Route of Administration

The more rewarding a drug is to the brain, the more likely that the user's brain will want to repeat the experience. How quickly the drug reaches the brain plays a major role in producing the initial rush or euphoria and in determining how rewarding the brain finds it. The more slowly a drug enters the brain, the less intense the initial euphoria. And the quicker the initial euphoria, the more rewarding it is, and the more the brain wants to repeat the experience.

The point is this: Drugs that are smoked and injected reach the brain the fastest, so the effects are felt sooner. The stronger the reward associated with a drug, the greater its potential for abuse, because the brain craves a repeat performance.

Take crack cocaine, for example. Although white powder cocaine was available for many years, not until cocaine was smoked (in the form of crack cocaine) did it become a widespread epidemiological phenomenon. Crack cocaine prompted a tremendous growth in the number of new cocaine users. It delivered the drug to the brain very rapidly, intensifying the initial rush. Thus, once crack became available, smoking cocaine soon replaced snorting as the main route of cocaine administration, and crack became a more widespread drug of abuse than snorted cocaine ever was.

Source: U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse, "Rate and Duration of Drug Activity Play Major Roles in Drug Abuse, Addiction, and Treatment," NIDA Notes vol. 12, no. 2 (1997)