Abstract: OBJECTIVE： In vitro cytotoxicity test was used to evaluate biological safety of 23 pharmaceutical packaging materials. METHODS： The sample mass/extract volume ratio was set to be 0.2 g/mL. Extracts of pharmaceutical packaging materials were prepared with MEM medium (37 ℃，24 h)，sodium chloride injection and deionized water (121 ℃，1 h). Mouse fibroblasts L929 were cultured in a 96-well plate. 100 μL of sample extracts was added to each well and cultured for 48 hours. The absorbance was measured with a microplate reader. According to the relative proliferation of the cells (RGR) for grading，grade ≤ 1 was negative，grade 2 was suspicious positive，and grade ≥ 3 was positive. RESULTS：The 23 samples of MEM medium extracts ranged between 0-1 grade. Nine samples tested in sodium chloride injection extracts were suspicious positive above grade 2，of which 3 were positive above grade 3. The suspected positive results of 9 test samples were rechecked with deionized water extract，only 3 were suspected positive above grade 2，of which 1 was positive at grade 3. CONCLUSION：In vitro test，excluding the interference of osmotic pressure and pH value， was conducted by culture medium prepared with the maximum dissolution extract as the solvent. The approach significantly increased the detection of positive results of pharmaceutical packaging materials.

Key words: pharmaceutical packaging materials, mouse fibroblasts L929, pretreatment method, dissolution, biosafety