Incorporation of chlorpromazine into bilayer liposomes for protection against microsomal metabolism and liver absorption

Ganglioside GM2 catabolism is inhibited by storage compounds of mucopolysaccharidoses and by cationic amphiphilic drugs

The catabolism of ganglioside GM2 is dependent on the lysosomal enzyme β-hexosaminidase A and a supporting lipid transfer protein, the GM2 activator protein. A genetically based disturbance of GM2 catabolism, leads to several subtypes of the GM2 gangliosidosis: Tay-Sachs disease, Sandhoff disease, the AB-variant and the B1-variant, all of them having GM2 as major lysosomal storage compound. Further on it is known that the gangliosides GM2 and GM3 accumulate as secondary storage compounds in mucopolysaccharidoses, especially in Hunter disease, Hurler disease, Sanfilippo disease and Sly syndrome, with chondroitin sulfate as primary storage compound. The exact mechanism of ganglioside accumulation in mucopolysaccaridoses is still a matter of debate. Here, we show that chondroitin sulfate strongly inhibits the catabolism of membrane-bound GM2 by β-hexosaminidase A in presence of GM2 activator protein in vitro already at low micromolar concentrations. In contrast, hyaluronan, the major storage compound in mucopolysaccharidosis IX, a milder disease without secondary ganglioside accumulation, is a less effective inhibitor. On the other hand, hydrolysis of micellar-bound GM2 by β-hexosaminidase A without the assistance of GM2AP was not impeded by chondroitin sulfate implicating that the inhibition of GM2 hydrolysis by chondroitin sulfate is most likely based on an interaction with GM2AP, the GM2AP-GM2 complex or the GM2-carrying membranes. We also studied the influence of some cationic amphiphilic drugs (desipramine, chlorpromazine, imipramine and chloroquine), provoking drug induced phospholipidosis and found that all of them inhibited the hydrolysis of GM2 massively.

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.

Chlorpromazine-induced increase in dipalmitoylphosphatidylserine surface area in monolayers at room temperature

The Langmuir technique revealed that the surface area of acidic glycerophospholipids (dipalmitoylphosphatidylserine, -glycerol, and dipalmitoylphosphatidic acid) in monolayers increased dramatically when micromolar concentrations of the antipsychotic drug chlorpromazine (CPZ) were present in the subphase. Monolayers of neutral glycerophospholipids (dipalmitoylphosphatidylcholine and -ethanolamine) did not show such a large effect with CPZ. Compared to CPZ, millimolar concentrations of the monovalent cations Li+, K+, Na+, Rb+, and Cs+ did not appear to influence the dipalmitoylphosphatidylserine monolayer, suggesting that the effect of CPZ, a monovalent cationic amphophile, was due to an interaction with the acyl chains of the lipids. In addition, the effect of CPZ was reduced by 150 mM Na+, suggesting that the sodium cations might screen the negatively charged headgroups from an electrostatic interaction with the positively charged drug molecule. Two CPZ analogs, chlorpromazine sulfoxide and CPZ with 2 carbons in the side chain, were also studied. These observations suggest that part of the biological effects of CPZ, being antipsychotic and/or side effects, may be due to CPZ's action on the acidic glycerophospholipids in nerve cell membranes.

Evaluation of incorporation characteristics of mitoxantrone into unilamellar liposomes and analysis of their pharmacokinetic properties, acute toxicity, and antitumor efficacy

Mitoxantrone (MTO) was incorporated into small unilamellar liposomes by formation of a complex between the anticancer drug and negatively charged lipids. The complex was formed at a 2:1 molar ratio between the lipids and MTO, with phosphatidic acid (PA) being the strongest complex-forming lipid. Weaker complexes and lower incorporation rates of MTO resulted when liposomes containing dicetylphosphate, phosphatidyl inositol, phosphatidyl serine, phosphatidyl glycerol, oleic acid, and tridecylphosphate were used. Thus, all further experiments were performed with PA-MTO liposomes that contained 0.1-3 mg MTO/ml and had mean vesicle sizes of 40-150 nm, depending on the drug concentration and the method of liposome preparation. In vitro incubations of free and liposomal MTO with human plasma showed that the drug is slowly transferred from the liposome membranes to the plasma proteins. For liposomal MTO a transfer rate of 48% was determined, whereas 75.8% of free MTO was bound to the plasma proteins. The organ distribution of the two preparations in mice showed that higher and longer-lasting concentrations of liposomal MTO were found in the liver and spleen. The terminal elimination halflives in the liver were 77 h for liposomal MTO and 14.4 h for free MTO. In the blood, slightly higher concentrations were detected for liposomal MTO, which also had slower biphasic elimination kinetics as compared with the free drug. Drug distribution in the heart was not significantly different from that in the kidneys. The LD25 of PA-MTO liposomes in mice was 19.6 mg/kg and that of free MTO was 7.7 mg/kg. The antitumor effects of PA-MTO liposomes were evaluated in murine L1210 leukemia, in various xenografted human tumors, and in methylnitrosourea-induced rat mammary carcinoma. Generally, the liposomal application form was more effective and less toxic than the free drug. The cytostatic effects were dependent on the tumor model, the application schedule, and the drug concentration. At doses that were toxic when free MTO was used, the liposomal preparation produced strong antitumor effects in some cases. In summary, the incorporation of MTO into liposomes changes the drug's plasma-binding properties, alters its organ distribution, reduces its acute toxicity, and increases its cytostatic efficiency in various tumor models. The liposomal PA-MTO complex represents a new application form of MTO that has advantageous properties.