ABSTRACT
Capreomycin (CS) is an antitubercular drug active against several Mycobacterium strains, in particular, against M. Avium. In spite of its activity, it is considered a second line drug because it can induce severe renal and hepatic damages when administered as free drug. However, it is possible to employ drug delivery systems, such as liposomes, to reduce the toxicity of the peptide without loss of its biological activity. For this purpose, appropriately validated time and money saving analytical methods are needed for a careful capreomycin dosage. In the present paper, UV spectroscopy and a reverse-phase HPLC (RP-HPLC) were investigated as alternative methods for capreomycin quantitative analysis. These techniques were validated against the USP XXVI microbiological turbidimetric assay and the normal-phase HPLC (NP-HPLC) method reported in the British Pharmacopoeia 2003. The results obtained showed that either UV spectrophotometry or RP-HPLC are techniques having higher accuracy and reproducibility with respect to the microbiological assay. Moreover, the RP-HPLC method provided improved performances if compared to NP-HPLC. In fact, RP-HPLC showed: (i) enhanced sensitivity and (ii) increased resolution. Thus we propose RP-HPLC and UV as valid alternative methods to the conventional procedures for capreomycin quantitative analysis.
Subject(s)
Antibiotics, Antitubercular/analysis , Capreomycin/analysis , Antibiotics, Antitubercular/administration & dosage , Bacillus subtilis/drug effects , Biological Assay , Calibration , Capreomycin/administration & dosage , Chemistry, Pharmaceutical , Chromatography, High Pressure Liquid , Half-Life , Indicators and Reagents , Klebsiella pneumoniae/drug effects , Linear Models , Liposomes , Microscopy, Electron, Transmission , Nephelometry and Turbidimetry , Phospholipids , Reproducibility of Results , Spectrophotometry, UltravioletABSTRACT
The aim of this work was to evaluate unilamellar liposomes as new potential capreomycin sulfate (CS) delivery systems for future pulmonary targeting by aerosol administration. Dipalmitoylphosphatidylcholine, hydrogenated phosphatidylcholine, and distearoylphosphatidylcholine were used for liposome preparation. Peptide-membrane interaction was investigated by differential scanning calorimetry (DSC) and attenuated total internal reflection Fourier-transform infrared spectroscopy (ATIR-FTIR). Peptide entrapment, size, and morphology were evaluated by UV spectrophotometry, photocorrelation spectroscopy, and transmission electron microscopy, respectively. Interaction between CS and the outer region of the bilayer was revealed by DSC and ATIR-FTIR. DSPC liposomes showed enhanced interdigitation when the CS molar fraction was increased. Formation of a second phase on the bilayer surface was observed. From kinetic and permeability studies, CS loaded DSPC liposomes resulted more stable if compared to DPPC and HPC over the period of time investigated. The amount of entrapped peptide oscillated between 10% and 13%. Vesicles showed a narrow size distribution, from 138 to 166 nm, and a good morphology. These systems, in particular DSPC liposomes, could represent promising carriers for this peptide.
Subject(s)
Anti-Bacterial Agents/administration & dosage , Capreomycin/administration & dosage , Drug Delivery Systems , Liposomes/chemistry , Anti-Bacterial Agents/chemistry , Capreomycin/chemistry , Drug Carriers , Drug Stability , Kinetics , Particle Size , Permeability , Spectroscopy, Fourier Transform Infrared , Technology, PharmaceuticalABSTRACT
Leucinostatin A (Leu-A) is a nonapeptide exerting a remarkable activity especially against Candida albicans and Cryptococcus neoformans; nevertheless, its employment is limited due its toxicity. Therefore, we recently developed liposomal formulations, as suitable delivery systems, in order to increase its therapeutic index. However, liposomes present disadvantages related to their long-term instability. For this reason poly(lactic-co-glycolic) nanospheres (NS) were chosen as alternative colloidal carriers for Leu-A delivery. NS were formulated by spontaneous emulsification solvent diffusion method. This study investigates the effects of different parameters on drug encapsulation efficiency and particle size as well. The best preparation obtained was also characterized for its in vitro release, in vivo acute toxicity (LD50), and effectiveness against C. albicans in mice. In vitro release was performed over 100 h and resulted sufficiently sustained with more than 93% of the peptide released. Acute toxicity showed that the LD50 was increased more than 18-fold and the study on systemic candidiasis models revealed high effectiveness of the NS in reducing either the growth of fungal colonies in infected mice liver or in the mortality index. In conclusion, we can propose that Leu-A loaded NS could represent a new promising therapeutic system against Candida infection.
