Impurity profiling of clarithromycin using high-performance liquid chromatography with ultraviolet detection

A Survey of the Quality of Generic???Clarithromycin Products from???18 Countries

OBJECTIVE

This study compared the quality of 65 generic clarithromycin products manufactured in 18 countries with that of the innovator product.

DESIGN

To assess quality, the generic products were examined visually, assayed by high-pressure liquid chromatography for clarithromycin content and impurities, tested for dissolution properties, and compared with the innovator product manufactured by Abbott Laboratories.

RESULTS

This survey found that many generic clarithromycin products were not equivalent to the innovator product and many of these generic products fell short of the approved specifications developed for the innovator product. Overall, 9% (6 of 65) of all generic tablets tested failed to contain between 95% and 105% of the clarithromycin claimed in the label, thus falling short of the approved registered specification for the innovator product. Seventeen percent (1 of 6) of tablets from Latin America (LA), 8% (3 of 38) of tablets from the Asia, Africa, Pacific (AAP) region, and 10% (2 of 21) of tablets from Europe did not contain the amount of clarithromycin drug content claimed in the label. A total of 34% (17 of 50) of the generic products tested released less drug in 30 minutes than did the innovator tablets. Although the majority of these generic products met the dissolution specification requiring that 80% of the drug must dissolve in 30 minutes, one generic product failed to meet this specification with 68% of drug dissolving in 30 minutes. Moreover, 19% (12 of 65) of all the generic products tested exceeded the Abbott Laboratories' 3% limit for total impurities in bulk drug, and 30% (20 of 65) exceeded the Abbott Laboratories' 0.8% limit for the known impurity 6,11 di-O-methyl erythromycin A.

CONCLUSIONS

These results demonstrated that generic tablets are often not comparable in vitro to the innovator product. These findings suggest that results achieved with branded clarithromycin (Abbott Laboratories) should not be extrapolated to generic products. In vivo studies would be needed to determine the clinical relevance of these findings.

A survey of the quality of generic clarithromycin products manufactured in Slovenia and Israel

This study evaluated the quality of 11 generic clarithromycin products obtained in Poland, Slovakia, Slovenia, or Israel and manufactured in Slovenia or Israel. The generic products were examined visually, assayed by high-pressure liquid chromatography for clarithromycin content and impurities, tested for dissolution properties, and compared with the innovator product manufactured by Abbott Laboratories. Fifty-five percent of generic products fell short of the specifications for the innovator product. Ten percent of the generic products did not contain the amount of clarithromycin claimed in the label; 18% released less drug than did the branded tablets in the standard dissolution assay. In light of these results, it is not possible to conclude that all generic tablets are of the same quality as the innovator product; clinical trial results achieved with branded clarithromycin should not be extrapolated to generic products.

Determination of macrolides in biological matrices by high-performance liquid chromatography with electrochemical detection

A liquid chromatographic method for the determination of macrolide antibiotics is described using a cyanopropyl column which proved to be as efficient or superior to the normally used apolar reversed-phase columns. The recovery of the macrolides from water and plasma was 80-90%. Using 0.5 ml of plasma, 30 ng/ml of clarithromycin, 50 ng/ml of roxithromycin and 10 ng/ml of azithromycin could be determined with acceptable precision and accuracy. The method has been employed in pharmacokinetic studies in humans for the determination of roxithromycin, clarithromycin and azithromycin in plasma, serum and other biological matrices. The particular selectivity of the cyanopropyl phase may also allow the simultaneous determination of erythromycin and its prodrug esters.

Analysis of macrolide antibiotics

The following macrolide antibiotics have been covered in this review: erythromycin and its related substances, azithromycin, clarithromycin, dirithromycin, roxithromycin, flurithromycin, josamycin, rokitamycin, kitasamycin, mycinamycin, mirosamycin, oleandomycin, rosaramicin, spiramycin and tylosin. The application of various thin-layer chromatography, paper chromatography, gas chromatography, high-performance liquid chromatography and capillary zone electrophoresis procedures for their analysis are described. These techniques have been applied to the separation and quantitative analysis of the macrolides in fermentation media, purity assessment of raw materials, assay of pharmaceutical dosage forms and the measurement of clinically useful macrolide antibiotics in biological samples such as blood, plasma, serum, urine and tissues. Data relating to the chromatographic behaviour of some macrolide antibiotics as well as the various detection methods used, such as bioautography, UV spectrophotometry, fluorometry, electrochemical detection, chemiluminescence and mass spectrometry techniques are also included.