The next stage in the production of ointments is the introduction of medicinal substances into the ointment base. At the same time, it is necessary to pay attention to the following factors: the degree of dispersion of medicinal substances; their uniform distribution over the entire mass of the base; the method of administration of medicinal substances into the base; time, speed and order of mixing of components; temperature regime, etc. Medicinal substances are injected into ointments taking into account their quantity and physico-chemical properties. They come in three types: soluble in the base; easily soluble in water; insoluble neither in the base nor in water.