Reactions known to occur with parenteral administration of iodinated
ionic contrast agents (see the listing below) are possible with any
nonionic agent. Approximately 95 percent of adverse reactions accompanying
the use of other water-soluble intravascularly administered contrast
agents are mild to moderate in degree. However, life-threatening reactions
and fatalities, mostly of cardiovascular origin, have occurred. Reported
incidences of death from the administration of other iodinated contrast
media range from 6.6 per 1 million (0.00066 percent) to 1 in 10,000
patients (0.01 percent). Most deaths occur during injection or 5 to
10 minutes later, the main feature being cardiac arrest with cardiovascular
disease as the main aggravating factor. Isolated reports of hypotensive
collapse and shock are found in the literature. The incidence of shock
is estimated to be 1 out of 20,000 (0.005 percent) patients.
Adverse reactions to injectable
contrast media fall into two categories: chemotoxic reactions and
idiosyncratic reactions. Chemotoxic reactions result from the physicochemical
properties of the contrast medium, the dose, and the speed of injection.
All hemodynamic disturbances and injuries to organs or vessels perfused
by the contrast medium are included in this category. During intrathecal
use, there is a lower incidence of electroencephalographic changes
as well as neurotoxicity by virtue of the intrinsic properties of
the iopamidol molecule.
Idiosyncratic reactions include all other reactions. They occur more
frequently in patients 20 to 40 years old. Idiosyncratic reactions
may or may not be dependent on the amount of drug injected, the speed
of injection, the mode of injection, and the radiographic procedure.
Idiosyncratic reactions are subdivided into minor, intermediate, and
severe. The minor reactions are self-limited and of short duration;
the severe reactions are life-threatening and treatment is urgent
and mandatory.
The reported
incidence of adverse reactions to contrast media in patients with
a history of allergy is twice that for the general population. Patients
with a history of previous reactions to a contrast medium are three
times more susceptible than other patients. However, sensitivity to
contrast media does not appear to increase with repeated examinations.
Most adverse reactions to intravascular contrast agents appear within
one to three minutes after the start of injection, but delayed reactions
may occur (see PRECAUTIONS-General).
Because measurable
plasma levels are attained following the intrathecal administration
of iopamidol, adverse reactions reported with the use of intravascular
contrast agents are theoretically possible. These include:
Cardiovascular: vasodilation (feeling of warmth), cerebral hematomas, hemodynamic
disturbances, sinus bradycardia, transient electrocardiographic abnormalities,
ventricular fibrillation, petechiae.
Digestive: nausea, vomiting,
severe unilateral or bilateral swelling of the parotid and submaxillary
glands.
Nervous: paresthesia, dizziness, convulsions, paralysis, coma.
Respiratory: increased
cough, asthma, dyspnea, laryngeal edema, pulmonary edema, bronchospasm,
rhinitis.
Urogenital: osmotic nephrosis of proximal tubular cells, renal failure, pain.
Special Senses: perversion of taste; bilateral ocular irritation; lacrimation; itching;
conjunctival chemosis, infection, and conjunctivitis.
Endocrine: Thyroid function
tests indicative of hypothyroidism or transient thyroid suppression
have been uncommonly reported following iodinated contrast media administration
to adult and pediatric patients, including infants. Some patients
were treated for hypothyroidism.
Skin and Subcutaneous Tissue Disorders: Reactions range from mild (e.g. rash, erythema, pruritus, urticaria
and skin discoloration) to severe: [e.g. Stevens-Johnson syndrome
and toxic epidermal necrolysis (SJS/TEN), acute generalized exanthematous
pustulosis (AGEP) and drug reaction with eosinophilia and systemic
symptoms (DRESS)]. Injection site pain usually due to extravasation
and/or erythematous swelling, skin necrosis, urticaria.
The following reactions may also
occur: neutropenia, thrombophlebitis, flushing, pallor, weakness,
severe retching and choking, wheezing, cramps, tremors, and sneezing.