Cytoprotection of human endothelial cells from oxidant stress with CDDO derivatives: network analysis of genes responsible for cytoprotection.

AIM: To identify drugs that may reduce the impact of oxidant stress on cell viability. METHODS: Human umbilical vein endothelial cells were treated with 200 nmol/l CDDO-Im (imidazole) and CDDO-Me (methyl) after exposure to menadione and compared to vehicle-treated cells. Cell viability and cytotoxicity were assessed, and gene expression profiling was performed. RESULTS: CDDO-Im was significantly more cytoprotective and less cytotoxic (p < 0.001) than CDDO-Me. Although both provided cytoprotection by induction of gene transcription, CDDO-Im induced more genes. In addition to a higher induction of the key cytoprotective gene heme oxygenase-1 (38.9-fold increase for CDDO-Im and 26.5-fold increase for CDDO-Me), CDDO-Im also induced greater expression of heat shock proteins (5.5-fold increase compared to 2.8-fold for CDDO-Me). CONCLUSIONS: Both compounds showed good induction of heme oxygenase, which largely accounted for their cytoprotective effect. Differences were detected in cytotoxicity at higher doses, indicating that CDDO-Me was more cytotoxic than CDDO-Im. Significant differences were detected in the ability of CDDO-Im and CDDO-Me to affect differential gene transcription. CDDO-Im induced more genes than did CDDO-Me. The source of the differences in gene expression patterns between CDDO-Im and CDDO-Me was not determined but may be important in long-term use of this class of drugs.

Development and validation of an LCMS method to determine the pharmacokinetic profiles of caffeic acid phenethyl amide and caffeic acid phenethyl ester in male Sprague-Dawley rats.

A validated LCMS method was developed for the quantitative determination of caffeic acid phenethyl amide (CAPA) and caffeic acid phenethyl ester (CAPE) from rat plasma. Separation was achieved using a reverse-phase C12 HPLC column (150 × 2.00 mm, 4 µm) with gradient elution running water (A) and acetonitrile (B). Mass spectrometry was performed with electrospray ionization in negative mode. This method was used to determine the pharmacokinetic profiles of CAPA and CAPE in male Sprague-Dawley rats following intravenous bolus administration of 5, 10 and 20 mg/kg of CAPA and 20 mg/kg of CAPE. The pharmacokinetic analysis suggests the lack of dose proportionality in the dose range of 5-20 mg/kg of CAPA. Total clearance values for CAPA ranged from 45 to 156 mL/min and decreased with increasing dose of CAPA. The volume of distribution for CAPA ranged from 17,750 to 52,420 mL, decreasing with increasing dose. The elimination half-life for CAPA ranged from 243.1 to 295.8 min and no statistically significant differences were observed between dose groups in the range of 5-20 mg/kg (p > 0.05). The elimination half-life for CAPE was found to be 92.26 min.

Stability of caffeic acid phenethyl amide (CAPA) in rat plasma.

A validated C18 reverse-phase HPLC method with UV detection at 320 nm was developed and used for the stability evaluation of caffeic acid phenethyl amide (CAPA) and caffeic acid phenethyl ester (CAPE) in rat plasma. CAPA is the amide derivative of CAPE, a naturally occurring polyphenolic compound that has been found to be active in a variety of biological pathways. CAPA has been shown to protect endothelial cells against hydrogen peroxide-induced oxidative stress to a similar degree to CAPE. CAPE has been reported to be rapidly hydrolyzed in rat plasma via esterase enzymes. CAPA is expected to display a longer half-life than CAPE by avoiding hydrolysis via plasma esterases. The stability of CAPA and CAPE in rat plasma was investigated at three temperatures. The half-lives for CAPA were found to be 41.5, 10 and 0.82 h at 25, 37 and 60 °C, respectively. The half-lives for CAPE were found to be 1.95, 0.35 and 0.13 h at 4, 25 and 37 °C, respectively. The energy of activation was found to be 22.1 kcal/mol for CAPA and 14.1 kcal/mol for CAPE. A more stable compound could potentially extend the beneficial effects of CAPE.

Micro-fabricated perforated polymer devices for long-term drug delivery.

Fabrication techniques have been developed to produce a perforated polymer microtube as a drug delivery device. The technique consists of first forming a silicon platform with trenches and alignment marks to hold the tubes for subsequent processing. Photolithography and reactive ion etching with an inductively coupled plasma source were used to fabricate micro holes on the surface of polyimide tubes. Several materials have been used to form the etching mask, including titanium film deposited by e-beam evaporation and SiO(2) and SiN(x) films deposited by high-density plasma chemical vapor deposition (HDPCVD). Three equidistant holes of 20 µm in diameter were fabricated on polyimide tubes (I.D. = 125 µm). The perforated tubes were loaded with ethinyl estradiol and tested for drug release in phosphate buffered saline (pH = 7.1) at 37°C. Zero order release was observed over a period of 30 days with a potential to be extended to 4 years.

Critical research gaps in electronic cigarette devices and nicotine aerosols.

Electronic cigarettes (e-cigs) are devices that aerosolize nicotine-containing liquids for delivery as an inhaled vapor. E-cigs are currently marketed as smoking cessation devices, though the emergence and rapid adoption of these devices in recent years has sparked a great deal of concern over their safety. Given the plethora of devices and nicotine solutions available on the market and the lack of regulation and quality control, it is imperative that these devices and nicotine formulations are studied to assess critical operating parameters, the pharmacokinetic profiles of the inhaled nicotine, and the toxicity profiles of the e-cig aerosols. This review aims to deliver an overview of current research regarding electronic cigarette devices, nicotine-containing liquid formulations, pharmacokinetics of nicotine, and toxicology studies in order to highlight areas lacking in research or requiring greater standardization and regulation.

Development and characterization of a scalable microperforated device capable of long-term zero order drug release.

A drug delivery system that consists of microperforated polyimide microtubes was developed and characterized. Two groups of polyimide tubes were used. One set consisted of microtubes (I.D. = 125 microm) with 32.9 +/- 1.7 microm size holes. The second set consisted of larger tubes (I.D. = 1000 microm) with 362-542 microm holes. The number of holes was varied between 1 and 3. The small tubes were loaded with crystal violet (CV) and ethinyl estradiol (EE) and the drug release studies were performed in 0.01 M phosphate buffered saline (PBS) (pH 7.1-7.4) at 37.0 +/- 1.0 degrees C for upto 4 weeks. The large tubes were loaded with CV and the drug release was studied in vitro in PBS and also ex vivo in rabbit's vitreous humor. Linear release rates with R(2) > 0.9900 were obtained for all groups with CV and EE. Release rates of 7.8 +/- 2.5, 16.2 +/- 5.5, and 22.5 +/- 6.0 ng/day for CV and 30.1 +/- 5.8 ng/day for EE were obtained for small tubes. For large tubes, a release rate of 10.8 +/- 4.1, 15.8 +/- 4.8 and 22.1 +/- 6.7 microg/day was observed in vitro in PBS and a release rate of 5.8 +/- 1.8 microg/day was observed ex vivo in vitreous humor.

Synthesis of a series of caffeic acid phenethyl amide (CAPA) fluorinated derivatives: comparison of cytoprotective effects to caffeic acid phenethyl ester (CAPE).

A series of catechol ring-fluorinated derivatives of caffeic acid phenethyl amide (CAPA) were synthesized and screened for cytoprotective activity against H2O2 induced oxidative stress in human umbilical vein endothelial cells (HUVEC). CAPA and three fluorinated analogs were found to be significantly cytoprotective when compared to control, with no significant difference in cytoprotection between caffeic acid phenethyl ester (CAPE) and CAPA.

Pharmacokinetics of caffeic acid phenethyl ester and its catechol-ring fluorinated derivative following intravenous administration to rats.

The pharmacokinetic profiles of caffeic acid phenethyl ester (CAPE) and its catechol-ring fluorinated derivative (FCAPE) were determined in rats after intravenous administration of 5, 10 or 20 mg/kg for CAPE and 20 mg/kg for FCAPE, respectively. The plasma concentrations of CAPE and FCAPE were measured using a validated liquid chromatography tandem mass spectrometric method. The pharmacokinetic parameters were estimated using non compartmental analysis (NCA) and biexponential fit. The results showed that the area under the plasma concentration-time curve for CAPE treatment increased in a proportion greater than the increase in dose from 5 to 20 mg/kg of CAPE. Total body clearance values for CAPE ranged from 42.1 to 172 ml/min/kg (NCA) and decreased with the increasing dose of CAPE. Similarly, the volume of distribution values for CAPE ranged from 1555 to 5209 ml/kg, decreasing with increasing dose. The elimination half-life for CAPE ranged from 21.2 to 26.7 min and was independent of dose. That FCAPE was distributed extensively into rat tissues and eliminated rapidly was indicated by a high value of volume of distribution and similar short elimination half-life as that of CAPE.

Reuse of cDNA microarrays hybridized with cRNA by stripping with RNase H.

DNA microarrays are powerful tools for global analysis of gene transcript expression. However, their high cost and the need for replication have limited their use. Here, we report a new stripping technique applicable to microarrays hybridized with cRNA with RNase H that is reproducible, leaving the DNA oligonucleotide probes intact and available for adding two additional uses. A Pearson correlation was used to assess the agreement between the first-round hybridization and the second- and third-round hybridizations. Significant correlations (R2, 0.9893 and 0.975; P < 0.001) were observed among virgin arrays and stripped arrays hybridized with the same sample. Additionally, statistical class comparison analysis globally indicated that there were essentially no differences detected following three hybridizations. Dye-swapped microarrays produced similar results. However, arrays stripped with RNase H exhibited decreased efficiency of hybridization signal with increasing use. In the present study, the oligonucleotide microarrays can be used three times.

Cytoprotection of human endothelial cells from menadione cytotoxicity by caffeic acid phenethyl ester: the role of heme oxygenase-1.

Caffeic acid phenethyl ester (CAPE), derived from various plant sources, has been shown to ameliorate ischemia/reperfusion injury in vivo, and this has been attributed to its ability to reduce oxidative stress. Here we investigated the cytoprotection of CAPE against menadione-induced oxidative stress in human umbilical vein endothelial cells (HUVEC) to evaluate potential gene expression involvement. CAPE exhibited dose-dependent cytoprotection of HUVEC. A gene screen with microarrays was performed to identify the potential cytoprotective gene(s) induced by CAPE. Heme oxygenase-1 (HO-1) was highly upregulated by CAPE and this was confirmed with reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting. Inhibition of HO-1 activity using the HO-1 inhibitor tin protoporphyrin IX (SnPPIX), resulted in loss of cytoprotection. Carbon monoxide, one of HO-1 catabolic products appeared to play a small role in CAPE protection. Caffeic acid, a potential metabolite of CAPE with similar free radical scavenging ability, however, didn't show any cytoprotective effect nor induce HO-1. These findings suggest an important role of HO-1 induction in CAPE cytoprotection against oxidant stress, which may not relate to CAPE structural antioxidant activity nor to its traditional enzymatic activity in decomposing heme but to a yet to be determined activity.

Quantitative determination of fluorinated caffeic acid phenethyl ester derivative from rat blood plasma by liquid chromatography-electrospray ionization tandem mass spectrometry.

The quantitative determination of caffeic acid phenethyl ester (CAPE) and its fluorinated derivative (FCAPE) from rat plasma using ultra-performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) is reported. CAPE and FCAPE were extracted using ethyl acetate in the presence of methyl caffeate (MC) as internal standard. Separation was achieved using a C(18) column (2.1 mm x 50 mm, 1.7 microm) and gradient elution with water and acetonitrile containing 0.2% and 0.1% formic acid, respectively. A non-linear response over a broad concentration range (1-1000 ng/ml, r(2)>0.995 using a quadratic regression model and 1/concentration weighting) was obtained. The inter-day and intra-day variability for CAPE and FCAPE were found to be less than 14.2% and 9.5%, respectively. Data are presented to illustrate the practicality of the method for the pharmacokinetic evaluation of CAPE and FCAPE after intravenous administration to rats.

Time Course Expression Analysis of 1[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole Induction of Cytoprotection in Human Endothelial Cells.

1[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), a synthetic derivative of oleanolic acid that exhibits antioxidant and anti-inflammatory activity in several animal and in vitro models, has been shown to be beneficial if given after injury. Although induction of heme oxygenase 1 appears to be a major effector of cytoprotection, the mechanism by which the overall effect is mediated is largely unknown. This study evaluated temporal gene expression profiles to better characterize the early transcriptional events and their relationship to the dynamics of the cytoprotective response in human umbilical vein endothelial cells (HUVEC) to CDDO-Im. Time-course gene expression profiling was performed on HUVEC treated with CDDO-Im for 0.5, 1, 3, 6, and 24 hours. More than 10 000 genes were statistically altered in their expression in at least 1 time point across the time course. Large alterations in immediate-early gene expression were readily detectable within 0.5 hour after administration of CDDO-Im.

Effects of citicholine and dimethylsulfoxide on transepithelial transport of passively diffused drugs in the Caco-2 cell culture model.

The objective of this study was to determine, using a Caco-2 cell monolayer model, the extent to which the paracellular and transcellular routes are altered by citicholine (CDP-Ch) and DMSO in the presence of human serum albumin (HSA). The apparent permeability (Papp) of mannitol in the presence of 4% (w/v) HSA was investigated using 0, 0.5, 1.0, 2.5, 5.0, and 10.0% (v/v)) of DMSO. The Papp for mannitol ranged from 0.56 x 10(-6) to 0.89 x 10(-6) cm/s (mean 0.77 x 10(-6)). Increasing the concentration of DMSO does not appear to have an effect on the paracellular transport of mannitol and on the transepithelial resistance (TEER) of the monolayer, (P>0.05). The effect of citicholine (CDP-Ch) was investigated in confluent Caco-2 cell monolayers incubated in the presence of 2, 4, 10, 40, 60, 100 and 200 mM CDP-Ch at 37 degrees C in an atmosphere of 7% CO(2) and 95% relative humidity. Papp of mannitol and diltiazem in the presence of CDP-Ch ranged from 0.53 x 10(-6) to 8.52 x 10(-6) cm/s and from 1.30 x 10(-5) to 2.71 x 10(-5) cm/s, respectively. CDP-Ch may have an effect on the stability of the tight junction complex resulting in an increase in the apparent permeability of mannitol.

Evaluation of a perforated drug delivery system in mice for prolonged and constant release of a hydrophilic drug.

A drug delivery system (DDS) consisting of a perforated microtube (polyimide, inside diameter = 1.8 mm, tube length = 20 mm, hole size = 0.15 mm) was characterized in vitro and in vivo for its usefulness for long-term release of hydrophilic drugs at a constant rate. Sodium fluorescein mixed with stearic acid was used as the model drug. The DDS was packed with sodium fluorescein and stearic acid in ratios of 50:50, 40:60, and 25:75, respectively, and in vitro drug release studies were performed in saline. Linear release rates with R (2) > 0.9700 were obtained for all groups. Release rates of 1,077.3 ± 264.6, 342.6 ± 146.4, and 14.4 ± 7.0 µg/day for sodium fluorescein were obtained from the three groups, respectively. After monitoring the in vitro release of fluorescein for 11 days, 7 tubes from the 40:60 group were implanted subcutaneously in each individual mice to study the in vivo release of fluorescein from the tubes by measuring the fluorescein in the urine for 84 days. An initial rapid release during the first 4 days was followed by a near zero order fluorescence from the tubes (R (2) = 0.9870). Following completion of the study, the DDSs were retrieved for histology. Morphological analysis indicated no clinical adverse reaction at the site of device implantation specific to the device. The DDS was found to be biocompatible and capable of long-term constant release of a hydrophilic drug such as sodium fluorescein.

Biowaiver monographs for immediate-release solid oral dosage forms: stavudine.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate-release (IR) solid oral dosage forms containing stavudine (d4T) are reviewed. According to Biopharmaceutics Classification System (BCS), d4T can be assigned to BCS class I. No problems with BE of IR d4T formulations containing different excipients and produced by different manufacturing methods have been reported and, hence, the risk of bioinequivalence caused by these factors appears to be low. Furthermore, d4T has a wide therapeutic index. It is concluded that a biowaiver is appropriate for IR solid oral dosage forms containing d4T as the single active pharmaceutical ingredient (API) provided that (a) the test product contains only excipients present in the IR d4T drug products that have been approved in a number of countries for the same dosage form, and (b) both test product and its comparator are either "very rapidly dissolving" or "rapidly dissolving" with similarity of dissolution profiles demonstrated at pH 1.2, 4.5, and 6.8.

Biowaiver monographs for immediate release solid oral dosage forms: metronidazole.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing metronidazole are reviewed. Metronidazole can be assigned to Biopharmaceutics Classification System Class I. Most BE studies that were identified reported the investigated formulations to be bioequivalent, indicating the risk of bioinequivalence to be low. Formulations showing differences in bioavailability showed dissimilarities in in vitro dissolution profiles. Furthermore, metronidazole has a wide therapeutic index. It is concluded that a biowaiver for solid IR formulations is justified, provided: (a) the test product and its comparator are both rapidly dissolving; (b) meet similarity of the dissolution profiles at pH 1.2, 4.5, and 6.8; (c) the test product contains only excipients present in IR drug products approved in International Conference on Harmonisation (ICH) or associated countries in the same dosage form; and (d) if the test product contains sorbitol, sodium laurilsulfate, or propylene glycol, the test product needs to be qualitatively and quantitatively identical to its comparator with respect to these excipients [corrected]..

Biowaiver monographs for immediate release solid oral dosage forms: levofloxacin.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing levofloxacin as the only active pharmaceutical ingredient (API) are reviewed. According to the current Biopharmaceutics Classification System, levofloxacin can be assigned to Class I. No problems with BE of IR levofloxacin formulations containing different excipients and produced by different manufacturing methods have been reported and hence the risk of bioinequivalence caused by these factors appears to be low. In addition, levofloxacin has a wide therapeutic index. On the basis of this evidence, a biowaiver is recommended for IR solid oral dosage forms containing levofloxacin as the single API provided that (a) the test product contains only excipients present in IR levofloxacin drug products that have been approved in International Conference on Harmonization (ICH) or associated countries and which have the same dosage form; (b) both the test and comparator dosage form are "very rapidly dissolving" or "rapidly dissolving" with similarity of the dissolution profiles demonstrated at pH 1.2, 4.5, and 6.8; and (c) if the test product contains polysorbates, it should be both qualitatively and quantitatively identical to its comparator in terms of polysorbate content.

Structure-activity relationships in the cytoprotective effect of caffeic acid phenethyl ester (CAPE) and fluorinated derivatives: effects on heme oxygenase-1 induction and antioxidant activities.

To determine the relationship between catechol ring modifications and the activity of caffeic acid phenethyl ester (CAPE) as a cytoprotective agent, six catechol ring-fluorinated CAPE derivatives were evaluated for their cytoprotective abilities, as well as for their antioxidant and heme oxygenase-1 (HO-1) inducing capacity in a human umbilical vein endothelial cell (HUVEC) model of oxidant stress. To ascertain the involvement of HO-1 induction in the cytoprotective effects of CAPE analogues, their ability to induce HO-1 at 20microM was determined by reverse transcriptase polymerase chain reaction, western blotting and the use of HO-1 inhibitor tin protoporphyrin IX. There was significant induction of HO-1 by CAPE derivatives. Inhibition of HO-1 enzymatic activity resulted in reduced cytoprotection. Modification of the catechol ring of CAPE by introduction of fluorine at various positions resulted in dramatic changes in cytoprotective activity. The maintenance of at least one hydroxyl group on the CAPE catechol ring and the phenethyl ester portion was required for HO-1 induction. CAPE and its derivatives were screened for their ability to scavenge intracellular reactive oxygen species generated in HUVECs by measuring 5-(and-6)-chlormethyl-2', 7'-dichlorodihydrofluorescein diacetate oxidation. The maintenance of 3, 4-dihydroxyl groups on the catechol ring was required for antioxidant activity, but antioxidant activity did not guarantee cytoprotection. Methylation or replacement of one hydroxyl group on the catechol ring of CAPE, however, provided both pro-oxidant and cytoprotective activities. These results indicate that the induction of HO-1 plays a more important role in the cytoprotective activity of CAPE derivatives than their direct antioxidant activity.

Challenges and opportunities in establishing scientific and regulatory standards for assuring therapeutic equivalence of modified-release products: workshop summary report.

Modified-release products are complex dosage forms designed to release drug in a controlled manner to achieve desired efficacy and safety. Inappropriate control of drug release from such products may result in reduced efficacy or increased toxicity. This workshop provided an opportunity for pharmaceutical scientists from academia, industry and regulatory agencies to discuss current regulatory expectations and industry practices for demonstrating pharmaceutical equivalence and bioequivalence of MR products, further facilitating the establishment of regulatory standards for ensuring therapeutic equivalence of these products.

Challenges and opportunities in establishing scientific and regulatory standards for assuring therapeutic equivalence of modified release products: workshop summary report.

Modified release products are complex dosage forms designed to release drug in a controlled manner to achieve desired efficacy and safety. Inappropriate control of drug release from such products may result in reduced efficacy or increased toxicity. This workshop provided an opportunity for pharmaceutical scientists from academia, industry, and regulatory agencies to discuss current industry practices and regulatory expectations for demonstrating pharmaceutical equivalence and bioequivalence of MR products, further facilitating the establishment of regulatory standards for ensuring therapeutic equivalence of these products.