The selective effects of drugs are known for all over-the-counter (OTC) and prescription medications. Individual variations in body composition, age, metabolism, and systemic conditions may affect drug actions, and these effects are not always known nor predictable.3,4AII drugs have the potential to cause adverse or harmful effects that can either be related or unrelated to the principal action of the drug.5,6Harmful effects that are directly related to drug action are predictable, and occur as a consequence of that action. For example, using aspirin causes increased bleeding due to its anticoagulant effect. These predictable effects are reversible when the drug is discontinued. However, reversal can be difficult for drugs associated with addiction, such as narcotics and alcohol, and at times, these effects can be fatal, as with hypoglycemic coma induced by insulin.5,6
