Transdermal iontophoretic delivery of enoxacin from various liposome-encapsulated formulations

The major purpose of this work was to study the effect of various liposome formulations on the iontophoretic transport of enoxacin through excised rat skin. The electrochemical stability of these liposomes was also evaluated. The encapsulation percentage of enoxacin was significantly enhanced after 6 h incubation in an electric field; whereas the fusion of liposomes was inhibited by application of electric current. The results of iontophoretic drug transport showed that the permeability of enoxacin released from liposomes was higher compared with that of free drug. The iontophoretic permeability of enoxacin released from liposomes increased with a decrease in the fatty acid chain length of the phospholipid, which may be due to the different phase transition temperatures of the phospholipids. Incorporation of charged phospholipid resulted in an alteration of the transdermal behavior of enoxacin: the iontophoretic permeation as well as the amount of enoxacin partitioned in skin was greatly reduced after incorporation of stearylamine in liposomes, which can be attributed to the competitive ion effect. The enoxacin released from stratum corneum-based liposomes showed the highest amount of enoxacin partitioned into skin depot. The results of employing cathodal iontophoresis on negative charged liposomes suggested that the liposomal vesicles or phospholipids may carry enoxacin into deeper skin strata via the follicular route.

In vitro study of transdermal nicotine delivery: influence of rate-controlling membranes and adhesives

The objective of this study was to evaluate the influence of a rate-controlling membrane and adhesive on the in vitro permeation of nicotine. The physicochemical properties of the adhesive, including adhesion and rheology (viscosity), were also detected. Higher permeability of nicotine was observed through a hydrophilic membrane than through a hydrophobic membrane. Natural rubber and silicone were used as the adhesive bases, respectively. The silicone adhesive showed the highest adhesion among all adhesive formulations. To increase the adhesion of natural rubber, a tackifier (polyisoprene) and a secondary tackifier (terpene polymer; Px 1150) were incorporated into the formulations to achieve acceptable adhesion. The nicotine permeation through silicone adhesive and three natural rubber adhesives with the secondary tackifier (2%, 4%, and 6% Px 1150) was close to that from a commercially available patch (Habitrol), although the loading amount of nicotine was not the same. A longer lag time during the in vitro permeation study of nicotine was required for the adhesives prepared in our laboratory than for the commercially available patch.

Cyclic monoterpene extract from cardamom oil as a skin permeation enhancer for indomethacin: in vitro and in vivo studies

The in vitro and in vivo effect of pretreatment by cardamom oil, a crude drug extract, in ethanol/water vehicles on the transdermal delivery of indomethacin was investigated. The cyclic monoterpene components in cardamom oil were also determined and quantified in this study. The permeation of indomethacin was significantly enhanced after pretreatment of cardamom oil both in the in vitro and in vivo studies. The result of various pre-treatment periods showed that the indomethacin flux decreased as the length of the pretreatment increased. Both natural cardamom oil and a cyclic monoterpene mixture composed of the components of the oil showed similar enhancement on indomethacin permeation, indicating cyclic monoterpenes are the predominant components altering the barrier property of stratum corneum. The results also showed that three minor components in cardamom oil (alpha-pinene, 6.5%; beta-pinene, 4.8%; alpha-terpineol, 0.4%) had a synergistic effect with 1,8-cineole (59.3%) and d-limonene (29.0%) to enhance the permeation of indomethacin.

Evaluation of transdermal iontophoresis of enoxacin from polymer formulations: in vitro skin permeation and in vivo microdialysis using Wistar rat as an animal model

Polymers were used in vehicles to form hydrogel matrices in this study to evaluate the in vitro permeation and in vivo microdialysis of enoxacin. The highest transdermal delivery determined by area under flux-time curve (AUC) and intracutaneous enoxacin concentration were observed in methylcellulose (MC) and polyvinylpyrrolidone (PVP) hydrogels, respectively. To avoid the pH shift in vehicles during iontophoresis, buffer species were added to formulations to increase the buffer capacity. As expected, the permeability of enoxacin of anodal iontophoresis was larger than that of cathodal iontophoresis. Combination of benzalkonium chloride, a cationic surfactant as an enhancer, and iontophoresis exerted an enhancing effect for anionic enoxacin at pH 10.0. However, no effect or a negative effect was detected for cationic enoxacin in deionized water or pH 5.0 buffer, due to the shielding of the negative charge in the skin. The skin residue of enoxacin was slightly increased after the incorporation of Azone in PVP hydrogel. The result of in vivo microdialysis was in accordance with that of in vitro study. The effect of Azone on the intracutaneous enoxacin was more significant for in vivo microdialysis than in the in vitro study indicating the clinical feasibility of Azone for iontophoretic delivery. Microdialysis can be considered as a useful technique to investigate the pharmacokinetics of transdermal iontophoresis in vivo.

Chitosan hydrogel as a base for transdermal delivery of berberine and its evaluation in rat skin

Berberine is the main ingredient of Coptis spp. This study selected berberine as a model drug to design a transdermal delivery system for the treatment of cutaneous leishmaniasis. Berberine was incorporated into chitosan hydrogel to prepare ointments. The physicochemical properties of the ointments and the release profile of berberine were investigated. The results indicated that the viscosity of chitosan hydrogel increased with an increasing amount of lactic acid or EDTA. The effect of EDTA on the viscosity was greater than that of lactic acid. By differential scanning calorimetry (DSC) measurement, no interaction was found to occur between chitosan and the soluble berberine. The release rate of berberine was inversely proportional to ointment viscosity. In in vitro skin perfusion studies, only trace amounts of berberine permeated through the rat skin due to its low oil-water partition coefficient. Surfactants were used as penetration enhancers to increase the percutaneous absorption of berberine. Among the enhancers, benzalkonium chloride was found to be the most efficient. Additionally, Tween 80 could increase the loading amount of berberine in the skin.

Transdermal iontophoretic delivery of diclofenac sodium from various polymer formulations: in vitro and in vivo studies

The objective of this study was to evaluate the in vitro and in vivo transdermal iontophoresis of various diclofenac sodium polymer formulations. The excised rat skin, human skin as well as cellulose membrane were used to examine the in vitro drug permeation whereas the microdialysis technique was used to monitor the drug concentration in vivo. Polymer solutions based on polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) binary system showed higher drug permeability than that of single polymer vehicle. The effect of formulations on drug permeation through cellulose membrane was quite different from those through rat skin and human skin, which can be explained by the different permeation pathways between them. It appeared to be a membrane-controlled mechanism but not the vehicle matrix-controlled mechanism for diclofenac hydrogels when using skin as the diffusion barrier. The recovery of diclofenac sodium in the in vivo microdialysis was approximately 80-90%, indicating this technique can be used in the intradermal drug monitoring. For all the polymer formulations tested, there was a good relationship between the in vitro and in vivo drug permeation. A synergistic effect on drug permeation was observed when transdermal iontophoresis combined with the pretreatment of cardamom oil as a permeation enhancer.

Mucoadhesive buccal disks for novel nalbuphine prodrug controlled delivery: effect of formulation variables on drug release and mucoadhesive performance

The objective of this work was to assess the effects of drug solubility and loading percent, as well as Carbopol 934/hydroxypropylcellulose (CP/HPC) ratio, on drug release and mucoadhesive performance of the nalbuphine prodrug loaded buccal disks. Drug release rates for the disks were found to be a function of drug solubility, with higher drug release rates for disks loaded with more hydrophilic prodrugs and an increased amount of beta-cyclodextrin. The drug release rates increased with loading percents for nalbuphine hydrochloride, whereas an opposite drug release trend was observed for disks loaded with nalbuphine enanthate, which can be explained by the diffusional drug release mechanism. The CP/HPC ratio affected release rates of nalbuphine enanthate, whereas the ratio had no impact on the release of nalbuphine hydrochloride. Within the 2 days of experiment time, all formulations attached well to the porcine buccal tissues, indicating those formulation variables had no influence on the mucoadhesive performance of CP/HPC-based buccal disks.

Evaluation of topical application of clobetasol 17-propionate from various cream bases

The effect of clobetasol 17-propionate (CP), a potent corticosteroid, in various cream bases on the permeation through artificial membrane was sought. Four formulations were then chosen for a further in vivo skin blanching assay. After calculation of the relationship between in vivo flux0-8 hr determined from a surface recovery technique and in vitro release rate0-8 hr of CP from various formulations, a high correlation coefficient of 0.9996 was achieved. Therefore, the in vitro release study could be used as an index to predict and evaluate the in vivo penetration capacity of CP cream to screen the effective formulation preclinically. After a series of in vivo investigations in this study, it was concluded that myristic acid-added formulations may show a bioequivalence with commercial Dermovate. Furthermore, the flux calculated from the surface recovery technique and delta E detected from the skin blanching assay may be useful as parameters evaluating the quality and effectiveness of CP cream.

Effect of trans-retinoic acid and folic acid on apoptosis in human gastric cancer cell lines MKN-45 and MKN-28

Induction of apoptosis has been implicated as an anticarcinogenic mechanism of both folic acid and retinoic acid. The ability of retinoic acid or folic acid to induce gastric cancer cell apoptosis was investigated in the human gastric cancer cell lines MKN-45 and MKN-28, and DNA fragmentation was studied in situ by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and DNA agarose gel electrophoresis. The rates of apoptosis in both the poorly differentiated MKN-45 and the well differentiated MKN-28 cell line were less than 5% after treatment with either retinoic or folic acid. Apoptosis may be induced by the administration of retinoic acid or folic acid, and the apoptosis indices of MKN-45 and MKN-28 cells were related to the doses of these drugs. The induction of gastric cancer cell apoptosis may play a role in the anticarcinogenic effect of retinoic acid and folic acid, both of which are potential agents for the treatment of human gastric cancer.

Transdermal delivery of sodium nonivamide propionate by iontophoresis

The aim of this study was to investigate the transdermal iontophoresis of a newly designed capsaicin derivative, sodium nonivamide propionate (SNP). The iontophoretic permeation of SNP from various pH buffers increased following the decrease of pH values. This trend was consistent with that of sodium nonivamide acetate (SNA) which is another synthetic analogue of capsaicin. However, the iontophoretic permeability of SNP was much lower than that of SNA. SNP was also delivered iontophoretically from hydrogel formulations. It is suggested that ionizable polymers should be avoided for iontophoretic delivery to maintain good penetration capacity of drugs. Both nonionic cellulose polymers of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) showed higher iontophoretic flux for SNP than the others did. Furthermore, the flux of SNP leveled off with an increase in the amount of polymers in hydrogel, indicating that the viscosity of vehicles plays an important role in the permeation of SNP. Comparing the various iontophoretic application modes, the discontinuous on/off cyclic mode showed higher penetration capacity than did the continuous mode although they possessed the same electrical energy. Moreover, the desorption time of SNP from skin was approximately 20 min which was longer than that of SNA.

Development and evaluation on transdermal delivery of enoxacin via chemical enhancers and physical iontophoresis

Iontophoresis and enhancers were performed to enhance percutaneous absorption of enoxacin so as to compare the enhancement between these two enhancing methods. The cationic surfactant of benzalkonium chloride showed the highest enhancing activity for enoxacin for all pH values of buffer vehicles. The enhancement factor of sodium laurylsulfate showed a dose-dependent property between the range of 0.1% to 3.0% concentration. Nonionic surfactant of Polysorbate 80 did not exhibit any enhancing effect on the percutaneous absorption of enoxacin. The highest enhancement factor of iontophoretic delivery was observed at pH 5.0 solution of anodal iontophoresis for cationic enoxacin. The cathodal iontophoresis of negative molecules and anodal iontophoresis of neutral molecules showed lower enhancing effect for enoxacin. The fact that the skin residuals of enoxacin after iontophoresis showed both tremendous and current density-dependent amounts for cationic enoxacin suggested local skin and soft tissue infections might be treated by this physical enhancement method. Combination of benzalkonium chloride and iontophoresis exerted a synergistic effect for anionic enoxacin in pH 10.0, which was possibly due to the shielding of negative charge in skin and the water molecules carried by chloride.

Topical application of clobetasol 17-propionate from various cream bases by using Wistar rat as an animal model

The effect of clobetasol 17-propionate (CP), a potent corticosteroid, participating in various cream bases on the permeation through rat skin was tested in vitro. Three commercially available formulations and three cream bases prepared in our laboratory according to Pharmacopoeia or registered patent were evaluated in this present study. The amount of CP in the receptor phase of diffusion cell was negligible in the beginning of administration due to the process of saturation of drug in skin reservoir, then the CP molecules pass through the skin directly because of the saturation of receptors in skin reservoir followed the higher flux of CP in the later period. It was suggested that the incorporation of penetration enhancers was the possible reason mainly controlling the flux of CP creams. Nevertheless, CP residue in skin and the lag time of formulations prepared in our laboratory were not significantly higher than those of commercial ones, which indicated penetration enhancer could not dominate the local pharmacological effectiveness of CP though they played a main part on the skin penetration capacity of formulations. The antiinflammatory activity of CP was assessed in the ear of Wistar rat. According to the result of antiinflammatory activity, all formulations showed significant inhibition on oedema suggesting the role of drug itself may be more important than that of vehicle in controlling the therapy efficacy.

Characterization and stability of various liposome-encapsulated enoxacin formulations

The necessity for antibacterial agents with greater intracellular efficacy has led to the development of endocytosable drug carriers such as liposomes. Enoxacin was selected as a model drug incorporated in various liposome formulations as a therapeutic dosage form using the ethanol injection method and freeze-drying. Liposomal behavior after preparation and stability test was characterized by determining the physicochemical properties of enoxacin encapsulation percent, vesicle size and turbidity. The non-phospholipid formulation of stratum corneum liposomes showed the highest encapsulation efficiency after preparation among nine liposomal formulations. The addition of dissacharides in liposomes also enhanced the encapsulation of enoxacin due to the protection of phospholipid bilayers during the freeze-drying process. The liposomes with negatively charged component and dissacharides showed lower enoxacin leakage after five weeks of storage at 45 degrees C, suggesting these formulations have high stability in long-term storage. The negative liposomes showed a different behavior than others in their decrease of size and turbidity during storage, possibly due to high surface charges of the negative formulation. Cholesterol stabilized bilayers interacted with plasma and high density lipoprotein (HDL) retained enoxacin in the vesicles. Nevertheless, liposomes with cholesterol caused a hydrolysis problem after incubation with normal saline. The formulation with trehalose not only showed high stability in storage but also in plasma and HDL. This suggested trehalose was useful to incorporate with phospholipids to produce a highly encapsulated and stabilized liposomes of enoxacin. This study also demonstrated that thought is required in utilizing turbidity as a direct index of liposomal vesicle size.

Relationship of plasma folic acid and status of DNA methylation in human gastric cancer

To evaluate the anti-cancer effects of folic acid at the molecular level, we determined plasma folic acid concentration by radioimmuno-assay and the degree of total genomic DNA methylation by incubating DNA with 3H-S-adenosylmethionine (3H-SAM) in the presence of a methylase, and analyzed the methylation status of the c-myc and c-Ha-ras oncogenes by Southern blotting in 21 patients with advanced gastric cancer. The degree of total genomic DNA methylation of cancerous tissues was significantly lower than that of paracancerous and non-cancerous tissues; c-myc and c-Ha-ras oncogenes from cancerous (10/21, 5/10) and paracancerous (13/21, 4/10) tissues were hypomethylated. The plasma folic acid concentration in patients who showed hypomethylation was lower than that patients showing normal methylation. These findings suggest that a decrease in folic acid, and the subsequent DNA hypomethylation, may be involved in human gastric carcinogenesis.

Langmuir-Blodgett and X-ray diffraction studies of isolated photosystem II reaction centers in monolayers and multilayers: physical dimensions of the complex

The photosystem II (PSII) reaction center (RC) is a hydrophobic intrinsic protein complex that drives the water-oxidation process of photosynthesis. Unlike the bacterial RC complex, an X-ray crystal structure of the PSII RC is not available. In order to determine the physical dimensions of the isolated PSII RC complex, we applied Langmuir techniques to determine the cross-sectional area of an isolated RC in a condensed monolayer film. Low-angle X-ray diffraction results obtained by examining Langmuir-Blodgett multilayer films of alternating PSII RC/Cd stearate monolayers were used to determine the length (or height; z-direction, perpendicular to the plane of the original membrane) of the complex. The values obtained for a PSII RC monomer were 26 nm2 and 4.8 nm, respectively, and the structural integrity of the RC in the multilayer film was confirmed by several approaches. Assuming a cylindrical-type RC structure, the above dimensions lead to a predicted volume of about 125 nm3. This value is very close to the expected volume of 118 nm3, calculated from the known molecular weight and partial specific volume of the PSII RC proteins. This same type of comparison was also made with the Rhodobacter sphaeroides RC based on published data, and we conclude that the PSII RC is much shorter in length and has a more regular solid geometric structure than the bacterial RC. Furthermore, the above dimensions of the PSII RC and those of PSII core (RC plus proximal antenna) proteins protruding outside the plane of the PSII membrane into the lumenal space as imaged by scanning tunneling microscopy (Seibert, Aust. J. Pl. Physiol. 22, 161-166, 1995) fit easily into the known dimensions of the PSII core complex visualized by others as electron-density projection maps. From this we conclude that the in situ PSII core complex is a dimeric structure containing two copies of the PSII RC.

Development and evaluation of transdermal patches of nonivamide and sodium nonivamide acetate

Transdermal patches were developed and evaluated for two synthetic derivatives of capsaicin, nonivamide (NVA) and sodium nonivamide acetate (SNA), by in vitro and in vivo skin permeation. The designed system was essentially based on natural rubber or polymeric Gelva dispersion. The characterization of physicochemical properties of the patches showed adequate adhesive force and low thickness which suggested these patch formulations possessed good quality. In the study of in vitro percutaneous experiment, the predicted therapeutic activities of patches were all higher than that of a commercially available plaster after the calculation of antinociceptive index. The highest in vitro penetration flux was found in the Gelva patch for NVA. The result of in vivo experiments revealed a high obverse correlation with that of in vitro experiments. The information of this present study is helpful for the further development of NVA and SNA transdermal drug delivery system.

Studies on the hypomethylation of c-myc, c-Ha-ras oncogenes and histopathological changes in human gastric carcinoma

In order to study the status of DNA methylation of specific oncogenes and the relationship between them and the pathological changes in gastric carcinoma, we analysed the methylated status of c-myc, c-Ha-ras oncogenes by Southern blot hybridization. Genomic DNA from cancerous, paracancerous and non-cancerous areas of surgically resected specimens were examined in 22 cases of advanced human gastric carcinoma. Specimens were digested by the restriction endonucleases MspI/HpaII, which are able to cleave between methylated and non-methylated cytosine at their nucleotide recognition site the DNA 5'-CCGG sequence, and were hybridized with c-myc, c-Ha-ras oncogene probes. Moreover, the corresponding pathological changes in gastric carcinoma were observed. The results showed that c-myc, c-Ha-ras oncogenes from cancerous (10/22, 5/10) and paracancerous areas (13/22, 4/10) were hypomethylated and that there was no significant relationship between them and the histopathological changes.

Trends in cancer incidence among children in the U.S

BACKGROUND

This report provides results of an analysis of temporal trends in childhood cancer incidence in the U.S. stratfied by age, sex, and to a lessor extent, race, within common histologic subtypes.

METHODS

Population-based data from nine registries of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute were analyzed. The analysis was limited to children age < or = 14 years. Cancer cases were restricted to those patients with a malignant neoplasm diagnosed between 1974 and 1991; more than 12,000 children were included. Average annual percentage change in incidence rates and corresponding 95% confidence intervals were estimated from the maximum likelihood method of Poisson regression.

RESULTS

Among children age < or = 14 years there was a 1% average yearly increase (95% CI 0.6, 1.3) in the incidence rates of all malignant neoplasms combined. The average annual percentage change was similar for males and females, and slightly higher for black children compared with white children. Rates increased an average of 2% or more per year for astroglial tumors, rhabdomyosarcomas, germ cell tumors, and osteosarcomas. The average annual percentage change for acute lymphoid leukemia was 1.6% and trends were somewhat stronger for blacks than whites. Cancer trends, in general, were strongest in young children. In particular, increases in astroglial tumors and rhabdomyosarcomas were most apparent among children age < 3 years, and for retinoblastoma and neuroblastoma among children in their first year of life. The average annual percentage change for acute lymphoid leukemia did not vary dramatically with age, however children age < 2 years had stronger trends compared with older children. We found little evidence for increasing trends in Wilms' tumor, primitive neuroectodermal tumors, or hematopoietic neoplasms other than acute lymphoid leukemia.

CONCLUSIONS

These results suggest that cancer occurrence among children within specific histologies increased modestly in the U.S. between 1974 and 1991, and that the increases were most apparent among young children.

In vitro effect of penetration enhancers on sodium nonivamide acetate in rat skin

Sodium nonivamide acetate (SNA) is a newly synthetic analogue of capsaicin which produces no overt pungent sensation or irritation. In this present study, the effects and roles of penetration enhancers for SNA through rat skin were investigated by in vitro skin penetration experiment and differential scanning calorimeter (DSC) determination. The penetration fluxes of SNA after the incorporation of enhancers increased in the order of Polysorbate 20 < sodium laurylsulfate < or = benzalkonium chloride. This result was consistent with that of DSC profiles which indicated the disruptive effects of surfactants on the rat stratum corneum increased in the order of Polysorbate 20 < sodium laurylsulfate < benzalkonium chloride. The information gained is particularly helpful in the development of SNA transdermal drug delivery system.

[Effect of yellow daphne on levels of plasma and decidual estradiol, prostaglandins, progesterone and its receptor in early pregnancy]

The changes of plasma concentration of estradiol (E2), progesterone (P) and prostaglandins (PG) and decidual level of prostaglandins and progesterone receptor (PR) after injection of Yellow Daphne for induction of abortion were observed. The results showed that the treatment with Yellow Daphne could induce degeneration and necrosis of decidual tissues as well as increase of PGE2 and PGF2 alpha concentration with lowering of PR level in the tissue. On the other hand, plasma level of PGE2 and PGF2 alpha remained unchanged and the levels of E2 and P declined. The data suggested that the contragestive mechanism of Yellow Daphne was mainly the involvement of decidual degeneration and the release of PG thus interfered the intrauterine environment for maintenance of pregnancy which subsequently led to abortion.

[Effect of fu-zheng qu-xie on gastric disease infected with Campylobacter pyloridis]

Chinese herbal medicine and gentamycin were used separately in the treatment of 75 cases of gastric disease by campylobacter pyloridis (CP). Surveying the changes of the gastrofiberscope, pathological test, bacteriology and immunology. This study, found that in the Chinese herbal medicine group clinical symptoms were obviously improving the effective rate for CP being 80% (24/30), the death rate for CP 30% (9/30), and the effective rate for patho-histological changes 50% (15/30). Differences of curative effective rate between the two groups were statistically insignificant (P greater than 0.05). This text pointed out that the principle of Chinese herbal medicine treatment of gastric disease by campylobacter pyloridis was fu-zheng qu-xie. Fu-zheng was achieved by Astragalus membranaceus, Atractylodes macrocephala and Paeonia lactiflora, whereas qu-xie by Taraxacum monogolicum and Oldenlandia diffusa. Chinese herbal medicine for fu-zheng played an important role in modulating immune function. Qu-xie was directly disinfective and indirectly anti-bacterial. Chinese herbal medicine combined with western drugs will decrease the side effects and enhance the curative effect at the same time.