Resveratrol isoforms and conjugates: A review from biosynthesis in plants to elimination from the human body.

The natural isomers of resveratrol, cis- and trans-resveratrol, are natural phenolic substances synthetized via the shikimate pathway and found in many sources, including grapes, peanuts, blackberries, pistachios, cacao, cranberries, and jackfruits. They have functional and pharmacological properties such as anticarcinogenic, antidiabetic, anti-inflammatory, and cardioprotective activities. The aim of this article is to review the data published on resveratrol and its isomers, and their biosynthesis in plants, food sources, health and toxic effects, and the excretion of their metabolites. Due to its contribution to the promotion of human health, it is convenient to gather more knowledge about its functional properties, food sources, and the interactions with the human body during the processes of eating, digestion, absorption, biotransformation, and excretion, to combine this information to improve the understanding of these substances.

Preparation of Peppermint Oil-Based Nanodevices Loaded with Paclitaxel: Cytotoxic and Apoptosis Studies in HeLa Cells.

In this work, several normal, oil-in-water (o/w) microemulsions (MEs) were prepared using peppermint essential oil, jojoba oil, trans-anethole, and vitamin E as oil phases to test their capacity to load paclitaxel (PTX). Initially, pseudo-ternary partial phase diagrams were constructed in order to find the normal microemulsion region using d-α-tocopherol polyethylene glycol 1000 succinate (TPGS-1000) as surfactant and isobutanol (iso-BuOH) as co-surfactant. Selected ME formulations were loaded with PTX reaching concentrations of 0.6 mg mL-1 for the peppermint oil and trans-anethole MEs, while for the vitamin E and jojoba oil MEs, the maximum concentration was 0.3 mg mL-1. The PTX-loaded MEs were stable according to the results of heating-cooling cycles and mechanical force (centrifugation) test. Particularly, drug release profile for the PTX-loaded peppermint oil ME (MEPP) showed that ∼ 90% of drug was released in the first 48 h. Also, MEPP formulation showed 70% and 90% viability reduction on human cervical cancer (HeLa) cells after 24 and 48 h of exposure, respectively. In addition, HeLa cell apoptosis was confirmed by measuring caspase activity and DNA fragmentation. Results showed that the MEPP sample presented a major pro-apoptotic capability by comparing with the unloaded PTX ME sample.

Laparoscopic cytoreductive surgery and HIPEC is effective regarding peritoneum tissue paclitaxel distribution.

BACKGROUND: In some patients with peritoneal carcinomatosis, we could perform the cytoreductive surgery and the HIPEC procedure by a complete laparoscopic approach to avoid morbidity. We consider that using laparoscopic approach for performing peritoneal carcinomatosis cytoreductive surgery and HIPEC with closed CO2 recirculation technique is possible and safe, with equal efficacy to conventional methods and hemodynamic complications. OBJECTIVE: Monitoring the effectiveness of the drug distribution in a laparoscopic ctoreductive and HIPEC surgery group with CO2 recirculation respect to a closed and open HIPEC group METHODS: Porcine model that included fifteen mini-pigs. Five pigs were operated with laparoscopic approach performing a pelvic and retroperitoneal lymphadenectomy. They later received a total laparoscopic closed HIPEC with CO2 recirculation (G1). Group 2 (G2): five pigs operated by an open cytoreductive surgery and closed HIPEC technique. Group 3 (G3): five animals in which an open cytoreductive surgery and an open HIPEC technique was performed. Blood and peritoneal determinations were realized after recirculation of the drug, at 60 min using chromatographic analysis. RESULTS: G1-G2: phrenic right peritoneum, p: 0.46. Phrenic left peritoneum, p: 0.46. Pelvic peritoneum, p: 0.17. Serum paclitaxel: p: 0.01. G1-G3: phrenic right peritoneum, p: 0.34. Phrenic left peritoneum, p: 0.34. Pelvic peritoneum, p: 0.17. Serum paclitaxel G1-G3, p: 0.02. CONCLUSIONS: A total laparoscopic approach for ctoreductive surgery and closed HIPEC with CO2 recirculation may be safe and feasible. In our experimental model there was no significant difference in tissue drug distribution respect the conventional techniques and there was a less toxicity because the serum drug concentration was significantly lower with laparoscopic approach respect the other groups.

Development of a method for quantitative determination of the cytotoxic agent piplartine (piperlongumine) in multiple skin layers.

This study reports the development of a simple and reproducible method, with high rates of recovery, to extract the cytotoxic agent piplartine from skin layers, and a sensitive and rapid UV-HPLC method for its quantification. Considering the potential of piplartine for topical treatment of skin cancer, this method may find application for formulation development and pharmacokinetics studies to assess cutaneous bioavailability. Porcine skin was employed as a model for human tissue. Piplartine was extracted from the stratum corneum (SC) and remaining viable skin layers (VS) using methanol, vortex homogenization and bath sonication, and subsequently assayed by HPLC using a C18 column, and 1:1 (v/v) acetonitrile-water (adjusted to pH 4.0 with acetic acid 0.1%) as mobile phase. The quantification limit of piplartine was 0.2 µg/mL (0.6 µm), and the assay was linear up to 5 µg/mL (15.8 µm), with within-day and between-days assay coefficients of variation and relative errors <15%. Piplartine recovery from SC and VS varied from 86 to 96%. The method was suitable to assay samples from skin penetration studies, enabling detection of differences in cutaneous delivery in different skin compartments resulting from treatment with various formulations and time periods.

Vincristine-loaded hydroxyapatite nanoparticles as a potential delivery system for bone cancer therapy.

Despite advances in the development of new therapeutic agents and diagnostic imaging techniques, the 5-year survival of osteosarcoma, the most common type of bone cancer, remains practically unaltered for the last three decades at around 60%. Nanoparticle-based carriers have emerged as new class of drug delivery systems that could potentially overcome conventional chemotherapy limitations, by promoting a better drug biodistribution profile by allowing a preferential accumulation of the drug in the desired tissue, while minimising non-targeted tissue toxicity, thus resulting in an improved overall therapeutic effectiveness. Hydroxyapatite nanoparticles (HANP) are known to be biocompatible and non-immunogenic and have shown to be preferentially accumulated in bone tissues being considered a promising carrier to bone tissues. Herein, we successfully synthesised mesoporous hydroxyapatite nanoparticles with mean size of 285.32 ± 10.29 nm and superficial area of 103.5 m2/g, containing significant quantities of chemotherapeutic drug vincristine. A spectrophotometric method was developed and validated aiming to quantify the vincristine (VCR)-loaded in nanoparticles. Chorioallantoic membrane assay revealed relevant anti-angiogenic activity of system, leading to accentuated reduction in the number of blood vessels in fertilised eggs. Findings presented in this paper suggested that VCR-loaded HANP has a promising future as a nanocarrier for bone cancer treatment.

Determination of irinotecan and its metabolite SN-38 in dried blood spots using high-performance liquid-chromatography with fluorescence detection.

Irinotecan (IRI) is an antineoplastic drug widely used for the treatment of colorectal and advanced pancreatic cancer. Despite its clinical utility, the clinical use of IRI is associated with potentially severe hematopoietic and gastrointestinal toxicities. The quantification of IRI and its active metabolite SN-38 in dried blood spots (DBS) may be an alternative to individualize the drug dose through a minimally invasive and easy collection method. The aim of this study was to develop and validate a simple and fast HPLC-FL assay for simultaneous IRI and SN-38 measurement in DBS, with adequate analytical performance for clinical use. The method employs liquid extraction of one 8mm disk of whole blood, followed by separation in a reversed phase Eclipse Plus C8 column (150×4.6mm, 5µm). Detection was performed with a fluorescence detector, with excitation wavelength of 370 and emission of 420 for IRI and 540nm for SN-38 and internal standard (camptothecin). Total analytical run time was 17min. Mobile phase was a mixture of 0.1M phosphate buffer pH 4.0 and acetonitrile (80:20, v/v), at 1mLmin-1. The assay was linear in the range 10-3,000ngmL-1 and from 0.5 to 300ngmL-1 for IRI and SN-38, respectively. Precision assays presented CV% of 2.71-5.65 and 2.15-10.07 for IRI and SN-38, respectively, and accuracy in the range of 94.26-100.93 and 94.24-99.33%. IRI and SN-38 were stable at 25 and 42°C for 14days in DBS samples. The method was applied to DBS samples obtained from fingerpicks from 19 volunteers receiving IRI in single or combined chemotherapy regimens, collected 1 and 24h after beginning of the infusion. The estimated plasma concentration of IRI and SN-38 in sample collected 1h after star of infusion had 16 of 19 values within the ±20% range of the measured plasma concentrations. On the other hand, predictions of IRI and SN-38 plasma concentrations from DBS measurements obtained 24h after the beginning of the infusion were poor. AUC of IRI that was calculated using plasma and DBS-estimated concentrations, with a high correlation (r=0.918). The method presented suitable characteristics for the clinical use. However, translation of IRI and SN-38 DBS to plasma concentrations is challenging due to the compound's variable plasma/blood partition.

Design, characterization and in vitro evaluation of linalool-loaded solid lipid nanoparticles as potent tool in cancer therapy.

Linalool (LN) is a monoterpene found in essential oils of plants and herbs that produces multiple effects on the mevalonate pathway and interesting antiproliferative activity in cancer cells. However, due to its poor aqueous solubility, an efficient vehicle is needed to improve its administration and bioavailability in physiological media. LN encapsulation in solid lipid nanoparticles (SLN) with different compositions was explored and in vitro tested in two cancer cell lines. SLN of myristyl myristate (MM), cetyl esters (SS) and cetyl palmitate (CP) were prepared by sonication in the presence of Pluronic®F68 as surfactant. Nanoparticle size, morphology and distribution were determined by dynamic light scattering in combination with optical and transmission electron microscopy (TEM). SLN showed spherical shape and mean diameters in the range of 90-130nm with narrow size dispersion (PDI values lower than 0.2) and Z potentials around -4.0mV. The encapsulation percentages of LN in SLN were higher than 80% for all tested formulations and exhibited in vitro LN controlled release profiles for at least 72h. The nanoparticles were physicochemically characterized by FTIR, XRD, DSC and TGA, and the incorporation of LN into SLN was higher than 80% in tested matrices. The developed formulations, and in particular SLN (MM)-LN, showed in vitro antiproliferative effects on hepatocarcinoma (HepG2) and lung adenocarcinoma (A549) cell lines in a dose-dependent response, and higher inhibitory effects were found in comparison with free LN. The cellular uptake of SLN was demonstrated by fluorescence microscopy, enhancing the ability of nanoparticles to intracellularly deliver the cargo molecules.

Technetium-99m radiolabeled paclitaxel as an imaging probe for breast cancer in vivo.

The high incidence and mortality of breast cancer supports efforts to develop innovative imaging probes to effectively diagnose, evaluate the extent of the tumor, and predict the efficacy of tumor treatments while concurrently and selectively delivering anticancer agents to the cancer tissue. In the present study we described the preparation of technetium-99m (99mTc)-labeled paclitaxel (PTX) and evaluated its feasibility as a radiotracer for breast tumors (4T1) in BALB/c mice. Thin Layer Chromatography (TLC) was used to determine the radiochemical purity and in vitro stability of 99mTc-PTX. PTX micelles showed a unimodal distribution with mean diameter of 13.46±0.06nm. High radiochemical purity (95.8±0.3%) and in vitro stability (over than 95%), up to 24h, were observed. Blood circulation time of 99mTc-PTX was determined in healthy BALB/c mice. 99mTc-PTX decays in a one-phase manner with a half-life of 464.3 minutes. Scintigraphic images and biodistribution were evaluated at 4, 8 and 24h after administration of 99mTc-PTX in 4T1 tumor-bearing mice. The data showed a significant uptake in the liver, spleen and kidneys, due to the importance of these routes for excretion. Moreover, high tumor uptake was achieved, indicated by high tumor-to-muscle ratios. These findings indicate the usefulness of 99mTc-PTX as a radiotracer to identify 4T1 tumor in animal models. In addition, 99mTc-PTX might be used to follow-up treatment protocols in research, being able to provide information about tumor progression after therapy.

Synthesis and characterization of 3,6-O,O'- dimyristoyl chitosan micelles for oral delivery of paclitaxel.

The aim of the present study was to investigate the potential application of 3,6-O,O'- dimyristoyl chitosan DMCh, an amphiphilic derivative of chitosan, for improving the oral bioavailability of paclitaxel (PTX), a water insoluble anticancer drug. The O-acylation of chitosan with myristoyl chloride was carried out by employing high (≈13.3) or low (2.0) molar excess of chitosan to result in samples DMCh07 and DMCh12, respectively. The successful O-acylation of chitosan was confirmed by FTIR and 1H NMR spectroscopy, the latter allowing also the determination of average degree of substitution (DS). The critical aggregation concentration (CAC) of samples DMCh07 (DS≈6.8%) and DMCh12 (DS≈12.0%) were 8.9×10-3mg/mL and 13.2×103mg/mL, respectively. It was observed by TEM that the DMCh micelles showed spherical shape while DLS measurements allowed the determination of their average size (287nm-490nm) and zeta potential (+32mV to +44mV). Such DMCh micelles were able to encapsulate paclitaxel with high drug encapsulation efficiency (EE), as confirmed by HPLC analyses. Studies on the cytotoxicity of DMCh07 micelles toward Caco-2 and HT29-MTX cells showed that, regardless the PTX loaded, DMCh07 micelles slightly decreased cellular viability at low micelles concentration (≤1µg/mL) while at high concentration (>10µg/mL) PTX-loaded DMCh07 micelles were less toxic toward Caco-2 cells when compared to free PTX. The PTX permeation across Caco-2 monoculture and Caco-2/HT29-MTX co-culture model confirmed the potential of DMCh micelles in improving the intestinal absorption of PTX. These results suggest that DMCh micelles may be a promising carrier to encapsulate PTX aiming cancer therapy.

Pharmacokinetic/pharmacodynamic modeling of etoposide tumor growth inhibitory effect in Walker-256 tumor-bearing rat model using free intratumoral drug concentrations.

The purpose of this study was to establish a population pharmacokinetic/pharmacodynamic (PK/PD) model linking etoposide free tumor and total plasma concentrations to the inhibition of solid tumor growth in rats. Walker-256 tumor cells were inoculated subcutaneously in the right flank of Wistar rats, which were randomly divided in control and two treated groups that received etoposide 5 or 10mg/kg i.v. bolus every day for 8 and 4days, respectively, and tumor volume was monitored daily for 30days. The plasma and intratumoral concentrations-time profiles were obtained from a previous study and were modeled by a four-compartment population pharmacokinetic (popPK) model. PK/PD analysis was conducted using MONOLIX v.4.3.3 on average data and by mean of a nonlinear mixed-effect model. PK/PD data were analyzed using a modification of Simeoni Tumor Growth Inhibition (TGI) model by introduction of an Emax function to take into account the concentration dependency of k2variable parameter (variable potency). The Simeoni TGI-Emax model was capable to fit schedule-dependent antitumor effects using the tumor growth curves from the control and two different administered schedules. The PK/PD model was capable of describing the tumor growth inhibition using total plasma or free tumor concentrations, resulting in higher k2max (maximal potency) for free concentrations (25.8mL·µg-1·day-1 - intratumoral vs. 12.6mL·µg-1·day-1 total plasma). These findings indicate that the plasma concentration may not be a good surrogate for pharmacologically active free tumor concentrations, emphasizing the importance of knowing drug tumor penetration to choose the best antitumor therapy.

Novel Soluplus(®)-TPGS mixed micelles for encapsulation of paclitaxel with enhanced in vitro cytotoxicity on breast and ovarian cancer cell lines.

The aim of this work was to develop mixed micelles based on two biocompatible copolymers of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus(®)) and D-α-tocopheryl polyethylene-glycol 1000 succinate (TPGS), to improve the aqueous solubility and the in vitro anti-tumor activity of paclitaxel (PTX). Pure and mixed nanomicelles were prepared by solvent evaporation method and characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Solubility of PTX was increased 60,000 and 38,000 times, when it was formulated in pure Soluplus(®) micelles and in mixed micelles (Soluplus(®):TPGS; 4:1 ratio), respectively. The in vitro PTX release profile from micellar systems was characterized employing the dialysis membrane method where all drug-loaded formulations showed a sustained and slow release of PTX. In vitro assays were conducted on human cancer cell lines including ovarian cancer cells SKOV-3, breast cancer cells MCF-7 and triple negative breast cancer cells MDA-MB-231. Cytotoxicity studies showed that mixed micelles exhibited better antitumor activity compared to PTX solution against the three cell lines. Furthermore mixed micelles showed a significant increase on PTX cellular uptake in comparison with pure Soluplus(®) micelles and free drug in all cell lines assayed. More important, blank mixed micelles have shown cytotoxic activity due to the ability of TPGS to induce apoptosis in cancer cells. This effect was associated with the expression levels of cleaved-PARP, an apoptosis-related protein. On the basis of these results, the mixed micelles developed in this study might be a potential nano-drug delivery system for cancer chemotherapy.

Use of cholesterol-rich nanoparticles that bind to lipoprotein receptors as a vehicle to paclitaxel in the treatment of breast cancer: pharmacokinetics, tumor uptake and a pilot clinical study.

PURPOSE: In animal experiments paclitaxel oleate associated with a cholesterol-rich nanoemulsion concentrated in the neoplastic tissues and showed reduced toxicity and increased antitumor activity compared with paclitaxel-Cremophor EL. Here, a clinical study was performed in breast cancer patients to evaluate the tumoral uptake, pharmacokinetics and toxicity of paclitaxel associated to nanoemulsions. METHODS: Twenty-four hours before mastectomy [(3)H]-paclitaxel oleate associated with [(14)C]-cholesteryl oleate-nanoemulsion or [(3)H]-paclitaxel in Cremophor EL were injected into five patients for collection of blood samples and fragments of tumor and normal breast tissue. A pilot clinical study of paclitaxel-nanoemulsion administered at 3-week intervals was performed in four breast cancer patients with refractory advanced disease at 175 and 220 mg/m(2) dose levels. RESULTS: T (1/2) of paclitaxel oleate associated to the nanoemulsion was greater than that of paclitaxel (t (1/2) = 15.4 +/- 4.7 and 3.5 +/- 0.80 h). Uptake of the [(14)C]-cholesteryl ester nanoemulsion and [(3)H]-paclitaxel oleate by breast malignant tissue was threefold greater than the normal breast tissue and toxicity was minimal at the two dose levels. CONCLUSIONS: Our results suggest that the paclitaxel-nanoemulsion preparation can be advantageous for use in the treatment of breast cancer because the pharmacokinetic parameters are improved, the drug is concentrated in the neoplastic tissue and the toxicity of paclitaxel is reduced.

Pharmacokinetics and tumor uptake of a derivatized form of paclitaxel associated to a cholesterol-rich nanoemulsion (LDE) in patients with gynecologic cancers.

OBJECTIVE: A cholesterol-rich nanoemulsion termed LDE concentrates in cancer tissues after injection into the bloodstream. The association of a derivatized paclitaxel to LDE showed lower toxicity and increased antitumoral activity as tested in a B16 melanoma murine model. Here, the pharmacokinetics of LDE-paclitaxel oleate and the ability of LDE to concentrate the drug in the tumor were investigated in patients with gynecologic cancers. METHODS: Either LDE-paclitaxel oleate doubly labeled with [(14)C]-cholesteryl oleate and [(3)H]-paclitaxel oleate or [(3)H]-paclitaxel-cremophor was intravenously injected into eight patients. Blood samples were collected over 24 h to determine the plasma decay curves. Fractional clearance rate (FCR) and pharmacokinetic parameters were calculated by compartmental analysis. Also, specimens of tumors and the corresponding normal tissues were excised during the surgery for radioactivity measurement. RESULTS: The LDE and paclitaxel oleate FCR were similar (0.092 +/- 0.039 and 0.069 +/- 0.027 h(-1), respectively, n = 5, P = 0.390). FCR of paclitaxel oleate associated to LDE was smaller than that of paclitaxel-cremophor (0.231 +/- 0.128 h(-1), P = 0.028). Paclitaxel oleate T (1/2 )and AUC were greater than those of paclitaxel-cremophor (T (1/2 )=( )14.51 +/- 3.23 and 6.62 +/- 2.05 h and AUC = 2.49 +/- 0.35 and 1.26 +/- 0.40, respectively, P = 0.009, P = 0.004). The amount of paclitaxel and LDE-radioactive labels in the tumor was 3.5 times greater than in the normal tissues. CONCLUSION: Paclitaxel oleate associated to LDE is stable in the bloodstream and has greater plasma half-life and AUC than those for paclitaxel-cremophor. LDE concentrates 3.5 times more paclitaxel in malignant tissues than in normal tissues. Therefore, association to LDE is an interesting strategy for using paclitaxel to treat gynecologic cancers.

Plasma kinetics and uptake by the tumor of a cholesterol-rich microemulsion (LDE) associated to etoposide oleate in patients with ovarian carcinoma.

OBJECTIVES: Previously, we reported that etoposide oleate associated to a cholesterol-rich microemulsion (LDE) is taken up by malignant cells overexpressing low-density lipoprotein (LDL) receptors. The association is stable, preserves antiproliferative activity of the drug, and reduces toxicity to animals. Here, we determined in patients the plasma kinetics of LDE-etoposide oleate and verified whether the complex concentrates in ovarian carcinomas. METHODS: [(3)H]-etoposide oleate associated to LDE labeled with [(14)C]-cholesteryl oleate was intravenously injected into four ovarian carcinoma patients (50 +/- 8.7 years) 24 h before surgery. Blood samples were collected over a 24-h period to determine the radioactivity plasma decay curves, and the plasma fractional clearance rate (FCR) was calculated by compartmental analysis. Specimens of tumors and normal ovaries excised during the surgery were collected for lipid extraction and radioactive counting. RESULTS: FCRs of LDE label and of the drug were similar (0.0985 and 0.1722, respectively, P = 0.2422). [(14)C]-LDE uptake was 4.9 times and [(3)H]-etoposide oleate uptake was 4.1 times greater in the ovarian tumors than in the contralateral normal ovaries (LDE uptake, in cpm/g = 560 +/- 171 and 146 +/- 59; etoposide oleate uptake = 346 +/- 75 and 103 +/- 56, respectively). CONCLUSIONS: Most of the drug is retained in the microemulsion particles until its removal from the circulation and internalization by the cells. In addition, LDE-etoposide oleate has the ability to concentrate in malignant ovarian tissues. Therefore, the complex may be used to direct and concentrate etoposide oleate in ovarian carcinomas.

Improvement of paclitaxel therapeutic index by derivatization and association to a cholesterol-rich microemulsion: in vitro and in vivo studies.

A cholesterol-rich microemulsion or nanoparticle termed LDE concentrates in cancer tissues after injection into the bloodstream. Here the cytotoxicity, pharmacokinetics, toxicity to animals and therapeutic action of a paclitaxel lipophilic derivative associated to LDE is compared with those of the commercial paclitaxel. Results show that LDE-paclitaxel oleate is stable. The cytostatic activity of the drug in the complex is diminished compared with the commercial paclitaxel due to the cytotoxicity of the vehicle Cremophor EL used in the commercial formulation. Competition experiments in neoplastic cultured cells show that paclitaxel oleate and LDE are internalized together by the LDL receptor pathway. LDE-paclitaxel oleate arrests the G(2)/M phase of cell cycle, similarly to commercial paclitaxel. Tolerability to mice is remarkable, such that the lethal dose (LD(50)) was ninefold greater than that of the commercial formulation (LD(50) = 326 microM and 37 microM, respectively). LDE concentrates paclitaxel oleate in the tumor roughly fourfold relative to the normal adjacent tissues. At equimolar doses, the association of paclitaxel oleate with LDE results in remarkable changes in the drug pharmacokinetic parameters when compared to commercial paclitaxel (t(1/2)=218 min and 184 min, AUC=1,334 microg h/ml and 707 microg h/ml and CL=0.125 ml/min and 0.236 ml/min, respectively). Finally, the therapeutic efficacy of the complex is pronouncedly greater than that of the commercial paclitaxel, as indicated by the reduction in tumor growth, increase in survival rates and % cure of treated mice. In conclusion, LDE-paclitaxel oleate is a stable complex and compared with paclitaxel toxicity is considerably reduced and activity is enhanced, which may lead to improved therapeutic index in clinical use.

Tumor retention and biodistribution studies of etoposide loaded tripalmitin nanoparticles after intratumoral administration in Dalton's Iymphoma tumor bearing mice

The objective of the present work is to study the biodistribution and tumor retention properties of etoposide (anticancer agent) and etoposide loaded tripalmitin nanoparticles (ETPL) after intratumoral administration in Dalton's lymphoma tumor bearing mice. ETPL nanoparticles were prepared by melt-emulsification and high pressure homogenization followed by spray drying technique. The nanoparticles were uniform and possessed 387 nm mean diameter and negative charge with excellent redispersibility in aqueous media. Radiolabeling of etoposide and ETPL nanoparticles with Technetium-99m (99mTc) resulted in complexes with high labeling efficiency and low radiocolloid formation. The labeled complexes showed good in vitro stability as indicated by low transchelation in presence of DTPA and cysteine and stability in human serum. Biodistribution and tumor retention studies were performed for etoposide and ETPL nanoparticles after intratumoral injection in mice bearing Dalton's lymphoma tumor. Etoposide experienced rapid clearance from the tumor, while the disposition of ETPL nanoparticles was slower. The tissue concentrations of ETPL nanoparticles increased with time (i.e. at 6h and 24h post injection) indicating its retention in tumor site for a longer time. Tumor retention of both etoposide and ETPL nanoparticles was studied upto 48h post injection. The tumor concentration of both etoposide and ETPL nanoparticles was high initially (8.57 percent and 41.8 percent injected dose at 0.5h post injection) and decreased with time (0.12 percent and 1.68 percent injected dose at 48h post injection). The concentration of etoposide rapidly declined from the tumor site while the tumor retention of ETPL nanoparticles was significantly higher than free etoposide (P < 0.001) at all the time points studied. The over all many fold higher tumor retention of ETPL nanoparticles (14 folds even at 48h post injection) compared to etoposide, coupled with lower tissue distribution signifies...

Clinical and pharmacokinetic study of fractionated doses of oral etoposide in pediatric patients with advanced malignancies.

BACKGROUND: The purpose of this phase I study was to evaluate the toxicity profile, dose-limiting toxicities (DLT), maximum tolerated dose (MTD), and plasma pharmacokinetics of oral etoposide, and to recommend a safe fractionated dose for phase II trials in pediatric patients with refractory solid tumors. MATERIAL/METHODS: All patients had tumors no longer amenable to established forms of treatment. The initial dose of etoposide was 20 mg/m(2) TID for 14 days every 21 days (dose-level I). Etoposide plasma pharmacokinetics were studied on day 1 of treatment and determined by HPLC. RESULTS: Seventeen children were enrolled, 13 of whom were included in the pharmacokinetic study, for a total of 64 courses. Nine patients were included at dose-level I; grade 2-3 leucopenia was observed in 5. The dose was then raised to 25 mg/m(2) (dose-level II) in another 8 patients; grade 3-4 leucopenia was observed in 4. This dose-level was therefore considered the MTD. The DLT was neutropenia. In patients at dose-level I and II the maximum plasma etoposide concentration was 2.97 and 8.59 mg/ml, respectively. Drug levels > 1 microg/ml were maintained for about 6.3 hours following drug administration at both dose-levels. Partial response was observed in 1 patient and 4 patients showed stable disease. CONCLUSIONS: Prolonged oral etoposide was well tolerated by our patients. Considering the MTD, and the fact that the patients included at dose-level I achieved an adequate (>1 microg/ml) plasma concentration of etoposide for a sufficient time, this dose level was recommended for phase II studies in pediatric malignancies.

Fractionated doses of oral etoposide in the treatment of patients with aids-related kaposi sarcoma: a clinical and pharmacologic study to improve therapeutic index.

The purpose of this study was to examine the antitumor activity, toxic effects, and plasma pharmacokinetics of fractionated doses of oral etoposide aiming at the achievement of prolonged safe and active plasma drug levels in patients with AIDS-related Kaposi sarcoma (KS). This was designed as a phase II trial in which consecutive patients with progressing AIDS-KS after at least 3 months of active antiretroviral therapy received oral etoposide at the dose of 20 mg/m2 every 8 hours daily for 7 days every 21 days, with the study of its plasma pharmacokinetics. Eligible patients were 18 to 60 years old, with a histopathologically confirmed diagnosis of AIDS-related KS, human immunodeficiency virus-positive test, progressing after at least 3 months of active antiretroviral therapy, World Health Organization (WHO) performance status 0 to 3, New York University staging IIA or greater, no active infection except oral candidiasis, normal bone marrow, liver, and renal function, and who signed an informed consent. Objective tumor responses were evaluated after at least one full treatment course according to a modified WHO criteria, and toxicity was evaluated weekly and graded using the National Cancer Institute-Common Toxicity Criteria (NCI-CTC) criteria. For the pharmacokinetic study, plasma was obtained from patients during the first drug administration immediately before and at various time points thereafter. Etoposide was measured after extraction from plasma by a standard high-performance liquid chromatography. Twenty-one patients were accrued for the study, and 18 of them met the eligibility criteria. They were all men, with median age of 36 years old (range: 25-50 years), median WHO performance status 0 (range: 0-3) median CD4+ count (cells/mm3) 67 (range: 8-443), prior AIDS diagnosis in 10 of 18 cases, NYU staging IIA (1 patient), IIB (1), IIIA (7), IIIB (1), IVA (4), and IVB (4) sites of disease: mucocutaneous only (5), mucocutaneous/lymph nodes (5), mucocutaneous/lung (5) and mucocutaneous/lymph nodes/lung (2); and prior cytotoxic treatment in two patients. Seventy-two percent of cases presented some form of toxic effect (NCI-CTC). Leukopenia was documented in 50% of cases, anemia occurred in 61%, whereas thrombocytopenia was documented in 17% of the patients. The main nonhematologic toxicities were nausea and vomiting in 17% of cases and alopecia in 44%. The overall objective response rate was 83%, with 2 complete remissions documented (11%). The median duration of responses was 12 weeks (range: 3-45 weeks). The median t1/2 of etoposide in plasma was 4.11 hours (range: 1.95-9.64), area under the curve was 13.51 microg/h/ml (range: 7.12-24.42), Cmax was 2.17 microg/ml (1.40-4.41), tmax (1.00-2.00), mean residence time 4.62 hours (range: 3.75-5.20 hours), CIt (total clearance) 3.13 l/m2/h (range: 1.49-5.20 l/m2/h), Vd 13.08 l/m2 (range: 6.23-19.65 l/m2), and the median etoposide plasma concentration time greater than 1 microg/ml was 3.69 hours (range: 1.00-6.80 hours). The use of fractionated oral daily doses of etoposide produced significant antitumor activity with manageable clinical toxicity in the individuals with AIDS-KS included in this trial. This more favorable therapeutic index of etoposide could be due to the achievement of more sustained plasma levels of the drug within safe but active concentrations.

Modulator activity of PSC 833 and cyclosporin-A in vincristine and doxorubicin-selected multidrug resistant murine leukemic cells.

Multidrug resistance (MDR) lines from a murine T-cell leukemia were selected in increasing vincristine (VCR) or doxorubicin (DOX) concentrations. Daunorubicin (DNR) efflux was evidenced after 25 additional passages with constant 160 ng ml(-1) of either VCR or DOX, an effect that was inhibited by verapamil, cyclosporin-A (CsA) and PSC 833. The expression of Pgp was not evidenced in the resistant cell lines using anti-human Pgp antibodies. Cell proliferation assay showed that cell lines resistant to VCR (LBR-V160) or DOX (LBR-D160) required higher doses of either drug to produce GI50 compared with control cell line obtained after culture in the absence of VCR or DOX. When resistant cell lines were maintained during 60 days in the absence of either VCR or DOX, MDR phenotype reversal was obtained in LBR-D160 while LBR-V160 remained resistant to the drug, as shown by cell proliferation assays and by drug efflux pump functionality. When VCR or DOX were used together with either CsA or PSC 833, the latter was more effective to produce reversal of resistance than the former, whereas CsA presented greater cytotoxic effect than PSC 833 for sensitive and resistant cells. Cross-resistance was found between VCR, DOX and other antineoplasic agents on murine leukemic cell line. VCR was more effective to induce MDR since the resistant cell lines were more stable to the MDR phenotype.

Bioavailability of etoposide after oral administration of the solution marketed for intravenous use: therapeutic and pharmacoeconomic perspectives.

BACKGROUND: Oral etoposide administration is a suitable alternative to the intravenous route; therefore, commercial capsules have been developed. Before these capsules were available in Mexico, we studied drug bioavailability after oral administration of the intravenous etoposide solution (IVES). METHODS: Eight adult cancer patients received a 50-mg oral etoposide dose as IVES and blood samples were collected over a period of 24 h. Plasma etoposide concentration was determined by high-performance liquid chromatography, plasma concentration against time curves were constructed, and bioavailability parameters were calculated. RESULTS: Oral IVES yielded an adequate bioavailability profile because Cmax was 2.38 +/- 0.30 micrograms/mL, AUC was 12.87 +/- 2.02 micrograms/mL and half-life was 6.72 +/- 0.97 h. CONCLUSIONS: Considering that the pharmacokinetic aim is to maintain plasma concentrations between 0.5 and 1.0 microgram/mL for several hours while avoiding high concentrations, i.e., of 10 micrograms/mL or higher, oral administration of 50-mg etoposide as IVES appears to be a suitable dosing option. In addition, oral IVES is considerably less expensive than intravenous administration in terms of both drug presentation and administration.