Microbiological examination of aerosols and sprays

Scientific relevance. Medicinal products formulated as aerosols and sprays are increasingly used in clinical practice, which makes the control of their quality, including microbiological testing, a highly topical issue. The current regulatory standards for microbiological testing of medicines provide little information on the quality control of metereddose aerosols. Proper microbiological sampling of these medicinal products can be difficult because of their primary packaging. The specialised analytical procedures set forth in international standards require verification and standardisation before use. Medicinal products in the form of sprays, despite being free from the disadvantages of aerosols, are more susceptible to the risk of microbial contamination.Aim. The study aimed to describe specific aspects of sampling, to analyse the results of microbiological testing of aerosols and sprays, and to study the spectrum of microbial contaminants in these dosage forms.Materials and methods. The authors retrospectively analysed the microbiological quality and sterility data for 181 batches of sprays, aerosols, and other inhalation dosage forms. The data were obtained at the Scientific Centre for Expert Evaluation of Medicinal Products of the Ministry of Health of Russia in 2020–2022. The Microbiology Laboratory tested the dosage forms according to the specifications provided by the manufacturers. The analysts used well-established testing procedures outlined in the current pharmacopoeias of the Russian Federation and the Eurasian Economic Union.Results. The microbial counts exceeded the acceptable limits in 2.8% of the batches tested. The authors identified the microbial species that contaminated the medicinal products found to be non-compliant with regulatory requirements. Most of the non-compliant sprays that contained benzalkonium chloride as an antibacterial preservative were contaminated with Burkholderia cepacia complex species.Conclusions. The authors consider it relevant to conduct research aiming at using the findings on potential contaminants to improve microbiological testing procedures for aerosols and sprays.