Study of general toxic and organotropic properties of ampicillin combined with sulbactam]

The effect of sulacillin, a combination of sulbactam and ampicillin (1:2), on the functions of the liver and kidneys, peripheral blood count, cardiovascular and central nervous systems was studied in acute and chronic experiments on animals of various species. The allergenic and local irritating properties of the combination were also studied. It was shown that the combination was low toxic and the interaction of sulbactam and ampicillin by the lethal effect was additive. When the combination was administered intravenously to mice, its LD50 amounted to 6 g/kg. In chronic experiments on rats parenterally given the combination in doses equivalent to the therapeutic ones there were no changes in the examined systems and organs. When used in the doses exceeding the therapeutic ones, sulacillin used during long periods induced a transitory elevation of blood levels of transaminases and alkaline phosphatases, an increase in the relative weight of the liver and kidneys, elongation the typhlon and an increase in glycogen levels in the hepatocytes without morphological changes. The combination had no significant effect of sulacillin and the painful injections alleviated by local anesthesia were recorded. The allergenic properties of the combination were moderate and did not differ from those of ampicillin. The data indicate that the combined sulacillin preparation greatly resembles its foreign analogue.     

Treatment of infectious complications of experimental acute radiation injury with combined antibiotic sulacillin

An anti-infectious effect of sulacillin (ampicillin/sulbactam) is higher than that of ampicillin in treatment of irradiated mice infected with a beta-lactamaseproducing strain of Kl. pneumoniae. Involving of sulacillin as a principal antibiotic into the therapeutic scheme for acute radiation sickness results in 67% dogs survival at LD90/45.     

A Preformulation Strategy for the Selection of Penetration Enhancers for a Transungual Formulation

Onychomycosis is associated with the cutaneous fungal infection of the nail and the nail folds (skin surrounding the nail). It is therefore important to target drug delivery into the nail folds along with nail plate and the nail bed. Systematic and strategic selection of the penetration enhancers specific for the skin and the nail is discussed. Twelve penetration enhancers were screened for their ability to improve solubility, in vitro nail penetration, in vitro skin permeation, and in vitro skin penetration of the antifungal drug ciclopirox olamine. In contrast to transdermal drug delivery, the main selection criteria for skin penetration enhancer in topical drug delivery were increased drug accumulation in the epidermis and minimal permeation across the skin. Thiourea improved the solubility and nail penetration of ciclopirox olamine. It also showed enhancement in the transungual diffusion of the drug. Propylene glycol showed a 12-fold increase in solubility and 3-fold increase in epidermal accumulation of ciclopirox olamine, while minimizing the transdermal movement of the drug. Thiourea was the selected nail permeation enhancer and propylene glycol was the selected skin penetration enhancer of ciclopirox olamine. A combination of the selected enhancers was also explored for its effect on drug delivery to the nail and nail folds. The enhancer combination reduced the penetration of ciclopirox in the skin and also the permeation through the nail. The proposed preformulation strategy helps to select appropriate enhancers for optimum topical delivery and paves way towards an efficient topical formulation for passive transungual drug delivery.     

Simulation of gentamicin delivery for the local treatment of osteomyelitis

In order to understand the effect of antibiotics delivery to bone tissue, by biodegradable polymeric drug disc, for the treatment of osteomyelitis, a three-dimensional simulation model is developed. The simulation investigates the effect of pressure-induced convection on drug distribution, by taking into account the pressure gradient that exists between capillaries and interstitial space, and also as a result of the surgical opening. The clotting process at the surgical opening is incorporated into the simulation, and the effect of clotting duration is investigated. The clotting duration for the baseline simulation is 2 days and it is observed that increasing this duration depresses the mean drug concentration in the marrow and cortical bone. The effect of double burst release profile is also studied and it is observed that drug concentration drops too rapidly after the first burst to provide any therapeutic effect. However, it is shown that the drug concentration after the second burst stays above the minimum inhibitory concentration of the bacteria for a longer period of time, than would have been observed for a mono-burst release. Inserting non-biodegradable polymethylmethacrylate (PMMA) beads into bone seems to cause a higher average concentration of drug in the marrow. However, this could be brought about by the difference in the geometry between the disc and the bead, and the amount of drug packed in each bead. Further simulations on the management of dead space shows the ineffectiveness of having the void filled up with surgical gel as it becomes an additional barrier to drug delivery to the infected tissues.     

Evaluation of multi-target and single-target liposomal drugs for the treatment of gastric cancer

We studied the effects of multi- and single-target liposomal drugs on human gastric cancer cell AGS both in vitro and in vivo. The cytotoxic effect of dihydrotanshinone I was significantly enhanced by treatment with octreotide-polyethylene glycol(PEG)-liposome, Arg-Gly-Asp(RGD)-PEG-liposome, and RGD/octreotide-PEG-liposome encapsulated with 0.5 mug/ml of dihydrotanshinone I to AGS cell for 24 h, compared to control. Furthermore, the AGS cell survival rate for multi-target versus single target liposomal drugs was significantly suppressed. Microscopic examination revealed that significant cell death occurred in the multi- and single-target liposomal encapsulated drug groups. Significant suppression of tumor growth in AGS cell xenograft nude mice given octreotide-PEG-liposome, RGD/octreotide-PEG-liposome encapsulated drug, versus those given a free drug was noted after 13 d of experimentation with the multi-targeted liposome: up to 60.75% and 41.2% reduction of tumor volume as compared to dimethylsulfoxide (DMSO) control and the free drug groups respectively. The treated animals showed no gross signs of toxicity. The results have potential clinical application.     

In silico evaluation for the potential naturally available drugs for breast cancer

Abstract

Breast cancer is one of the major causes of deaths in women. During the incidence of breast cancer, the HER-2 is amplified and over expressed. This transmembrane receptor is involved in the signal transduction pathway. The present article evaluates 14 naturally available breast cancer drugs, in silico and the ADMET studies were conducted. The HER-2, a validate breast cancer target was taken for the present study. The protein was prepared for docking on the Discovery Studio 2.5. About 14 ligand molecules were used to dock with HER-2 after they were prepared for docking. The ADMET assessment was also done. The dock results showed that the ligand 4′-epidoxorubicin to be the potential drug with the highest dock score of 49.386. Among the 14 naturally available breast cancer drugs, our results evaluated that 4′-epidoxorubicin as the best drug for breast cancer. Further, the ADMET studies give an idea about the drug molecules.     

Mixing Time Effects on the Dispersion Performance of Adhesive Mixtures for Inhalation

This paper deals with the effects of mixing time on the homogeneity and dispersion performance of adhesive mixtures for inhalation. Interactions between these effects and the carrier size fraction, the type of drug and the inhalation flow rate were studied. Furthermore, it was examined whether or not changes in the dispersion performance as a result of prolonged mixing can be explained with a balance of three processes that occur during mixing, knowing drug redistribution over the lactose carrier; (de-) agglomeration of the drug (and fine lactose) particles; and compression of the drug particles onto the carrier surface. For this purpose, mixtures containing salmeterol xinafoate or fluticasone propionate were mixed for different periods of time with a fine or coarse crystalline lactose carrier in a Turbula mixer. Drug detachment experiments were performed using a classifier based inhaler at different flow rates. Scanning electron microscopy and laser diffraction techniques were used to measure drug distribution and agglomeration, whereas changes in the apparent solubility were measured as a means to monitor the degree of mechanical stress imparted on the drug particles. No clear trend between mixing time and content uniformity was observed. Quantitative and qualitative interactions between the effect of mixing time on drug detachment and the type of drug, the carrier size fraction and the flow rate were measured, which could be explained with the three processes mentioned. Generally, prolonged mixing caused drug detachment to decrease, with the strongest decline occurring in the first 120 minutes of mixing. For the most cohesive drug (salmeterol) and the coarse carrier, agglomerate formation seemed to dominate the overall effect of mixing time at a low inhalation flow rate, causing drug detachment to increase with prolonged mixing. The optimal mixing time will thus depend on the formulation purpose and the choice for other, interacting variables.     

On the alcianophilia of the drug suramin used as a tool for inducing experimental mucopolysaccharidosis

The trypanocidal drug suramin was previously reported to induce mucopolysaccharidosis in rats; apart from the biochemical demonstration of increased tissue concentrations of sulfated glycosaminoglycans (GAGs), a strongly positive staining reaction with the cationic dye Alcian Blue was taken as indicating GAG-storage (Constantopoulos et al. 1983). The purpose of the present report is to point out a methodical pitfall. In model experiments it was found that suramin itself, being a polysulfated compound, gives a strongly positive reaction with Alcian Blue at pH 1. It is known that suramin is accumulated in the lysosomes and that high drug concentrations are retained in the tissues for weeks. Therefore a positive staining reaction with Alcian Blue observed in a given cell cannot be conclusively attributed to the storage of sulfated GAGs as has been done in the past. The present report may be a warning that, in the case of the suramin-induced animal model of mucopolysaccharidosis, the usual histochemical strategy, i.e. staining with cationic dyes, is not suitable for analysing the cellular distribution pattern of GAG-storage, since the inducing drug by itself reacts with the indicator dye.     

On the alcianophilia of the drug suramin used as a tool for inducing experimental mucopolysaccharidosis

Summary The trypanocidal drug suramin was previously reported to induce mucopolysaccharidosis in rats; apart from the biochemical demonstration of increased tissue concentrations of sulfated glycosaminoglycans (GAGs), a strongly positive staining reaction with the cationic dye Alcian Blue was taken as indicating GAG-storage (Constantopoulos et al. 1983). The purpose of the present report is to point out a methodical pitfall. In model experiments it was found that suramin itself, being a polysulfated compound, gives a strongly positive reaction with Alcian Blue pH 1. It is known that suramin is accumulated in the lysosomes and that high drug concentrations are retained in the tissues for weeks. Therefore a positive staining reaction with Alcian Blue observed in a given cell cannot be conclusively attributed to the storage of sulfated GAGs as has been done in the past. The present report may be a warning that, in the case of the suramin-induced animal model of mucopolysaccharidosis, the usual histochemical strategy, i.e. staining with cationic dyes, is not suitable for analysing the cellular distribution pattern of GAG-storage, since the inducing drug by itself reacts with the indicator dye.     

On the mechanism for the red-cell accumulation of mefloquine,an antimalarial drug

The accumulation of the antimalarial drug mefloquine by human red blood cells has been studied by ¹⁹F-NMR spectroscopy. The uptake process was nonlinearly dependent on the external drug concentration. Concentrations inside cells as high as 60-times greater than those in the extracellular phosphate-buffered-saline were observed. Red-cell ghosts were also found to accumulate mefloquine with high-affinity binding sites for the drug. Hemoglobin was found to bind mefloquine with low affinity, but due to the high concentration of this protein it is a significant drug compartment in the red cell. Analysis of the ¹⁹F-NMR chemical shifts and linewidths of mefloquine in the presence of red cells, red-cells ghosts and hemoglobin indicates restricted mobility of the drug in the membrane-bound state and slow exchange with the extracellular medium. This is a significant characteristic of the reaction in connection with the prophylactic activity of the drug. Exchange of the drug between hemoglobin and the red-cell membrane, however, is fast and may play an important role in the bioavailability of the drug to the parasite.     

Slow-release Drug Delivery through Elvax 40W to the Rat Retina: Implications for the Treatment of Chronic Conditions

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.     

A Method for the Assessment of Reports of Drug Trials

A stepwise method for the assessment of reports of drug trials was used to determine the validity of drug reports published in The Canadian Medical Association Journal during the five-year period, January 1, 1956, to December 31, 1960. The method is simple and consists of applying four criteria: (1) the presence of adequate controls; (2) randomization of treatments; (3) objective assessment of drug effects; and (4) statistical analysis of results. If these criteria were absent, the assessment was stopped, and the report was felt to be invalid. A total of 203 articles were reviewed and 11 were found to fulfil these criteria. During the same period of time there were 93 additional case reports of drug effects, 39 of which described the effectiveness of a drug without there being adequate controls. The remainder of the case reports described drug toxicities.     

A novel approach for assessing the susceptibility of Escherichia coli to antibiotics

The dynamic growth process of Escherichia coli CVCC249 under different concentrations of antibiotics was analyzed. The results suggested that the main reason that definitive results cannot be obtained by antibiotic susceptibility testing (AST) is that the ratio of drug concentration to the population of bacteria and the combined effect of drug concentration and action time cannot be completely determined with the methods used. Based on the analysis of the growth process with a series of concentrations of gentamicin acting for a certain time, and according to the forward difference method, a novel method for AST was proposed. The net increase in turbidity of the bacterial population was used to eliminate the existing effects of resting cells, and then the recurrent coefficient for a growing sequence was used to characterize the effect of antibiotics on bacterial division, and the contour plot was used to display and analyze the combined effect of drug concentration and action time. The inhibition rate of the antibiotics can be characterized as the dynamic change in the composite function of the antibiotic concentration and action time, which indicated that the inhibition rate was dependent on the combined effect of time and concentration of antibiotics. The effectiveness of this new method has been verified with different kinds of antibiotics, such as enrofloxacin, levofloxacin, and ceftriaxone, having different antibacterial mechanisms.     

Neoglycoproteins as Carriers for Receptor-Mediated Drug Targeting in the Treatment of Experimental Visceral Leishmaniasis

ABSTRACT. Methotrexate (MTX) coupled to mannosyl bovine serum albumin (BSA) was taken up efficiently through the mannosyl receptors present on macrophages. Binding experiments indicate that conjugation does not decrease the affinity of the neoglycoprotein for its cell surface receptor. The drug conjugate eliminated intracellular amastigotes of Leishmania donovani in mouse peritoneal macrophages about 100 times more efficiently than free drug on the basis of 50% inhibitory dose. Inhibitory effect of the conjugate was directly proportional to the density of sugar on the neoglycoprotein carrier. Colchicine and monensin, inhibitors of receptor-mediated endocytosis, can prevent the leishmanicidal effect of the conjugate. Antileishmanial effect of the conjugate can be competitively inhibited by mannose-BSA and mannan. In a murine model of experimental visceral leishmaniasis the drug conjugate reduced the spleen parasite burden by more than 85% in a 30-day model whereas the same concentration of free drug caused little effect. These results indicate that MTX-neoglycoprotein conjugate binds specifically to macrophages, and is internalized and degraded in lysosomes releasing the active drug to act on Leishmania parasites. These results also represent the potential for a general approach to intracellular targeting of clinical agents for macrophage-associated disorders.     

Neoglycoproteins as carriers for receptor-mediated drug targeting in the treatment of experimental visceral leishmaniasis

Methotrexate (MTX) coupled to mannosyl bovine serum albumin (BSA) was taken up efficiently through the mannosyl receptors present on macrophages. Binding experiments indicate that conjugation does not decrease the affinity of the neoglycoprotein for its cell surface receptor. The drug conjugate eliminated intracellular amastigotes of Leishmania donovani in mouse peritoneal macrophages about 100 times more efficiently than free drug on the basis of 50% inhibitory dose. Inhibitory effect of the conjugate was directly proportional to the density of sugar on the neoglycoprotein carrier. Colchicine and monensin, inhibitors of receptor-mediated endocytosis, can prevent the leishmanicidal effect of the conjugate. Antileishmanial effect of the conjugate can be competitively inhibited by mannose-BSA and mannan. In a murine model of experimental visceral leishmaniasis the drug conjugate reduced the spleen parasite burden by more than 85% in a 30-day model whereas the same concentration of free drug caused little effect. These results indicate that MTX-neoglycoprotein conjugate binds specifically to macrophages, and is internalized and degraded in lysosomes releasing the active drug to act on Leishmania parasites. These results also represent the potential for a general approach to intracellular targeting of clinical agents for macrophage-associated disorders.     

Anatomical substrates for the discriminative stimulus effects of methamphetamine in rats

Methamphetamine is a psychostimulant drug acting on central monoaminergic neurons to produce both acute psychomotor stimulation and long-lasting behavioral effects including addiction and psychosis. Drug discrimination procedures have been particularly useful in characterizing subjective effects of addictive drugs. In the present study, to identify potential anatomical substrates for the discriminative stimulus effects of methamphetamine, we investigated the drug discrimination-associated Fos expression in Sprague-Dawley rats trained to discriminate methamphetamine from saline under a two-lever fixed ratio 20 (FR-20) schedule of food reinforcement. The rats that fulfilled the criteria for learning the discrimination were anesthetized and perfused 2 h after the drug discrimination test, and Fos immunoreactivity was examined in 15 brain regions. Fos expression in the brains of rats that discriminate methamphetamine from saline was significantly increased in the nucleus accumbens (NAc) and the ventral tegmental area (VTA), but not in other areas including the cerebral cortex, caudate putamen, substantia nigra, hippocampus, amygdala and habenulla, as compared with the expression in control rats that were maintained under the FR-20 schedule. The present findings suggest a role for the VTA and NAc as possible neuronal substrates in the discriminative stimulus effects of methamphetamine.     

Sensitive cell viability assay for use in drug screens and for studying the mechanism of action of drugs in Dictyostelium discoideum

In order to increase the effectiveness of Dictyostelium discoideum as a lead genetic model for drug discovery, a luminescence-based assay has been adapted and standardized for sensitive and rapid cell viability measurements. The applicability of the assay was demonstrated by measuring the cytotoxicity of several drugs in wild-type and mutant cells. The robustness and ease of the assay demonstrate that it can be used in high-throughput applications such as drug or mutant screens. Conclusions from these studies are applicable to evaluating cell viability assays in other systems as well.     

The application of electrosprayed minocycline-loaded PLGA microparticles for the treatment of glioblastoma

The survival of patients with glioblastoma multiforme (GBM), the most common and invasive form of malignant brain tumors, remains poor despite advances in current treatment methods including surgery, radiotherapy, and chemotherapy. Minocycline is a semi-synthetic tetracycline derivative that has been widely used as an antibiotic and more recently, it has been utilized as an antiangiogenic factor to inhibit tumorigenesis. The objective of this study was to investigate the utilization of electrospraying process to fabricate minocycline-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles with high drug loading and loading efficiency and to evaluate their ability to induce cell toxicity in human glioblastoma (i.e., U87-MG) cells. The results from this study demonstrated that solvent mixture of dicholoromethane (DCM) and methanol is the optimal solvent combination for minocycline and larger amount of methanol (i.e., 70:30) resulted in a higher drug loading. All three solvent ratios of DCM:methanol tested produced microparticles that were both spherical and smooth, all in the micron size range. The electrosprayed microparticles were able to elicit a cytotoxic response in U87-MG glioblastoma cells at a lower concentration of drug compared to the free drug. This work provides proof of concept to the hypothesis that electrosprayed minocycline-loaded PLGA microparticles can be a promising agent for the treatment of GBM and could have potential application for cancer therapies.     

New Mechanisms to Explain the Effects of Added Lactose Fines on the Dispersion Performance of Adhesive Mixtures for Inhalation

Fine excipient particles or ‘fines’ have been shown to improve the dispersion performance of carrier-based formulations for dry powder inhalation. Mechanistic formulation studies have focussed mainly on explaining this positive effect. Previous studies have shown that higher drug contents may cause a decrease in dispersion performance, and there is no reason why this should not be true for fines with a similar shape, size and cohesiveness as drug particles. Therefore, the effects on drug detachment of ‘fine lactose fines’ (FLF, X₅₀ = 1.95 µm) with a similar size and shape as micronised budesonide were studied and compared to those of ‘coarse lactose fines’ (CLF, X₅₀ = 3.94 µm). Furthermore, interactions with the inhalation flow rate, the drug content and the mixing order were taken into account. The observed effects of FLF are comparable to drug content effects in that the detached drug fraction was decreased at low drug content and low flow rates but increased at higher flow rates. At high drug content the effects of added FLF were negligible. In contrast, CLF resulted in higher detached drug fractions at all flow rates and drug contents. The results from this study suggest that the effects of fines may be explained by two new mechanisms in addition to those previously proposed. Firstly, fines below a certain size may increase the effectiveness of press-on forces or cause the formation of strongly coherent fine particle networks on the carrier surface containing the drug particles. Secondly, when coarse enough, fines may prevent the formation of, or disrupt such fine particle networks, possibly through a lowering of their tensile strength. It is recommended that future mechanistic studies are based on the recognition that added fines may have any effect on dispersion performance, which is determined by the formulation and dispersion conditions.