Cocaine is a highly addictive drug. In recent years it has become well known that people who smoke cocaine (in the form of crack or the free base) may become more easily addicted and more readily abuse cocaine than people who snort cocaine. Why would people show different patterns of abuse of the same drug, when administered by different routes? To answer this question, one needs to understand the chemical nature of cocaine and how it gets from the site of administration to the brain, where it produces its psychoactive effects.
1. Most drugs are weak acids or weak bases. Is cocaine a weak acid or weak base?
2. A weak acid or base can exist in 2 forms – charged (ionized) or uncharged (unionized). What is the major factor that determines whether the weak acid or base is charged or un-charged?
3. In what chemical form (charged or uncharged) is cocaine snorted? Smoked? Why are they different?
Cocaine must pass through several barriers (cell membranes) to get from the nostrils or the lungs into the blood.
4. What kinds of molecules make a cell membrane? Are there charges present on cell membranes?
5. In what form (charged or uncharged) must molecules, such as drugs, be to pass through a cell membrane?
6. What forces play a role in helping a drug such as cocaine cross a cell membrane?
Once in the blood, cocaine travels throughout the body, including the brain, where there is a very special membrane barrier. The barrier consists of tightly packed cells that only allow certain compounds to cross from the blood into the brain.
7. How does the cocaine get from the blood vessels in the nose to the brain? How does the cocaine get from the blood vessels in the lungs to the brain? Which route is most direct to the brain?
8. In what form (charged or uncharged) must cocaine be to cross the barrier and enter the brain?
Scientists in the fields of pharmacology and drug abuse have found that there is a relationship between the speed at which a psychoactive drug reaches the brain and its potential to be abused. This is especially the case for drugs like cocaine that activate specific areas of the brain involved in addictive behavior.
9. Does cocaine reach the brain faster by smoking or snorting? Why? What about injecting it into a vein?
10. Is a user more likely to take more cocaine after smoking it or snorting it? Will this result in a greater addiction potential? Why?
