Development of lipid nanocarriers for tuberculosis treatment: evaluation of suitable excipients and nanocarriers

BACKGROUND

Lipid nanocarriers have been widely tested as drug delivery systems to treat diseases due to their bioavailability, controlled release, and low toxicity. For the pulmonary route, the Food and Drug Administration favors the use of substances generally recognized as safe, as well as biodegradable and biocompatible to minimize the possibility of toxicity. Tuberculosis (TB) remains a public health threat worldwide, mainly due to the long treatment duration and adverse effects. Therefore, new drug delivery systems to treat TB are needed.

OBJECTIVE

Physicochemical characterization of different lipid-based nanocarriers was used to optimize carrier properties. Optimized systems were incubated with Mycobacterium tuberculosis to assess whether lipid-based systems act as an energy source for the bacteria, which could be counterproductive to therapy.

METHOD

Several excipients and surfactants were evaluated to prepare different types of nanocarriers using high-pressure homogenization.

RESULTS

A mixture of trimyristin with castor oil was chosen as the lipid matrix after differential scanning calorimetry analysis. A mixture of egg lecithin and PEG-660 stearate was selected as an optimal surfactant system as this mixture formed the most stable formulations. Three types of lipid nanocarriers, solid lipid nanoparticles, nanostructured lipid carriers (NLC), and Nano emulsions, were prepared, with the NLC systems showing the most suitable properties for further evaluation. It may provide the advantages of increasing the entrapment efficiency, drug release, and the ability to be lyophilized, producing powder for pulmonary administration being an alternative to entrap poor water-soluble molecules.

CONCLUSION

Furthermore, the NLC system can be considered for use as a platform for the treatment of TB by the pulmonary route.

Factors associated with ciprofloxacin and levofloxacin resistance in gram-negative bacilli isolated from urinary tract infections

Background and Objectives: Fluoroquinolones are one of the most frequently prescribed antimicrobial classes for the treatment of urinary tract infections (UTIs) of both hospital and community origin. This study aims to determine the frequency and the factors associated with resistance to ciprofloxacin and levofloxacin in gram-negative bacilli isolated from patients with UTIs treated in a hospital in southern Brazil. Methods: We performed a transversal and analytical study based on cases of urinary tract infection caused by gram-negative bacteria (GNB) in patients at the Hospital Universitário Dr. Miguel Riet Correa Jr. in Rio Grande/RS from August 2012 to July 2013. Independent variables such as the age and sex of patients, source of infection of the UTI and the characteristics of the bacterial strains were analyzed. Results: Of the 562 GNB analyzed, the total frequencies of ciprofloxacin and levofloxacin resistance were, respectively, 25.5% and 23.3% in strains of community origin and 62.6% and 59% in strains of hospital origin. The risk factors associated with ciprofloxacin and levofloxacin resistance were sex (male), infections acquired in the hospital, longer hospitalization times, and the presence of extended spectrum β-lactamases (ESBLs) in the bacterial strains. Conclusions: We observed a strong association between GNB resistance, the time spent in the hospital and the presence of ESBLs. To control antibiotic resistance and to reduce the cost of health care, a strong hospital policy of vigilance is required regarding the use of and resistance to antibiotics.

ANTHELMINTIC ACTIVITY OF LAPACHOL, β-LAPACHONE AND ITS DERIVATIVES AGAINST Toxocara canis LARVAE

Anthelmintics used for intestinal helminthiasis treatment are generally effective; however, their effectiveness in tissue parasitosis (i.e. visceral toxocariasis) is moderate. The aim of this study was to evaluate the in vitro activity of lapachol, β-lapachone and phenazines in relation to the viability of Toxocara canis larvae. A concentration of 2 mg/mL (in duplicate) of the compounds was tested using microculture plates containing Toxocara canis larvae in an RPMI-1640 environment, incubated at 37 °C in 5% CO2 tension for 48 hours. In the 2 mg/mL concentration, four phenazines, lapachol and three of its derivatives presented a larvicide/larvistatic activity of 100%. Then, the minimum larvicide/larvistatic concentration (MLC) test was conducted. The compounds that presented the best results were nor-lapachol (MLC, 1 mg/mL), lapachol (MLC 0.5 mg/mL), β-lapachone, and β-C-allyl-lawsone (MLC, 0.25 mg/mL). The larvae exposed to the compounds, at best MLC with 100% in vitro activity larvicide, were inoculated into healthy BALB/c mice and were not capable of causing infection, confirming the larvicide potential in vitro of these compounds.

Inhaled corticosteroids increase the risk of oropharyngeal colonization by Streptococcus pneumoniae in children with asthma

BACKGROUND AND OBJECTIVE

Recent studies have raised concerns about the link between use of inhaled corticosteroids (ICS) and risk of pneumonia in patients with chronic obstructive pulmonary disease. This cross-sectional study aimed to investigate the association between ICS and oropharyngeal colonization by Streptococcus pneumoniae (S. pneumoniae) among children (up to 18 years old) with asthma.

METHODS

Two age-matched groups of patients were consecutively recruited: (i) exposed group: children who had persistent asthma and were being treated with daily ICS for at least 30 days and (ii) non-exposed group: children who had asthma and were not being treated with ICS at study entry. Oropharyngeal specimens from the tonsillar area and posterior pharyngeal wall were collected. S. pneumoniae was identified according to National Committee for Clinical Laboratory Standards recommendations.

RESULTS

A total of 200 consecutive patients were recruited and 192 (96 in each group) were included in the analysis. In the exposed group, the mean daily dose of ICS was 400 µg of beclomethasone or equivalent and the mean duration of treatment was 8.6 months. The prevalence of oropharyngeal colonization by S. pneumoniae was higher in the exposed group compared with the non-exposed group (27.1% vs 8.3%, P = 0.001). After adjusting for potential confounders, use of ICS was an independent risk factor for oropharyngeal carriage of S. pneumoniae, with an adjusted prevalence ratio of 3.75 (95% confidence interval: 1.72-8.18, P = 0.001).

CONCLUSIONS

Regular use of ICS is associated with an increased risk of having oropharyngeal colonization by S. pneumoniae in children with asthma.