DOSAGE AND ADMINISTRATION
It is advisable that HEXABRIX be at or close to body temperature when injected.
The patient should be instructed to omit the meal that precedes the examination. Appropriate premedication, which may include a barbiturate, tranquilizer or analgesic drug, may be administered prior to the examination.
A preliminary film is recommended to check the position of the patient and the x-ray exposure factors prior to the injection of the contrast medium.
If during administration a minor reaction occurs the injection should be slowed or stopped until the reaction has subsided. If a major reaction occurs the injection should be discontinued immediately.
Under no circumstances should other drugs be administered concomitantly in the same syringe or IV administration set because of a potential for chemical incompatibility.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.
HEXABRIX may be administered by catheter injection into the chambers of the heart or associated large blood vessels. Rapid injection is essential and satisfactory results usually require injection of the total dosage in 1-2 seconds.
In addition to the general precautions previously described, it is advisable to monitor for ECG and vital signs changes throughout the procedure.
When large individual doses are administered sufficient time should be allowed for any observed changes to return to or near baseline prior to making the next injection.
Caution should be used when making right heart injections in patients with pulmonary hypertension or incipient heart failure since this may lead to increased right side pressures with subsequent bradycardia and systemic hypotension. Patients with pulmonary disease present additional risks.
Caution is advised in cyanotic infants since apnea, bradycardia, other arrhythmias and a tendency to acidosis are more likely to occur.
Since infants are more likely to respond with convulsions than are adults, the amount of total dosage is of particular importance. Repeated injections are hazardous in infants weighing less than 7 kg, particularly when these infants have pre-existing compromised right heart function or obliterated pulmonary vascular beds.
In addition to the adverse reactions previously listed, this procedure has been complicated by intramural injection with marked adverse effects on cardiac function.
The volume of individual doses should be determined by the size of the structure to be visualized and the anticipated degree of hemodilution at the site of injection. Valvular competence should also be taken into consideration.
Older Children: Catheter angiocardiography usually requires single doses of 30-45 mL of HEXABRIX.
Infants and Young Children: The recommended single dose of HEXABRIX is about 1.5 mL/kg (range 1 mL/kg to 2 mL/kg). In addition, small test volumes of about 2 mL may be used for catheter placement.
The usual total dose of HEXABRIX per procedure, which includes diagnostic and test doses is about 4 mL/kg. This dosage may be as small as 1.5 mL/kg and should not normally exceed 5 mL/kg.
SELECTIVE CORONARY ARTERIOGRAPHY WITH OR WITHOUT LEFT VENTRICULOGRAPHY
During the administration of large doses of HEXABRIX, continuous monitoring of vital signs is desirable. Caution is advised in the administration of large volumes to patients with incipient heart failure because of the possibility of aggravating the pre-existing condition. Hypotension should be corrected promptly since it may result in serious arrhythmias.
Special care regarding dosage should be observed in patients with right ventricular failure, pulmonary hypertension, or stenotic pulmonary vascular beds because of hemodynamic changes which may occur after injection into the right heart outflow tract.
Patients may have clinically insignificant ECG changes during the procedure. The following adverse effects have occurred in conjunction with the administration of iodinated intravascular contrast agents for this procedure: hypotension, shock, anginal pain, myocardial infarction, cardiac arrhythmias (bradycardia, ventricular tachycardia, ventricular fibrillation) and cardiac arrest. Fatalities have been reported.
Complications to the procedure include dissection of coronary arteries, dislodgement of atheromatous plaques, perforation, hemorrhage and thrombosis.
The usual adult dose for left coronary arteriography is 8 mL (range 2-14 mL) and for right coronary arteriography is 5 mL (range 1-10 mL). The doses may be repeated as necessary; doses up to a total of 150 mL have been given. For left ventriculography, the usual adult dose in a single injection is 45 mL (range 35-45 mL) and repeated as necessary. The total dose for combined selective coronary arteriography and left ventriculography should not exceed 250 mL.
HEXABRIX may be injected to visualize the peripheral arterial circulation. Arteriograms of the upper and lower extremities may be obtained by any of the established techniques.
The procedure is normally performed with local anesthesia. Rarely, general anesthesia may be required. (See PRECAUTIONS, General.)
A preliminary radiograph is usually made prior to the injection of the contrast agent.
In addition to the general precautions previously described, moderate decreases in blood pressure occur frequently with intra-arterial (brachial) injections. This change is usually transient and requires no treatment, however, the blood pressure should be monitored for approximately ten minutes following injection.
Extreme caution during injection of the contrast agent is necessary to avoid extravasation and fluoroscopy is recommended. This is especially important in patients with severe arterial disease.
In addition to the general adverse reactions previously described, hemorrhage and thrombosis have occurred at the puncture site of the percutaneous injection. Brachial plexus injury has been reported following axillary artery injection.
The single adult dose for aorto-iliac runoff studies is 45 mL (range 20-80 mL). The single adult dose for the common iliac, the external iliac and the femoral arteries is 30 mL (range 10-50 mL). These doses may be repeated as necessary. For the upper limb, the usual single adult dose is 20 mL (range 15-30 mL), repeated as necessary. The total procedural dose should not exceed 250 mL.
AORTOGRAPHY AND SELECTIVE VISCERAL ARTERIOGRAPHY
HEXABRIX may be used to visualize the aorta and its major abdominal branches.
The usual dose for injections into the aorta is 25 to 50 mL; the celiac artery is 40 mL; the superior mesenteric artery is 20 to 40 mL; the inferior mesenteric artery is 8 to 15 mL. These doses may be repeated as necessary. The total dose should not exceed 250 mL.
HEXABRIX may be used to visualize the cerebral vasculature by any of the accepted techniques.
Cerebral angiography is normally performed with local or general anesthesia. (See PRECAUTIONS, General.)
In addition to the general precautions previously described, cerebral angiography should be performed with special caution in patients with advanced arteriosclerosis, severe hypertension, cardiac decompensation, senility, recent cerebral thrombosis or embolism, and migraine.
The major causes of cerebral arteriographic adverse reactions appear to be repeated injections of the contrast material, administration of doses higher than those recommended, the presence of occlusive atherosclerotic vascular disease and the method and technique of injection.
Adverse reactions are normally mild and transient. A feeling of warmth in the face and neck is frequently experienced. Infrequently, a more severe burning discomfort is observed. Transient visual hallucinations have been reported.
Serious neurological reactions that have been associated with cerebral angiography and not listed under Adverse Reactions, General, include stroke, amnesia and respiratory difficulties.
Visual field defects with anopsia and reversible neurological deficit lasting from 24 hours to 48 hours have been reported. Confusion, disorientation with hallucination, and absence of vision sometimes lasting for one week have also been reported.
Cardiovascular reactions that may occur with some frequency are bradycardia and either an increase or decrease in systemic blood pressure. The blood pressure change is transient and usually requires no treatment.
The usual dosage employed varies with the site and method of injection and the age and condition of the patient. In adults, cerebral angiography is usually performed by a selective injection of 9 mL (range 6-12mL) for the common carotid arteries and 8 mL (range 5-12 mL) for the vertebral arteries. Additional injections may be made as indicated. When aortic arch injections (four vessel studies) are performed in conjunction with cerebral angiography, the usual dose is 40 mL (range 30-50 mL). Other dosages may be employed for more selective injections, depending upon the vessel injected. The total dose per procedure should not exceed 150 mL.
INTRA-ARTERIAL DIGITAL SUBTRACTION ANGIOGRAPHY (IA-DSA)
Intra-arterial digital subtraction angiography (IA-DSA) is a radiographic modality which produces arterial images similar to conventional film-screen systems following arterial injection. The advantages include: the use of less contrast medium; the use of lower iodine concentrations; a decreased need for selective arterial catheterization; and a shortened examination time.
No special patient preparation is required for IA-DSA. However, it is advisable to insure that patients are well hydrated prior to examination.
In addition to the general precautions described, the risks associated with IA-DSA are those usually attendant with catheter procedures. Following the procedure, gentle pressure hemostasis is required, followed by observation and immobilization of the limb for several hours to prevent hemorrhage from the site of arterial puncture.
Patient motion, including respiration and swallowing, can result in misregistration leading to image degradation and non-diagnostic studies.
As a general rule, the volume and concentration used for IA-DSA are about 50%, or less, of that used for conventional procedures. The actual dosage and flow rate will vary depending on the selectivity of the injection site and the area being examined.
The most versatile concentration of HEXABRIX is a 1:1 dilution with Sterile Water for Injection, U.S.P. This dilution provides 16% iodine and is isotonic.
The following suggested volumes per injection are intended only as a guide. Injections may be repeated as necessary. It is advisable to inject at rates approximately equal to the flow rate of the vessel being injected.
| Carotid Arteries
| Vertebral Arteries
| Subclavian or Brachial Arteries
| Major Branches of the Abdominal Aorta
INTRAVENOUS DIGITAL SUBTRACTION ANGIOGRAPHY
Intravenous digital subtraction angiography (IV DSA) is a radiographic modality which allows dynamic imaging of the arterial system following intravenous injection of iodinated x-ray contrast media through the use of image intensification, enhancement of the iodine signal and digital processing of the image data. Temporal subtraction of the images obtained prior to and during the “first arterial pass” of the injected contrast medium yields images which are devoid of bone and soft tissue.
IV DSA is most frequently used to examine the heart, including coronary by-pass grafts; the pulmonary arteries; arteries of the brachiocephalic circulation; the aortic arch; the abdominal aorta and its major branches; the iliac arteries; and the arteries of the extremities.
No special patient preparation is required for IV DSA. However it is advisable to insure that patients are well hydrated prior to examination.
In addition to the general precautions previously described, the risks associated with IV DSA include those usually attendant with catheter procedures and include intramural injections, vessel dissection and tissue extravasation. The potential risk is reduced when small test injections of contrast medium are made under fluoroscopic observation to insure that the catheter tip is properly positioned and, in the case of peripheral placement, that the vein is of adequate size.
Patient motion, including respiration and swallowing, can result in misregistration leading to image degradation and non-diagnostic studies.
HEXABRIX may be injected centrally, in either the superior or inferior vena cava or right atrium; or peripherally into an appropriate arm vein. For central injections, catheters may be introduced at the antecubital fossa into either the basilic or cephalic vein or at the leg into the femoral vein and advanced to the distal segment of the corresponding vena cava. For peripheral injections, the catheter is introduced at the antecubital fossa into an appropriate size arm vein. In order to reduce the potential for extravasation during peripheral injection, a catheter of approximately 20 cm in length should be employed.
Depending on the area to be imaged, the usual dose range per injection is 30-50 mL. Injections may be repeated as necessary. The total procedural dose should not exceed 250 mL.
Injection rates will vary depending on the site of catheter placement and vessel size. Central catheter injections are usually made at a rate of between 10 and 30 mL/second. Peripheral injections are usually made at a rate of between 12 and 20 mL/second. Since the injected medium can sometimes remain in the arm vein for an extended period, it may be advisable to flush the vein, immediately following injection with an appropriate volume (20-25 mL) of 5% Dextrose in water or normal saline.
PERIPHERAL VENOGRAPHY (PHLEBOGRAPHY)
HEXABRIX may be injected to visualize the peripheral venous circulation. Venograms are obtained by injection or infusion into an appropriate vein in the upper or lower extremity. Post-venography thrombophlebitis, as detected by fibrinogen I-125 uptake studies, is significantly less in patients receiving HEXABRIX when compared to conventional contrast agents.
In addition to the general precautions previously described, special care is required when venography is performed in patients with suspected thrombosis, phlebitis, severe ischemic disease, local infection or a totally obstructed venous system.
Extreme caution during injection of contrast media is necessary to avoid extravasation and fluoroscopy is recommended. This is especially important in patients with severe arterial or venous disease.
The dose for adults will usually range from 50-100 mL per extremity of full strength (32% iodine) HEXABRIX as a single rapid injection. The dosage will vary according to the patient's size and condition and the technique employed. Smaller or larger volumes may be indicated in some cases.
Reduced concentrations to as low as 20% w/v iodine may be effectively employed. These dilute solutions may be prepared by addition of normal saline (Sodium Chloride Injection, U.S.P.), 5% Dextrose in water (D5W) or Water for Injection, U.S.P. To prepare a 20% w/v solution, dilute each milliliter of HEXABRIX with 0.6 milliliters of the diluent selected (e.g., 50 mL HEXABRIX plus 30 mL of diluent equals 80 mL of a 20% iodine concentration). The usual dose of dilute medium will range from 75-150 mL per extremity.
Following the procedure, the venous system should be flushed with any one of the diluents listed above. Massage and elevation are also helpful for clearing the contrast medium from the extremity.
Following intravenous injection, HEXABRIX is rapidly excreted by the kidneys. HEXABRIX may be visualized in the renal parenchyma one minute following bolus injection. Maximum radiographic density in the calyces and pelves occurs in most instances within 7 to 12 minutes after injection. In patients with severe renal impairment, contrast visualization may be substantially delayed.
A low residue diet the day preceding the examination and a laxative the evening before the examination may be given, unless contraindicated.
Infants and small children should not have any fluid restrictions prior to excretory urography. (See WARNINGS and PRECAUTIONS, General concerning preparatory dehydration.)
Adults — The usual adult dose is 50 to 75 mL (0.7 to 1.0 mL/kg). The total dose is normally injected within 30 to 90 seconds. A higher dosage may be indicated where poor visualization is anticipated (e.g., elderly patients, obese patients, patients with impaired renal function or patients in whom dense opacification of the pelvo-calyceal system and ureters is desired). In these patients, a dose of 100 to 150 mL (1.5 to 2.0 mL/kg) may be used.
Children — The following schedule is recommended for infants and children.
| Under 6 months of age
| Over 6 months of age
| The total dosage in children should not exceed
CONTRAST ENHANCEMENT OF COMPUTED TOMOGRAPHIC (CT) HEAD IMAGING
HEXABRIX may be useful to enhance the presence and better define the extent of primary and metastatic malignancies of the head. In cases where lesions have calcified, there is less likelihood of enhancement. Following therapy, tumors may show decreased or no enhancement.
The use of HEXABRIX may also be beneficial in the image enhancement of non-neoplastic lesions, such as cerebral infarcts, sites of active infection, arterio-venous malformations and aneurysms.
The opacification of the inferior vermis occurs occasionally in normal studies.
No special preparation is required, however, it is advisable to insure that patients are well hydrated prior to examination.
For adults weighing up to 150 pounds, the usual dosage is 0.9 mL/lb. Patients weighing more than 150 pounds can usually undergo satisfactory examination with a dose of 135 mL not to exceed 150 mL.
CONTRAST ENHANCEMENT IN BODY COMPUTED TOMOGRAPHY
No special patient preparation is required. However, it is advisable to insure that patients are well hydrated. In patients undergoing abdominal or pelvic examination, opacification of the bowel may be valuable in scan interpretation.
In addition to the general precautions described, patient cooperation is essential since patient motion, including respiration, can markedly affect image quality. The use of an intravascular contrast medium can obscure tumors in patients undergoing CT evaluation of the liver resulting in a false negative diagnosis. Dynamic CT scanning is the procedure of choice for malignant tumor enhancement. (See CLINICAL PHARMACOLOGY.)
HEXABRIX may be administered by bolus injection, rapid infusion or by a combination of both. Depending on the area to be examined, doses of 30-150 mL (0.4-0.9 mL/lb) may be administered. When prolonged enhancement is required up to 150 mL can be used, usually with 25-50 mL as a rapid bolus and the remainder as an infusion.
Due to the low osmolality of HEXABRIX, the concomitant use of epinephrine is not necessary since the rate of contrast medium absorption as well as the production of synovial fluid and consequent dilution of the medium are reduced.
In addition to the general precautions previously described, strict aseptic technique is required to prevent the introduction of infection. Fluoroscopic control should be used to insure proper introduction of the needle into the synovial space and prevent extracapsular injection. Aspiration of excessive synovial fluid will reduce the pain on injection and prevent the dilution of the contrast agent. It is important that undue pressure not be exerted during the injection.
In addition to the general adverse reactions previously described, arthrography may induce joint pain or discomfort which is usually mild and transient but occasionally may be severe and persist for 24 to 48 hours following the procedure. Effusion requiring aspiration may occur in patients with rheumatoid arthritis.
Arthrography is usually performed under local anesthesia. The amount of contrast agent required is solely dependent on the size of the joint to be injected and the technique employed.
The following dosage schedule for normal adult joints should serve only as a guide since joints may require more or less contrast medium for optimal visualization.
| Knee, hip
| Shoulder, ankle
Passive or active manipulation is used to disperse the medium throughout the joint space.
The lower volumes of contrast medium are usually employed for double contrast examinations in which 30-100 cc of either filtered room air or carbon dioxide may be introduced for examination of the knee and lesser volumes for other joints.
It is preferable to perform the procedure approximately eight to ten days after the onset of menses. The patient should empty the bladder before the examination.
Caution should be exercised in patients suspected of having cervical or tubal carcinoma to avoid possible spread of the lesion by the procedure. Delayed onset of pain and fever (1-2 days) may be indicative of pelvic infection.
In addition to the general adverse reactions described previously, fever and pain, cramping and tenderness of the abdomen have been reported.
The total volume administered will vary depending upon anatomical variations and/or disease processes. The usual dose varies from 5 to 15 mL, administered slowly under fluoroscopic control, without undue pressure.