Justification of the effectiveness of antimicrobial preservatives and microbiological control of the medical pencil in the storage process

Abstract

Microbiological purity and stability of medicinal products is a prerequisite for their introduction into production and medical use. The need for microbiological control of medicines is explained by the importance of ensuring their safety and, accordingly, reducing the risk of adverse reactions when used by the consumer.  The purpose of the work is to substantiate the choice and optimal concentration of an antimicrobial preservative, to study the microbiological purity of a medical pencil with reparative, anti-inflammatory, antimicrobial and antiviral effects in accordance with the requirements of the State Pharmacopoeia of Ukraine (SPU) during storage.  Material & methods. The objects of the study are samples of a new drug in the form of a medical pencil. When obtaining a medical pencil, mango extract and oil extract of medicinal plant raw material were used as an APIs (the extract was obtained from sage, marigold, chamomile and eucalyptus), cocoa butter, beeswax, lanolin, carnauba wax, candelilla wax were used as excipients. Propylparaben (Nipazol) and phenoxyethanol were selected as preservatives recommended for the development of medicinal products according to the scientific literature in medium-effective concentrations recommended by the manufacturer. Testing the effectiveness of antimicrobial preservatives and determining the microbiological purity of the dosage form under different temperature conditions for 15 months was carried out according to the State Pharmacopoeia of Ukraine method. Staphylococcus aureus АТСС 6538, Pseudomonas aeruginosa АТСС 9027, Candida albicans АТСС 885-653, Aspergillus brasiliensis АТСС 16404 were used as test microorganisms. Nutrient media and research conditions were used in accordance with the requirements of the State Pharmacopoeia of Ukraine. The criterion for evaluating of antimicrobial preservatives’ effectiveness was determination of the logarithm (lg) of decrease in the number of viable cells of microorganisms during the corresponding period of storage after sample contamination. The microbiological purity of the studied samples was determined immediately after obtaining and during storage at a temperature of 25 ± 2°C and 5 ± 3°C after 3, 6, 9, 12 and 15 months.  The method of surface seeding offered by State Pharmacopoeia of Ukraine was used for the analysis of microbiological purity, the total number of viable aerobic microorganisms (TAMS), the total number of yeast and mold fungi (TYMC) and the absence of bacteria of the Staphylococcus aureus and Pseudomonas aeruginosa family were determined.  Results & discussion. The obtained experimental results showed that, according to microbiological indicators, the samples of the pencil without preservative № 7 do not meet the requirements of the State Pharmacopoeia of Ukraine, because the logarithm of the decrease in the number of viable bacterial microorganisms (Staphylococcus aureus and Pseudomonas aeruginosa) is less than 2.0 and 3.0 after 2 days and 7 days, respectively, and the number of Pseudomonas aeruginosa bacteria continues to increase after 28 days (2.91). The Lg of decrease in the number of viable cells in the samples for the cells of Candida albicans and Aspergillus brasiliensis fungi should be at least 2.0 on the 14th day according to the requirements of the State Pharmacopoeia of Ukraine, while in samples №. 7 we observed 1.82 (Candida albicans) and 1.78 (Aspergillus brasiliensis), which also does not meet the requirements. Thus, the obtained results prove the necessity of adding antimicrobial preservatives to the composition of the developed medical pencil. The research results show that the studied pencil samples with preservatives nipazol 0,04%, 0,06% and phenoxyethanol 0,4%, 0,6% fully meet the requirements of the State Pharmacopoeia of Ukraine (class "A" criterion) in relation to the cells of Staphylococcus aureus microorganisms ATCC 6538, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 885-653 and Aspergillus brasiliensis ATCC 16404. For pencil samples with the preservatives nipazol 0,02% and phenoxyethanol 0,2%, the logarithm of the decrease in the number of viable microorganisms after 2 days of storage was for cultures of Pseudomonas aeruginosa ATCC 9027 was 1.65 and 1.98, which does not meet the requirements of the State Pharmacopoeia of Ukraine (the logarithm of the decrease in the number of viable bacterial cells is less than 2).  On the basis of the conducted studies, the expediency of introducing the medical preservative phenoxyethanol as more effective into the composition of the pencil was established, and the optimal concentration of 0,4% was chosen, further increasing the concentration is not advisable.  Determining the microbiological purity of medical pencil drug samples using the surface seeding method showed that the total number of viable aerobic microorganisms (TAMC) is 10 CFU/g after 12 months of storage at a temperature of 25±2°С and 10 CFU/g after 15 months of storage at a temperature of 5±3°C. The total number of yeast and mold fungi (TYMC) does not exceed 10 CFU/g during the entire storage period (15 months) at two storage temperature regimes. The conducted studies showed that during the entire storage period under different conditions the presence of Staphylococcus aureus and Pseudomonas aeruginosa bacteria was not detected.  Conclusion. Microbiological studies were conducted to study the effectiveness of the antimicrobial preservatives nipazol and phenoxyethanol in the composition of a medical pencil containing mango extract, oil extract of a mixture of medicinal plant raw material and cocoa butter, beeswax, carnauba wax, candelilla wax and lanolin. Based on the obtained results, the expediency of using phenoxyethanol at a concentration of 0.4% as a preservative was experimentally substantiated. The microbiological purity of medical pencil samples was experimentally investigated under different temperature conditions (25 ± 2°С and 5 ± 3°С) during 15 months of storage by the method of surface seeding in accordance with the requirements of the State Pharmacopoeia of Ukraine.

Keywords: antimicrobial preservatives, nipazol, phenoxyetanol, microbiological purity, medical pencil