Lopidam

INDICATIONS AND USAGE Iopamidol Injection is indicated for intrathecal administration in adult neuroradiology including myelography (lumbar, thoracic, cervical, total columnar), and for contrast enhancement of computed tomographic (CECT) cisternography and ventriculography. Iopamidol Injection, 41% is indicated for thoraco-lumbar myelography in children over the age of two years.

DOSAGE AND ADMINISTRATION In adults a solution that is approximately isotonic (Iopamidol Injection, 41%) is recommended for examination of the lumbar region. For movement of the contrast medium to distant target areas the more concentrated Iopamidol Injection, 61% preparation should be used to compensate for dilution of Iopamidol Injection with cerebrospinal fluid. The usual recommended adult dose range for iopamidol is 2000-3000 mg iodine. Iopamidol formulated to contain more than 300 mgI/mL should not be used intrathecally in adults. The minimum dose needed to perform a procedure should always be used. In pediatric patients , a solution that is approximately isotonic (Iopamidol Injection, 41%) is recommended for all intrathecal procedures. In children, loss of contrast due to mixing on movement of the medium is less apt to occur because of their shorter spinal cord. The usual recommended pediatric dose range for iopamidol is 1400-2400 mg iodine. Iopamidol formulated to contain more than 200 mgI/mL should not be used intrathecally in children. The minimum dose needed to perform a procedure should always be used. See pediatric dosage table for recommended dosage . Anesthesia is not necessary. However, young children may require general anesthesia for technical reasons. Premedication with sedatives or tranquillizers is usually not needed. In patients with a history of seizure activity who are not on anticonvulsant therapy, premedication with barbiturates or phenytoin should be considered. Lumbar puncture is usually made between L3 and L4; if pathology is suspected at this level, the interspace immediately above or below may be selected. A lateral cervical puncture may also be used. Rate of Injection: To avoid excessive mixing with cerebrospinal fluid and consequent loss of contrast as well as premature cephalad dispersion, injection must be made slowly over one to two minutes; the needle may then be removed. An interval of at least 48 hours should be allowed before…

CLINICAL PHARMACOLOGY The pharmacokinetics of intravenously administered iopamidol in normal subjects conform to an open two-compartment model with first order elimination (a rapid alpha phase for drug distribution and a slow beta phase for drug elimination). The elimination serum or plasma half-life is approximately two hours; the half-life is not dose dependent. No significant metabolism, deiodination, or biotransformation occurs. Iopamidol is rapidly absorbed into the bloodstream from cerebrospinal fluid (CSF); following intrathecal administration, iopamidol appears in plasma within one hour and virtually all of the drug reaches the systemic circulation within 24 hours. Iopamidol is excreted mainly through the kidneys following intrathecal administration, and the drug is essentially undetectable in the plasma 48 hours later. In patients with impaired renal function, the elimination half-life is prolonged dependent upon the degree of impairment. In the absence of renal dysfunction, the cumulative urinary excretion for iopamidol, expressed as a percentage of administered intravenous dose is approximately 35 to 40 percent at 60 minutes, 80 to 90 percent at 8 hours, and 90 percent or more in the 72- to 96-hour period after administration. In normal subjects, approximately 1 percent or less of the administered dose appears in cumulative 72- to 96-hour fecal specimens. Iopamidol displays little tendency to bind to serum or plasma proteins. No evidence of in vivo complement activation has been found in normal subjects. Animal studies indicate that iopamidol does not cross the blood-brain barrier to any significant extent following intravascular administration.

ADVERSE REACTIONS The most frequently reported adverse reactions following intrathecal administration of iopamidol are headache, nausea, vomiting, and musculoskeletal pain. These reactions usually occur 1 to 10 hours after injection, almost all occurring within 24 hours. They are usually mild to moderate in degree, lasting for a few hours and usually disappearing within 24 hours. Rarely, headaches may be severe or persist for days. Headache is often accompanied by nausea and vomiting, and tends to be more frequent and persistent in patients not optimally hydrated. Backache, neck stiffness, numbness and paresthesias, leg or sciatic-type pain occurred less frequently, often in the form of a transient exacerbation of pre-existing symptomatology. Transient alterations in vital signs may occur and their significance must be assessed on an individual basis. The following table of incidence of reactions is based on clinical studies with Iopamidol Injection in about 686 patients. Adverse Reactions Estimated Overall Incidence System > 1% ≤ 1% Body as a Whole headache (16.4%) pyrexia muscle weakness hot flashes malaise fatigue weakness Digestive nausea (7.3%) diarrhea vomiting (3.6%) heartburn Musculoskeletal back pain (2.2%) leg cramps leg pain (1.4%) sciatica neck pain (1.1%) cervicobrachial irritation meningeal irritation radicular irritation lumbosacral other musculoskeletal pain involuntary movement burning sensation Cardiovascular hypotension (1.1%) tachycardia hypertension chest pain Nervous none emotional stress dizziness paresthesia confusion hallucinations lightheadedness syncope numbness cold extremities ataxia irritability Urogenital none urinary retention Respiratory none dyspnea Skin and Appendages none rash Miscellaneous none injection site pain Other adverse effects reported in clinical literature for iopamidol include facial neuralgia, tinnitus, and sweating. Major motor seizures have been reported in the clinical literature and since market introduction in…

CONTRAINDICATIONS Intrathecal administration of corticosteroids with iopamidol is contraindicated. Because of overdosage considerations, immediate repeat myelography in the event of technical failure is contraindicated (see interval recommendation under DOSAGE AND ADMINISTRATION ). Myelography should not be performed in the presence of significant local or systemic infection where bacteremia is likely.

WARNINGS The need for myelographic examination should be carefully evaluated. Iopamidol should be administered with caution in patients with increased intracranial pressure or suspicion of intracranial tumor, abscess or hematoma, those with a history of convulsive disorder, severe cardiovascular disease, chronic alcoholism, or multiple sclerosis, and elderly patients. Particular attention must be given to state of hydration, concentration of medium, dose, and technique used in these patients. Contrast media may promote sickling in individuals who are homozygous for sickle cell disease when injected intravenously or intra-arterially. Although Iopamidol Injection is not injected intravascularly, measurable plasma levels are attained after intrathecal administration of iopamidol. If frankly bloody cerebrospinal fluid is observed, the possible benefits of a myelographic examination should be considered in terms of risk to the patient. Patients on anticonvulsant medication should be maintained on this therapy. Direct intracisternal or ventricular administration for standard radiography (without computerized tomographic enhancement) is not recommended. Inadvertent intracranial entry of a large or concentrated bolus of the contrast medium, which increases the risk of neurotoxicity, can be prevented by careful patient management. Also, effort should be directed to avoid rapid dispersion of the medium causing inadvertent rise to intracranial levels (e.g., by active patient movement). If such intracranial entry of the medium occurs, prophylactic anticonvulsant treatment with diazepam or barbiturates orally for 24 to 48 hours should be considered. Use of medications that may lower the seizure threshold (phenothiazine derivatives, including those used for their antihistaminic properties; tricyclic antidepressants; MAO inhibitors; CNS stimulants; analeptics; antipsychotic agents) should be carefully evaluated. While the contributory role of such medications has not been…

Drug Interactions Other drugs should not be admixed with iopamidol (see CONTRAINDICATIONS , and DOSAGE AND ADMINISTRATION : Drug Incompatibilities ).