Isolation and identification of four major impurities in capreomycin sulfate.

Capreomycin has good clinical utility to treat multidrug resistant tuberculosis, but it is only used as a second line drug due to its adverse reactions. Literature has demonstrated that the toxicity of capreomycin product is significantly influenced by the impurities in it. Unfortunately, so far, no one impurity in capreomycin has ever been isolated and definitely identified due to its extremely strong basic character and high polarity. An ion-pair method reported in literature can provide separation of capreomycin and its impurities, but it is hard to be used for the preparative purpose. In this study, this ion-pair method was further improved to detect more impurities in capreomycin sulfate substance. Besides the four main components (IA, IB, IIA and IIB), four impurities (impurity A-D) with their contents much higher than the identification threshold were observed. Furthermore, a two dimensional (2D) LC quadrupole-time of flight (Q-TOF) MS method was established to realize high resolution MS analysis of these impurities. For the purpose of preparative isolation, a hydrophilic interaction chromatography (HILIC) method was established. The four main components were well isolated, but unfortunately, the four impurities were co-eluted with each other or with IB by the HILIC method. Fortunately, the degradation experiments revealed that IA and IB could yield clean impurity A and B respectively in acidic medium, and can yield clean impurity D and C respectively in alkaline medium. Therefore, IA and IB were first isolated by the preparative HILIC method, then pure IA and IB underwent acid degradation and base degradation separately and followed by re-isolation by the HILIC method to obtain pure impurity A-D respectively. Based on Q-TOF MS and NMR analysis, the structures (including absolute configuration) of the four isolated impurities were definitely identified.

Quantitative assay of capreomycin oleate levels in a drug formulation for inhalation with a fully validated HPLC method.

Capreomycin sulfate (CS), a mixture of 4 closely related compounds (powder mainly comprised of 2 forms), commonly injected intramuscularly is intended to be administer by inhalation for the treatment of pulmonary tuberculosis. In order to increase the drug residence time in the lung, capreomycin hydrophobicity was enhanced by substituting sulfate with oleate, thus obtaining capreomycin oleate (CO). The generation of a more hydrophobic ion-pair allows the reduction of the drug solubilisation in the bronchoalveolar fluids as well as its systemic absorption. The aim of the present study was to quantify CO in an in-house prepared drug formulation for inhalation. In this regard, a Hydrophilic Liquid Interaction Chromatography (HILIC) method was optimized with acetonitrile (ACN)/water containing eluents and a diol-type stationary phase. The optimal eluent composition [ACN/water-80/20 (v/v), 20mM ammonium formate, 3.0 wspH] produced a good separation (α equal to 1.15) between the two main peaks. The developed HILIC method succeeded in the quantitative assay of CO in the drug formulation and was fully validated. Very good precision and accuracy in the short- and long-period along with appreciably low LOD and LOQ values (respectively 1.75 and 5.25µg/mL) turned out.

Development and validation of a liquid chromatographic method for the analysis of capreomycin sulfate and its related substances.

A gradient LC method for the analysis of capreomycin sulfate and its related substances was developed. The chromatographic conditions include the use of a Hypersil base deactivated C(18) (250 mm x 4.6mm, 5 microm) column maintained at 25 degrees C, a mobile phase containing acetonitrile, phosphate buffer pH 2.3 and 0.025M hexanesulfonate at a flow rate of 1.0 mL/min and UV detection performed at 268 nm. Good separation of the four active components of capreomycin and eleven unknown impurities was achieved. A system suitability test to check the quality of the separation is specified. The method shows good repeatability, linearity and robustness.

UV spectroscopy and reverse-phase HPLC as novel methods to determine Capreomycin of liposomal fomulations.

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.

Chromatographic analysis of antituberculosis drugs in biological samples.

Numerous chromatographic and non-chromatographic methods of analysis for anti-tuberculosis drugs and metabolites in biological tissues have been discussed in this review. Depending upon the analytical methodology selected, limits of detection range from microgram to picogram levels. A number of examples have been given of the correlation between different types of assay procedures. The metabolism and pharmacokinetics have been described along with some of the commonly associated problems of sample collection and storage.