When drugs are used time and time again, developing a tolerance to them is a real possibility. NCBI occurs when the person no longer responds to the medication in the way that they initially did. It takes a higher dose of a given drug to achieve the desired effects they felt initially. For some drugs, such as opioids, tolerance can develop much quicker than other substances.
Tolerance is not considered an addiction, but it is merely the starting point on the road of a substance use disorder. The process of tolerance development, fortunately, is reversible, and at this stage, it is much easier to treat before someone spirals into a full-blown addiction. Tolerance can involve physiological and psychological factors.
Although different types of drugs will affect our bodies differently, the concept of developing tolerance, in essence, remains the same. Over time, the body adjusts to the drug and will become desensitized to its effects. Drug tolerance can be extremely dangerous because it will push a user into taking much higher doses, which can increase the risk of an overdose.
As mentioned above, tolerance is the first step that is followed by a chemical dependency, which eventually can lead to an addiction. There are a few ways that drug tolerance develops.
There are two types of tolerance to keep in mind. They are:
A physiological tolerance will develop as a result of long-term use. As a person continually abuses a drug, the body will grow accustomed to its presence and adapt. The brain begins to produce chemicals that combat the drugs in the person’s system to balance the chemistry. Eventually, the body will become desensitized to its effects, and the person will begin to feel a physical need to take more of the drug to achieve the desired results.
A behavioral tolerance is comprised of the user feeling as though they cannot function regularly without using the drug. Someone who uses can become accustomed to the way a drug makes them feel and compensate to appear sober to others. Tolerance is just as much behavioral as it is physiological.
There are also three main types of tolerance:
Acute tolerance is short-term and is caused by repeated exposure to a drug over a short period. Cocaine abuse is an example of acute tolerance. After the first dose of cocaine, the user experiences a euphoric high and increased heart rate. Even when they double the level of drugs in the blood when someone consumes a second dose of cocaine, it will not result in a dose-dependent increase.
A long-term tolerance develops when a person’s body adapts to constant exposure to a drug over weeks or months. Those who use prescriptions opioids regularly will build up a chronic tolerance to the effects of the medications. In turn, this will lead to increase the dosage or switching to more potent ways of taking the drug such as snorting or injecting.
A learned tolerance can result from frequent exposure to certain drugs. Those who abuse alcohol for months or even years will not appear intoxicated to others. Studies have shown that some people who drink can compensate for the effects of alcohol on their coordination when they practice a task repeatedly while under the influence. The tolerance, however, will disappear if the function is altered.
It’s safe to say that even drugs used to treat specific ailments can be addictive. For example, pain medications can be one of the most addicting substances on the planet, while depressants like benzodiazepines that treat anxiety and sleep disorders can cause tolerance in a short period. Listed below are some of the drugs that can cause tolerance and what to look out for in case it happens to you.
Drugs such as codeine, fentanyl, oxycodone (OxyContin, Percocet), morphine, meperidine (Demerol), hydrocodone (Vicodin, Norco), and hydromorphone (Dilaudid) are causes for concern when it comes to tolerance. In many cases, the narcotic medications are prescribed for long periods. Long-term opioid administration eventually reaches a dose ceiling that is attributable to the rapid onset of analgesic tolerance.
Tolerance to opioids begins at the level of cellular targets. When morphine binds to natural receptors, it triggers the inhibition of an enzyme that orchestrates chemicals in the cell to maintain the firing of impulses. After repeated activation, the catalyst will adapt so that morphine no longer causes changes in cell firing. The dose at this point is diminished, and more is required to activate these cells.
A study found that tolerance to benzodiazepines can occur in as little as 14 days, and long-term use of the medication was not seen as positive. With benzos, the receptors in the brain become adapted or accustomed to the action of the original dose, and more of the drug is needed for the necessary therapeutic effect. One theory about why tolerance occurs from benzo use is something known as receptor uncoupling, which is the process of receptor-binding sites or domains becoming separated, moving alignments, or becoming internalized, resulting in drug tolerance from prolonged exposure.
It is said that those being treated for an unrelated ailment developed anxiety as a result of using the drug, and the worsening of symptoms are from something known as tolerance withdrawal. This occurs directly because of increasing the amount taken because the dose was ineffective. Tolerance to benzos, however, may be partial, and some chronic users report continued efficacy of the drugs.
Alcohol tolerance refers to how the body responds to the functional effects of ethanol in alcoholic beverages. The way alcohol tolerance is increased is by someone who regularly drinks. Over time, the body reduces its sensitivity to alcohol consumption, and it requires that higher quantities of alcohol be consumed to achieve the same effects as before the tolerance was established. Like all stages in a substance use disorder, prolonged consumption can lead to alcohol dependency.
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Someone’s body size will dictate a direct alcohol tolerance. Those who are more substantial in mass require more alcohol to reach their desired level of intoxication. Men, who, on average, are larger than women, will have a naturally higher tolerance to alcohol. Alcohol tolerance is connected with the activity of alcohol dehydrogenases, which are a group of enzymes that breakdown alcohol in the liver and bloodstream. Those who possess higher levels of dehydrogenases activity will break down ethanol much quicker.
Alcohol tolerance can become extremely dangerous based on the part of the brain it affects. Much like benzodiazepines, alcohol is a depressant, and when it is continually used, it can lead to seizures upon withdrawal or delirium tremens (also known as DTs). Alcohol dependency is among the most dangerous despite its legality and can lead to an array of health problems. Due to alcohol being so readily available, its strength of withdrawal due to tolerance should never be discounted.
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