Pharmacology is defined as the scientific study of the action of drugs and their effects on a living organism. It is the scientific study of drugs which includes their origin, actions, interactions and properties. There are two terms we should know when we remember the term pharmacology: pharmacokinetics, which is the body's effect on the drug, and pharmacodynamics, which is the drug's effect on the body. An addiction counselor should always have a lot of knowledge about pharmacology, because without it, a counselor may have difficulty understanding. the very important factors that play a key role in understanding medicines, such as side effects, potency, withdrawals and safety of a particular medicine. Pharmacokinetics is an important term to know when it comes to drug administration and its effects. Pharmacokinetics is the branch of pharmacology that deals with what happens to drugs when they are ingested or administered. The effects of a substance are influenced by how the substance enters the body. There are many routes of administration, for example; a medicine can be inhaled and absorbed into the lungs, taken by mouth, injected into a vein, muscles or under the skin, snorted through the nose or absorbed through the mucous membranes, drunk and absorbed through the small intestine or absorbed through the skin .Inhalation, drugs such as nicotine, solvents, marijuana and other drugs used for lung disorders are inhaled through the mouth. Some drugs, like cocaine, are usually inhaled (snorted) through the nose, where they are then absorbed through the mucous membranes of the nose. Injection is a way of introducing medicine (liquid) into the body using a needle and syringe, usually by injection...... middle of paper ...... consequences harmful effects as well as neurochemical changes in the brain (this roughly meets the DSM definition of addiction, but remember that the DSM uses the term addiction). Another definition of addiction is that it is the psychological and physical dependence on a substance. There are many different definitions of appends because dependencies vary. For example, some treat addiction as behavioral, does this mean that addiction is only related to behavioral problems? It is logical to say that not every drug substance is equally addictive, just like the effect of the drug itself. However, the potential for addiction depends on many interrelated factors, such as the substance's ability to act at the pleasure center of the brain (the site of addiction). Therefore, the definition varies, because what a doctor, researcher, etc. defines may vary depending on the following scientist, etc...