Rate of absorption of IM injection is determined by:Repeat, refer Q 97 2007

Ans: a (Vascularity)Ref: KDT 6th ed. Pg. 15Rate of absorption of IM injection is determined by vascularity.Factors affecting absorption of a drug are:Aqueous solubility: Drugs given in solid form mustdissolve in aqueous biophase before they are absorbed.Hence drugs given as watery solution is absorbed fasterthan when the drug is given in solid form.Concentration: Passive diffusion depends on concentrationgradient; drug given as concentrated solution is absorbedfaster than from dilute solution.Area of absorbing surface: Larger the area, faster theabsorption.Vascularity of the absorbing surface: Blood circulationremoves drug from site of absorption.Increased blood flow increases drug absorption.Route of administration: When a drug is given intramuscularly, the drug is deposited near the capillaries. It then passes through the capillary endothelium into circulation. When vascularity increases more drug is absorbed. Likewise if vasoconstriction occurs drug absorption decreases.