Drug-Drug and Pharmacodynamic Interactions

Flashcards covering pharmacokinetic and pharmacodynamic drug interactions, including common inducers, inhibitors, and clinical examples.

Complexation

A mechanism by which interactions alter drug administration or absorption through processes like chelation in the GI tract.

Distribution Interactions

Drug interactions resulting from the displacement of drugs bound to protein sites, occurring primarily with drugs that have a high degree of plasma protein binding, a greater affinity for the same binding site, a narrow therapeutic index (NTI), or a small volume of distribution.

CYP 450 enzymes

The main enzymes involved in drug metabolism that play a key role in therapeutically important drug interactions through induction or inhibition.

Big inducers: PS PORCS

• Phenytoin

• Smoking

• Phenobarbital

• Oxcarbazempine

• Rifampin (rifabutin, rifapentine)

• Carbamazepine

• St. John’s Wort

Big inhibitors: G PACMAN

• Grapefruit

• PIs (protease inhibitors)

• Azole antifungals

• Cimetidine

• Macrolides

• Amiodarone

• non-DHP CCBs

Pharmacodynamic Interactions

Interactions that occur when the response of one drug is modified by the presence of another without alterations in pharmacokinetics (PK), resulting in additive or antagonistic effects.

QT prolongation

A reflection of ventricular depolarization and repolarization that serves as a risk factor for ventricular tachyarrhythmias and sudden cardiac death.

5HT3 blockers

Antiemetic medications, such as odansetron, that can contribute to additive pharmacodynamic interactions like QT prolongation.

Drug-food interactions

Examples include Grapefruit + simvastatin and Green leafy veggies + warfarin.

Drug-herbal interactions

Examples include St. John’s Wort + clopidogrel and Ginseng + warfarin.

Alert Fatigue

The process by which busy workers become desensitized to safety alerts, leading them to ignore or fail to respond appropriately to warnings.