| Term | Definition |
| Bioavailability | The portion of the original drug dose that reaches its site of action |
| half-life | The amount of time that must pass for the amount of drug in the body to be reduced by half |
| solubility | The ease with which a compound can be dissolved or entered into a solution |
| efficacy | the most intense or peak level of a drug effect |
| synergism | Any enhancing drug interaction |
| antagonism | The diminished or reduced effect of a drug when another drug is present |
| dispositional tolerance | an increase in the rate of metabolizing a drug as a result of its regular use |
| functional tolerance | Decreased behavioral effects of a drug as a result of its regular use |
| acute tolerance | a type of functional tolerance that occurs within a course of action of a single drug dose |
| protracted tolerance | a type of functional tolerance that occurs over the course of two or more drug administrations |
| behavioral tolerance | adjustment of behavior through experience in using a drug to compensate for its intoxicating effect |
| cross tolerance | tolerance to a drug or drugs never taken that results from protracted tolerance to another drug |
| naloxone | a short acting opiate antagonist |