Perflutren

When used in conjunction with diagnostic ultrasound, perflutren provides opacification of cardiac chambers, improvement in delineation of endocardial borders, enhancement of the Doppler signal, and visualisation of wall motion and blood flow within the heart.

The ultrasound echoes from blood and biological soft tissues such as fat and muscles are generated at interfaces due to small differences in the ultrasonic properties of the tissues. The ultrasonic properties of microspheres containing perflutren are very different from that of soft tissue and will generate strong echoes.

Following intravenous injection of 0.21 to 0.33 ml/kg of perflutren to healthy volunteers, the perflutren component of perflutren was rapidly and nearly completely eliminated in less than 10 minutes with a dominating pulmonary elimination half-life of 1.3±0.7 minutes. The perflutren levels detected in blood following this dosage were too low and transient to accurately determine pharmacokinetic parameters.

The disposition and elimination of the albumin microspheres have not been studied in humans. Information obtained from a preclinical study in rats with ¹²⁵I-labelled albumin microspheres indicated that microspheres were rapidly cleared from the circulation, and radio-labelled microspheres, albumin shells and ¹²⁵I were taken up primarily in the liver. The primary route of elimination of radioactivity was the urine. High levels of radioactivity were also retained in lungs for a considerable time, approx. 10% of the total dose 40 minutes after dose administration (cf. 35% in liver).

Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, acute and repeated dose toxicity and genotoxicity. In the rabbit embryotoxicity study, a significant increase in the number of foetuses with dilated ventricles in the brain was observed. No such finding was observed in the rat embryotoxicity study.