Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Definity (Bristol-Myers Squibb)
vials containing 6.52 mg/mL
Appproved indications: echocardiography, ultrasound of liver and kidney

Ultrasound studies, such as echocardiography, are not always clear. To improve image quality it may be necessary to use a contrast medium.

Perflutren is a gas so it will produce echoes which are distinct from those of the surrounding tissues. To transport this inert gas to the heart, it has to be enveloped in a microsphere. A vial containing perflutren and liquid lipid is shaken by a machine for 45 seconds. This creates a suspension containing perflutren within lipid microspheres. The activated substance is then slowly injected intravenously or given as an infusion, depending on the investigation. Its half-life is less than two minutes with the gas being eliminated through the lungs.

Perflutren has been compared with saline in 211 patients, who had previously had a suboptimal echocardiography, in a double-blind trial. Depending on the dose, perflutren enhanced the imaging of the left ventricle in 87-91% of patients. There was no enhancement with saline.1 In addition to opacifying the cardiac chambers, perflutren can be used in regional wall motion studies. After administration of perflutren the agreement with magnetic resonance imaging of wall motion increased, however it did not improve the accuracy of measurements of the ejection fraction. Although there have been fewer trials, perflutren has also been approved for use in characterising focal lesions in the liver and kidney.

Injecting patients with gas bubbles is not without risk, particularly in patients who may have a cardiac shunt or compromised pulmonary vessels. Patients with congestive heart failure also have a higher incidence of adverse effects. While headache is the most frequent adverse reaction, there have been serious hypersensitivity reactions and seizures. This has prompted a revision of the product information in the USA.

Read about The Transparency Score Manufacturer provided the clinical evaluation

The Transparency Score ( ) is explained in New drugs: transparency', Vol 37 No 1, Aust Prescr 2014;37:27.