Effects of Pimozide Derivatives on pSTAT5 in K562 Cells.

STAT5 is a transcription factor, a member of the STAT family of signaling proteins. STAT5 is involved in many types of cancer, including chronic myelogenous leukemia (CML), in which this protein is found constitutively activated as a consequence of BCR-ABL expression. The neuroleptic drug pimozide was recently reported to act as an inhibitor of STAT5 phosphorylation and is capable of inducing apoptosis in CML cells in vitro. Our research group has synthesized simple derivatives of pimozide with cytotoxic activity and that are able to decrease the levels of phosphorylated STAT5. In this work we continued the search for novel STAT5 inhibitors, synthesizing compounds in which the benzoimidazolinone ring of pimozide is either maintained or modified, in order to obtain further structure-activity relationship information for this class of STAT5 inhibitors. Two compounds of the series showed potent cytotoxic activity against BCR-ABL-positive and pSTAT5-overexpressing K562 cells and were able to markedly decrease the levels of phosphorylated STAT5.

Inhibition of activated STAT5 in Bcr/Abl expressing leukemia cells with new pimozide derivatives.

STATs are transcription factors acting as intracellular signaling after stimulation with cytokines, growth factors and hormones. STAT5 is also constitutively active in many forms of cancers, including chronic myelogenous leukemia, acute lymphoblastic leukemia and Hodgkin's lymphoma. Recently, literature reported that the neuroleptic drug pimozide inhibits STAT5 phosphorylation inducing apoptosis in CML cells. We undertook an investigation from pimozide structure, obtaining simple derivatives with cytotoxic and STAT5-inhibitory activity, two of them markedly more potent than pimozide.

Effect of polymer hygroscopicity on the phase behavior of amorphous solid dispersions in the presence of moisture.

It has been previously observed that exposure to high relative humidity (RH) can induce amorphous-amorphous phase separation in solid dispersions composed of certain hydrophobic drugs and poly(vinylpyrrolidone) (PVP). The objective of this study was to investigate if this phenomenon occurred in solid dispersions prepared using less hygroscopic polymers. Drug-polymer miscibility was investigated before and after exposure to high RH using infrared (IR) spectroscopy and differential scanning calorimetry (DSC). PVP, poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA), and hypromellose acetate succinate (HPMCAS) were selected as model polymers, and felodipine, pimozide, indomethacin, and quinidine were selected as model drugs. Drug-polymer mixing at the molecular level was confirmed for all model systems investigated. Moisture-induced drug-polymer demixing was observed in felodipine-PVPVA, quinidine-PVP, quinidine-PVPVA, pimozide-PVPVA, and pimozide-HPMCAS systems, but was absent in the other HPMCAS dispersions and for indomethacin-PVPVA. It is concluded that the balance between the thermodynamic factors (enthalpy and entropy of mixing) in a ternary water-drug-polymer system is the important factor in determining which solid dispersion systems are susceptible to moisture-induced amorphous-amorphous phase separation. Systems with strong drug-polymer interactions and a less hygroscopic polymer will be less susceptible to moisture-induced phase separation, while more hydrophobic drugs will be more susceptible to this phenomenon even at low levels of sorbed moisture.

Phase behavior of poly(vinylpyrrolidone) containing amorphous solid dispersions in the presence of moisture.

The objective of this study was to investigate the phase behavior of amorphous solid dispersions composed of a hydrophobic drug and a hydrophilic polymer following exposure to elevated relative humidity. Infrared (IR) spectroscopy, differential scanning calorimetry (DSC) and moisture sorption analysis were performed on five model systems (nifedipine-poly(vinylpyrrolidone) (PVP), indomethacin-PVP, ketoprofen-PVP, droperidol-PVP, and pimozide-PVP) immediately after production of the amorphous solid dispersions and following storage at room temperature and elevated relative humidity. Complete miscibility between the drug and the polymer immediately after solid dispersion formation was confirmed by the presence of specific drug-polymer interactions and a single glass transition (T(g)) event. Following storage at elevated relative humidity (75-94% RH), nifedipine-PVP, droperidol-PVP, and pimozide-PVP dispersions formed drug-rich and polymer-rich amorphous phases prior to crystallization of the drug, while indomethacin-PVP and ketoprofen-PVP dispersions did not. Drug crystallization in systems exhibiting amorphous-amorphous phase separation initiated earlier (<6 days at 94% RH) when compared to systems that remained miscible (>or=46 days at 94% RH). Evidence of moisture-induced amorphous-amorphous phase separation was observed following storage at as low as 54% RH for the pimozide-PVP system. It was concluded that, when an amorphous molecular level solid dispersion containing a hydrophobic drug and hydrophilic polymer is subjected to moisture, drug crystallization can occur via one of two routes: crystallization from the plasticized one-phase solid dispersion, or crystallization from a plasticized drug-rich amorphous phase in a two-phase solid dispersion. In the former case, the polymer is still present in the same phase as the drug, and can inhibit crystallization to a greater extent than the latter scenario, where the polymer concentration in the drug phase is reduced as a result of the amorphous-amorphous phase separation. The strength of drug-polymer interactions appears to be important in influencing the phase behavior.

Pimozide: use in dermatology.

Pimozide is widely used in psychiatry for chronic psychoses, schizophrenia, the syndrome of Gilles de la Tourette and to a certain extent, also in dermatology. The only dermatological indication is for delusions of parasitosis. Though there is a good rationale for using pimozide in this disease, the majority of the studies on pimozide in dermatology are uncontrolled trials and case reports.

Pharmacological profile of neuroleptics at human monoamine transporters.

Using radioligand binding techniques, we determined the equilibrium dissociation constants (K(D)) for 37 neuroleptics and one metabolite of a neuroleptic (haloperidol metabolite) for the human serotonin, norepinephrine, and dopamine transporters with [3H]imipramine, [3H]nisoxetine, and [3H]WIN35428, respectively. Among neuroleptics, the four most potent compounds at the human serotonin transporter were triflupromazine, fluperlapine, chlorpromazine, and ziprasidone (K(D) 24-39 nM); and at the norepinephrine transporter, chlorpromazine, zotepine, chlorprothixene, and promazine (K(D) 19-25 nM). At the human dopamine transporter, only pimozide (K(D) = 69+/-3) ziprasidone (K(D) = 76+/-5) had notable potency. These data may be useful in predicting therapeutic and adverse effects, including drug interactions of neuroleptics.

A crystallographic and molecular modeling study of butyrophenones.

The X-ray crystal structures of four butyrophenone analogues have been completed and are reported herein. These include spiperone hydrochloride (I), N-methylspiperone hydrochloride (II), pimozide (III), and fluspirilene (IV). These structures were compared to other structurally similar molecules with similar pharmacological activity. In addition, a molecular modeling study was done in order to determine the low energy conformations of these molecules. It was found that calculations of parameters that describe the molecular conformations showed that all four molecules were structurally similar. Crystallographic data: [see text]

Modified radioimmunoassay for pimozide.

Tritium labelled pimozide, the tracer in Michiels' RIA of pimozide, can be substituted for a derivative of pimozide with tritium labelled tag, prepared in a more convenient way than the original tracer. In the synthesis of the immunogen the conjugation rate is optimized to be 12 to 13.

Partition of dopamine antagonists into synthetic lipid bilayers: the effect of membrane structure and composition.

Partition coefficients, Kp, of four dopamine antagonists (pimozide, fluspirilene, haloperidol and domperidone) between the aqueous phase and lipid bilayer vesicles were determined as a function of lipid chain length, unsaturation and temperature encompassing the range of the lipid phase transition. Model membranes of egg phosphatidylcholine (PC), dimyristoyl (DMPC)-, dipalmitoyl (DPPC)-, distearoyl (DSPC)- and dioleoyl (DOPC)-phosphatidylcholines were studied. Kp values of the drugs are different in the various membranes under study and depend on temperature, aliphatic carbon chain-length and on the presence of unsaturation in the aliphatic lipid chain. First-order transition of membrane lipids from the gel to the liquid crystalline state is accompanied by a sharp increase of the partition coefficient of pimozide and fluspirilene in DMPC, DPPC and DSPC bilayers. For domperidone, Kp values are maximal within the mid-point of phase transition of DMPC and DPPC, while for DSPC Kp values increase progressively with increasing temperature. Haloperidol Kp values display a maximum at the mid-point of phase transition of DMPC, while a progressive increase of Kp is observed in DPPC and DSPC. The four drugs are easily accommodated in bilayers of short aliphatic chain lipids (DMPC), the partition coefficients being 17,137 for pimozide, 18,700 for fluspirilene, 686 for domperidone and 722 for haloperidol, at temperatures 10 degrees C below the mid-point of the lipid phase transition. Except for haloperidol, the partition of the drugs in DOPC (18:1) is higher than that in DSPC (18:0) bilayers at a temperature above the phase transition temperature of both lipids.(ABSTRACT TRUNCATED AT 250 WORDS)