The influence of sepsis on antimicrobials tissue penetration: The use of microdialysis technique to access free drug distribution

Abstract Sepsis is described as a life-threatening organ dysfunction caused by a host's response to infection, leading to an unbalance in body homeostasis. It is one of the leading causes of death in developed countries. Considering that in critically ill patients, such as those with sepsis, plasma concentrations do not necessarily reflect tissue concentrations, one way to assess tissue concentrations is through the microdialysis technique, which allows direct measurements of free drug at the site of action. This review was carried out after searching the Pubmed, Scielo and Web of Science databases, using the following descriptors: (microdialysis AND (sepsis OR septic shock OR severe sepsis OR septicemia)) OR (microdialysis AND (sepsis OR septic shock OR severe sepsis) OR septicemia) AND (antimicrobial OR antibiotic OR antifungal)). The physiological changes generated by sepsis may imply changes in pharmacokinetic parameters, such as in clearance, which may be reduced in these patients and in volume of distribution, which presents an expansion, mainly due to edema. Both events contribute to a high inter- individual variability in tissue penetration of antimicrobials which is generally observed in patients with sepsis.

Free interstitial levels of metformin in the liver of healthy and diabetic Wistar rats

Abstract In the present study, free interstitial levels reached by metformin in the liver were investigated in control and diabetic rats by microdialysis. Firstly, a bioanalytical method using an HPLC-UV system to determine the drug concentration in microdialysis samples was validated. The blood glucose levels and biochemical parameters were investigated in control and diabetic animals. Following that, both groups received a dose of 50 mg/kg of metformin iv bolus and the free interstitial levels reached in the liver were assessed by microdialysis. The method was validated according to FDA guidelines being suitable to quantify free concentrations of metformin in the liver of control and diabetics rats. Free exposure to metformin was similar in control and diabetic animals: AUC0-∞ 118.50 ± 40.18 vs 112.93 ± 50.25 µg.h/mL, respectively. The half-life in tissue was similar to that described in the literature for plasma. Hence diabetes induced by streptozotocin after administration of nicotinamide in our study did not damage the renal and hepatic function of the animals. The levels reached in the liver were 1.6 times higher than the free plasma concentrations, demonstrating higher liver penetration of metformin. This is the first investigation in liver interstitial concentration of metformin in control and diabetic rats

LC-UV method to assay raloxifene hydrochloride in rat plasma and its application to a pharmacokinetic study

A specific, precise, and accurate LC-UV method was developed and validated to assay raloxifene hydrochloride in rat plasma. Raloxifene was analyzed after liquid-liquid extraction and quantified by reversed phase liquid chromatography (C18 column) using acetonitrile and ammonium acetate buffer 0.05 M (pH 4.0) as mobile phase at a flow rate of 1 mL.min-1 and UV detection at 287 nm. Retention times of raloxifene and internal standard (dexamethasone) were approximately 11 min and 14 min, respectively. Linearity was checked for a concentration range between 25 ng.mL-1 and 1000 ng.mL-1. Intra- and inter-day precision had relative standard deviation lower than 10% and 15%, respectively. Recovery from plasma was higher than 90%. Accuracy values were 98.21%, 99.70%, and 102.70% for lower, medium, and upper limits of quantification, respectively. Limit of quantification was 25 ng.mL-1. Drug stability was analyzed at room temperature using plasma kept in a freezer at -80 °C for 45 days after processing for 6 h and three freeze-thaw cycles. The advantages of the method developed include stability under different conditions and low limit of quantification. Its applicability was confirmed by the analysis of raloxifene levels in plasma samples in a designed pharmacokinetic study in rats after intravenous administration (5 mg.kg-1).

In vitro evaluation of cutaneous penetration of acyclovir from semisolid commercial formulations and relation with its effective antiviral concentration

ABSTRACT The evaluation of drug permeation/penetration of semisolid formulations into animal skin can be useful to supplement the pharmaceutical equivalence. This paper describes the in vitro assessment of acyclovir (ACV) into porcine skin from commercial formulations with etermination of drug concentration in different layers of cutaneous tissue to correlate with effective antiviral concentration in order to improve the equivalence decision. Studies were conducted using Franz cells and porcine skin. Selected pharmaceutical creams containing ACV had identical (reference and generic) and different (similar) excipients. A software program was employed for the simulation of antiviral effectiveness in the skin. Regarding ACV skin penetration, the first batch of the generic product showed a significant difference from reference and similar products, while in the second batch all products demonstrated equivalent drug penetration in the skin. Simulation studies suggest that formulations analysed exhibit a pharmacological effect even when in contact with Herpes simplex strains of high IC50 (inhibitory concentration required to reduce viral replication by 50%). According to results, it can be assumed that the in vitro cutaneous permeation/penetration study does not supply sensitivity information regarding small alterations of ACV semisolid formulations due to the variability inherent to the method, although it can be relevant to pharmaceutical equivalence studies in the development of semisolid products.

Investigação da atividade antihiperglicemiante da farinha da casca de Passiflora edulis Sims, Passifloraceae, em ratos diabéticos induzidos por aloxano / Investigation of antihyperglycemic activity of Passiflora edulis Sims, Passifloraceae, in alloxan-induced diabetic rats

O presente estudo objetivou a modelagem farmacodinâmica da ação antihiperglicemiante da farinha da casca de maracujá (Passiflora edulis Sims, Passifloraceae) em ratos diabéticos induzidos por aloxano. Os animais foram divididos em três grupos (n = 9): grupo diabético tratado com 20 mg/kg, 40 mg/kg ou 160 mg/kg da farinha. As amostras sanguíneas foram coletadas da veia lateral da cauda e a glicemia foi determinada com auxílio de um glucômetro em 0, 1, 2, 4 e 6 h após o tratamento via oral. Observou-se que o efeito antihiperglicemiante da farinha da casca de maracujá foi dependente da dose, obtendo um efeito expressivo observado em quatro horas para todas as doses, sendo mais pronunciado na dose de 160 mg/kg. O efeito, expresso como redução da glicemia basal em relação ao tempo zero, pode ser modelado através de um modelo dose-efeito clássico, o qual permitiu a determinação do efeito máximo (Emax) e da dose necessária para alcançar 50 por cento deste efeito (DE50). Após a modelagem dos dados, obteve-se um valor de Emax = 58,41 por cento e de DE50 = 23,61 mg/kg. Esta abordagem pode permitir a comparação do efeito antihiperglicemiante de Passiflora edulis com outras espécies que apresentem atividade sobre a redução da glicemia, mediada pela presença de fibras solúveis.

This study goals the pharmacodynamic modeling of anti hyperglycemic action of flour of Passion fruit bark (Passiflora edulisSims, Passifloraceae) in alloxan-induced diabetic rats. The animals were divided into three groups (n = 9) that received different doses: 20, 40 or 160 mg/kg of flour. The blood samples were collected from the tail vein and the blood glucose was determined using a glucometer Prestige IQ in 0, 1, 2, 4 and 6 h after the oral treatment. It was observed that the effect of the flour of Passion fruit bark was dose dependent, getting an expressive effect observed in four hours from all doses tested, being more pronounced at the 160 mg/kg dose. This effect was expressed as reduction of basal blood glucose in respect to zero time and can be modeled through a classic dose effect model. It allowed the determination of maximum effect (Emax) and the necessary dose to reach 50 percent of this effect (ED50). After the data modeling, it was gotten a value of Emax = 58,41 percent and ED50 = 23,61 mg/kg. This approach allows the comparison of antyhyperglicemic effect of Passiflora eduliswith other species that present activity lowering the glycemia, through the presence of soluble fibers.