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Interlaboratory study comparing the microbiological potency of spiramycins I, II and III
1Laboratorium voor Farmaceutische Chemie en Analyse van Geneesmiddelen, Faculteit Farmaceutische Wetenschappen, Katholieke Universiteit Leuven, Belgium.
Abstract:
An interlaboratory study has been performed to determine the relative potencies of spiramycins (SPMs) I, II and III by diffusion or/and turbidimetric assays with Bacillus subtilis or Staphylococcus aureus as the test organisms. Six laboratories from three countries participated. Experimental procedures were according to the European Pharmacopoeia, 3rd ed. The activity of SPM I is markedly higher than that of SPM II and III. By diffusion, the activities of SPM II and III relative to SPM I were found to be 57 and 72%, respectively. The interlaboratory relative standard deviations (RSD) varied from 3.6 to 16.3%. By turbidimetry, the activities of SPM II and III relative to SPM I were found to be 45 and 52%, respectively. The interlaboratory RSD values varied from 2.6 to 7.7%. The results of the study were analyzed according to the ISO 5725-2 guidelines to determine the repeatability, the between-laboratory and the reproducibility variances of both methods.
Insights
This study compared the potency of spiramycin (SPM) I, II, and III using microbial assays. Spiramycin I demonstrated significantly higher activity than SPM II and III across multiple laboratories and methods.
Area of Science:
- Microbiology
- Pharmacology
- Analytical Chemistry
Background:
- Spiramycins (SPMs) are macrolide antibiotics with varying potencies.
- Accurate determination of relative potencies is crucial for pharmaceutical applications.
- Standardized interlaboratory studies ensure reliable comparative data.
Purpose of the Study:
- To determine the relative potencies of spiramycin I, II, and III.
- To compare the performance of diffusion and turbidimetric assays for SPM potency determination.
- To assess interlaboratory variability in SPM activity measurements.
Main Methods:
- An interlaboratory study involving six laboratories across three countries.
- Assays performed according to European Pharmacopoeia, 3rd ed. guidelines.
- Utilized Bacillus subtilis and Staphylococcus aureus as test organisms for diffusion and turbidimetric assays.
Main Results:
- Spiramycin I exhibited markedly higher activity compared to SPM II and III.
- Diffusion assays showed SPM II and III activities at 57% and 72% of SPM I, respectively.
- Turbidimetric assays indicated SPM II and III activities at 45% and 52% of SPM I, respectively.
- Interlaboratory relative standard deviations ranged from 2.6% to 16.3%.
Conclusions:
- Spiramycin I is the most potent of the three variants.
- Both diffusion and turbidimetric methods are viable for relative potency determination, with turbidimetry showing lower interlaboratory variability.
- The study provides robust data on SPM potencies and assay reliability for quality control.