Iranian Journal of Pharmaceutical Research
Volume:5 Issue: 3, Summer 2006

Infection is the primary source of mortality in burn patients. One of the main treatment methods of burn wound infections is topical antimicrobial therapy, in which drugs have to permeate a dead tissue called eschar. Unfortunately, most antimicrobial agents can not permeate eschar in therapeutic levels. Surprisingly, permeation properties of this barrier and effects of chemical or environmental conditions on it, including hydration level which is the subject of the present investigation, is not thoroughly studied as yet.Here, permeation of silver sulfadiazine (SSD), the most frequently used topical agent in burn management, from its’ 0.6 mg/ml solution through human third-degree burn eschar was studied in vitro at different hydration levels of fully-hydrated, semi-hydrated and dry eschar. The experiments were performed at 32°C, using Franz-type diffution cells. Hydration level was adjusted by controlling the contact condition of eschar tissue with an aqueous medium.Results showed that hydration can severely affect permeation of SSD through the burn eschar. Permeation of SSD through fully-hydrated tissue was about 20 times more than that of semi-hydrated samples. Permeation of SSD through dry eschar was initially (up to 3 h) more than those of semi- or fully hydrated tissues, but it ceased and reached a plateau at this time point, while for the other systems continued and became more than that of the dry eschar at later stages. The cumulative amount of drug permeated through the fully-hydrated tissue in 8 h was about 30 times more than that of the dry eschar.Our results showed that hydration can clearly improve permeation of SSD and possibly other drugs through third-degree burn eschar. A property which could easily change during patient management, e.g., by covering, washing, or application of occlusive formulations.

Among the drug delivery and targeting (DDT) routes, lung alveolar epithelium has been given enormous attentions in terms of the delivery of a wide range of macromolecules such as gene- or protein-based nanopharmaceuticals. However, little is known about cellular modulation of lung transport characteristics by endogenous and/or exogenous agents. Thus, in the current study, impact of dexamethasone (DEX), which is a customary additive to the culture media of alveolar epithelial cells, was assessed with respect to some transport properties of the human adenocarcinoma A549 cells, which is a well-known cell-based in vitro model for lung epithelia. To achieve such goal, we studied the trans epithelial electrical resistance (TEER) and barrier restrictiveness using the paracellular marker, mannitol. Further more, the effect of DEX on the expression of clathrin, the main integral protein of clathrin coated pits, as well as dynamin (GTP binding protein essential for the vesicle budding off process) were assessed. A549 cells treated with DEX displayed distinct phenotypic and growth changes, also resuling in higher TEER values (~ 100 Ω.cm2) compared to the untreated cells (~ 45 Ω.cm2). Such paracellular tightness properties were also confirmed by mannitol permeability assay, showing a marked difference in the permeability coefficient between untreated and DEX-treated A549 cells, i.e., 7.83± 0.3.7 (× 10-6 cm.s-1) and 3.46 ± 0.22 (× 10-6 cm.s-1), respectively. Although DEX exerted little impact on expression of the clathrin mRNA, it elicited a significant increase in dynamin protein expression. Therefore, it is proposed that DEX supplementation of alveolar epithelial A549 cells culture media may confer a better model for pulmonary DDT investigations. However, more extensive work is needed to be carried out in order to clarify the precise role of DEX in cellular transport of macromolecules via receptor-mediated endocytosis/transcytosis.

The purpose of this research was to study the neutralization efficacy of a universal neutralizer proposed by the CTPA on a range of antimicrobial agents and its potential toxicity for microorganisms that are used for antimicrobial preservation testing. Several types of antimicrobial agents including a mixture of methylisothiazolinone and its 5-chloro derivative, dimethylol dimethyl hydantoin, Quaternium-15®, Bronopol®, benzalkonium chloride, phenoxyethanol, methyl and propyl paraben, chlorhexidine, imidazolidinyl urea, triclosan and thiomersal built-in pharmaceutical, cosmetic or health care products, as well as 6 types of these antimicrobials, i.e. a combination of methyl paraben (0.18% w/v) and propyl paraben (0.02%), imidazolidinyl urea (0.3%), chlorhexidine (0.01%), benzalkonium chloride (0.02%), Bronopol® (0.1%) and thiomersal (0.02%) in their pure and soluble form were tested. Validation of microbial recovery was carried out according to the US Pharmacopeia 27 guidelines. The universal neutralizer could inactivate all the studied antimicrobial agents against different strains tested except Staphylococcus aureus. With regards to this microorganism, only seven preservative chemicals consisting of parabens, dimethylol dimethyl hydantoin, Quaternium-15®, Bronopol®, benzalkonium chloride, Phenonip® and imidazolidinyl urea were effectively inactivated. In addition, a pure solution of 0.02% thiomersal retained its antimicrobial properties against all studied microorganisms. The neutralizer solution showed no toxicity on any of the test organisms. In conclusion, CTPA proposed neutralizing solution is not an inclusive neutralizer. Moreover, each organism to be used in the test must be included in the validation study.

Zinc sulphate is currently used for treatment of zinc deficiency. Its uptake by the body is poor, necessitating the administration of high doses. This leads to a range of unpleasant side effects. In order to increase the bioavailability of zinc, several zinc complexes have been designed and synthesized using bidentate ligands of hydroxypyranones and hydroxypyridinones. Elemental analysis in each zinc complex was consistent with the formulations of ZnL2 species L: bidentate ligand) with 1.5 or 7 water molecules per zinc and the water molecules were removed by heating in a vacuum oven to yield anhydrous zinc complexes.The partition coefficients (Kpart)of the complexes were also determined in 1-octanol/buffer (at pH 7.40) system by using shake-flask method. It was found that, the complexes with hydroxypyranone ligands possess higher Kpart values than those with hydroxypyidinone ligands. Therefore, the comparison of the complexes highlights the hydroxypyranone zinc complexes as the most promising candidates for using in zinc deficiency. Since it was anticipated that this type of complexes probably possesses suitable lipophilicity to facilitate their penetration into the gastrointestinal tract.

To evaluate the acute effect of lovastatin on diabetic endothelial dysfunction, we examined this effect on the aortic rings of streptozotocin-diabetic rats. The endothelial function was assessed in aortic rings isolated from diabetic rats, 12 weeks after treatment with streptozotocin (45 mg/kg, i.p.). The concentration-response curve to acetylcholine (Ach) in the aortic rings precontracted with phenylephrine (10-6 M) was significantly diminished in diabetic groups; and maximum relaxation in control and diabetic groups were 82±1.93% and 48±2.39% respectively (a 42% decrease, P<0.001). Incubation with lovastatin (10-5M) for 10 min, significantly improved the Ach-induced relaxation of diabetic groups and the maximum relaxation increased to 74.2 ±3.3% (a 54% increase, P<0.001).Incubation with NG –nitro-L-arginine methyl ester hydrochloride (L-NAME; 5x10-7 M) for 20 min eliminated a significant difference in Ach – induced relaxation responses in diabetic and control groups and also eliminated the improving effect of lovastatin in diabetic groups. On the other hand 10 min incubation with indomethacin (10-5 M) did not eliminate the difference in Ach-induced relaxation responses in diabetic and control groups and also did not eliminate the improving effect of lovastatin in diabetic groups. Lovastatin did not modify sodium nitroprosside-induced relaxation in either diabetic or control groups and also did not induce any direct relaxation.Therefore, it is concluded that incubation of aortic rings with lovastatin significantly improves endothelium-dependent relaxation in diabetic groups by increasing the nitric oxide bioavailability, most probably due to its’ antioxidant effects.

In this study, the possible involvement of L-type voltage-operated calcium channels in the vasorelaxant effect of the flavonoid quercetin was investigated, using the isolated aortic rings from normal male rats. Addition of quercetin (0.1 µM-1 mM) caused a significant dose-dependent relaxation of noradrenaline (NA)- and KCl-preconstricted rings and nifedipine attenuated this response, especially for noradrenaline (P<0.05). It is concluded that the flavonoid quercetin produces a potent relaxation of the rat aorta and blockade of voltage-operated calcium channels could attenuate this effect.

Programmed cell death is a highly regulated form of cell death, mostly distinguished by the activation of a family of cystein-aspartate proteases (caspases) that cleave various proteins resulting in morphological and biochemical changes characteristic of this form of cell death. Several recent studies have addressed the role of programmed cell death in inflammatory and chronic pain states. Caspase-3 plays a central role in mediating nuclear programmed cell death including chromatin condensation and DNA fragmentation as well as cell blebbing. The aims of this study were to investigate the effect of duration and severity of persistent pain on the induction of programmed cell death. Formalin was administered subcutaneously in the Wistar rat hind paws for 1, 4 or 7 consecutive days, and then the activity of caspase-3 was measured in both the rat liver and brain cells. Morphological changes characterizing programmed cell death were also studied using the Sigma’s Apoptosis Detection kit, Annexin V-Cy3. Our findings showed that caspase-3 activity and apoptotic phenotype significantly increased in liver but not brain cells following the increase in duration and severity of formalin induced persistent pain.

The oxidative modification of low density lipoprotein (LDL) may play an important role in atherogenesis. Antioxidants that can prevent LDL oxidation may act as antiatherogens. Our understanding of the mechanism of LDL oxidation and factors that determine its susceptibility to oxidation is still incomplete. Copper is a candidate for oxidizing LDL in atherosclerotic lesions. The binding of copper ions to LDL is usually thought to be a prerequisite for LDL oxidation by copper. Therefore we investigated the effect of α-tocopherol (as a major fat soluble antioxidant) on copper bound to LDL and furthermore effect of this binding on the susceptibility of LDL to oxidative modification. In this study LDL was isolated from EDTA-plasma (1 mg EDTA/ml blood) by ultracentrifugation using a single-step discontinuous gradient. Then α-tocopherol was added to LDL and incubated for 1 h at 37° C. The oxidation rate of LDL was estimated by thiobarbitoric acid reactive substances (TBARS) after CuSO4 addition. Finally, the effect of α-tocopherol on formation of LDL-copper complex by gel filtration was studied. Our results showed that α-tocopherol (dose dependently) suppressed the formation of TBARS and LDL-copper complex. The α-tocopherol with concentrations of 10, 50 and 100 µM reduced susceptibility of LDL to oxidative modification approximately by 2, 13 and 21 percent, respectively. Furthermore, addition of α-tocopherol to the LDL and CuSO4 mixture containing before hand prevented the formation of LDL-copper complex, approximately by 30 percent.In conclusion we found that α-tocopherol with inhibition of copper binding to LDL may decrease the susceptibility of LDL oxidation to this ion and thus could play a role in prevention of atherosclerosis.

Concomitant use of several drugs by ICU(Intensive Care Unit) patients is often unavoidable. In these patients, pharmacokinetic drug interactions are very likely. The current study was designed to evaluate these interactions in patients hospitalized in an ICU of a teaching hospital in Tehran, Iran.A questionnaire was designed and used to collect study data. The study was done in the ICU of a teaching hospital affiliated to the Shaheed Beheshti Medical University. Overall information extracted from 567 ICU prescriptions from March 2005 to December 2005. The extent of occurrence and frequency of potential pharmacokinetic interactions were categorized based on the reference text Drug Interactions Facts. All of the pharmacokinetic drug interactions were extracted and evaluated in terms of mechanism, significance, severity, documentation and onset.There were 413 pharmacokinetic interactions in 567 studied prescriptions, which were divided into 64 types of pharmacokinetic interactions. The most observed interaction was between ciprofloxacin and sucralfate. Mechanisms of the pharmacokinetic interactions were related to metabolism (%60.05), absorption (% 38.26), elimination (%0.97) and distribution (%0.73). There was a direct relationship between the number of drugs per prescription and the frequency of pharmacokinetic interactions (p<0.001, r =0.98) Findings obtained in this study revealed that there is a significant number of rapid occurring, moderate, probable and definite interactions among the ICU prescriptions. This highlights the necessity for the presence of a drug specialist (i.e. clinical pharmacist) to rationalize the therapy and minimize major interactions.

Effects of different carbon sources on growth and production of antifungal agent(s) by Gymnopilus spectabilis were investigated. Different carbon sources including; Glucose, fructose, lactose, maltose, manitol and sucrose at the concentration of 10 g/l and slow releasing carbon sources including malt extract and soluble starch at the concentration of 2g/l were used. Inhibition of spore germination of Aspergillus niger was used to test antifungal activity. The results showed that the highest activity (90% inhibition of spore germination) and biomass concentration (2.4 g/l) were obtained when glucose was used as carbon source. Other media with different carbon sources showed antifungal activity ranging from 30% to 70% inhibition of spore germination. Combination of glucose with malt extract as a slow releasing carbon source was also increased activity to 100% inhibition.

The potential of tobacco waste as a viable source of medicinally important flavonoids like rutin has been investigated. Three flavonoids, apigenin, quercetin and rutin, have been isolated from waste tobacco leaves, and their identities have been confirmed by UV-visible, 1H-NMR and 13C-NMR spectroscopy. By using analytical HPLC, the amount of rutin present in the tobacco leaves, before and after fermentation, and also in waste tobacco leaves, has been determined as 1.5, 0.5 and 0.6%, respectively.