Preparation, characterization and in vitro antiviral activity evaluation of foscarnet-chitosan nanoparticles.

A new nanoparticulate system for foscarnet delivery was prepared and evaluated. Nanoparticles were obtained by ionotropic gelation of chitosan induced by foscarnet itself, acting as an ionotropic agent in a manner similar to tripolyphosphate anion. A Doehlert design allowed finding the suitable experimental conditions. Nanoparticles were between 200 and 300nm in diameter (around 450nm after redispersion). Nanoparticle size increased after 5h, but no size increase was observed after 48h when nanoparticles were crosslinked with glutaraldehyde. Zeta potential values of noncrosslinked and crosslinked nanoparticles were between 20 and 25mV, while drug loading of noncrosslinked nanoparticles was about 40% w/w (55% w/w for crosslinked nanoparticles). Nanoparticle yield was around 25% w/w. Crosslinked nanoparticles showed a controlled drug release. Foscarnet released from nanoparticles maintained the antiviral activity of the free drug when tested in vitro against lung fibroblasts (HELF) cells infected with HCMV strain AD-169. Moreover, nanoparticles showed no toxicity on non-infected HELF cells. These nanoparticles may represent a delivery system that could improve the therapeutic effect of foscarnet.

Poloxamer 407 as a solubilising agent for tolfenamic acid and as a base for a gel formulation.

A solubility phase study was carried out to investigate the ability of Poloxamer 407 (P407) to solubilise tolfenamic acid. P407 considerably enhanced the solubility of this anti-inflammatory agent, by increasing its concentration in aqueous solution at least 2000-fold (up to C=4mM), when present at 12% (w/w) at 25 degrees C. The solubilisation process was spontaneous and exothermic, as indicated by thermodynamic parameters. A mixture experimental design was used to investigate the physical and release properties of P407-based gel formulations. The experimental design allowed verifying that drug release, occurring through a Fickian diffusion mechanism, was independent of the bulk viscosity of the system. The sustained release of tolfenamic acid towards the receptor phase constituted by isopropyl myristate was accompanied, in its early stage, by the concomitant release of ethanol and tetrahydrofurfuryl alcohol (THFA) used as cosolvents to obtain a drug loading of 0.6% (w/w). The poloxamer micellar phase was directly involved in the late stage of drug release, thus indicating that a strong interaction occurred in the gel between the poloxamer and tolfenamic acid. Results point out the possibility of both the systemic and topical administration of tolfenamic acid by means of aqueous solutions or gels containing P407 at an adequate concentration.

Preparation and evaluation of nanoparticles made of chitosan or N-trimethyl chitosan and a cisplatin-alginate complex.

In this work, nanoparticles with a negative or positive surface charge were prepared through electrostatic interaction of an anionic cisplatin-alginate complex with a cationic polyelectrolyte, namely chitosan or N-trimethyl chitosan (substitution degree of 85%). Statistical experimental design allowed the study of the influence of component amounts on the characteristics of nanoparticles. Mean particle diameter ranged from 180 nm to 350 nm. After 24 h, while the cisplatin-alginate complex released almost all the drug in saline-buffered solution at pH 7.4, approximately 40% w/w of total cisplatin was released from negative nanoparticles and roughly 50% w/w from positive ones. The same cumulative amounts of released drug were found after 48 h, with a progressive reduction to lower values up to 6 days. Drug loading of nanoparticles with a positive zeta potential (43 mV-60 mV) ranged from 13% w/w to 21% w/w and particle yield, referred to total polymers, was about 15% w/w (50% w/w if referred to cisplatin-alginate complex). Nanoparticles with a negative zeta potential (-34 mV) were obtained with a yield of 40% w/w and a drug loading of 18% w/w. These nanoparticles were the least active on all cell lines tested, while the cytotoxic activity of the positive nanoparticles was similar to or lower than that of cisplatin, probably depending on the combination of sizes and zeta potential values, on P388 murine and A2780 human cells. On A549 human cells, the nanoparticles with the smallest size and the lowest positive zeta potential were more active than cisplatin and showed a similar capability in inducing apoptosis in A2780 human cells. These results indicate that cisplatin complexes with polycarboxylate polymers can be transformed into cisplatin particulate carriers of high potential interest.

Preparation and evaluation of a chitosan salt-poloxamer 407 based matrix for buccal drug delivery.

The aim of this work was to prepare and evaluate a matrix for buccal drug delivery composed of a chitosan salt and poloxamer 407. Different chitosan salts were formed by reacting chitosan with acetic, citric, and lactic acid. Various proportions of poloxamer 407 were added to the aqueous solution of chitosan salt, and the residue obtained by lyophilisation was compressed into discs, using a 30 kN compression force. An experimental design (3(2)) was used to study the influence of the type of chitosan salt and of the relative amount of poloxamer on drug release capacity, swelling, erosion, and mucoadhesiveness of matrices. The results showed that matrix properties depended significantly on both relative amount of poloxamer and chitosan salt type. The rank orders of chitosan salts for the four processes evaluated were as follows: drug release: chitosan acetate>chitosan citrate>chitosan lactate; swelling: chitosan lactate>chitosan acetate=chitosan citrate; erosion: chitosan citrate>chitosan lactate>chitosan acetate; mucoadhesion: chitosan lactate>chitosan acetate=chitosan citrate. Mucoadhesion was particularly favoured when poloxamer 407 was present at about 30% (w/w). The matrix composed of chitosan lactate and poloxamer 407 showed the best characteristics for buccal administration.

Embryotoxicity of cisplatin and a cisplatin-procaine complex (DPR) studied in chick embryo.

Cisplatin is widely used as an antitumor drug. To reduce its toxic side effects in patients, cisplatin has been bound with procaine in a cisplatin-procaine complex (DPR). The lethal and teratogenic effects of cisplatin alone and of complexed cisplatin were determined in the chick embryo in ovo in order to compare their influence on rapidly proliferating embryonic tissues. The embryotoxic (lethal + teratogenic) effect was examined after a single intra-amniotic injection of one of six different doses, ranging from 0.03 to 30.0 microg, on embryonic days (ED) 3, 4 or 5. The minimal embryotoxic dose was lower for cisplatin alone (0.03-0.3 microg) than for cisplatin in the DPR complex (0.3-3.0 microg), suggesting that cisplatin alone is more embryotoxic than complexed cisplatin. Both substances caused malformations in the surviving embryos evaluated on ED 9. These malformations included microphthalmia, microcephaly, hypoplasia of the upper and lower jaw, cleft beak, and haemocephaly. Moreover, heart septum defects and limb reduction deformities were found after exposure to the DPR complex. The embryotoxicity of complexed cisplatin exhibited a stage-response effect. It was highest on day 3 and gradually decreased until ED 5. Such an apparent stage-response effect was not observed for cisplatin alone. The embryotoxicity of procaine hydrochloride - a component of the complex - was also tested. Procaine hydrochloride alone did not produce any embryotoxic effect, not even after a single injection of the maximal tested dose (100.0 microg per embryo). We also examined the protective effect of procaine hydrochloride, whose separate administration at ED 4 was followed by the injection of 0.3 microg cisplatin. We did not observe any protective effect of procaine hydrochloride if injected separately.

Stability study of hard gelatin capsules containing retinoic acid.

Retinoic acid (RA) is employed in the therapeutic treatment of acute promyelocytic leukemia (APL). In this paper, the chemical stability and the most favorable storage conditions of RA in hard gelatin capsules containing alpha-lactose monohydrate, used in clinical experimentation, are reported. A secondary goal of this work was to show the usefulness of a robust regression technique, repeated median with replicates (RMWR) in a solid-state shelf life prediction by accelerated studies. The capsules were stored at room temperature and in the freezer. Their residual RA content was assayed for more than 3 years. RA chemical degradation was monitored by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) stability-indicating methods previously validated and able to detect various potential degradation products. Possible physical modifications were checked by dissolution tests and differential scanning calorimetry (DSC) of the content of the capsules. The shelf life was also predicted by an accelerated isothermal method to confirm room temperature results, and the activation energy estimated through this study was 12.5 +/- 1.1 kcal/mol (95% confidence interval). In the conditions of climatic zone II, the shelf life for the capsules stored at room temperature in light-resistant containers was equal to 678 days, while the capsules stored in the freezer retained the initial content of drug after 1289 days. From the results gathered in this study, the usefulness of RMWR for shelf life prediction in the presence of outliers is evident.

Reduction of cisplatin nephrotoxicity by procainamide: does the formation of a cisplatin-procainamide complex play a role?

Procainamide protects mice bearing P388 leukemic cells against the toxicity of cisplatin without diminishing antitumor activity. The mechanism of action of procainamide protection was investigated both in vitro and in vivo. HPLC studies showed that procainamide forms a complex with cisplatin in vitro that has a UV spectrum similar to that of DPR, a triamine platinum complex that contains procaine as ligand. We report here the effect of the reaction product of cisplatin and procainamide on both cisplatin-induced DNA interstrand cross-links (ISCLs) and on the total DNA platination of isolated DNA. Total DNA platination in vitro of isolated DNA was increased by 113% (P <.01) and 17% (P <.05) after incubation times of 1.75 and 6 h, respectively, compared with products from the reaction of cisplatin with water. Furthermore, the reaction product of cisplatin and procainamide was bound to DNA to a significantly greater extent than was cisplatin itself. ISCLs were decreased by 41% when this drug combination was incubated with DNA for 1.75 h, but no changes were observed after incubation for 6 h. We also examined the influence of the time interval between administration of cisplatin and procainamide on normal kidney injury, the renal distribution and urinary excretion of platinum, and the formation of cisplatin-DNA adducts in renal tissue of Sprague-Dawley rats after i.p. administration of 7.5 mg/kg cisplatin either with or without procainamide. The plasma concentrations of urea and creatinine and kidney histology demonstrated that procainamide provided effective protection in vivo in the rat when administered either simultaneously or at 0.5 and 1 h before or after cisplatin. The protection was accompanied by both higher renal levels of platinum and cisplatin-DNA adducts and by an increase in the formation of ISCLs. Moreover, a dose-dependent reduction of urinary excretion and concentration of platinum was also observed. We propose that procainamide, after accumulation in the kidney, may coordinate with cisplatin to form a less toxic DPR-like complex that renders rats less susceptible to cisplatin-induced toxicity.

Development and in vitro evaluation of buccoadhesive tablets using a new model substrate for bioadhesion measures: the eggshell membrane.

For oral delivery of antimicrobial and anti-inflammatory drug, mucoadhesive tablets based on gelatin/hydroxypropylcellulose (HPC), gelatin/hydroxypropylmethyl-cellulose (HPMC), and gelatin/sodium carboxymethylcellulose (NaCMC) at different ratios were prepared by direct compression of the mixed powders. Metronidazole and benzydamine were used as model drugs. The in vitro bioadhesive properties, evaluated by a commercial tensile tester, were significantly affected by the model substrate employed, that is, a polypropylene (PP) membrane or a biological membrane (eggshell membrane). The use of the biological substrate seemed to supply more reliable data. All studied formulations showed an erosion-diffusion mechanism of release, anomalous or non-Fickian release, in agreement with the behavior of the swellable systems.

Neurotoxic effect of cisplatin and the cisplatin-procaine complex DPR studied in organotypic cultures of chick embryonic dorsal root ganglia.

Neurotoxic effects of cisplatin and the cisplatin-procaine complex cis-diaminechloro-[2-(diethylamino)ethyl 4-aminobenzoate, N4]-chlorideplatinum(II) monohydrochloride monohydrate (DPR) were compared in organotypic cultures of chick embryonic dorsal root ganglia maintained in a semi-solid (soft agar) culture medium. The changes of two characteristics of the neurite outgrowth, the mean radial length of neuritic processes growing out from the ganglia and the area of neurite outgrowth around the ganglion, were used as parameters to evaluate the toxic effect of both compounds. The drugs were administered to the cultures at concentrations ranging from 13 to 120 microM. The half-maximum inhibition concentration (IC50) was determined from the concentration-response curves for both the mean radial length of neurites and the area of neurite outgrowth. An analysis of these parameters revealed that DPR was significantly less neurotoxic than cisplatin. In fact, considering the mean radial length of neurite processes, the IC50s of cisplatin were 56, 65 and 66 microM after 24, 48 and 72 h of exposure, respectively. By contrast, for DPR the IC50s were 116 microM after 24 h, and greater than 120 microM after 48 and 72 h of exposure. When we considered the area index (i.e. the area of neurite outgrowth normalized for the area of the ganglia), the IC50s for cisplatin were 41, 52 and 55 microM after 24, 48 and 72 h of exposure, respectively, whereas for DPR the IC50s were 59 microM after 24 h, and greater than 120 microM after 48 and 72 h of exposure. Our results support previous findings of lower toxicity of DPR to non-neoplastic tissues, as compared to cisplatin.

Combination of cisplatin-procaine complex DPR with anticancer drugs increases cytotoxicity against ovarian cancer cell lines.

DPR, cis-diamminechloro-[2-(diethylamino)ethyl 4-amino-benzoate, N4]-chlorideplatinum(II) monohydrochloride monohydrate, is a newly developed water-soluble platinum compound which possess minimal cross-resistance to cisplatin and shows relatively less side effects. In an attempt to establish whether the combination of DPR with other conventional anticancer drugs would be of any benefit we assessed in vitro the cytotoxic effects of combinations of DPR with the antimetabolites 5-fluorouracil (5-FU) and methotrexate (MTX), the alkylating agents mitomycin C (MMC) and cisplatin, the antimicrotubule agent taxol (TAX), and the intercalating agent of the anthracycline group doxorubicin (DOX) on murine M5076 ovarian reticulosarcoma and human A2780 ovarian carcinoma cells. These agents were selected because of their common use in the clinic and because they represent four distinct categories of antineoplastic mechanisms. Cells were incubated for 72 h in the presence of single or combined drugs, and the cytotoxic effect was determined by the MTT assay. The analysis of combination treatment was made by the isobole method. In human A2780 cells, an overall synergy was found for DPR combined with 5-FU, DOX and cisplatin. Synergistic effects were also observed for most combinations with MTX or MMC. A DPR concentration-dependent additivity and antagonism was seen at the highest MTX concentration (1 microM), while additive effects were observed for the combined treatments of DPR and low concentrations of MMC (0.008 and 0.0016 microM). Additive effects were also observed for the association of DPR and TAX over most combinations tested. In murine M5076 cells, synergism was the prevailing result observed when DPR was combined with 5-FU, DOX, MMC or cisplatin. When administered together with MTX we observed additivity over most combinations tested. These findings suggest that DPR, when simultaneously administered with standard anticancer agents, may be advantagious for cytokilling.

Study of the interaction of dithranol with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin in solution and in the solid state.

The interaction between dithranol and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMBCyD) has been investigated in aqueous solution containing isoascorbic acid (0.2% w/v) as antioxidant and in the solid state. The interaction in the solid state was studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray powder diffractometry (XPD) and a dissolution-rate method. The extent of complexation between the two substances was poor, as indicated by the low value of the slope of the linear part of the solubility curve. A phase diagram was constructed by measuring the thermal behaviour of various re-solidified physical mixtures of dithranol and of TMBCyD previously subjected to heating until melting of the TMBCyD. The loss of dithranol, owing to sublimation and degradation caused by the thermal treatment used, was less than 10%. In keeping with XPD and IR data, the phase diagram indicated that a complex was formed containing 13.7% dithranol (molar ratio 1:1) which had a congruent melting point at 164 degrees C. The drug dissolution rate from the 1:1 complex was measurable, unlike that of the corresponding physical mixture, and was significantly increased when the complex was dispersed in the glassy matrix of TMBCyD, as it was in re-solidified mixtures containing 2-7% dithranol. The results show that the solubility of dithranol is increased significantly as a consequence of its interaction with TMBCyD, despite the low extent of complexation between the two substances.

Effect of the cisplatin-procaine complex DPR in combination with several anticancer agents on murine P388 leukemic cells in vitro and in vivo.

We evaluated in vitro the antiproliferative activity of DPR (Fig. 1), a new cisplatin-derived compound, in combination with five conventional anticancer drugs: the antimetabolites 5-fluorouracil (5FU) and methotrexate (MTX), the alkylating agent mitomycin C (MMC), the antimicrotubule agent taxol (TAX) and the intercalating agent of the antracycline group doxorubicin (DOX), against murine P388 leukemic cells. MTT assay was used to determine growth inhibition after incubation of cells for 72 hours in the presence of single or combined drugs. The additive, synergistic or antagonistic nature of the combined drug effect was determined using the isobole method. In our cellular model, synergism was the prevailing result observed when DPR was combined with MMC. Conversely, antagonism was observed when DPR was combined with TAX. When DPR was administered together with the other antineoplastic drugs, the final effect was dependent on the concentrations of single agents. The study in vitro of the association between DPR and MMC was extended in vivo in BDF-1 female mice bearing i.p. P388 leukemic cells. Our data in vivo confirmed those obtained in vitro, demonstrating the therapeutic advantage of the association of ineffective doses of DPR (2 and 7 mg/kg) and MMC (3.2 mg/kg) over the administration of MMC alone.

Cisplatin combined with the new cisplatin-procaine complex DPR: in vitro and in vivo studies.

The administration of combinations of platinum compounds is considered as a useful alternative therapeutic strategy to avoid the complications of toxic events during cancer chemotherapy in order to obtain a therapeutic advantage. On the basis of previous in vitro and in vivo findings, suggesting an antitumour activity of the new cisplatin-derived compound cis-diamminechloro-[2-(diethylamino)ethyl 4-amino-benzoate, N4]-chlorideplatinum(II) monohydrochloride monohydrate (DPR), we investigated the effectiveness of the combination of cisplatin (DDP) and DPR in vitro on murine leukaemic cells, which were either sensitive (P388) or resistant (L1210/DDP) to DDP, and on the murine M5076 reticulum cell sarcoma, and in vivo in BDF1 female mice transplanted with P388 leukaemic cells or cisplatin-resistant L1210/DDP leukaemic cells. The contemporaneous exposure in vitro to both platinum compounds gave a significantly higher cell growth inhibition than that expected on the basis of dose-response curves for single agents in all tumour models tested. In vivo, the combinations of DDP plus DPR elicited significant enhancement over the activity of the drugs alone both in the ascitic and solid P388 models. The combined treatment of 10 mg/kg DDP and 14 mg/kg DPR yielded 62.5% tumour-free mice compared with 6.2% with 10 mg/kg DDP alone, the best single agent. It is noteworthy that the combined application of DDP and DPR was also very effective in the solid cisplatin-resistant L1210/DDP model, inducing a significant reduction in the volume of tumour. A therapeutic advantage was achieved with combination treatments that had no effect on platinum-mediated body weight loss and were generally well tolerated by the mice. At equitoxic concentrations of DPR and carboplatin, the treatment with DDP plus DPR proved to have a higher efficacy against this tumour model compared to that observed after the combined treatment with DDP and carboplatin. In summary, the combination of DDP and DPR showed a therapeutic advantage over single drug treatment and has demonstrated promise at the preclinical level in its ability to circumvent acquired resistance to DDP both in vitro and in vivo.

Median-based robust regression methods in prediction of drug stability.

The classical isothermal approach for the prediction of drug stability exploits least squares regression. In this paper the use of some robust regression techniques to estimate the rate constants at different temperatures has been evaluated. These techniques are able to give accurate estimates when data are contaminated by the presence of outliers. The successful application of two robust methods, single median and repeated median, to real stability data from the literature is shown. Moreover, the authors have modified the original methods in order to apply them to data sets with replicates, typical of stability studies. The performances of the modified techniques have been investigated with simulated data sets containing outliers and with real data. They appear suitable for preliminary stability studies, especially on solid dosage forms. For a quick implementation of these methods, macroprograms written for a widely used spreadsheet are reported.

Comparison of the toxicities of cisplatin and a new cisplatin-procaine complex to rat renal cortical slices.

1. Procaine has previously been shown to diminish the nephrotoxicity of cisplatin and the nephrotoxic effects of cisplatin and a new cisplatin complex (cis-diamminechloro-[2-(diethylamino) ethyl-4-aminobenzoate, N4]-chlorideplatinum (II) monohydrochloride monohydrate; DPR), that contains procaine hydrochloride were compared with rat renal cortical slices. 2. Cisplatin at 1 mM caused toxicity to the slices, as shown by an increase in the leakage of aspartate aminotransferase and lactate dehydrogenase from the slices into the incubation medium and a decrease in the reduction of a tetrazolium dye (MTT assay). Addition of procaine (1 mM) protected against cisplatin-induced toxicity. DPR either at 1 mM or at 4 mM had no effect either on the enzyme leakage or MTT reduction by the renal slices, but DPR at 10 mM produced a similar magnitude of enzyme leakage to cisplatin (1 mM). 3. DPR lowered the concentration of ATP and glutathione (GSH) in the slices but was less potent than cisplatin. Thiobarbituric acid reactive substances, indicators of lipid peroxidation, released into the medium were increased by the highest concentration of DPR (10 mM), which suggests that DPR has the potential to cause oxidative stress. 4. The results suggest that DPR was far less toxic than either cisplatin alone or a mixture of cisplatin and procaine.

Chemical and biological properties of a new cis-diammineplatinum (II) complex containing para-aminobenzoic acid as amino ligand.

In this paper we report on the synthesis, characterization and preliminary pharmacological evaluation of a new platinum (II) complex obtained by reaction of cis-diamminedichloroplatinum(II) (DDP) with para-aminobenzoic acid (PABA). The structure of this platinum compound was defined by UV, IR, 1H-NMR and elemental analysis. DPAB tested in vitro and in vivo against P388 leukemic cells displayed good antiproliferative (IC50 values after 48 h exposure of cells = 3 micrograms/ml) and antitumor activity (T/C% = 150). This compound also possesses desirable physical properties, such as a good solubility and stability in aqueous media, and a low toxicity (LD50 > 1200 mg/kg body weight) combined with a moderate nephrotoxic activity [plasma urea nitrogen (PUN) level: 36 +/- 8(SD) mg/100 ml]. DPAB was cleared from plasma ultrafiltrate (UF-plasma) very rapidly [clearance (CL), 55.3 ml x min-1 x kg-1], showing a half-life of 13.6 min. Platinum exposure (AUC) in the kidney was 2.6 times greater than that found in UF-plasma. AUCS for liver, stomach and UF-plasma were similar, while the AUC value for the spleen was 1.7 times lower than that of UF-plasma. These preliminary results seem to hold interest for further preclinical evaluation of the biological activity of this new platinum compound.

Cytotoxicity and cellular accumulation of a new cis-diammineplatinum (II) complex containing procaine in murine L1210 cells sensitive and resistant to cis-diamminedichloroplatinum (II).

The emergence of drug resistance during tumor chemotherapy is one of the main problems associated with cancer treatment, particularly with cisplatin (cis-DDP). In the hope of overcoming this problem, various cis-DDP-derived compounds have been synthesized, and their pharmacological activity was compared with that of cis-DDP. In this paper we report on studies on the cytotoxic activity induced by cis-diamminechloro-[2-(diethylamino)ethyl-4-aminobenzoate, N4]- chlorideplatinum(II) monohydrochloride monohydrate (DPR), a new complex of platinum containing procaine. All experiments were carried out on murine leukemic cells, which were either sensitive (L1210) or resistant (L1210/DDP) to cis-DDP. A tetrazolium dye (MTT) assay conducted 5 days after a 2-h exposure of cells to both drugs was utilized to determine the resistance factor (RF) of L1210/DDP cells as compared with the sensitive wild-type cells. Drug accumulation and efflux, together with the amount of platinum bound to DNA, were also investigated. The activity of DPR on sensitive cells was not significantly different from that of cis-DDP. Conversely, DPR was 4.3 times more effective than cis-DDP on resistant cells. A decreased drug accumulation is one of the mechanisms of resistance to cis-DDP of L1210/DDP cells. However, DPR accumulation was not significantly different in sensitive and resistant L1210 cells. Under culture conditions that yielded similar intracellular platinum concentrations, treatment with DPR produced significantly greater DNA platination than did treatment with cis-DDP in both cell lines. No difference in efflux was observed between L1210 and L1210/DDP cells exposed to either cis-DDP or DPR. Our results show that in parental cells, DPR is as potent as cis-DDP on a molar basis, and it is also minimally cross-resistant with cis-DDP in L1210/DDP cells. A direct implication of our results is that DPR could be useful in those human tumors showing a mechanism of resistance similar to that of L1210/DDP cells.

Modifications of cell-cycle induced by dpr, a new platinum-triamine complex containing procaine.

cis-diamminechloro-[2-(diethylamino)ethyl 4-amino-benzoate, N4]-chlorideplatinum(II) monohydrochloride monohydrate (DPR) is a new platinum-triamine complex containing as ligand the local anesthetic procaine. In this study DPR was compared to the parent compound cisplatin (cis-DDP) in order to study the influence of both molecules on the cell cycle phases, and particularly on the induction of apoptosis. P388 murine leukemic cells were used as cellular model, and were exposed in vitro to either compound, continuously for 24 hours. At the end of the incubation, the thymidine uptake, the trypan blue dye exclusion assay, and the flow cytometry were assessed. Both the cytotoxic activity and the inhibition of DNA synthesis evaluated after 24 h incubation with DPR or cis-DDP were comparable. Moreover, cell cycle was modified in a comparable manner by both molecules. In particular the induction of the apoptotic effect was similarly induced by the same concentrations of the compounds and time exposure. In conclusion, DPR and cis-DDP seem to have a similar effect on the cell cycle of P388 leukemic cells and particularly on the induction of the programmed cell death.

Cis-diamminedichloroplatinum (II)-procaine pharmacokinetic interaction in mice bearing P388 leukemia.

The distribution and elimination kinetics of cis-diamminedichloroplatinum (II) (DDP) in female BDF1 mice bearing 6-day P388 leukemia were investigated in the presence and absence of procaine hydrochloride (P.HCl) exposure. DDP was administered as a single i.p. dose of 8 mg/kg in a 0.9% NaCl solution 6 days after tumor inoculum. P.HCl was administered as a single i.v. dose of 40 mg/kg immediately after DDP. The combined treatment with P.HCl produced marked changes in the plasma concentration-time profile of Pt. The unbound fraction of Pt was significantly increased both in the ascites fluid and plasma following DDP + P.HCl administration. P.HCl treatment induced a significant reduction (P < 0.01) in the rate constant of the protein-bound of Pt in plasma of tumored mice. Urinary excretion of Pt was unaffected by P.HCl, and there was no significant P.HCl-induced modification in the concentrations of Pt in the P388 leukemic cells. A statistically significant reduction of kidney and spleen Pt content was observed in female mice exposed to a dose of 8 mg/kg DDP + P.HCl. A similar reduction was observed in kidneys and testes of tumored mice receiving 16 mg/kg DDP along with 40 mg/kg P.HCl, which also showed lower renal and testicular cisplatin-DNA adducts after DDP + P.HCl than after DDP treatment. Potential explanations for the ability of P.HCl to interfere with the pharmacokinetics and biodistribution of DDP are discussed.