Added: Keenon Griffis - Date: 05.07.2021 11:07 - Views: 21464 - Clicks: 9221
Home » Module 1: Acids, Bases and Cocaine Addicts » Content Background: How the route of cocaine administration affects its rate of entry into the brain. Cocaine, like many drugs 1 can enter the body a variety of ways Figure 4. The easiest way to get cocaine or any drug into the bloodstream is to inject it directly into a vein since there are no membranes to traverse in order to get there.
In contrast, if cocaine is smoked, snorted 2 or ingested by mouth, it must pass several membrane barriers before reaching the bloodstream, and some of these processes are slower than others. Smoking a drug such as cocaine, nicotine or heroin, enables its entry into the bloodstream almost as fast as injecting also see Figure 5. The lungs have a very large surface area for absorption of the drug from the alveoli very small sacs where gas is exchanged into the capillaries. Capillaries are the smallest form of blood vessels and are very numerous.
In fact they are able to deliver nutrients such as oxygen and glucose to every cell in the body. They also pick up waste such as carbon dioxide and metabolic products. Once in the capillaries, the drug travels in the oxygenated blood to the heart and then gets pumped throughout the body organs such as brain, liver and kidneys that have a high blood flow receive blood first to reach all cells.
The blood brain barrier consists of tightly packed capillary endothelial cells 4so there are no pores through which charged compounds can pass Figure 3.
Drugs that are highly lipophilic 5 lipid-loving such as cocaine penetrate most quickly. Other drugs that cross the blood brain barrier easily include nicotine, marijuana and heroin. Some drugs can be transported across How does cocaine work when snorted blood brain barrier by binding to transport proteins. By restricting only certain molecules and drugs from reaching the brain, the brain can be protected from dangerous compounds. If a drug such as cocaine is snorted, it takes a little longer to get to the brain where it produces its psychoactive 6 effects.
Cocaine diffuses through special epithelial cells 7 mucosal cells 8 lining the nasal passages into nearby capillaries. There is a very extensive capillary network in the nasal passages so drugs are absorbed into the bloodstream fairly quickly. Then, the cocaine travels within the venous system to the heart, then to the lungs, and back to the heart for distribution throughout the body Figure 4. The slowest way to get a drug into the bloodstream is by ingestion. When a drug is ingested by mouth, it travels first to the gut, where it must pass through mucosal cells lining the gut in order to get to the capillaries.
Most drugs are weak acids 9 or bases and their charge will be determined by the pH of the surrounding medium.
The very acidic pH of the stomach will keep weak acids in their uncharged non-polar 10 or unionized form. In contrast, weak bases 11like cocaine, will be mostly charged or ionized 12 polar 13 at low pH. As discussed above, ionized compounds have difficulty passing through most membranes other than capillarieswhile unionized compounds are more lipophilic, and slide through the membrane easily. Another factor that slows the appearance of drugs taken by mouth into the brain is metabolism.
The capillaries in the gut connect to blood vessels that go directly to the liver, so as drugs leave the gut they travel to the liver first this is called the portal circulation. There, some of the drug is metabolized and inactivated as it passes through. Metabolites are often more polar forms of the parent drug, allowing them to be excreted in the urine more How does cocaine work when snorted. After the drug leaves the liver, it travels to the heart, then to the lungs and finally back to the heart to be distributed throughout the rest of the body Figure 4. Thus, in this case, less cocaine in its active form reaches the brain.
This is one reason why abusers do not take cocaine orally see below. Definitions: 1 A substance that affects the structure or function of a cell or organism. With reference to cocaine, it is the hydrochloride salt. It restricts passage of drugs and other molecules across the cell layer into the brain to include only those that are lipophilic uncharged.
Unlike epithelial cells, these cells have no contact with the environment outside the body. Lipophilic compounds dissolve readily in oil or organic solvent. They exist in an uncharged or non-polar form and cross biological membranes very easily. This protects the cells lining the tissue. A non-polar or non-charged compound mixes well with organic solvents and lipids but not with water. Therefore it acquires a net negative or positive charge. A polar substance or drug mixes well with water but not with organic solvents and lipids.
Polar or charged compounds do not cross cell membranes lipid very easily. Figure 3 Cross section of capillary showing endothelial cells. In the non-brain capillary fenestrae are present. In the brain capillaries the endothelial cells are tightly packed and no fenestrae are present. Figure 4 Modes of drug administration into the body. Red is the arterial side and blue is the venous side. Adapted from Ray O. Drugs, Society, and Human Behavior, pg. McGraw-Hill: New York. Figure 5 The relationship between the mode of cocaine intake and the intensity and duration of its euphoric effects.
Please read the Duke Wordpress Policies. Contact the Duke WordPress team. The Pharmacology Education Partnership. Home About Effectiveness Downlo Contact. Search Search. Content Background: How the route of cocaine administration affects its rate of entry into the brain Content Background: Why is smoked cocaine crack more likely to be abused or addictive than snorted cocaine?
It's Radical! Content Background: How the route of cocaine administration affects its rate of entry into the brain Cocaine, like many drugs 1 can enter the body a variety of ways Figure 4. Figures: Figure 3 Cross section of capillary showing endothelial How does cocaine work when snorted. All Rights Reserved.How does cocaine work when snorted
email: [email protected] - phone:(571) 121-1221 x 5891
Differences Between Swallowing and Snorting Drugs