Ion-pair complex-based solvent extraction combined with chemiluminescence determination of chlorpromazine hydrochloride with luminol in reverse micelles

A new chemiluminescence (CL) method is proposed for the determination of chlorpromazine hydrochloride, which is based on the dichloromethane solvent extraction of ion-pair complex of tetrachloroaurate(III) with chlorpromazine hydrochloride and luminol chemiluminescence detection in a reversed micellar medium formed by the cation surfactant cetyltrimethylammonium bromide in a dichloromethane-cyclohexane (1:1 V/V)-water (0.3 mol/L Na2CO3 buffer solution with the pH of 11.5). The ion-pair complex of tetrachloroaurate(III) with chlorpromazine hydrochloride produced an analytical chemiluminescence signal when it entered the reversed micellar water pool. In the optimum conditions, CL intensities are proportional to concentrations of the studied drug over the range 0.05 approximately 10 microg/mL with a detection limit (DL) of 6 ng/mL. The relative standard deviation (R.S.D.) is 2.6% for 1.25 microg/mL chlorpromazine hydrochloride (n = 11). R.S.D. (precision) of inter-day and intra-day is less than 6%, and accuracy of inter-day and intra-day is satisfactory. The method has been applied to the determination of studied drug in pharmaceutical preparations and biological fluids with satisfactory results.

Spectroelectrochemical determination of chlorpromazine hydrochloride by flow-injection analysis

An original, simple and sensitive flow-injection spectroelectroanalytical method for the determination of chlorpromazine in pure form or in pharmaceutical formulations is described. The method is based on the formation of a stable cationic radical by electro-oxidation in sulfuric acid medium (0.1 mol l(-1)), monitored in situ at lambda=524 nm. The determination of chlorpromazine hydrochloride in pure form or in pharmaceutical formulations was explored, considering the amperometric and the absorptiometric signal. The association of these two signals enhanced the selectivity of the analysis and proved decisive when other electroactive compounds or excipients like ascorbic acid were present in the formulation. The analytical parameters have been evaluated and the results obtained using standard additions are in agreement with the reference methods.

Compatibility of nitroglycerin, diazepam and chlorpromazine with a new multilayer material for infusion containers

The stability and compatibility of three drugs: nitroglycerin, diazepam and chlorpromazine, with a new multilayer infusion bag were studied. The study was carried out comparatively with PVC bags with which these drugs are incompatible. The drugs were diluted in 5% dextrose or in 0.9% sodium chloride isotonic solutions. Solutions were stored during 8 or 48 h with or without any protection against light. Remaining concentrations of drug were determined by high-performance liquid chromatography (HPLC) during the storage. The admixtures were also monitored for precipitation, color change and pH. Whatever the isotonic solution used, the loss of drugs is in discredit of the use of PVC bags for their storage. So, these three drugs would not be stored in PVC bags. In multilayer bags, no loss of drugs and no color change were detected throughout the storage period. pH values were stable during the same storage period. These three drugs were compatible with multilayer bags in all tested conditions for 8 or 48 h. The leaching of the plasticizer di-(2-ethylhexyl) phthalate (DEHP), that is incorporated into PVC to make the bags soft and pliable was not detected in the three drug solutions during storage period. Our study confirms that these three drugs are incompatible with PVC bags, on the contrary the new materiel tested was proved to be interesting for drug storage.

Interaction of two phenothiazine derivatives with phospholipid monolayers

This paper addresses the cooperative interaction of two phenothiazine drugs, viz. trifluoperazine (TFP) and chlorpromazine (CPZ), with phospholipid monolayers as the model membrane system. Surface pressure and surface potential isotherms were obtained for mixed Langmuir monolayers of either dipalmitoyl-phosphatidyl-choline (DPPC) or dipalmitoyl-phosphatidyl-glycerol (DPPG) co-spread with TFP or CPZ. The changes in monolayer behavior caused by incorporation of a few molar ratio of drug molecules were practically within the experimental dispersion for the zwitterionic DPPC, and therefore a more refined analysis will be required to probe the interactions in an unequivocal way. For the charged DPPG, on the other hand, the surface pressure and the dipole moment were significantly affected even for TFP or CPZ concentrations as low as 0.002 molar ratio. Overall, the effects from CPZ and TFP are similar, but small differences exist which are probably due to the different protonation properties of the two drugs. For both drugs, changes are more prominent at the liftoff of the surface pressure, i.e. at the gas-condensed phase transition, with the surface pressure and surface potential isotherms becoming more expanded with the drug incorporation. With DPPG/CPZ monolayers, in particular, an additional phase transition appears at higher CPZ concentrations, which resembles the effects from increasing the subphase temperature for a pure DPPG monolayer. The dipole moment for DPPG/CPZ and DPPG/TFP monolayers decreases with the drug concentration, which means that the effects from the charged drugs are not associated with changes in the double-layer potential. Otherwise, the effective dipole moment should increase with the drug concentration. The changes caused in surface pressure and dipole moment by small concentrations of TFP or CPZ can only be explained by some cooperative effect through which the contribution from DPPG molecules changes considerably, i.e. even DPPG molecules that are not neighbor to a CPZ or TFP molecule are also affected. Such changes may occur either through a significant reorientation of the DPPG molecules or to a change in their hydration state. We discuss the cooperativity semi-quantitatively by estimating the number of lipid molecules affected by the drug interaction. CPZ and TFP also affect the morphology of DPPG monolayers, which was confirmed with Brewster angle microscopy. The biological implications from the cooperative, non-specific interaction of CPZ and TFP with membranes are also commented upon.

Chlorpromazine N-Demethylation by Hydroperoxidase Activity of Covalent Immobilized Lipoxygenase

This work describes the application of the N-demethylase activity of immobilized soybean lipoxygenase to the oxidative degradation of xenobiotics. Previously (1) we have shown that immobilized lipoxygenase produces the oxidative degradation of CPZ in the presence of hydrogen peroxide. As a continuation of this work, here we studied the N-demethylation of CPZ by the hydroperoxidase activity of covalent immobilized soybean lipoxygenase. The obtained results clearly reveal that the immobilized system produces the N-demethylation of CPZ in the presence of hydrogen peroxide, maintaining a high level of activity in comparison with free enzyme. Additionally, the immobilized lipoxygenase shows stability higher than that of free enzyme, making feasible its use in a bioreactor operating in continuous or discontinuous mode. The results obtained in this work, together with those obtained previously by us for the oxidation of CPZ, suggest that hydroperoxidase activity of immobilized lipoxygenase may constitute a valuable tool for oxidative xenobiotics degradation or for application to synthetic processes in which a N-demethylation reaction is involved.

ESR studies on the effect of cholesterol on chlorpromazine interaction with saturated and unsaturated liposome membranes

In this study, the effects of chlorpromazine (CPZ) on lipid order and motion in saturated (DMPC, DMPG) and unsaturated (SOPC) liposome membranes were investigated by electron spin resonance (ESR) spin labeling technique. We have shown that above the main phase transition temperature of membrane lipids (T(M)), CPZ slightly increases lipid order in membranes without cholesterol, whereas below T(M) it has a strong opposite effect. Addition of 30 mol% of cholesterol into DMPC and SOPC membranes changes significantly the CPZ effects both above and below T(M). Additionally, above T(M), the ordering effect of CPZ on pure SOPC membrane is stronger at pH 7.4 than at pH 9.0, whereas below T(M), as well as in the presence of cholesterol, pH does not seem to play a role in CPZ effect on both membranes. Because of the strong influence of membrane composition on CPZ effect on membranes, the use of cholesterol as a marker of CPZ photosensitized reactions has been discussed.

Permeation characteristics of a hydrophilic basic compound across a bio-mimetic artificial membrane

In the present study, the permeation characteristics of a hydrophilic basic compound (HBC) in a bio-mimetic parallel artificial membrane permeability assay (bio-mimetic PAMPA) were investigated in detail. The bio-mimetic PAMPA membrane was constructed on a hydrophobic filter by impregnating a lipid solution consisting of phosphatidylcholine (0.8%, w/w), phosphatidylethanolamine (0.8%, w/w), phosphatidylserine (0.2%, w/w), phosphatidylinositol (0.2%, w/w), cholesterol (1.0%, w/w), and 1,7-octadiene (97.0%, w/w). The pH-permeability curve (pH 3-10), the effect of lipid composition, concentration dependency (0.02-2.00 mM), and inhibition by other cationic compounds, were investigated for several HBCs. Ketoprofen and methylchlorpromazine were also employed as an acidic and a quaternary ammonium compound, respectively. At pH 3-6, the permeability of timolol, a HBC, was higher than expected from the pH-partition hypothesis, especially in the PI-containing membrane, whereas the pH-permeability curve of ketoprofen followed the pH-partition hypothesis. Permeation of HBC was saturable and inhibited by basic and quaternary ammonium compounds. Similar results were also found for methylchlorpromazine. The permeation characteristics of HBC observed in the present study are not usually expected in a passive permeation process across an artificial membrane. The participation of facilitated permeation of cationic species was suggested, in addition to a simple passive diffusion of un-dissociated species. Ion pair transport was suggested as a possible permeation mechanism of cationic species. However, further investigation is necessary to clarify the reason for the permeation characteristics of HBC.

[Stimulatory response to the oxidation of benzidine and other xenobiotics mediated by lipoxygenase in the presence of phenothiazines]

OBJECTIVE

To test the possibility that certain efficient substrates for lipoxygenase (LOX) produce shuttle oxidants that stimulate the generation of reactive oxygen species from other chemicals.

METHODS

Metabolic interactions were conducted in vitro between chlorpromazine (BZ) or other phenothiazines and benzidine or other xenobiotics mediated by soybean lipoxygenase (SLO) or purified human term placental lipoxygenase (HTPLO) in the presence of hydrogen peroxide, and the rates of xenobiotics oxidation were measured by spectroscopic analysis.

RESULTS

Chlorpromazine cation radical (CPZ(*+)) generated by lipoxygenase triggered a rapid oxidation of benzidine to benzidine diimine cation. Under the experimental conditions used, the metabolic interaction resulted in a 42-fold greater stimulation than BZ alone in the rate of BZ oxidation. The magnitude of stimulation of benzidine oxidation exhibited a dependence on the pH of the reaction medium, amount of the enzyme, and concentration of chlorpromazine, BZ, and hydrogen peroxide. A number of other phenothiazines were also found to stimulate BZ oxidation, albeit to a lesser degree. Chlorpromazine cation radical stimulated the oxidation of all six other xenobiotics tested. The highest stimulation (94-fold) was noted in the oxidation of tetramethyl phenylenediamine to Wursters blue radical, while the lowest stimulatory response (2-fold) was observed in guaiacol. Preliminary data showed that purified HTPLO also displayed a similar stimulatory response to benzidine oxidation in the presence of chlorpromazine.

CONCLUSION

Both soybean lipoxygenase and purified human term placental lipoxygenase can mediate stimulatory response to the oxidation of benzidine and other xenobiotics in the presence of phenothiazines.

Calcium and chlorpromazine binding to the EF-hand peptides of neuronal calcium sensor-1

Neuronal calcium sensor-1, a protein of calcium sensor family, is known to have four structural EF-hands. We have synthesised peptides corresponding to all the four EF-hands and studied their conformation and calcium-binding. Our data confirm that the first putative site, a non-canonical one (EF1), does not bind calcium. We have investigated if this lack of binding is due to the presence of non-favoured residues (particularly at +x and -z co-ordinating positions) of the loop. We have mutated these residues and found that after modification the peptides bound calcium. However, these mutated peptides (EF1 and its functional mutants) do not show any Ca(2+) induced changes in far-UV CD. EF2, EF3, and EF4 peptides bind Ca(2+), EF3 being the strongest binder, followed by EF4. Our data of Ca(2+)-binding to individual EF peptides show that there are three active Ca(2+)-binding sites in NCS-1. We have also studied the binding of a neuroleptic drug, chlorpromazine, with the protein as well as with its EF-hands. CPZ binds myristoylated as well as non-myristoylated NCS-1 in Ca(2+)-dependent manner, with dynamic interaction to myristoylated protein. CPZ does not bind to EF1, but binds to functional EF-hand peptides and induces changes in far-UV CD. Our results suggest that NCS-1 could be a target of such antipsychotic and neuroleptic drugs.

Chlorpromazine interaction with phosphatidylserines: A 13C and 31P solid-state NMR study

Chlorpromazine (CPZ), a cationic, amphiphilic phenothiazine derivative is widely used as an antipsychotic drug because it antagonizes dopaminergic receptors. (13)C and (31)P solid-state NMR techniques were employed on phospholipid bilayers with and without CPZ. Phosphatidylserine from pig brain (PBPS), 1-palmitoyl-2-oleoyl phosphatidylserine (POPS), synthetic 1,2-dipalmitoyl phosphatidylcholine (DPPC) and chlorpromazineHCl were used to make phospholipid bilayers containing two types of phospholipids: DPPC (60%)/PBPS (40%) as well as POPS and PBPS bilayers without and with 10% CPZ. CPZ is found to prefer binding to the phosphate of phosphatidylserine, but also binding to the carboxyl of the serine head group in the DPPC/PBPS/CPZ bilayer is present. (31)P-NMR spectra indicate an effect of acyl chain unsaturation on the anisotropic motion of the charged serine head group. This implies that the serine head group anisotropic motion is restricted by intermolecular rather than intramolecular effects. The degree of phospholipid acyl chain unsaturation determines part of the CPZ bilayer interaction. The PBPS bilayer has the 22:6 acyl chain at 34 mol% and the C(4)?C(5) group of this acyl appears to be a determinant for CPZ bilayer interdigitation.

Dissociation constants of phenothiazine drugs incorporated in phosphatidylcholine bilayer of small unilamellar vesicles as determined by carbon-13 nuclear magnetic resonance spectrometric titration

The dissociation constants (pKms) of the phenothiazine drugs promazine, chlorpromazine, and triflupromazine, incorporated in the phosphatidylcholine (PC) bilayer of small unilamellar vesicles (SUV), were investigated by a 13C nuclear magnetic resonance (NMR) titration method employing their N-13CH3 (ionizable group) labelled derivatives. Use of the labelled drugs enabled direct observations of the ionization equilibrium of the N-dimethyl group. A second derivative spectrophotometric study proved that 95-98% of the phenothiazine species in the sample solutions (200 microM phenothiazine in the presence of 27 mM PC SUV) were incorporated into the PC bilayer, which simplified the calculation of pKm values by allowing that the phenothiazines in the aqueous phase could be neglected. The pKm values were calculated from the chemical shift dependence of the N-dimethyl 13C NMR signal on the pH value of sample solutions. The pKm values obtained were smaller than those measured in aqueous solutions by about one unit. The existence of cholesterol (30 mol%) in the PC bilayer showed little effect on the pKm values, suggesting that cholesterol in the bilayer does not largely affect the interfacial region where the N-dimethyl group of the incorporated phenothiazines is located. The results offered clear evidence for the pKm decrease and provided their precise values.

Chlorpromazine interactions to sera albumins. A study by the quenching of fluorescence

Binding of chlorpromazine (CPZ) and hemin (Hmn) to human (HSA) and bovine (BSA) serum albumin was studied by fluorescence quenching technique. Intrinsic fluorescences of BSA and HSA were measured by selectively exciting their tryptophan residues. Gradual quenching was observed by titration of both proteins with CPZ and Hmn. CPZ is a widely used anti-psychosis drug that causes severe side effects and strongly interacts with biomembranes, both in its lipidic and proteic regions. CPZ also interacts with blood components, influences bioavailability, and affects the function of several biomolecules. Albumin plays an important role in the transport and storage of hormones, ions, fatty acids and others substances, including CPZ, affecting the regulation of their plasmatic concentration. Hmn is an important ferric residue of hemoglobin that binds within the hydrophobic region of albumin with great specificity. Hmn added to HSA and BSA solutions at a molar ratio of 1:1 quenched about half of their fluorescence. Stern-Volmer plots obtained from experiments carried out at 25 and 35 degrees C showed the quenching of fluorescence of HSA and BSA by CPZ to be a collisional phenomenon. Hmn quenches fluorescence by a static process, which specifically indicates the formation of a complex. Our results suggest the prime binding site for CPZ and Hmn on both HSA and BSA to be near tryptophan residues.

Kinetic Determination of Total Iodine in Urine and Foodstuffs Using a Mixed Acid as a Pretreatment Agent

An analytical method for the determination of total iodine at the ng level in urine, biological materials and foods was investigated. The organic substances were completely decomposed using a mixed solution of nitric, perchloric and sulfuric acids as pretreatment agents at ca. 230 degrees C. Iodine in the resulting solution was analyzed by a kinetic-photometric method based on the catalytic effect of iodine on the oxidation of chlorpromazine by hydrogen peroxide. The relative standard deviation was 1.6% for 100 ng of iodide and the detection limit of the method was 1.6 ng (3sigma). The proposed method was successfully applied to the determination of iodine at ng levels in real samples.

Selective amphipathic nature of chlorpromazine binding to plasma membrane bilayers

Chlorpromazine (CPZ), an antipsychotic agent shown to inhibit the action of various neurophysiological receptors, also exhibits preferential association with the plasma membrane, inducing stomatocytic morphological response in red blood cells (RBC). Given the cationic nature of CPZ, fluorimetry, pH titration, and red cell morphological studies were performed to assess the associative predilection of CPZ for anionic membrane components. CPZ fluorescence intensity increased 320-370% upon addition of phosphatidylcholine (PC) small unilamellar vesicles (SUVs) to aqueous CPZ, indicating an affinity of the drug for lipidic phases. After removal of unbound drug, CPZ fluorescence increased up to 92% with increasing phosphatidylserine (PS) in the lipid phase (up to 30 mol% of total lipid), suggesting a preferential association of the drug with anionic lipids. In studies of pH titration, the pK(a) of CPZ in the presence of Triton X-100 micelles or phospholipid SUVs increased with increasing anionicity of the lipidic phase [7.8 with Triton X-100, 8.0 with PC, 8.3 with phosphatidylglycerol (PG)], lending further support to preferential drug interaction with anionic lipidic components. At 0 degrees C, CPZ-induced red cell shape change was less extensive in cells made echinocytic by adenosine triphosphate (ATP) depletion, compared to cells made echinocytic by PS treatment following vanadate preincubation. This suggests that polyphosphoinositide lipids are CPZ membrane binding sites. Since polyphosphoinositide lipids are implicated as important intermediates in a number of receptor-mediated cell signaling pathways, evidence of association with these specific lipids provides a means by which psychoactive drugs may induce neurophysiological effects through direct interaction with general membrane components.

Abnormal dissolutions of chlorpromazine hydrochloride tablets in water by paddle method under a high agitation condition

All sugar-coated tablets of chlorpromazine hydrochloride except for those produced by one manufacture showed concave dissolution profiles in water by paddle method at 100 rpm but not at 50 rpm. The study was undertaken to clarify the agitation-dependent abnormal dissolutions. The strange dissolutions were also observed in water at different ionic strengths but not in buffer solutions of pH 1.2, 4.0 and 6.8. When monitored, the pH's of water in dissolution vessels for the abnormal tablets increased with time at 100 rpm and some of them exceeded pH 8 but did not at 50 rpm. The solubility of chlorpromazine hydrochloride decreased with the increase of pH which was too low to dissolve the whole amount of drug contained in a tablet at pH 8. The elevation of pH seemed to be mainly brought about by dissolution of calcium carbonate popularly used for sugar-coated tablets, because larger amount of calcium ion was dissolved out from the abnormal tablets at 100 rpm than from a normal tablet and from them at 50 rpm. These findings indicate that the concave dissolution profiles should be caused by the decrease of drug solubility with increase in pH of water, probably because of dissolution of calcium carbonate. We should pay attention to the change in pH of water which may differ depending on the agitation speed of dissolution tests.

Effect of chlorpromazine free radical on tyrosine hydroxylase of bovine adrenal medulla

The effect of preincubation with chlorpromazine and chlorpromazine free radical on tyrosine hydroxylase activity was studied. Chlorpromazine free radical inhibited the enzyme activity to a greater extent than chlorpromazine. More than a two-fold decrease in the enzyme activity was observed following the preincubation of the enzyme with chlorpromazine free radical. This observation may suggest interaction between chlorpromazine free radical and -SH group located on the active site of the apoenzyme. Another interaction between chlorpromazine free radical and the coenzyme (DMPH4) was confirmed from spectral studies.

Ca2+ -dependence and inhibition of transformation by trifluoperazine and chlorpromazine in Thermoactinomyces vulgaris

Ca(2+) enhanced the transformation frequency of Thermoactinomyces vulgaris (stock no. 1278) of an auxotrophic strain by the chromosomal DNA isolated from a prototrophic strain (stock no. 1227). The number of transformants showed a marked increase with increasing concentration of CaCl(2) upto 0.05 mM; and above this concentration, the transformation frequency decreased significantly. Antipsychotic drugs that are potent calmodulin inhibitors, like trifluoperazine and chlorpromazine, when applied in the concentration range of 0.01-0.04 mM along with optimal CaCl(2) concentration to the cultures of the recipient cells, resulted in a significant inhibition in the frequency of Ca(2+)-stimulated transformation. The results of present investigation suggest the involvement of a Ca(2+)-dependent protein activator in the development of Ca(2+)-mediated competence, which could have played an important role in the enhancement of genetic transformation in this aerobic spore forming thermophilic actinomycete.

Chlorpromazine oxidation by hydroperoxidase activity of covalent immobilized lipoxygenase

The application of the hydroperoxidase activity of immobilized lipoxygenase to xenobiotic metabolization is reported in this work. Soya bean lipoxygenase has been immobilized by covalent coupling to oxirane acrylic beads. This immobilized system has been applied to the oxidation of chlorpromazine (CPZ), a phenothiazine of wide pharmacological use which in some cases presents toxicity. Immobilized lipoxygenase produces the oxidation of CPZ in the presence of hydrogen peroxide at acidic pH, maintaining a high level of activity and stability. In comparison with free lipoxygenase, the immobilized enzyme system shows higher catalytic efficiency and protection against enzymic inactivation produced by the presence of H(2)O(2). When the system of immobilized enzyme was loaded into a bioreactor operating in continuous mode, the level of CPZ oxidation was higher than obtained using a discontinuous procedure or the free enzyme. The results obtained in this work suggest that a system of covalent immobilized lipoxygenase operating in continuous mode may constitute a valuable tool for xenobiotic detoxification or metabolization studies.

Bioelectric toxicity caused by chlorpromazine in human lung epithelial cells

Endogeneous and exogeneous amine-containing substances possess pneumophilic properties. Among them, tricyclic amphiphilic amine drugs like neuroleptics intensively accumulate in the lung cell membrane and occasionally cause severe respiratory disorders. In the present study, we examined the bioelectric toxicity of chlorpromazine (CPZ), a commonly used neuroleptic, in human lung epithelial cells. CPZ concentration-dependently inhibited the isoproterenol (ISO)-generated short-circuit current (I(sc)) sensitive to a nonselective K(+) channel blocker, clotrimazole (30 microM), but insensitive to a selective Ca(2+)-activated K(+) (K(Ca)) channel blocker, charybdotoxin (ChTx, 100 nM). The effects of apical CPZ on the ISO-induced responses were greater than those of basolateral CPZ. Forskolin- and 8-bromo-cyclic AMP-induced I(sc) were partially prevented by CPZ. Nystatin permeabilization of the monolayers revealed that CPZ attenuated the basolateral K(+) current elicited by ISO more than that elicited by forskolin and that the apical Cl(-) current elicited by forskolin was instead potentiated by CPZ, although it inhibited the ISO-induced Cl(-) current. 1-Ethyl-2-benzimdazolinone (1-EBIO, a K(Ca) channel opener, 500 microM)- and ionomycin (Ca(2+) ionophore, 1 microM)-evoked Cl(-) secretions were also sensitive to CPZ. These results indicate that CPZ inhibits transepithelial Cl(-) transport, affecting at least two different targets: the beta-adrenergic receptor and the basolateral K(+) channels (especially the K(Ca) channel). Electrostatic interactions at the inner surface of the membrane between the protonated amines of CPZ and negatively charged portions of the plasma membrane may be involved in the mechanisms.

Excess plasma membrane and effects of ionic amphipaths on mechanics of outer hair cell lateral wall

The interaction between the outer hair cell (OHC) lateral wall plasma membrane and the underlying cortical lattice was examined by a morphometric analysis of cell images during cell deformation. Vesiculation of the plasma membrane was produced by micropipette aspiration in control cells and cells exposed to ionic amphipaths that alter membrane mechanics. An increase of total cell and vesicle surface area suggests that the plasma membrane possesses a membrane reservoir. Chlorpromazine (CPZ) decreased the pressure required for vesiculation, whereas salicylate (Sal) had no effect. The time required for vesiculation was decreased by CPZ, indicating that CPZ decreases the energy barrier required for vesiculation. An increase in total volume is observed during micropipette aspiration. A deformation-induced increase in hydraulic conductivity is also seen in response to micropipette-applied fluid jet deformation of the lateral wall. Application of CPZ and/or Sal decreased this strain-induced hydraulic conductivity. The impact of ionic amphipaths on OHC plasma membrane and lateral wall mechanics may contribute to their effects on OHC electromotility and hearing.

Chlorpromazine and Sodium Dodecyl Sulfate Mixed Micelles Investigated by Small Angle X-Ray Scattering

Small-angle X-ray scattering (SAXS) studies are reported on the interaction of chlorpromazine (CPZ) with micelles of anionic surfactant sodium dodecyl sulfate (SDS). Isotropic solutions of SDS (40 and 100 mM) at pH 4.0, 7.0, and 9.0 in the absence and presence of CPZ (2-25 mM) were investigated at the National Laboratory of Synchrotron Light (LNLS, Campinas, Brazil). The data were analyzed through the modeling of the micellar form factor and interference function. The results evidence a micellar shape transformation from prolate ellipsoid to cylinder accompanied by micellar growth and surface charge screening as the molar ratio CPZ : SDS increases in the complex. Small ellipsoids with axial ratio nu=1.5+/-0.1 at 40 mM SDS grow and reassemble into cylinder-like aggregates upon 5 mM drug incorporation (1 CPZ : 8 SDS monomers) with a decrease of the micelle surface charge. At 10 mM CPZ : 40 mM SDS cylindrical micelles are totally screened with an axial ratio nu approximately 2.5. The data also indicate the presence of small prolate ellipsoids (nu=1.7+/-0.1) in solutions of 100 mM SDS (no drug) and micellar growth (nu approximately 2.0 and 4.0) when 10 and 25 mM CPZ are added to the system. In the latter case, the aggregate is also better represented by a cylinder-like form. Therefore, our results demonstrate that the axial ratio and shape evolution of the surfactant : phenothiazine complex are both SDS concentration and drug : SDS molar ratio dependent. The drug location close to the SDS polar headgroup region without disrupting in a significant way both the paraffinic hydrophobic core and the polar shell thickness is inferred. SAXS data made it possible to obtain the shapes and dimensions of CPZ/SDS aggregates.

Novel phenothiazine antimalarials: synthesis, antimalarial activity, and inhibition of the formation of beta-haematin

We report the synthesis of a series of novel phenothiazine compounds that inhibit the growth of both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. We found that the antimalarial activity of these phenothiazines increased with an increase in the number of basic groups in the alkylamino side chain, which may reflect increased uptake into the parasite food vacuole or differences in the toxicities of individual FP-drug complexes. We have examined the ability of the parent phenothiazine, chlorpromazine, and some novel phenothiazines to inhibit the formation of beta-haematin. The degree of antimalarial potency was loosely correlated with the efficacy of inhibition of beta-haematin formation, suggesting that these phenothiazines exert their antimalarial activities in a manner similar to that of chloroquine, i.e. by antagonizing the sequestration of toxic haem (ferriprotoporphyrin IX) moieties within the malaria parasite. Chlorpromazine is an effective modulator of chloroquine resistance; however, the more potent phenothiazine derivatives were more active against chloroquine-sensitive parasites than against chloroquine-resistant parasites and showed little synergy of action when used in combination with chloroquine. These studies point to structural features that may determine the antimalarial activity and resistance modulating potential of weakly basic amphipaths.

Studies on the size and stability of chlorpromazine hydrochloride nanostructures in aqueous solution

The mean aggregate number (MAN) of the antipsychotic drug chlorpromazine hydrochloride (CPZ) nanostructure was investigated by fluorescence quenching using 9-methylanthracene (9-MA) as the quencher. The method was designed to take advantage of the intrinsic fluorescent properties of CPZ. The validity of this method was supported by the results obtained for the MAN which was determined to be approximately 37 for a solution of 10 mM CPZ in 0.1 M pH 6.5 phosphate buffer. An increase in the aggregate size with increasing drug concentration confirmed the stepwise aggregation theory of CPZ micelle formation. Differential scanning calorimetry was used to examine the effects of concentration on the thermodynamics of micellization. The enthalpy of demicellization increased with increasing CPZ concentration (5-12 mM), suggesting a greater stability of the aggregates at higher concentrations. At amphiphile concentrations higher than 12 mM, a plateau of approximately 10 kJ/mol was observed as the enthalpy of demicellization. Fluorescence lifetime results revealed a two-component system at low CPZ concentration, while data at amphiphile concentrations higher than 12 mM could not be fitted to either single or multi-component lifetime values, suggesting an increase in dispersity in these nanostructures at higher CPZ concentrations. Temperatures higher than 40 degrees C tend to destabilize the larger micelles, and demicellization was observed after approximately 45 degrees C. Changes in osmotic pressure in the presence of dextrose up to 0.3 M had no significant effect on the size of these micellar nanostructures.

A kinetic method for the determination of nitrite by its catalytic effect on the oxidation of chlorpromazine with nitric acid

A catalytic spectrophotometric method for the determination of trace amounts of nitrite is proposed. In acidic solution, chlorpromazine (CP) is oxidized by nitric acid to form a red compound, which is further oxidized to a colorless compound. The reaction is accelerated by trace amounts of nitrite and can be followed by measuring the absorbance at 525 nm: nitrite ion is regenerated and multiplied by nitric acid. The absorbance of the reaction increased with an increase in the reaction time, reached a maximum and decreased rapidly. Since the time required for the absorbance to reach the maximum decreased with increasing nitrite concentration, this value was used as the measured parameter for the nitrite determination. Under the optimum experimental conditions (2.3 M nitric acid, 1.2 x 10(-5) M CP, 40 degrees C), nitrite can be determined in the range 0-100 microg l(-1). The relative standard deviations (n = 6) are 4.7 and 1.8% for 40 and 100 microg l(-1) nitrite, respectively. The detection limit of this method (3sigma) is 1.2 microg l(-1). This method was successfully applied to a determination of nitrite in natural water samples.