Surgery – Means for introducing or removing material from body for... – Infrared – visible light – ultraviolet – x-ray or electrical...
Patent
1998-05-05
2000-10-31
Bockelman, Mark
Surgery
Means for introducing or removing material from body for...
Infrared, visible light, ultraviolet, x-ray or electrical...
604501, A61N 130
Patent
active
061415820
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP96/02286 filed on Aug. 12, 1996.
FIELD OF ART
The present invention relates to an iontophoresis system for introducing a drug into the living body by putting electrodes provided with the drug in contact with skin or mucosal membrane to apply electric current between the electrodes, and its current process for control.
BACKGROUND ART
Studies have recently been performed about the iontophoresis using the electric driving force in order to enhance the absorption of drugs which have been introduced from the skin or mucosal membrane into the living body. The iontophoresis is a process comprising steps of applying a donor device having an electrode including a drug holding layer and a reference device pairing off with said donor device and having an electrode free from drug to the skin or mucosal membrane, and applying an electric current across the both electrodes, one of them forming an anode or another an cathode, so as to promote absorption of the drugs into the living body.
In contrast to the oral administration known as a general drug administration method, the iontophoresis is characterized in that it may be easy to administer a drug, maintain the concentration of the drug in the blood, and avoid any side effect of the drug on the digestive organs, and the iontophoresis system provided with the donor device, reference device, and a current-carrying device for energizing these devices have been studied eagerly and developed.
The relationship between the value of a supplied electric current and a dose at the time when a drug administration takes place using the conventional iontophoresis system will now be described with reference to FIG. 12.
FIG. 12 shows an equivalent circuit of identifying the skin electrically, where R1 designates an ohmic resistance, R2 a polarization resistance, and C a polarization capacity.
When a direct current or voltage/current having pulse wave-forms is applied between the donor and reference devices so as to energize the skin, the electric current will be allowed to pass through the ohmic resistance R1 and polarization resistance R2, and at the same time, an electric charge will be accumulated in the polarization capacity C. And then, if the electric charge of a predetermined quantity of electricity is accumulated in the polarization capacity C, most of the electric currents will pass through the ohmic resistance R1, and then, an electric current having a value substantially equal to that of the current as applied between the donor and reference devices will pass through the skin. At this time, since the current value present in the skin and the quantity of drug delivered to the skin (thereafter referred to as "drug delivery quantity") are directly proportional to each other, the drug delivery quantity can be predicted to some degree based on said electric value.
However, with the process for applying direct current or pulse wave form voltage/current, a complete charging of the polarization capacity C may cause the whole electric currents to concentrate on the ohmic resistance R1 so as to give an electric stimulus to the skin or mucosal membrane, whereby any supplied current value can not be raised to a higher level, with the consequential restriction laying down on the dose.
It would be possible that in the application of pulse wave-form voltage/current, electric charges as accumulated in the polarization capacity C during the suspension of voltage/current application are fully discharged with an exceedingly reduced ratio of the time for which the application of voltage/current is carried out for one pulse (thereafter referred to as pulse duty ratio); such a method will prolong the period of time required for drug administration, such that there had arisen a problem that the drugs applied may not work effectively.
In this connection, a variety of studies have been performed about the power supply, donor device, and reference device as well as the current-carrying method in order to reduce as much as possible electric stimulus which may
REFERENCES:
patent: 4764164 (1988-08-01), Sasaki
patent: 5499967 (1996-03-01), Teillaud et al.
patent: 5697896 (1997-12-01), McNichols et al.
Higo Naruhito
Kuzumaki Noriyuki
Mori Kenji
Nakamura Katsuhiro
Bockelman Mark
Hisamitsu Pharmaceutical Co., Ltd.
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