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Mechanism of Action
Iopromide is a nonionic, water soluble, tri-iodinated x-ray contrast agent for intravascular administration.
Intravascular injection of iopromide opacifies those vessels in the path of flow of the contrast agent, permitting radiographic visualization of the internal structures until significant hemodilution occurs.
Following ULTRAVIST administration, the degree of contrast enhancement is directly related to the iodine content in the administered dose; peak iodine plasma levels occur immediately following rapid intravenous injection. Iodine plasma levels fall rapidly within 5 to 10 minutes. This can be accounted for by the dilution in the vascular and extravascular fluid compartments.
Intravascular Contrast: Contrast enhancement appears to be greatest immediately after bolus injections (15 seconds to 120 seconds). Thus, greatest enhancement may be detected by a series of consecutive two-to-three second scans performed within 30 to 90 seconds after injection (that is, dynamic computed tomographic imaging).
ULTRAVIST Injection may be visualized in the renal parenchyma within 30–60 seconds following rapid intravenous injection. Opacification of the calyces and pelves in patients with normal renal function becomes apparent within 1–3 minutes, with optimum contrast occurring within 5–15 minutes.
In contrast CT, some performance characteristics are different in the brain and body. In contrast CT of the body, iodinated contrast agents diffuse rapidly from the vascular into the extravascular space. Following the administration of iodinated contrast agents, the increase in tissue density to x-rays is related to blood flow, the concentration of the contrast agent, and the extraction of the contrast agent by various interstitial tissues. Contrast enhancement is thus due to any relative differences in extravascular diffusion between adjacent tissues.
In the normal brain with an intact blood-brain barrier, contrast is generally due to the presence of iodinated contrast agent within the intravascular space. The radiographic enhancement of vascular lesions, such as arteriovenous malformations and aneurysms, depends on the iodine content of the circulating blood pool.
In tissues with a break in the blood-brain barrier, contrast agent accumulates within interstitial brain tissue. The time to maximum contrast enhancement can vary from the time that peak blood iodine levels are reached to 1 hour after intravenous bolus administration. This delay suggests that radiographic contrast enhancement is at least in part dependent on the accumulation of iodine containing medium within the lesion and outside the blood pool. The mechanism by which this occurs is not clear.
After intravenous administration to healthy young volunteers, plasma iopromide concentration time profile shows an initial distribution phase with a half-life of 0.24 hour; a main elimination phase with a half-life of 2 hours; and a terminal elimination phase with a half-life of 6.2 hours. The total volume of distribution at steady state is about 16 L suggesting distribution in to extracellular space. Plasma protein binding of iopromide is 1%.
Iodinated contrast agents may cross the blood-brain barrier [see WARNINGS AND PRECAUTIONS].
Iopromide is not metabolized.
The amounts excreted unchanged in urine represent 97% of the dose in young healthy subjects. Only 2% of the dose is recovered in the feces. Similar recoveries in urine and feces are observed in middle-aged and elderly patients. This finding suggests that, compared to the renal route, biliary and/or gastrointestinal excretion is not important for iopromide. During the slower terminal phase only 3% of the dose is eliminated; 97% of the dose is disposed of during the earlier phases, the largest part of which occurs during the main elimination phase. The ratio of the renal clearance of iopromide to the creatinine clearance is 0.82 suggesting that iopromide is mainly excreted by glomerular filtration. Additional tubular reabsorption is possible. Pharmacokinetics of iopromide at intravenous doses up to 80 g iodine, are dose proportionate and first order.
The mean total and renal clearances are 107 mL/min and 104 mL/min, respectively.
A pharmacokinetic study was conducted in 11 patients with renal impairment [see Use in Specific Populations].
ULTRAVIST Injection was administered to 708 patients; 1 patient was less than 18 years of age, 347 patients were between 18 and 59 years of age, and 360 patients were equal to or greater than 60 years of age; the mean age was 56.6 years (range 17–88). Of the 708 patients, 446 (63%) were male and 262 (37%) were female. The racial distribution was: Caucasian 463 (65.4%), Black 95 (13.4%), Hispanic 36 (5.1%), Asian 11 (1.6 %), and other or unknown 103 (14.5%). Efficacy assessment was based on the global evaluation of the quality of the radiographs by rating visualization as either excellent, good, poor, or no image, and on the ability to make a diagnosis. Five (5) intra-arterial and three (3) intravenous procedures were studied with 1 of 4 concentrations (370 mg I/mL, 300 mg I/mL, 240 mg I/mL, and 150 mg I/mL). These procedures were: aortography/visceral angiography, coronary arteriography and left ventriculography, cerebral arteriography, peripheral arteriography, intra-arterial digital subtraction angiography (IA-DSA), contrast computed tomography (CT) of head and body, excretory urography, and peripheral venography.
Cerebral arteriography was evaluated in two randomized, double-blind clinical trials of ULTRAVIST Injection 300 mg I/mL in 80 patients with conditions such as altered cerebrovascular perfusion and/or permeability occurring in central nervous system diseases due to various CNS disorders. Visualization ratings were good or excellent in 99% of the patients with ULTRAVIST Injection; a radiologic diagnosis was made in the majority of the patients. Confirmation of the radiologic findings by other diagnostic methods was not obtained.
Coronary arteriography/left ventriculography was evaluated in two randomized, double-blind clinical trials and one unblinded, unrandomized clinical trial of ULTRAVIST Injection 370 mg I/mL in 106 patients with conditions such as altered coronary artery perfusion due to metabolic causes and in patients with conditions such as altered ventricular function. Visualization ratings were good or excellent in 99% or more of the patients a radiologic diagnosis was made in the majority of the patients. A confirmation of the radiologic findings by other diagnostic methods was not obtained.
Aortography/visceral angiography was evaluated in two randomized, double-blind clinical trials in 78 patients with conditions such as altered aortic blood flow and/or visceral vascular disorders. Visualization ratings were good or excellent in the majority of the patients; a radiologic diagnosis was made in 99% of the patients with ULTRAVIST Injection. A confirmation of radiologic findings by other diagnostic methods was not obtained. The risks of renal arteriography could not be analyzed.
Contrast CT of head and body was evaluated in three randomized, double-blind clinical trials of ULTRAVIST Injection 300 mg I/mL in 95 patients with vascular disorders. Visualization ratings were good or excellent in 99% of the patients; a radiologic diagnosis was made in the majority of the patients. A confirmation of contrast CT findings by other diagnostic methods was not obtained.
ULTRAVIST Injection was evaluated in a blinded reader trial for CT of the head and body. Among the 382 patients who were evaluated with ULTRAVIST Injection 370 mg I/mL, visualization ratings were good or excellent in approximately 97% of patients.
Peripheral venography was evaluated in two randomized, double-blind clinical trials of ULTRAVIST Injection 240 mg I/mL in 63 patients with disorders affecting venous drainage of the limbs. Visualization ratings were good or excellent in 100% of the patients; a radiologic diagnosis was made in the majority of the patients. A confirmation of radiologic findings by other diagnostic methods was not obtained.
Similar studies were completed with comparable findings noted in intra-arterial digital subtraction angiography, peripheral arteriography and excretory urography.
Last reviewed on RxList: 5/24/2012
This monograph has been modified to include the generic and brand name in many instances.
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