PHARMACOLOGY: Derived from the Greek words “pharmakon,” meaning remedy, and “logos,” meaning knowledge, the word pharmacology loosely translates to “the knowledge of drugs.”

PHARMACOKINETICS: A branch of pharmacology that refers to the rate of drug absorption, distribution, metabolism, and excretion (ADME).

PHARMACODYNAMICS: A branch of pharmacology that refers to the biological and physical effects of the drug on the body.

BRAND NAME: A proprietary name protected by a patent. This is often referred to as the manufacturer’s trademarked name. The first letter of a brand name is always capitalized.

GENERIC NAME: A nonproprietary name approved by the United States Adopted Names (USAN) Council. The generic drug must have the same active ingredient, dosage strength, and formulation as the brand name drug, but it may have different inactive ingredients. The first letter of a generic name is not capitalized.

CHEMICAL NAME: A name given to a drug during the initial clinical investigation, referring to its atomic or molecular structure.

DOSAGE FORM: The physical manifestation of the drug or how the drug is supplied.

DRUG CLASSIFICATION: Drugs are grouped by their common actions and effects on the body (e.g., anti-infective, anxiolytic, analgesic).

THERAPEUTIC EQUIVALENCE: This classification is given to drugs that meet certain criteria. The drugs must be proven to be safe and effective, and they must be deemed as pharmaceutically equivalent. This means that identical amounts of active drug are present. The dosage form and route must also be the same. Standards of strength, purity, and quality must be met. Bioequivalence must also be proven. According to the FDA, this is completed through testing to prove the drugs have similar rates of absorption under similar conditions and dosage parameters. Therapeutic equivalence can be checked by looking at the Approved Drug Products with Therapeutic Equivalence Evaluations, which is commonly referred to as the Orange Book. This publication is the U. S. Food and Drug Administration’s (FDA) official listing for prescription, over-the-counter, biologic, military, discontinued, or otherwise never-marketed drugs.

SIDE EFFECTS: Secondary effects of the drug other than the primary therapeutic effect it was originally intended for.

DRUG INTERACTIONS: A desirable or an undesirable effect that can occur when the effect of one drug is altered by the action of another drug or substance. This phenomenon can produce undesirable effects, resulting in a lack of efficacy or even toxicity. Factors that contribute to an increased number of drug interactions include multiple prescribers, poor patient compliance, taking multiple drugs, advanced age, and comorbidity.

• Drug-drug interactions: Occur when a drug interacts with or interferes with another drug. This interaction may be:

  • Additive: Two drugs given in combination have an effect equal to the sum of the individual effects.
  • Synergistic: Drugs given in combination produce an effect greater than the sum of the individual effects.
  • Potentiated: One drug intensifies the activity of another drug.
  • Antagonistic: Drugs given in combination cause a decreased, or diminished, effect in one or more drugs.

• Drug-food interactions: Occur when a drug reacts with a food. An example of this is when drinking grapefruit juice causes an increase in the serum concentration of the antihyperlipidemic drug lovastatin (Mevacor).

• Drug-disease interactions: May occur when a prescription or an over-the-counter medication interacts or interferes with an existing medical condition. For example, a drug-disease interaction occurs when an individual with hypertension takes pseudoephedrine.

• Drug-nutritional supplement interactions: Occur when a drug affects vitamin absorption or metabolism. For example, anticonvulsants, such as phenytoin, can cause vitamin D deficiency.

• Drug-laboratory interactions: Occur when a drug or a substance alters the concentrations of substances in the body. For example, potassium-sparing diuretics, such as triamterene, increase serum potassium levels. In addition, the H2 blocker cimetidine can elevate serum creatinine levels.

• Drug-nutrient interactions: Occur when a drug affects the use of a nutrient in the body. The drug may affect the nutrient’s absorption, the use of the nutrient by the body, or the excretion of the nutrient. For example, antihyperlipidemic agents, such as cholestyramine, can decrease the absorption of the fat-soluble vitamins (vitamins A, D, E, and K).