Pharmacological Considerations in Diagnostic Radiology: Contrast Agents, Adverse Reactions, Drug–Imaging Interactions, And Patient Safety.

Abstract

Contrast-enhanced imaging is a pharmacological intervention as well as an imaging procedure. Iodinated contrast media (ICM), gadolinium-based contrast agents (GBCAs), and ultrasound contrast agents (UCAs) differ substantially in molecular structure, physicochemical behaviour, biodistribution, clearance, dose-response relationships, and adverse-event profiles. These differences influence how patients should be screened, how agents should be selected, and how repeated examinations should be scheduled. This structured narrative review synthesises contemporary evidence, emphasising guidance and peer-reviewed studies published predominantly from 2021 through August 2026. PubMed/MEDLINE was used for primary bibliographic verification, while Scopus and Google Scholar were used for broader discovery and citation tracking, and ResearchGate was used only as a supplementary full-text discovery source. The review focuses on pharmacokinetics and pharmacodynamics; immediate and delayed hypersensitivity; contrast-associated acute kidney injury (CA-AKI); iodine-related thyroid dysfunction; nephrogenic systemic fibrosis (NSF); gadolinium retention; UCA safety; drug–contrast issues, including metformin and laboratory-test interference; extravasation; special populations; and pharmacovigilance. Current evidence favours risk-adapted contrast administration rather than routine contrast avoidance. The clinically important determinants of risk are patient-specific: prior reaction phenotype, kidney function and active acute kidney injury, haemodynamic status, thyroid susceptibility, pregnancy or childhood, concomitant medications, exposure frequency, and the diagnostic necessity of enhancement. Major contemporary guidance also shows that some historical practices require reconsideration, particularly routine premedication and indiscriminate withholding of contrast in chronic kidney disease. The principal contribution of this review is to integrate pharmacology with radiological decision-making in a practical framework that links agent properties to individualised risk, prevention, emergency readiness, and future precision contrast administration.