Crack Cocaine Addiction

07/01/2008

Pharmacodynamics: cocaine's interaction with the human organism

Like all stimulant drugs, those prescribed by physicians as well as those taken recreationally, cocaine produces a psychoactive effect by interacting with the central nervous system, stimulating it to perform its ordinary functions more intensely. This system operates through the release of various neurochemical transmitters (from the nerve cells in which they are produced) and their binding to receptor sites on neighboring cells. The constant release and binding of these neurotransmitters forms a pathway of  "messages" that travel throughout the body, sustaining life and making possible the organism’s response to the environmental stimuli.

Cocaine also has an impact in the autonomic (or involuntary) division of the central nervous system, which helps regulate a variety of bodily functions that are generally free of volitional impact, including respiration, circulation, digestion and bodily temperature. Ordinarily, these functions are maintained at relatively stable levels throughout the day. But they are slowed down during periods of the rest through diminished production, release and binding of neurotransmitters and can be speeded up, as needed, through increased neurotransmitter activity. 

Cocaine operates in this system by increasing the concentration and binding activity of the body’s own neurotransmitters-particularly dopamine. Thus, what people experience as cocaine’s stimulant effect is an intensification of the body’s normal stimulatory mechanisms.

Cocaine is both a quick-acting and a short-acting drug. When cocaine enters the bloodstream directly, via injection, it reaches the brain quickly, and users feel its effects within minutes. Inhalation also delivers cocaine quickly to the brain because air passages in the lungs are positioned close to capillary accesses to the bloodstream. When cocaine is sniffed, the onset of the effect is slower because the drug must pass through the nasal mucosa before entering the bloodstream. Swallowing cocaine delays delivery to the brain even more because most of the drug is passed through the gastrointestinal tract before it crosses through cell membranes into the bloodstream.
Controlling for dose, sniffing and swallowing also produce less intense effects.

This is not only because these routes of administration cause active cocaine molecules to reach the brain more gradually, and therefore in lower concentrations, but also because the additional passage of time allows more of the cocaine molecules to be transformed into inactive byproducts (or metabolites) before they reach the brain. Both injection and inhalation deliver a greater number of active cocaine molecules per dose to the brain than snorting.

Crack in America - edited by Craig Reinarman and Harry G. Levine

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