Many factors determine how addictive a given substance is including the rate and route of administration.
If all we knew about drugs were the portrayals we see in the popular media, we would assume that some drugs like heroin or crack cocaine are instantly addictive and can never be used in a controlled fashion by anyone, whereas other drugs like coca-cola or candy bars are completely safe and never addict anyone. However, the reality is that nothing is ever so simple and so black-and-white. Research by people like Zinberg and Inciardi gives many instances of controlled use of drugs like heroin or crack cocaine–in fact controlled heroin use may be the norm rather than the exception. We should know from our experience with alcohol that many people–but not all–control their use. Not all drug or alcohol use is addiction–supposing that we can even agree on what the word “addiction” means. WHO in the 1950s classified nicotine as a non-addictive substance–whereas today nicotine is considered perhaps the most addictive substance there is.
There are many factors which determine whether an individual will be able to control the use of a drug or whether that individual will become a compulsive user. These factors include the following:
- · The drug itself (some drugs are harder to control than others)
- · The individual who uses the drug (some people are more likely to get hooked than others)
- · The environment the drug is used in
- · Maximum plasma concentration attained
- · Frequency of use
- · Rate and rout of ingestion
- · And many more
In this article we are going to concentrate on the rate and route of ingestion.
Even when the same concentration of the same drug is reached in the brain, the drug will be far more addictive if the concentration level rose quickly than if it rose slowly. Moreover, the effect of the drug on the brain will be much stronger if the level of concentration of the drug rises rapidly than if it rises slowly.
This happens because the neurons which comprise our brain are constantly compensating for the things which stimulate them. Neurons adapt to a continuing stimulus by responding less to it. The longer the stimulus continues, the less the neurons respond.
When the level of concentration of a given drug in the brain rises rapidly, the neurons do not have time to compensate for the effects of the drug, and the drug totally overwhelms the brain.
For example, a 150 pound man may achieve a BAC (blood alcohol concentration) of 0.16 by drinking six shots of whiskey in one hour–or by drinking nine shots of whiskey over the course of six hours. In the first case there may be blackouts and total drunken insanity, In the second case the person my feel only mildly tipsy and pleasantly buzzed–in spite of the fact that the BAC and the concentration of alcohol in the brain is IDENTICAL!
Why? Because when the BAC rises rapidly, the neurons do not have a chance to compensate for it. Therefore, the same concentration of alcohol has a far greater effect when the BAC rises rapidly than when it rises slowly. Moreover, when people guzzle alcohol quickly they are far more likely to get addicted to alcohol than when they sip slowly–even though the same total amount of alcohol is consumed.
This is also why smoked cocaine is more addictive than snorted cocaine. When people smoke cocaine–it does not matter if it is crack or free-base–it goes from the lungs to the brain in seconds. When people snort powder cocaine it has to go through the mucous membranes of the sinuses to be absorbed, and this is a far slower process. The South American Indians who chew coca leaves get the lowest concentrations of cocaine at the slowest rates, which is why this is the least addictive way of using cocaine.
Rate and route of administration also determine how addictive opiate use is. Opium eaters are less likely to become addicted and become less severely addicted than those who smoke or inject the same quantities of opiates. This is because the levels of concentration of opiates rise much more slowly when they have to pass through the gastro-intestinal tract than when they are smoked or injected and reach the brain almost immediately. Before tobacco smoking was introduced to China, everyone who used opium ate it. The introduction of tobacco smoking into China gave people the idea that opium could be smoked as well. The switch from opium eating to opium smoking was one of several factors which led to the crises of opium addiction in 19th century China.
Cigarettes tend to be far more addictive than cigars because most people inhale cigarettes whereas most people do not inhale cigars. When nicotine is absorbed through the lungs it leads to a rapid rise in nicotine levels in the brain. When the nicotine has to go through the mucous membranes of the mouth, the nicotine levels in the brain rise much more slowly.
High octane oral tobacco like Copenhagen or Skoal is also more addictive than oral leaf tobacco like Beech-Nut or Red Man. Anyone who has experimented with chewing tobacco can tell you that the ground dipping tobaccos like Copenhagen or Skoal release all their nicotine at once in a fast blast that goes straight to the brain. Nicotine from the leaf tobaccos is released far more slowly, lasts longer, and does not hit the brain all at once.
People who use marijuana can also tell you that there is a major qualitative difference between the slow, mellow, long lasting high which comes from eating has brownies and the immediate rush of smoking a joint.
In recent years an alcohol inhalation device called AWOL (Alcohol WithOut Liquid) has been introduced and it is also banned in many states. AWOL leads to a very rapid and short term alcohol high–and it is surely more addictive than drinking alcohol.
In conclusion, the quickest ways of getting a drug into the brain are inhalation and injection, and these are the routes of ingestion with the greatest addictive potential. Eating, drinking, absorbing a drug through mucous membranes or through the skin with a transdermal patch are all far slower routes of ingestion with far lower potential for addiction. Moreover, liquids are absorbed far more quickly through the small intestine than through the stomach, so drinking on an empty stomach is far more likely to lead to addiction than drinking on a full stomach because when the stomach is full the pyloric valve closes and prevents the alcohol from reaching the small intestine more than a little at a time. Because of this it is probably a good idea in general to avoid taking drugs on an empty stomach.
Remember, the addictive potential of a drug depends not only on what you use, how much you use, how often you use, and where you use–it also depends on HOW you ingest the substance as well.
For more information about addiction and harm reduction please visit our web site: http://hamsnetwork.org or buy our book: How to Change Your Drinking: a Harm Reduction Guide to Alcohol
Inciardi, McElrath. (2007). The American Drug Scene: An Anthology. Oxford University Press, USA; 5 edition.
Rotgers F, et al (2002) Responsible Drinking. New Harbinger. Oakland, CA.
Jones. (1990). The Pharmacology Of Cocaine Smoking In Humans. Originally published in (eds. C. Nora Chiang, Ph.D., Richard L. Hawks, Ph.D.) NIDA Research Monograph 99 (Research Findings on Smoking of Abused Substances), 1990, p. 30-41. http://www.druglibrary.org/schaffer/cocaine/cokesmoke.htm
Zinberg N. (1984). Drug, set, and setting: the basis for controlled intoxicant use. Yale University Press. New Haven.