Microbiological aspects of heat sterilization of drugs

International Journal of Clinical Pharmacy - In order to calculate the minimum sterilization process conditions to obtain the generally accepted sterility level (less than 1·10?6...     

Quantitative pp65-antigenemia assay for the prediction of human cytomegalovirus disease in HIV-infected patients

OBJECTIVE: To evaluate the ability of a quantified pp65-antigenemia assay to predict the development of human cytomegalovirus (HCMV) disease in patients with an advanced HIV infection. DESIGN: A prospective longitudinal study between March 1993 and December 1996. Blood samples for the pp65-antigenemia assay were drawn at 2-3 month intervals. SETTING: AIDS department of an institutional tertiary care centre. PATIENTS: A total of 101 HIV-infected patients with CD4 lymphocyte counts of 100/mm3 or less were enrolled. Ninety-seven patients were eligible for analysis. All patients gave informed consent. MAIN OUTCOME MEASURES: The development of HCMV disease. RESULTS: Of the 97 patients, 24 developed HCMV disease after a median follow-up of 10.6 months. Three months before the development of HCMV disease, an increase in the median number of pp65-antigen-positive leukocytes was observed. The highest combination of sensitivity (45%) and specificity (94%) for the development of HCMV disease within the next 3 months was found when an assay cut-off level of 48/10(5) pp65-antigen-positive leukocytes was applied, with a positive predictive value (PPV) for the development of HCMV disease of 75%. The Kaplan-Meier estimate of HCMV disease-free survival after patients reached 48/10(5) or more antigen-positive leukocytes on longitudinal follow-up was a median 3.7 months [95% confidence interval (CI), 2.5-8.5]. The hazard ratio (HR) of this threshold level for the development of HCMV disease was 9.6 (95% CI, 4.2-21.8). CONCLUSION: Longitudinal follow-up using the pp65-antigenemia assay of HIV-infected patients with a low CD4 lymphocyte count improves the identification of patients who will develop HCMV disease in the foreseeable future, and should be considered for the selection of patients who may benefit from pre-emptive HCMV treatment.     

Microbiological aspects of heat sterilization of medicines

In order to verify whether the sterilization process of 60 min at 100°C for invert sugar 20% is sufficiently effective to attain the generally accepted probability of survival of maximum 1×10^–6, we determined the bioburden and the bioburdens heat resistance for this product.We examined 98 bottles by the membrane filtration method and found 84 bottles with o colony forming units (CFU's) and 14 bottles with 1–9 CPU's. Because none of the isolated CPU's was heat resistant (Bacillus species), we isolated heat resistant CPU's from the environment and determined the heat resistance in invert sugar, water and NaCl solution 0.9% of four differentBacillus species. The results in invert sugar for the most heat resistantBacillus species were a D-value of 0.92 min at 100°C.For the determination of the D-value the end-point method is the most practical one, and the D-value calculation with the most probable number method is sufficiently accurate. Because of unavoidable inaccuracies in the experimentally determined D-value, safety margins of 100% have to be taken into account in the sterilization process calculations in which these D-values are used. Hence, in our case, we have to use a D-value of 2×0.92 min in the sterilization process calculation for invert sugar 20%.The maximum bioburden in the examined 98 test bottles was 9 CFU's. The maximum heat resistant bioburden which must be used in sterilization process calculations may be safely fixed at 10% of the total bioburden, therefore we have to use 0.9 micro-organisms in our calculation. Hence using these values of 0.9 microorganisms and the maximum bioburden heat resistance (D-value=2×0.92 min at 100°C), the minimum sterilization process time for invert sugar 20% in our hospital pharmacy is calculated to be 10.96 min at 100°C.