Drug interaction

interactdrug interactionsdrug-drug interactioninteractiondrug-drug interactionsinteractionsdrug–drug interactioninteractions with other medicationsherb-drug interactionsinteracts
A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug.wikipedia
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Cimetidine

TagametCimehexal
Due to its non-selective inhibition of cytochrome P450 enzymes, cimetidine has numerous drug interactions.

Drug metabolism

metabolismxenobiotic metabolismmetabolic stability
Many drug interactions are due to alterations in drug metabolism.
Drug metabolism also affects multidrug resistance in infectious diseases and in chemotherapy for cancer, and the actions of some drugs as substrates or inhibitors of enzymes involved in xenobiotic metabolism are a common reason for hazardous drug interactions.

CYP2D6

2D6cytochrome P450 2D6cytochrome p-450 cyp2d6
Of the various families that are present in human beings the most interesting in this respect are the 1, 2 and 3, and the most important enzymes are CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4.
If such a drug is taken at the same time as a second drug that is a CYP2D6 substrate, the first drug may affect the elimination rate of the second through what is known as a drug-drug interaction.

Grapefruit

pink grapefruitCitrus paradisiCitrus x paradisi
Grapefruit and grapefruit juice have been found to interact with numerous drugs and in many cases, to result in adverse direct and/or side effects (if dosage is not carefully adjusted.)

Cytochrome P450

cytochrome P450 oxidaseP450CYP450
One notable system involved in metabolic drug interactions is the enzyme system comprising the cytochrome P450 oxidases. Cytochrome P450 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.
Effects on CYP isozyme activity are a major source of adverse drug interactions, since changes in CYP enzyme activity may affect the metabolism and clearance of various drugs.

Pharmacokinetics

pharmacokineticsteady-stateSteady-state levels
For example, one drug may alter the pharmacokinetics of another.

Warfarin

CoumadinAthrombinAthrombin-K
The most commonly implicated conventional drugs in herb-drug interactions are warfarin, insulin, aspirin, digoxin, and ticlopidine, due to their narrow therapeutic indices.
Warfarin interacts with many commonly used drugs, and the metabolism of warfarin varies greatly between patients.

Monoamine oxidase inhibitor

MAOImonoamine oxidase inhibitorsMAOIs
The most significant risk associated with the use of MAOIs is the potential for drug interactions with over-the-counter and prescription medicines, ‘controlled’ drugs or medications, and some dietary supplements (e.g., St. John's wort, tryptophan).

Enzyme

enzymologyenzymesenzymatic
Cytochrome P450 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.
Induction or inhibition of these enzymes can cause drug interactions.

Carbamazepine

TegretolEpitolAtretol
Carbamazepine has a potential for drug interactions; caution should be used in combining other medicines with it, including other antiepileptics and mood stabilizers.

Aspirin

acetylsalicylic acidBufferinASA
The most commonly implicated conventional drugs in herb-drug interactions are warfarin, insulin, aspirin, digoxin, and ticlopidine, due to their narrow therapeutic indices.
Aspirin is known to interact with other drugs.

Pharmacist

pharmacistsdruggistchemist
Pharmacists undergo university or graduate-level education to understand the biochemical mechanisms and actions of drugs, drug uses, therapeutic roles, side effects, potential drug interactions, and monitoring parameters.

Polypharmacy

pill burdenmultiple chronic diseasesmixing multiple drugs simultaneously
Concerns about polypharmacy include increased adverse drug reactions, drug interactions, prescribing cascade, and higher costs.

Benzodiazepine

benzodiazepinesbenzodiazapinesbenzo
Individual benzodiazepines may have different interactions with certain drugs.

Amphetamine

Benzedrinespeedamphetamines
Many types of substances are known to interact with amphetamine, resulting in altered drug action or metabolism of amphetamine, the interacting substance, or both.

Amiloride

Midamor
Amiloride may have important drug-drug interactions when combined with other medications that also increase potassium levels in the blood, leading to hyperkalemia.

Ginger

Zingiber officinaleginger rootZingiberis Rhizoma
It is on the FDA's "generally recognized as safe" list, though it does interact with some medications, including the anticoagulant drug warfarin and the cardiovascular drug nifedipine.

Intrinsic activity

efficacyE max IA
A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug.

Side effect

side effectsside-effectsside-effect
A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug.

Concomitant drug

concomitantconcomitantlyConcomitant administration
A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug.

Signal transduction

signaling pathwayssignaling cascadesignal transduction pathways
Alternatively, drug interactions may result from competition for a single receptor or signaling pathway.

Synergy

synergisticsynergiessynergistically
When two drugs are used together, their effects can be additive (the result is what you expect when you add together the effect of each drug taken independently), synergistic (combining the drugs leads to a larger effect than expected), or antagonistic (combining the drugs leads to a smaller effect than expected).

Antagonism (chemistry)

antagonisticantagonismAntagonistic interaction
When two drugs are used together, their effects can be additive (the result is what you expect when you add together the effect of each drug taken independently), synergistic (combining the drugs leads to a larger effect than expected), or antagonistic (combining the drugs leads to a smaller effect than expected).