ABSTRACT
A drug can be taken through different routes — oral (PO), intravenous (IV), intraperitoneal (IP), intramuscular (IM), etc. Once the drug enters the body, before it is metabolized into an inactive form through one of many different pathways and excreted from the body, it produces a desired pharmacological effect. Drug interactions occur through different forms of macromolecules that may have specific functions. The autocoids could be short-lived biochemicals whose actions are often limited to receptors found on the cells or tissues within a close viscinity from the origin of the autocoids. Communication between cells is required to coordinate the activities of different organs within the body. Cells of various organs and tissues interact with each other by transmitting chemical signals. The signaling molecules involved in autocrine and paracrine function are the local chemical mediators that are normally referred as autocoids. Signaling molecules can be either water soluble or lipid soluble.
