Weight-Based Erythromycin Capsule Formulation

Three experimental batches of 50 capsules containing 20 mg of erythromycin were formulated with using a weight-based method. Traditionally, our capsules were compounded with a volume-based method, but recent findings have encouraged us to use a weight-based method for hospital preparations [23 (link)]. First, the tapped density of the erythromycin/cellulose mixture was found to be equal to 0.460 g.mL^-1. One gram of pharmaceutical-grade erythromycin (Cooper^® France) and 3.8 grams of microcrystalline cellulose (Cooper^® France) were weighed on a qualified precision balance (Precisa XT220A, Precisa^®). Approximatively 2 mg ± 0.4 mg (one spatula tip) of red carmine (Fagron^® France) were added as a homogenization tracer. The mixture was transferred to a mortar for gentle mixing with a pestle. Fifty hard gelatin capsules (size 4, ivory) were placed on a manual capsule-filling machine (ProFiller 3700, LGA^®). The caps were separated from the empty bodies and the entire mixture was inserted into the capsule bodies. The caps were then replaced, and the capsules were sealed. Routinely, these quantities were multiplied by 6 to obtain batches of 300 hard gelatin capsules.