition of SM-doxorubicin>SP1049C>DaunoXome>Doxil. The MPS profiling platform in rats, but not dogs, could differentiate between colloid forming and non-colloid forming drugs. The results of the MPS profiling platform were generally consistent with in vivo clearance rates of NP and SM anticancer drugs in mice and rats. This study suggests the MPS profiling platform is an effective method to screen and differentiate the important characteristics of NPs and colloid-forming drugs that affect their in vivo clearance. Implications of these findings on preclinical prediction of human clearance are discussed.

Post-injection delirium/sedation syndrome in patients with schizophrenia treated with olanzapine long-acting injection, II: investigations of mechanism.

BACKGROUND: Olanzapine long-acting injection (LAI) is a salt-based depot antipsychotic combining olanzapine and pamoic acid. The slow intramuscular dissolution of this practically insoluble salt produces an extended release of olanzapine lasting up to 4 weeks. However, in a small number of injections (< 0.1%), patients experienced symptoms suggestive of olanzapine overdose, a phenomenon that has been termed "post-injection delirium/sedation syndrome" (PDSS). The authors conducted a series of parallel investigations into the possible reasons PDSS events occur. METHODS: Healthcare providers involved in the PDSS cases were queried for clinical information around the events. Plasma samples from patients experiencing PDSS were collected when possible (12/30 cases) and olanzapine concentrations compared with the known pharmacokinetic profile for olanzapine LAI. Product batches and used vials from the PDSS cases were evaluated for compliance with established manufacturing standards and/or possible user error. Because this depot formulation depends upon slow dissolution at the intramuscular injection site, in-vitro experiments were conducted to assess solubility of olanzapine pamoate in various media. RESULTS: Injection administrators reported no unusual occurrences during the injection. No anomalies were found with the product batches or the remaining suspension in the used vials. Olanzapine concentrations during PDSS events were higher than the expected 5-73 ng/mL range, with concentrations exceeding 100 ng/mL and in some cases reaching >600 ng/mL during the first hours after injection but then returning to the expected therapeutic range within 24 to 72 hours. Solubility and dissolution rate of olanzapine pamoate were also found to be substantially greater in plasma than in other media such as those approximating the environment in muscle tissue. CONCLUSIONS: Manufacturing irregularities, improper drug reconstitution, and inappropriate dosing were ruled out as possible causes of PDSS. In-vitro solubility and in-vivo pharmacokinetic investigations suggest that PDSS is related to exposure of the injected product to a substantial volume of blood. This exposure is most likely the result of unintended partial intravascular injection or blood vessel injury during the injection (occurring even with proper injection technique) with subsequent seepage of the medication into the vasculature, which would produce higher than intended olanzapine concentrations and symptoms consistent with PDSS. TRIAL REGISTRATION: ClinicalTrials.gov ID; URL: http://http//www.clinicaltrials.gov/: NCT00094640, NCT00088478, NCT00088491, NCT00088465, and NCT00320489.

An investigation into the influence of counterion on the properties of some amorphous organic salts.

Amorphous solids and crystalline salts are both of interest as a means of improving the dissolution characteristics and apparent solubility of poorly water soluble active pharmaceutical ingredients which have low bioavailability in humans. The theory and selection of both crystalline drug substance salt forms and amorphous products have been extensively studied. However, less is known about the impact of different counterions on the properties of amorphous drug substance salts. In this study, several salts of either nicardipine or propranolol were prepared and characterized with respect to glass transition temperature, crystallization tendency and moisture sorption behavior. Although the moisture sorption behavior and crystallization tendency varied depending on the counterion used, no trends were readily apparent. The glass transition temperature was found to be dependent on the counterion used to form the salt, and was higher in all instances for the salts than for the neutral compound. Several molecular descriptors were calculated for the various counterions, and multivariate analysis was used to build a model that successfully correlated Tg with a number of these parameters. Important parameters which influenced Tg included counterion pKa and electrophilicity index. In conclusion, it is apparent that, as for crystalline salts, the counterion has an effect on the properties of amorphous materials.