[Particulate contamination of amino acid solutions for parenteral use]

Three industrial batches of a 10% (w/v) amino acid solution have been checked for particulate contamination. The batches differed in preparative technology and/or type of additives. In particular, one batch was prepared under nitrogen, filled under vacuum and with the addition of sodium metabisulfite and cysteine. The other two batches were simply prepared under nitrogen and differed in the presence or not of cysteine and sodium metabisulfite. Accelerated stability tests were performed (40, 50, e 60 degrees C) and controls were effected both at room (25 degrees C) and refrigerator (6 degrees C) temperature. The results show that the preparation under nitrogen and the presence of cysteine result in an improved chemical stability and allow the particulate contamination level to be maintained within the limits of the Italian Pharmacopoeia. In particular, the batch prepared under nitrogen and filled under vacuum is characterized by a particulate contamination level which remains within the more restrictive limits of the British Pharmacopoeia for the entire period of the stability studies. Moreover, the particulate contamination control performed at 6 degrees C has proved to be a useful predictive tool with regards to batch quality evaluation.