Drug interaction
Drug interactions alter drug effects via pharmacodynamics or pharmacokinetics.
Drug interactions occur when a drug's mechanism of action is affected by the concomitant administration of substances such as foods, beverages, or other drugs. They are a significant concern in pharmaceutical sciences, particularly for elderly people who regularly use five or more medications or supplements, increasing the risk of side-effects from drug–drug interactions.
- field
- Pharmaceutical sciences
- known_for
- Effects of concomitant administration of substances on drug action
- types
- additive, synergistic, antagonistic
- key_enzyme_system
- Cytochrome P450 oxidases (CYP450)
- notable_example
- Grapefruit effect on drug metabolism
Lore & Background
Oligonucleotide therapeutics, such as siRNA drugs, do not significantly induce or inhibit cytochrome P450 enzymes, requiring distinct frameworks for evaluating drug–drug interactions. Mechanisms include transporter competition, carrier protein binding, indirect CYP modulation, and on-target miRNA network perturbation. Regulatory guidance from the FDA recommends assessing DDI potential through in vitro transporter studies and induction assays where indirect CYP modulation is plausible.
Reader's Guide
Drug interactions are a critical consideration in clinical practice and drug development. The risk of a drug–drug interaction increases with the number of drugs used, making polypharmacy in elderly populations a particular concern. Understanding the three types of interactions—additive, synergistic, and antagonistic—helps predict outcomes, though distinguishing between synergistic and additive effects can be difficult. Pharmacodynamic interactions, such as those involving GABAA receptors, and pharmacokinetic interactions, especially those mediated by cytochrome P450 enzymes, are central to assessing safety. The emergence of oligonucleotide therapeutics introduces novel interaction mechanisms that do not rely on direct CYP inhibition, requiring updated evaluation frameworks. The example of grapefruit juice increasing drug bioavailability illustrates the importance of food–drug interactions. Overall, awareness of drug interactions guides dosing adjustments, timing of administration, and avoidance of harmful combinations.
Did You Know?
- Both Zolpidem and alcohol affect GABAA receptors, and their simultaneous consumption can lead to loss of consciousness.
- Mixing thiopentone and suxamethonium before intravenous injection can lead to the precipitation of thiopentone.
- Grapefruit juice increases the bioavailability of various drugs beyond its inhibitory activity on first pass metabolism.
- Approved RNAi-based therapeutics such as siRNA drugs do not significantly induce or inhibit cytochrome P450 enzymes.
More in Addictive Substances & Medications 1-24
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