A systematized listing of drugs according to their primary actions, mechanisms, chemical nature, clinical uses and/or other relevant characteristics is the first step to learn about them. The mental exercise to prescribe a drug for a patient starts with identifying the class of drugs to be prescribed and then selecting the specific member most appropriate for that patient according to its subclass/group/individual characteristic. For example, the first thing one decides is whether an analgesic or an antihypertensive or an antibiotic is to be prescribed; then proceeds to consider which type of analgesic (opioid/nonopioid), or antihypertensive (calcium channel blocker/ACE inhibitor, etc.), or antibiotic (β-lactam/fluoroquinolone, etc.) is required and then which specific member is most suitable. On the other hand, every drug is known by the class and subclass, to which it belongs, e.g. furosemide is a high-ceiling diuretic, glibenclamide is a sulfonylurea antidiabetic. As such, drug classifications are pivotal to pharmacology students and greatly helpful to prescribing doctors. The phenomenal increase in the number of drugs in recent years has further underscored the need for drug classifications.