Evaluation of density variations to determine impact on sterile compounding

To determine the density variation between (1) the measured density and manually calculated density, (2) density variation of different lots, and (3) density variation of different drug manufacturers in order to support institutions using gravimetric compounding methods.

Seventeen sterile injectable ingredient (drug) vials frequently used to make compounded sterile products (CSPs) were identified based on the ability to ensure that for each drug there were vials produced by 2 different manufacturers and 2 lots produced by the same manufacturer. Each drug's density was measured using a density meter and by manual calculation using the institution's density formula. Density differences were compared between the 2 different methods. Overall, the average drug density difference between the measured versus calculated density was determined to be 0.022. Further analysis revealed the average difference between the different lot numbers of the same manufacturers was 0.005 for the nonhazardous drugs and 0.0001 for the hazardous drugs. The average difference between the different manufacturers of the same drug was determined to be 0.008 for the nonhazardous drugs and 0.001 for hazardous drugs.

No clinically meaningful difference exists when manually calculating a drug's density compared to measuring a drug's density using a density meter. In addition, there does not appear to be a sizeable density variation between the same drugs in separate lots or produced by different manufacturers.