Survey on Stability of Pharmaceutical Products in National List of Essential Drugs Used in Hospitals in Thailand

Abstract

A survey on stability problems of essential drugs purchased by 989 hospitals and provincial public health offices in Thailand has been carried out since 1993. During 1990-1997, selective sampling of 1799 cases related to stability problems of 206 drug substances was undertaken through questionnaires sent to 658 government hospitals and from laboratory findings. The stability problems were identified and categorised into pharmacopoeial non-compliance (25.2 per cent) and physical appearances (74.8 per cent). Most problems (91.7 per cent) occur in locally-made drug products. In addition, 84.2 per cent of drugs were found to have no expiration dates stated on the labels and instability was found between <15 days and over 11 years after manufacturing, with the highest frequency of occurrences falling within 10-12 months (45.6 per cent). For products with a stated shelf-life (15.8 per cent), stability problems occurred from within 2 months after manufacturing to over 5 years; with maximum occurence at 61-70 per cent of shelf-life. Factors affecting the stability of drug products have already been stated in many textbooks on stability. Therefore, to avoid stability problems, proper formulations must be developed using standard quality raw material and packaging under Good Manufacturing Practices requirements. The means of drug transportation to hospitals, drug distribution chains and storage conditions in hospitals have also been considered as factors creating stability problems. The authors suggest that manufacturers should use high-quality active ingredients, suitable formulations and packaging which comply with current Good Manufacturing Practices, in order to prevent stabilty problems occurring in drug products. Proper storage conditions in accordance with the labelling should be strictly practiced in hospitals. Moreover, stability study on transportation factor should be included in stability study protocol for at least 30 days.