TABLE 2.

Release characteristics of rifampin-loaded microsphere formulations in MM6 and J774 monocytic cell lines^a

Time (days)	Value for MM6 cellsb			Value for J774 cellsb
	Formulation 5	Formulation 6	Formulation 7	Formulation 5	Formulation 6	Formulation 7
2	<0.008c	<0.008c	<0.008	0.026 ± 0.006	<0.008	<0.008c
4	0.037 ± 0.005	0.011 ± 010	0.009 ± 0.0002	0.026 ± 0.004	0.0084 ± 0.0006	0.0097 ± 0.0008
7	0.044 ± 0.001	0.017 ± 0.002	0.005 ± 0.001	0.040 ± 0.005	0.015 ± 0.001	0.026 ± 0.002

^aExperiments were conducted for 7 days as described in Materials and Methods. Rifampin concentrations in cell supernatants were quantitated by means of a bioassay, which is also described in Materials and Methods. Each experiment was conducted in triplicate, and values are reported as the means ± standard errors of the means. 

^bValues are in micrograms of rifampin per milliliter. 

^cDetectable level of the bioassay was 0.008 μg/ml.