A drug interaction is a situation in which a substance (usually another drug) affects the activity of a drug when both are administered together. This action can be synergistic (when the drug’s effect is increased) or antagonistic (when the drug’s effect is decreased) or a new effect can be produced that neither produces on its own. Typically, interactions between drugs come to mind (drug-drug interaction). However, interactions may also exist between drugs and foods (drug-food interactions), as well as drugs and medicinal plants or herbs (drug-plant interactions). People taking antidepressant drugs such as monoamine oxidase inhibitors should not take food containing tyramine as hypertensive crisis may occur (an example of a drug-food interaction). These interactions may occur out of accidental misuse or due to lack of knowledge about the active ingredients involved in the relevant substances.
It is therefore easy to see the importance of these pharmacological interactions in the practice of medicine. If a patient is taking two drugs and one of them increases the effect of the other it is possible that an overdose may occur. The interaction of the two drugs may also increase the risk that side effects will occur. On the other hand, if the action of a drug is reduced it may cease to have any therapeutic use because of under dosage. Notwithstanding the above, on occasion these interactions may be sought in order to obtain an improved therapeutic effect. Examples of this include the use of codeine with paracetamol to increase its analgesic effect. Or the combination of clavulanic acid with amoxicillin in order to overcome bacterial resistance to the antibiotic. It should also be remembered that there are interactions that, from a theoretical standpoint, may occur but which in clinical practice have no important repercussions.
The pharmaceutical interactions that are of special interest to the practice of medicine are primarily those that have negative effects for an organism. The risk that a pharmacological interaction will appear increases as a function of the number of drugs administered to a patient at the same time.
It is possible that an interaction will occur between a drug and another substance present in the organism (i.e. foods or alcohol). Or in certain specific situations a drug may even react with itself, such as occurs with dehydration. In other situations the interaction does not involve any effect on the drug. In certain cases, the presence of a drug in an individual’s blood may affect certain types of laboratory analysis (analytical interference).
It is also possible for interactions to occur outside an organism before administration of the drugs has taken place. This can occur when two drugs are mixed, fro example, in a saline solution prior to intravenous injection. Some classic examples of this type of interaction include that Thiopentone and Suxamethonium should not be placed in the same syringe and same is true for Benzylpenicillin and Heparin. These situations will all be discussed under the same heading due to their conceptual similarity.
Drug interactions may be the result of various processes. These processes may include alterations in the pharmacokinetics of the drug, such as alterations in the absorption, distribution, metabolism, and excretion (ADME) of a drug. Alternatively, drug interactions may be the result of the pharmacodynamic properties of the drug, e.g. the co-administration of a receptor antagonist and an agonist for the same receptor.
Other articles related to "drug interactions, drugs, drug interaction, drug, interactions":
... by other central nervous system depressant drugs such as barbiturates, benzodiazepines, opioids, phenothiazines, and anti-depressants ...
... and or supplements that put them at risk of a major drug interaction ... Potential drug-drug interactions have increased over time and are more common in the low educated elderly even after controlling for age, sex, place ...
... twilight sleep, also the name of a proprietary drug available in the past in ampoules of injectable fluid containing morphine sulfate and scopolamine hydrobromide (and in some cases the phenothiazine ...
... is contraindicated in patients taking a class of antidepressant drugs known as non-selective monoamine oxidase (MAO) inhibitors such as phenelzine and tranylcypromine ... Combining Stalevo with these drugs could cause serious—possibly life-threatening—side effects ... Stalevo may be combined with the drugs rasagiline or selegiline ...
... Many drugs may increase or decrease the activity of various CYP isozymes either by inducing the biosynthesis of an isozyme (enzyme induction) or by directly inhibiting the ... This is a major source of adverse drug interactions, since changes in CYP enzyme activity may affect the metabolism and clearance of various drugs ... For example, if one drug inhibits the CYP-mediated metabolism of another drug, the second drug may accumulate within the body to toxic levels ...
Famous quotes containing the words interactions and/or drug:
“In our interactions with people, a benevolent hypocrisy is frequently requiredacting as though we do not see through the motives of their actions.”
—Friedrich Nietzsche (18441900)
“Narcotics have been systematically scapegoated and demonized. The idea that anyone can use drugs and escape a horrible fate is an anathema to these idiots. I predict that in the near future, right wingers will use drug hysteria as a pretext to set up an international police apparatus.”
—Gus Van Sant, U.S. screenwriter and director, and Dan Yost. Father Tom Murphy (William S. Burroughs)