Sensitive and specific determination of clindamycin in human serum and bone tissue applying liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

A sensitive human bone assay for quantitation of tigecycline using LC/MS/MS

Tigecycline (Tygacil,Wyeth) is a first-in-class, broad spectrum antibiotic with activity against multiple-resistant organisms. In order to address the unexpectedly low tigecycline concentrations in human bone samples analyzed using a LC/MS/MS method developed elsewhere, we have developed and validated a new and sensitive human bone assay for the quantitation of tigecycline using LC/MS/MS. The new method utilizes the addition of a stabilizing agent to the human bone sample, homogenization of human bone in a strong acidic-methanol extraction solvent, centrifugation of the bone suspension, separation by liquid chromatography, and detection of tigecycline by mass spectrometry. Linearity was demonstrated over the concentration range from 50 to 20,000 ng/g using a 0.1g human bone sample. The intra- and inter-day accuracy of the assay was within 100+/-15%, and the corresponding precision (CV) was <15%. The stability of tigecycline was evaluated and shown to be acceptable under the assay conditions. The extraction recovery of tigecycline with the current method was 79% when using radio-labeled rat bone samples as a substitute for human bone samples. Twenty-four human bone samples collected previously from volunteers without infections who had elective orthopedic surgery after receiving a single dose of tigecycline were re-analyzed using the current validated method. Tigecycline concentrations in these samples ranged from 238 to 794 ng/g with a mean value 9 times higher than the mean concentration previously reported. The data demonstrated that the current method has significantly higher extraction efficiency than the previously reported method.

Update on clindamycin in the management of bacterial, fungal and protozoal infections

Lincomycin and clindamycin are the only members of the relatively small lincosamide antimicrobial class marketed for use in humans. This paper only reviews data regarding clindamycin, with an emphasis on data published over the last decade. Clindamycin exhibits a broad spectrum of antimicrobial activity, including Gram-positive aerobes/anaerobes, Gram-negative anaerobes and select protozoa (Toxoplasma gondii, Plasmodium falciparum, Babesia spp.) and fungi (Pneumocystis jiroveci). It still enjoys use in the therapy and prophylaxis of a large number of bacterial, protozoal and fungal infections, despite > 40 years of clinical use. However, the spectre of resistance by an increasing number of microorganisms is beginning to cast a shadow over the future use of this valuable agent. With the emergence and spread of infections due to community-acquired methicillin-resistant Staphylococci (for which clindamycin is a first-line agent), it is hoped that the issues of resistance can be mitigated and the use of clindamycin extended for at least the foreseeable future.

Separation and characterization of clindamycin and related impurities in bulk drug by high-performance liquid chromatography-electrospray tandem mass spectrometry

A simple high-performance liquid-electrospray ionization tandem mass spectrometric (HPLC-ESI-MSn) method has been developed for the rapid identification of clindamycin and its related minor impurities in bulk drug. The ESI-MSn results obtained allowed us to propose plausible schemes for their fragmentations, which were confirmed further by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) using collision-induced dissociation (CID) method at high mass resolution. The positive ESI-MS/MS of clindamycin and its derivative compounds showed some diagnostic fragments, such as the neutral losses of H2O, HCl, methanethiol and 2-methylthio-ethenol, and the residue of 3-propyl-N-methylpyrrolidine and 3-ethyl-N-methylpyrrolidine, which are specific and useful for the identification of the lincosamide antibiotics and related impurities. According to the fragmentation mechanism of mass spectrometry and HPLC-UV-ESI-MSn data, six impurities of clindamycin have been identified on-line. Additionally, the positive ion mode extracted ion current (EIC) method has been used to separate and identify these lincosamide compounds.

Simple method for the assay of clindamycin in human plasma by reversed-phase high-performance liquid chromatography with UV detector

A rapid and simple high-performance liquid chromatography (HPLC) method was developed and validated for the quantification of clindamycin in human plasma. After precipitation with 50% trichloroacetic acid (TCA) containing the internal standard, propranolol, the analysis of the clindamycin level in the plasma samples was carried out using a reverse-phase cyano (CN) column with ultraviolet detection (204 nm). The chromatographic separation was accomplished with an isocratic mobile phase consisting of acetonitrile-distilled water-7.6 mm tetramethylammonium chloride (TMA) (60:40:0.075, v/v/v), adjusted to pH 3.2. The proposed method was specific and sensitive with a lower limit of quantitation (LLOQ) of 0.2 microg/mL. This HPLC method was validated by examining the precision and accuracy for inter- and intraday analysis in the concentration range 0.2-20.0 microg/mL. The relative standard deviations (RSD) in the inter- and intraday validation were 6.1-14.9 and 6.0-16.1%, respectively. In the stability test, clindamycin was found to be stable in human plasma during the storage and assay procedure. The present HPLC method was applied to the analysis of samples taken up to 12 h after a single oral administration of clindamycin in healthy volunteers.

A new HPLC/UV method for the determination of clindamycin in dog blood serum

A new HPLC method for the quantitative determination of clindamycin in dog blood serum at levels down to 80 ng/ml has been developed. Samples were deproteinised with acetonitrile and clindamycin was extracted with dichloromethane. Chromatographic analysis was carried out on a C(18) reversed-phase analytical column in the presence of tetra-n-butylammonium hydrogen sulfate (TBA), as an ion-pairing agent. UV detector wavelength was set at 195 nm. The assay was validated for a concentration range from 80 to 6000 ng/ml serum. Good linearity was observed in the entire concentration range. The limit of quantification (LOQ) was 80 ng/ml and the limit of detection (LOD) was 60 ng/ml. Regression of accuracy data yielded an overall mean recovery value (+/-S.E.M.) of 93.98+/-0.42%, while precision data revealed coefficient of variation (CV (%)) values lower than 4.41%. The method was successfully applied to determine drug concentrations in serum samples from dogs that had been orally administered clindamycin hydrochloride.

Quantitative analysis of lincomycin in animal tissues and bovine milk by liquid chromatography electrospray ionization tandem mass spectrometry

A sensitive method for determining lincomycin in bovine milk, animal muscles and organs using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) is presented. Milk and homogenized animal tissues were extracted with acetonitrile twice after addition of an appropriate amount of clindamycin, a lincosamide analogue as the internal standard. The combined extracts were finally made up to 10 ml with distilled water and partitioned with hexane to remove the animal fats prior to analysis. Analytes in the extracts were separated on a reversed phase C18 column (250 mm x 2.1 mm, 5 microm) using a mobile phase of a 3:7 (v/v) mixture of 0.1% formic acid in acetonitrile and an ammonium formate buffer (ammonium formate:formic acid:acetonitrile:water, 1:5:50:950, v/v/v/v) running at a flow rate of 0.2 ml min(-1). Presence of lincomycin was confirmed by the presence of two characteristic product ions at m/z 126.1 and 359.2 within a defined retention time window from the precursor ion at m/z 407.2, whilst quantification was based on the relative ratio of the sum of the peak areas at m/z 126.1 and 359.2 for lincomycin to that of the internal standard (peaks at m/z 126.1 and 377.2) with reference to the respective ratios of the calibration standards. The validated method that was found to have linear responses in the calibration range from 25 to 3000 microg kg(-1) and satisfactory intra-day and inter-day accuracy (94.4-107.8%) and precision (1.3-7.8%) at concentrations ranging from 100 to 1500 microg kg(-1) has been applied to real samples and matrix spiked samples. It is considered robust and suitable for analysis of lincomycin in milk and animal tissues.

Determination of lincomycin and tylosin residues in honey using solid-phase extraction and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

An analytical method for the determination of residues of the antibiotic drugs lincomycin and tylosin in honey was developed. The procedure employed a solid-phase extraction for the isolation of lincomycin and tylosin from diluted honey samples. The antibiotic residues were subsequently analyzed by reversed-phase HPLC with atmospheric pressure chemical ionization mass spectrometric detection. Average analyte recoveries for lincomycin and tylosin ranged from 84 to 107% in replicate sets of honey samples fortified with drug concentrations of 0.01, 0.5, and 10 microg/g. The method detection limits were determined to be 0.007 and 0.01 microg/g for lincomycin and tylosin, respectively.

Lincomycin, cultivation of producing strains and biosynthesis

Lincomycin and its derivatives are antibiotics exhibiting biological activity against Gram-positive bacteria. The semi-synthetic chlorinated lincomycin derivative is used in clinical practice. The chemical structure of lincosamide antibiotics, cultivation of producing strains and analytical procedures used for separation and isolation of these compounds are described in this review. Biosynthesis of lincomycin and related compounds and its genetic control are briefly discussed.

Quantitative analysis of clindamycin in human plasma by liquid chromatography/electrospray ionisation tandem mass spectrometry using d1-N-ethylclindamycin as internal standard

A new method for the quantitative analysis of clindamycin in human plasma by liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) is presented. Recently published methods possess a disadvantage because of their use of internal standards with extraction and ionisation properties different from those of clindamycin. To avoid these problems, d(1)-N-ethylclindamycin was synthesised for use as internal standard by N-demethylation and subsequent d(1)-N-ethylation. Plasma sample preparation was done by an easy and rapid liquid-liquid extraction using ethyl acetate. The method was validated in the expected concentration range for a pharmacokinetic study. Calibration graphs were linear within the range 0.05-3.2 microg/mL plasma. Intra-day precision was between 0.90% (2.8 microg/mL) and 3.25% (0.05 microg/mL), inter-day variability was found to be between 1.33% (0.7 microg/mL) and 2.60% (0.05 microg/mL). Inter-day accuracy showed deviations between 0.4% (0.05 microg/mL) and -4.8% (0.2 microg/mL). The method is simple and robust, and has been applied to the batch analysis of clindamycin during a pharmacokinetic study.

Determination of clindamycin in animal plasma by high-performance liquid chromatography combined with electrospray ionization mass spectrometry

A method for the quantification of clindamycin in animal plasma using high-performance liquid chromatography combined with electrospray ionization mass spectrometry (LC/ESI-MS/MS) is presented. Lincomycin is used as the internal standard. The sample preparation includes a simple deproteinization step with trichloroacetic acid. Chromatographic separation is achieved on an RP-18 Hypersil column using gradient elution with 0.01 M ammonium acetate and acetonitrile as mobile phase. Good linearity was observed in the range 0-10 microg ml(-1). The limit of quantification of the method is 50 ng ml(-1) and the limit of detection is 1.3 ng ml(-1). The method was shown out to be of use for pharmacokinetic studies of clindamycin formulations in dogs.

Analysis of peptides using partial (no discharge) atmospheric pressure chemical ionization conditions with ion trap mass spectrometry

A novel approach, based on the use of atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-ITMS) conditions, but without using corona discharge, was used to analyze peptides. The proposed method was applied to three standard peptides (bombesin, trityrosine and tyrosine-glycine-glycine) as well as peptides obtained through enzymatic digestion of two standard proteins (horse cytochrome c and horse myoglobin).

Analysis of protein ions in the range 3000-12000 Th under partial (no discharge) atmospheric pressure chemical ionization conditions using ion trap mass spectrometry

A new approach, based on the use of atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-ITMS), but without a corona discharge, was investigated for application to creating and monitoring protein ions. It must be emphasized that APCI is not usually used in protein analysis. In order to verify the applicability of the proposed method to the analysis of proteins, two standard proteins (horse cytochrome c and horse myoglobin) were analyzed. A mixture of the two proteins was also analyzed showing that this novel approach, based on the use of APCI, can be used in the analysis of protein mixtures.