Gadopentetic acid
Gadopentetic acid is a linear ionic paramagnetic gadolinium chelate used as a radiographic contrast agent for magnetic resonance imaging (MRI). It is utilized to identify areas of abnormal vascularization, delineate masses, and demonstrate disruption of the blood-brain barrier and areas of inflammation. **Clinical Pearl:** Unbound gadolinium is highly toxic, so it is chelated to reduce toxicity. It does not cross the normal blood-brain barrier due to its large molecular size.
Mechanism: Gadolinium is a paramagnetic agent that exerts its effects due to **seven unpaired electrons** → causes a shortening of **T1 and T2 relaxation times** of adjacent tissues → results in increased signal intensity on T1-weighted MR images.
Dosing by species
- MRI examination (CNS, whole body) · 0.1 mmol/kg · IV · single dose · Repeat doses up to 0.3 mmol/kg total may be helpful in some cases · Give as bolus if performing MRA, dynamic contrast or liver studies. Enhancement visible up to 45-60 minutes post-administration.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Severe renal impairment
Adverse effects
- Nephrogenic systemic fibrosis (reported in humans)
- Prolonged QT interval
- Arrhythmias
- Tissue irritation and necrosis if extravasated
- Anaphylaxis (rare, 0.001%-0.01% in humans)
- Transient increase in serum bilirubin
Drug interactions
- Class 1a antiarrhythmics · Potential interaction affecting cardiac rhythm · moderate
- Class 3 antiarrhythmics · Potential interaction affecting cardiac rhythm · moderate
Monitoring
- Cardiac rhythm (in case of overdose)
- Renal function
Overdose
Accidental overdosage may lead to an increase in QT interval and other arrhythmias. **Cardiac monitoring** is recommended in the event of an overdose.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.