Page 16 - controlled drug delievery
P. 16
II- Biological Factors
1- Absorption
• A formulator has to consider rate & uniformity of absorption:
• Poor candidates for Oral SR/CR formulation are:
• Slowly absorbed drugs so that Ka <<< Kr?
• Drugs with narrow absorption window i.e specific absorption
site in the GIT
E.g. Ferrous sulphate is mainly absorbed from the jejunum and
upper duodenum?
Gastric-retentive delivery system
• Drugs with erratic absorption e.g. Kanamycin & gentamicin
