Drugs can enter the body in numerous ways. Whether a particular substance is taken for strictly medicinal purposes or for recreational purposes, no effect(s) will occur in the body unless absorption of the substance takes place. In the case of drugs of abuse (i.e., psy-choactive drugs), the central nervous system will be activated in some way in order to cause the desired, and often times undesired, effect(s).

Absorption of substances can occur through either an enterai route or a parenteral route. Enterai routes include those methods that require absorption through the gastrointestinal tract (e.g., oral ingestion or rectal absorption). Enterai routes are generally safer in that the active substance may get diluted or broken down prior to reaching the bloodstream; this safety is also a disadvantage ...