indication

Metrizamide is used for lumbar, thoracic, cervical, and total columnar myelography to determine the presence of abnormalities in the spinal column, spinal canal, and central nervous system (CNS) as well as for cisternography by direct injection using standard radiologic techniques to visualize the basal cistern of the brain. For computerized tomography (CT) of the intracranial subarachnoid spaces and for ventriculography by direct injection using standard radiologic techniques to visualize the cerebral ventricles. Also used in pediatric angiocardiography to visualize lesions or malformations of the heart and obstructions or anomalies of the major thoracic vessels. Also used in adult peripheral arteriography to visualize specific regions of the vascular system and blood flow in such areas to help in the diagnosis and evaluation of neoplasms (known or suspected) or vascular diseases (congenital or acquired) that may cause changes in normal vascular anatomy or physiology. Metrizamide is also indicated in adults for intravenous digital arteriography of head and neck.

pharmacology

Metrizamide is a radiocontrast agent used to improve the contrast of internal body structures using different imaging techniques such as computed tomography scans (CT) or radiography (X-ray imaging).

mechanism of action

Organic iodine compounds such as metrizamide block x-rays as they pass through the body, thereby allowing body structures containing iodine to be delineated in contrast to those structures that do not contain iodine. The degree of opacity produced by these compounds is directly proportional to the total amount (concentration and volume) of the iodinated contrast agent in the path of the x-rays. After intrathecal administration into the subarachnoid space, diffusion of metrizamide in the CSF allows the visualization of the subarachnoid spaces of the head and spinal canal. After intravascular administration, metrizamide makes opaque those vessels in its path of flow, allowing visualization of the internal structures until significant hemodilution occurs. Metrazamide also has some toxic effects which are thought to be due to its ability to inhibit glucose metabolism.

toxicity

Non-ionic radiocontrast agents like metrizamide are cytotoxic to renal cells. The toxic effects include apoptosis, cellular energy failure, disruption of calcium homeostasis, and disturbance of tubular cell polarity, and are thought to be linked to oxidative stress.

absorption

Absorption from gastrointestinal tract is negligible following oral or rectal administration.

drug interactions

Chlorpromazine: Increased risk of convulsions

Fluphenazine: Increased risk of convulsions

Mesoridazine: Increased risk of cardiotoxicity and arrhythmias

Methotrimeprazine: Increased risk of convulsions

Perphenazine: Increased risk of convulsions

Prochlorperazine: Increased risk of convulsions

Promethazine: Increased risk of convulsions

Propericiazine: Increased risk of convulsions

Thioridazine: Increased risk of convulsions

Trifluoperazine: Increased risk of convulsions