This definition applies to interactions of drugs with other drugs (drug-drug interactions), as well as drugs with food (drug-food interactions) and other substances. Use WebMD's Drug Interaction Checker tool to find and identify potentially of an appropriately qualified and licensed physician or other health care provider. Alcohol is a drug that when taken in combination with other drugs – including medicines or illicit drugs These occur because the two drugs interact in the body.
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This concept is recognized by the majority of authors,  although other authors only refer to synergy when there is an enhanced effect. These authors use the term "additive effect" for additive synergy and they reserve use of the term "synergistic effect" for enhanced synergy.
Two drugs are antagonistic when their interaction causes a decrease in the effects of one or both of the drugs. Both synergy and antagonism can both occur during different phases of the interaction of a drug with an organism, with each effect having a different name. For example, when the synergy occurs at a cellular receptor level this is termed agonism , and the substances involved are termed agonists.
On the other hand, in the case of antagonism the substances involved are known as inverse agonists. The different responses of a receptor to the action of a drug has resulted in a number of classifications, which use terms such as "partial agonist", "competitive agonist" etc. These concepts have fundamental applications in the pharmacodynamics of these interactions. The proliferation of existing classifications at this level, along with the fact that the exact reaction mechanisms for many drugs are not well understood means that it is almost impossible to offer a clear classification for these concepts.
It is even likely that many authors would misapply any given classification. It is possible to take advantage of positive drug interactions. However, the negative interactions are usually of more interest because of their pathological significance and also because they are often unexpected and may even go undiagnosed. By studying the conditions that favour the appearance of interactions it should be possible to prevent them or at least diagnose them in time.
The factors or conditions that predispose or favor the appearance of interactions include: The detection of laboratory parameters is based on physicochemical reactions between the substance being measured and reagents designed for this purpose. These reactions can be altered by the presence of drugs giving rise to an over estimation or an underestimation of the real results. Levels of cholesterol and other blood lipids can be overestimated as a consequence of the presence in the blood of some psychotropic drugs.
These overestimates should not be confused with the action of other drugs that actually increase blood cholesterol levels due to an interaction with its metabolism. Most experts consider that these are not true interactions, so they will not be dealt with further in this discussion. These chemical reactions are also known as pharmacological incompatibilities.
The reactions occur when two or more drugs are mixed outside the body of the organism for the purpose of joint administration. Examples of these types of interactions include the mixing of penicillins and aminoglycosides in the same serum bottle, which causes the formation of an insoluble precipitate , or the mixing of ciprofloxacin with furosemide.
The interaction of some drugs with the transport medium can also be included here. This means that certain drugs cannot be administered in plastic bottles because they bind with the bottle's walls, reducing the drug's concentration in solution. Many authors do not consider them to be interactions in the strictest sense of the word. The change in an organism's response on administration of a drug is an important factor in pharmacodynamic interactions.
These changes are extraordinarily difficult to classify given the wide variety of modes of action that exist and the fact that many drugs can cause their effect through a number of different mechanisms.
This wide diversity also means that, in all but the most obvious cases, it is important to investigate and understand these mechanisms. The well-founded suspicion exists that there are more unknown interactions than known ones.
Modifications in the effect of a drug are caused by differences in the absorption, transport, distribution, metabolization or excretion of one or both of the drugs compared with the expected behaviour of each drug when taken individually. These changes are basically modifications in the concentration of the drugs. In this respect two drugs can be homergic if they have the same effect in the organism and heterergic if their effects are different.
Some drugs, such as the prokinetic agents increase the speed with which a substance passes through the intestines. If a drug is present in the digestive tract's absorption zone for less time its blood concentration will decrease. The opposite will occur with drugs that decrease intestinal motility. Certain drugs require an acid stomach pH for absorption. Others require the basic pH of the intestines.
Any modification in the pH could change this absorption. However, this occurs less often than an increase in pH causes an increase in absorption. Such as occurs when cimetidine is taken with didanosine. In this case a gap of two to four hours between taking the two drugs is usually sufficient to avoid the interaction.
The main interaction mechanism is competition for plasma protein transport. In these cases the drug that arrives first binds with the plasma protein, leaving the other drug dissolved in the plasma, which modifies its concentration. The organism has mechanisms to counteract these situations by, for example, increasing plasma clearance , which means that they are not usually clinically relevant.
However, these situations should be taken into account if other associated problems are present such as when the method of excretion is affected. Many drug interactions are due to alterations in drug metabolism. Cytochrome P is a very large family of haemoproteins hemoproteins that are characterized by their enzymatic activity and their role in the metabolism of a large number of drugs.
As a result of these interactions the function of the enzymes can either be stimulated enzyme induction or inhibited enzyme inhibition. If drug A is metabolized by a cytochrome P enzyme and drug B inhibits or decreases the enzyme's activity, then drug A will remain with high levels in the plasma for longer as its inactivation is slower.
As a result, enzymatic inhibition will cause an increase in the drug's effect. This can cause a wide range of adverse reactions. Ask your pharmacist or doctor for advice if you are confused by the medical jargon.
Drug interactions can also contribute to the cost of healthcare, as a serious drug interaction could result in injury, hospitalization, or rarely, death. Not all drug interactions are bad. Some medications may be better absorbed if taken with food or may have more favorable blood levels if taken with other medications that affect metabolic enzymes.
Major drug interactions that are life-threatening are not common, but are of serious concern. However, if you can avoid a possible drug interaction by selecting a different medication, that is always your best bet. In fact, for some drugs, stopping the medication could also affect the levels of other drugs in your system.
Being proactive in your own health, checking for drug interactions, and discussing concerns with your healthcare provider can be a life-saving task. How often a drug interaction occurs, and your risk for a drug interaction, also depends upon factors such as:.
For example, taking a pain medication such as hydrocodone-acetaminophen Vicodin with alcohol can cause additive drowsiness, may dangerously decrease your breathing rate, and in large doses may be toxic to the liver due to the combination of acetaminophen Tylenol and alcohol. Taking a medication that was prescribed for someone else or bought off of the Internet can be dangerous, too and lead to unexpected drug interactions. Communication with your healthcare provider is key in helping to prevent drug interactions.
Keep an up-to-date list of your medications, over-the-counter products, vitamins, herbals, and medical conditions.
Share this list with your doctor, pharmacist, and nurse at each visit so that they can also screen for drug interactions. However, you can also use our online drug interaction checker to learn more about possible drug interactions, too. This tool explains what the interaction is, how it occurs, the level of significance major, moderate, or minor and usually a suggested course of action.
It will also display any interactions between your chosen drug s and food, beverages, or a medical condition. Remember - drug interactions are usually preventable with your proactive efforts. Always check for drug interactions even when you purchase OTC medications, herbal supplements or vitamins. The Drug Interaction Checker explains the mechanism of each drug interaction, the level of significance of the interaction major, moderate or minor , and in certain cases, can provide the recommended course of action to manage the interaction.
The Drug Interaction Checker will also display any interactions between your chosen drug s , food or beverages, and even other diseases. By keeping all of your prescriptions at one pharmacy, a regular drug review and drug interaction screen can be done electronically that incorporates all of your medicines. Talk with your pharmacist and doctor and communicate new and discontinued medications with all of your health care providers.
Communication is key to preventing drug interactions. When you buy OTCs or herbal supplements, ask your pharmacist to double check for interactions and ask if they can add the agent to your regular drug profile for future drug interaction checks. Be sure to read the Drug Facts Label on each OTC product you use, too, paying attention to any specific drug interactions noted there.
Your pharmacist or doctor may ask about specific foods or drinks you consume depending upon which drugs you take. Common food items involved in drug interactions include foods rich in vitamin K, which can interact with certain blood thinners like warfarin and make them less effective, possibly leading to a clot.
Certain citrus juices like grapefruit juice are notorious for changing blood levels of some drugs, too. Calcium can bind with some drugs and prevent absorption. For example, if you take the blood thinner warfarin , increasing vitamin K levels in the body can increase clotting and reduce the effectiveness of warfarin, which could result in a stroke.
Foods rich in vitamin K include beef liver, broccoli, brussels sprouts, cabbage, collard greens, endive, kale, lettuce, mustard greens, parsley, soy beans, spinach, Swiss chard, turnip greens, watercress, and several other foods.
While there is no need to avoid products that contain vitamin K, you should maintain a consistent level of consumption of these products. Grapefruit or grapefruit juice consumption can also result in drug interactions that may increase the level of the medicine in your blood, possibly causing drug toxicity. Not all medicines contained in a class of drugs like the statins may lead to the interaction, so your doctor will be able to prescribe another drug.
Cranberry juice, orange juice, pomegranate juice, and even garlic can lead to interactions with drugs, too. A Possible Deadly Mix? Socially-used drugs can have an especially harsh effect with other drugs. For example, some asthma drugs like the beta-2 agonist albuterol Proventil HFA, Ventolin HFA can have a stimulant effect, and if combined with caffeine, can interfere with sleep or lead to a rapid heart rate, which can be dangerous in people with heart disease.
The stimulant effect from caffeine can be additive to stimulation from decongestants , too. Alcohol can worsen drowsiness, especially when mixed with other drugs that cause sedation, which may put you at a higher risk for a fall or a car accident. Alcohol should never be combined with opioid painkillers or anxiety medications like benzodiazepines.
Life-threatening respiratory depression can occur. A particularly concerning, yet often unknown interaction between alcohol and cocaine has been reported. The National Institute on Drug Abuse NIDA has found that the human liver combines cocaine and alcohol and manufactures a third substance, cocaethylene, that intensifies cocaine's euphoric effects but may increase the risk of sudden death.
According to the NIDA, this drug-drug interaction, between cocaine and alcohol, is a common two-drug combination that results in drug-related deaths. Illicit drugs combined with other illicit drugs can be particularly dangerous.
Top 9 Ways to Prevent a Deadly Drug Interaction
Prescription drugs that interact with alcohol include benzodiazepines, when mixed with other sedating drugs, or counteract the effect of stimulant drugs. Analyze prescription and OTC drug interactions to determine which drug combinations your patients should avoid. Includes food, alcohol, and herbal. The more medications you take, the greater the chance for your drug interacting with another medicine. Drug-drug interactions can decrease how well your.