Nausea contrast agents

Some side-effects of angiographic contrast agents such as allergy-like events (nausea, vomiting) have been related to the fipophificity (lack of hydrophificity) of the contrast agents. However, clear-cut structure-activity relationships have not been established. 

The safety of gadobenate dimeglumine has been evaluated in 2367 adults aged 18-88 years and 173 children. The overall incidence of adverse events was 20%. Events related to the contrast agent were reported in 15 % of the adults. Most of the adverse events were mild and transient and resolved spontaneously. Headache, injection site reactions, nausea, taste disturbance, and vasodilatation were the most common, with frequencies of 1.0-2.6%. Serious adverse events potentially related to the contrast agent were reported in 0.2%. These events included laryngospasm, which developed 10 minutes after the contrast injection in a 51-year-old woman, severe vomiting in a 5-year-old child, and pulmonary edema in a 65-year-old patient. 

Adverse events associated with the non-ionic, gadolinium-based contrast agent gadodiamide have been reported in 1-2% of patients. Most of the commonly reported adverse events have been headache, dizziness, or nausea and vomiting. 

Nausea and vomiting can occur in reaction to contrast agents. Diarrhea is less common but has been repeatedly reported, sometimes with angioedema of the bowel (143). 

Of 30 patients undergoing contrast enhanced MRI scanning for focal liver lesions only two complained of slight nausea during the injection of mangafodipir (20). In all other cases the contrast agent was well tolerated. 

Artefacts that arise from gas in the stomach and adjacent bowel often limit the diagnostic accuracy of abdominal ultrasound. Research to overcome this problem has focused on cellulose-based suspensions. An agent has been developed based on simethicone-coated cellulose— SonoRx (Bracco Diagnostics, Princeton, NJ), which displaces and disperses gas bubbles. In a phase 2 chnical study, 93 patients underwent upper abdominal sonography before and after a randomized dose of the contrast agent (200, 400, 600, 800, or 1000 ml) (15). Anatomical visualization was improved as follows the stomach in 82% of patients, the duodenum in 63%, the pancreatic head and body in 61%, and the pancreatic tail in 67%. There were 14 adverse events in 11 patients and only five were considered to be related to the contrast agent. The main adverse effects were mild diarrhea and nausea. 

Less serious reactions to contrast agents are nausea and vomiting, mild skin reactions (hives) and more serious generalized skin reactions with urticaria. Nausea and vomiting rarely require treatment with antiemetics, for example domperidone. Skin reactions can be treated with oral or intravenous antihistamines, which also have an antiemetic effect. Intravenous corticosteroids may be required for serious urticaria. 

Adverse reactions to iodine contrast agents are rare, especially with the newer non-ionic dimers of low osmolality. Adverse reactions range from mild effects, such as nausea and vomiting, to moderate effects, such as erythema and chest pain. Severe adverse reactions, for example bronchospasm and anaphylactic shock, always need emergency treatment. 

Since the late 1990s, therapy radiographers have been trained to administer medicines for the management of radiotherapy side effects, such as pain rectal symptoms, constipation, diarrhoea skin reactions, wound care oral care nausea and vomiting. They are also beginning to use PGDs for X-ray contrast agents. 

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