Drug carrier and ultrasound apparatus

Abstract

A drug carrier and an ultrasound apparatus used in combination therewith for releasing a drug. The drug carrier undergoes a reversible phase change from liquid to gas upon ultrasound irradiation, so that the presence of the drug can be detected with a diagnostic apparatus without causing the spilling of the encased drug. The drug carrier includes a drug that is contained in a mixture of a poorly water-soluble substance having a boiling point of 37° C. or lower and a poorly water-soluble substance having a boiling point of higher than 37° C., which mixture is further encapsulated by a membrane of amphipathic substance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C show conceptual charts illustrating the structure of the drug carrier according to the invention.

FIG. 2 shows the configuration of an experiment system for testing the effect of the drug carrier of the invention.

FIG. 3 shows an example of a test demonstrating reversibility concerning ultrasound irradiation of the drug carrier of the invention.

FIG. 4 shows an example of a test demonstrating reversibility concerning ultrasound irradiation of the drug carrier of the invention.

FIG. 5 shows an example of a test demonstrating the effect of a composition of the drug carrier of the invention on reversibility concerning ultrasound irradiation.

FIG. 6 shows an example of a test demonstrating irreversibility concerning ultrasound irradiation of the drug carrier of the invention.

FIG. 7 shows the configuration of an embodiment of the drug-releasing ultrasound apparatus of the invention.

Claims

1. A drug carrier comprising: a mixture of a first poorly water-soluble compound having a boiling point below the body temperature of a subject of administration of a drug, and a second poorly water-soluble compound having a boiling point exceeding the body temperature of the subject; anda drug contained in the mixture,wherein the mixture is encased in a membrane made of an amphipathic substance.

2. The drug carrier according to claim 1, wherein the body temperature is 37° C., and the first poorly water-soluble compound and the second poorly water-soluble compound have a molar ratio of 10:90 or greater and 80:20 or smaller.

3. The drug carrier according to claim 1, wherein the first poorly water-soluble compound is vaporized by ultrasound irradiation, and the second poorly water-soluble compound is secondarily vaporized by the ultrasound absorption by the vaporized first poorly water-soluble compound.

4. The drug carrier according to claiin 1, wherein the mixture is liquid when administered and rendered gaseous upon ultrasound pulse irradiation with a peak intensity of 1 to 20 W/cm2, the mixture returning to the original liquid upon termination of ultrasound irradiation.

5. The drug carrier according to claim 1, wherein the second poorly water-soluble compound has a structure such that at least one hydrogen atom or halogen atom of the first poorly water-soluble compound is substituted with an alkyl group or an alkyl halide group.

6. The drug carrier according to claim 1, wherein the second poorly water-soluble compound has a structure such that at least one halogen atom of the first poorly water-soluble compound is substituted with a hydrogen atom.

7. The drug carrier according to claim 1, wherein the drug is water-soluble.

8. The drug carrier according to claim 1, wherein the drug is lipophilic.

9. An ultrasound apparatus comprising: an ultrasound transducer for transmitting and receiving ultrasound to and from a subject;a control unit for controlling the ultrasound transducer; andan image generating unit for generating an image based on a signal received by the ultrasound transducer,wherein the control unit causes the ultrasound transducer to be operated in a first mode in which the transducer emits a ultrasound pulse having a peak intensity of 1 to 20 W/cm2, a second mode in which a ultrasound image of the subject is obtained, and a third mode in which the transducer emits an ultrasound pulse having a peak intensity of 10 to 10 kW/cm2.

10. The ultrasound apparatus according to claim 9, comprising a plurality of ultrasound transducers, wherein one of the ultrasound transducers is a dedicated ultrasound transducer for the third mode.

11. The ultrasound apparatus according to claim 9, wherein operation in the third mode is permitted on the condition that operation in the first mode has been carried out.

12. The ultrasound apparatus according to claim 10, wherein a region of an ultrasound image obtained in the second mode immediately after the first mode in which the brightness exceeds a predetermined level is irradiated with an ultrasound pulse in the third mode.