At dosage levels of 1 mL/lb, the incidence of unpleasant side effects increases. At total dosage of 2 mL/lb, administered over a short period of time (eg, 30 minutes), clinical signs of systemic intolerance appear (mostly related to hyperosmolar effects) and are manifest as tremors, irritability, and tachycardia. Above these maximal tolerated dosage levels in otherwise healthy adults, an increasing incidence and severity of dyspnea and pulmonary edema should be expected.
Four cases of overdosage in infants, during urography, are reported. Three of the infants died within 19 hours of the injection. The overdose ranged from slightly above the recommended pediatric dosage to a dose exceeding 19 g/kg. The symptoms of overdosage appeared between 10 minutes to several hours after injection of the contrast medium. Adverse effects were life-threatening, affecting mainly the pulmonary and cardiovascular systems. The symptoms included: cyanosis, bradycardia, acidosis, pulmonary hemorrhage, convulsions, coma, and cardiac arrest. All infants showed a poor visualization of the kidneys and a diffuse opacification of all the tissues and vasculature. Autopsy findings showed acute pulmonary damage and/or edema of subcutaneous tissues. Treatment of an overdose of injectable radiopaque contrast media is directed toward the support of all vital functions, and prompt institution of symptomatic therapy.
The acute intravenous LD50 of diatrizoate meglumine in mice is equivalent in iodine content of 5.3 gI/kg to 8.0 gI/kg and seem to be directly proportional to the rate of injection.
Diatrizoate meglumine is dialyzable.
Preparation of the patient will vary with preference of the radiologist and the type of radiological procedure performed. Specific radiographic procedures used will depend on the state of the patient and the diagnostic indications. Individual dose should be tailored according to age, body size, and indication for examination. (See INDIVIDUAL INDICATIONS AND USAGE section for specific Dosage and Administration.)
Solutions of radiopaque diagnostic agents for intravascular use should be at body temperature when injected and may need to be warmed before use. In the event that crystallization occurs, the solution may be clarified by placing the vial in a water bath at 40°C to 50°C and shaking it gently for two to three minutes or until the solids redissolve. If the particles still persist, do not use this vial but discard it. The solution should be protected from light and any unused portion remaining in the container should be discarded.
Dilution and withdrawal of the contrast agents should be accomplished under aseptic conditions with sterile syringes.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration. Avoid contaminating catheters, syringes, needles, and contrast media with glove powder or cotton fibers.
Pediatric doses of injectable radiopaque diagnostic agents are generally determined on a weight basis and should be calculated for each patient individually. (See INDIVIDUAL INDICATIONS AND USAGE section.)
Diatrizoate salts are incompatible in vitro with some antihistamines and many other drugs. It is believed that one of the chief causes of in vitro incompatibility is an alteration of pH. Turbidity of solutions of intravascular contrast medium occurs between pH 2.5 and 4.1. Another cause is chemical interaction; therefore, other pharmaceuticals should not be mixed with contrast agents in the same syringe.
THE FOLLOWING SECTIONS FOR INDIVIDUAL INDICATIONS AND USAGE CONTAIN CONTRAINDICATIONS, WARNINGS, PRECAUTIONS, ADVERSE REACTIONS, AND DOSAGE AND ADMINISTRATION SECTIONS RELATED TO THE SPECIFIC PROCEDURES. HOWEVER, IT SHOULD BE UNDERSTOOD THAT THE INFORMATION IN THE GENERAL SECTIONS IS ALSO LIKELY TO APPLY TO ALL OF THESE SPECIFIC USES.
Hydration —With the possible exception of urography, patients should be fully hydrated prior to the following procedures.
Diatrizoate salts are used in small, medium, and large dose urography (see Dosage and Administration—EXCRETORY UROGRAPHY). Visualization of the urinary tract can be achieved by either direct intravenous injection, intravenous drip infusion, or sometimes by intramuscular or subcutaneous injections, or incidentally following intra-arterial procedure. Visualization of the urinary tract is delayed in infants less than 1 month old, and in patients with urinary tract obstruction (see CLINICAL PHARMACOLOGY).
Urography is contraindicated in patients with anuria.
See PRECAUTIONS—General. Some clinicians consider multiple myeloma a contraindication to excretory urography because of the great possibility of producing transient to fatal renal failure. Others believe that the risk of causing anuria is definite but small. If excretory urography is performed in the presence of multiple myeloma, dehydration should be avoided since it favors protein precipitation in renal tubules.
Although azotemia is not considered a contraindication, care is required in patients with advanced renal failure. The usual preparatory dehydration should be omitted, and urinary output should be observed for one to two days in these patients. Adequate visualization may be difficult or impossible to attain in patients with severely impaired renal and/or hepatic function. Use with extreme caution in patients with concomitant hepatorenal disease.
Because of the possibility of temporary suppression of urine, it is wise to allow an interval of at least 48 hours before excretory urography is repeated in patients with unilateral or bilateral reduction of normal renal function. Inadvertent retrograde cystourethrography can cause malignant hyperthermia, disseminated intravascular coagulation and fatality.
Preparatory dehydration is dangerous in infants, young children, the elderly, and azotemic patients (especially those with polyuria, oliguria, diabetes, advanced vascular disease, or preexisting dehydration). The undesirable dehydration in these patients may be accentuated by the osmotic diuretic action of the medium.
Dehydration may improve image quality in patients with adequate renal function particularly if a low dose is used. Dehydration, however, will not improve contrast quality in patients with substantial renal insufficiencies and will increase risk of contrast induced renal damage. Dehydration in these patients is therefore contraindicated.
Adults: A dose of 30 mL to 60 mL produces excellent shadows in the majority of adults subjected to partial dehydration and effective purgation. In persons of slight build, 20 mL produces adequate shadows. For best results and minimal reactions, the total 30 mL to 60 mL should be injected in one to three minutes and compression may be used. A small intravenous test dose may be administered as a possible aid in determining sensitivity to the medium. (See PRECAUTIONS—General.)
Children: The suggested dosage for children up to 12 years old is presented in the table below. Children older than 12 years may be given an adult dose.
|Under 2 years||up to 10 lb||5 mL to 10 mL|
|10 to 30 lb||10 mL to 15 mL|
|2 to 12 years||30 to 60 lb||15 mL to 30 mL|
|over 60 lb||30 mL|
Although clear shadows are often seen in patients who have had no preliminary preparation for urography, the largest percentage of satisfactory films is obtained in patients who abstain from fluids for 12 to 15 hours before the intravenous injection so that partial dehydration results. (See PRECAUTIONS—General concerning dehydration.) Unless contraindicated, a laxative may be taken at bedtime to eliminate gas from the intestine.
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