The lente types of Semilente, Lente and Ultralente are also called zinc suspension insulins. Semilente insulin is defined as a short-acting insulin containing zinc microcrystals in an acetate buffer. This insulin is known by two other names: Prompt Zinc and Prompt Lente; this to distinguish it from the Lente and Ultralente insulins which are also part of the zinc suspension group, but whose onsets are slower and whose durations are longer. British Pharmacoepia (BP) and United States Pharmacoepia (USP)'s definitions of semilente insulin: