JP2782195B2 - Electric circuit for iontophoresis - Google Patents

Description

The present invention relates to an electric circuit for use in iontophoresis, and more particularly, this electric circuit is connected to an electrode of iontophoresis.

[Prior art] Iontophoresis has been applied since the beginning of this century as a method of penetrating ionized drugs into epidermal tissue, and has recently been adopted for the administration of lidocaine and epinephrine as local anesthesia, and in the dermatology area after shingles. In the treatment of neuralgia, it is also used for administration of steroids in combination with the above-mentioned local anesthetic, and good results have been obtained. In the field of dentistry, fluoride iontophoresis has been in the spotlight.

Such an iontophoresis is composed of a positive electrode and a negative electrode in which a drug is contained in at least one of the two electrodes, an electrical component for providing a desired potential difference between the two electrodes, and a power supply for driving the electrical component. And a part.

[Problems to be solved by the invention]

As described above, iontophoresis is becoming effective and safe for topical treatment, but is not generally put into practical use as a therapeutic means having a systemic effect. The possible causes are that it is difficult to set the optimal voltage waveform according to the medicine to be administered and the individual difference, and that skin irritation including burns can never be ignored if power is supplied to the same part of the skin for a long time. However, in particular, the volume component of the skin does not facilitate the introduction of iontophoresis or long-term application.

In general, human skin resistance and capacity vary greatly among individuals, but are generally about 50 kΩ and 0.1 μF, respectively. In addition to these individual variations, there are also changes over time, long-term changes, and changes due to sweating conditions. Due to this capacitance component, the voltage waveform that can be expected of the therapeutic effect is extremely distorted,
In DC iontophoresis, the situation is the same as charging the skin volume unilaterally, and it is difficult to apply it for long-term continuous administration.

In addition, a high-frequency power source is appropriate in terms of lowering the polarization impedance of the skin, but it has been confirmed that the movement of the drug cannot follow the high frequency, so that the high-frequency power source is not suitable for iontophoresis. Improper.

Accordingly, it is an object of the present invention to enhance the transdermal absorption of a drug without being affected by the skin volume component.

[Means for solving the problem]

The present invention relates to a circuit for connecting to an electrode of an iontophoresis, in which energization and suspension are performed periodically, and during the suspension, the electrode of the iontophoresis is short-circuited or has a low impedance, which results. The drawbacks of the prior art were solved by allowing the drug to permeate with a current opposite to the direction of the current flow.

That is, the feature of the electric circuit of the present invention is to provide a timer mechanism and a switch mechanism for periodically repeating the energization and the pause in order to effectively use the capacitance component of the skin, and during the pause, both electrodes of the iontophoresis are used. Short-circuiting or low impedance is achieved, and the drug can be permeated not only by the supplied current but also by the reverse current generated during the pause. Further, if the ratio between the power-on period and the rest period is set to 1: 5 or 1:20, an iontophoresis with less possibility of burns and reddening can be realized for a long time.

As is clear from the description so far, the conventional method employs either a DC method or a pulse method, or JP-A-60-188176, 61-31.
In the methods disclosed in JP-A Nos. 169 and 55-54961, for example, in the case of a drug that positively dissociates ions, the electrode containing the drug is generally set to the positive electrode (see FIG. 5). .

However, in the present invention, as shown in FIG. 4 (a), the direction of the energizing current shown in FIG. After the current flows in the reverse direction, the drug is permeated by a short-circuit current as shown in FIG.

The electric circuit of the present invention has a switch mechanism for energizing and pausing and a timer mechanism for setting the time, but both mechanisms are not particularly limited, and the switch mechanism itself has a timer function. Alternatively, for example, the timer mechanism may be performed using an IC clock, and the switching mechanism may be performed by a switching function of a transistor (including FET and SIT).

The iontophoretic agent applied to the electric circuit of the present invention is preferably an ion-dissociating agent,
Those which do not dissociate ions can also be applied. Preferred examples of the drug include indomethacin, diazepam, ibuprofen, ketoprofen, and cephalexin and erythromycin as antibiotics. Local anesthetics such as lidocaine hydrochloride and steroids are also applicable.

〔Example〕

Hereinafter, an electric circuit for iontophoresis of the present invention will be described with reference to the drawings.

FIG. 1 shows an electric circuit of the embodiment. The positive electrode 1 and the negative electrode 2 for iontophoresis are attached to the skin 3 of a human body, and the positive electrode 1 is connected to one of the switch mechanisms 4 by a switch mechanism 4 having a timer function.
An energization-side circuit including a 1 mA DC constant-current power supply (or DC constant-voltage power supply) 5 or a pause-side circuit including a diode 6 connected to the other end of the switch mechanism 4 and a monitoring DC ammeter 7 is periodically connected. It has become.

Such an electric circuit is connected to both electrodes 1, 2 of the iontophoresis.
In order to perform the drug administration by connecting to, the switch mechanism 4 repeats the energization and suspension of the skin 3. That is, as shown in FIG. 2, the skin 3 is energized by the DC power supply 5 during the period t _H (for example, 1 minute) when the switch mechanism 4 is on the ○ side, and the t _L period (for example, 19 minutes) on the ● side. In (), the positive electrode 1 and the negative electrode 2 of the iontophoresis are short-circuited.

Here, a DC ammeter 7 for monitoring is used in the electric circuit of FIG.
The reason for the establishment is described.

Current sources of iontophoresis are broadly classified into DC constant voltage power supplies, DC constant current power supplies, and others (pulse waves, AC, etc.). In general, the amount of drug permeated by iontophoresis is said to be proportional to the product of the amount of current and the duration of current, so if individual differences in skin impedance of the human body or changes over time are taken into account, the DC constant current It can be said that the method has the least individual difference.

However, in the circuit of the present invention, since the skin has capacity, the drug is transmitted by the discharge current,
If you choose DC constant current power source 5 as a power source to be used, short-circuit current following the energizing current will flow with a peak current I _d in accordance with the energizing current value I _o as shown in Figure 3. That is, the individual difference in the skin volume directly becomes the individual difference in the drug permeation amount. Therefore, it is necessary to change the current value I _o or the voltage at t _H (when energized) while monitoring the short-circuit peak current I _d with the DC ammeter 7 in the current change as shown in FIG.

〔Example〕

An experimental example using the electric circuit of the present invention will be described below.

Attach the rat skin to a glass permeation cell so that the part corresponding to the front side is in contact with the aqueous solution containing the drug (sodium salicylate), and the part corresponding to the back side is also in contact with physiological saline, and energized for 1 minute. This was repeated 16 times (20 × 16 = 320 minutes as a whole) with one cycle of a 19-minute short circuit. The measurement was carried out by quantifying the drug (sodium salicylate) that had permeated into the physiological saline in the above cell by high performance liquid chromatography. The current density during energization was 350 μA / cm ² .

As a result, a drug permeation of 14 μg / cm ² was obtained. This means that percutaneous absorption of the drug was remarkably promoted, considering that the permeation amount when left for 320 minutes without conducting or discharging was 1 μg / cm ² or less.

〔The invention's effect〕

Since the electric circuit for iontophoresis of the present invention is configured as described above, it has the following effects.

It has an energizing side circuit and a rest side circuit, and the circuit connected to the electrode of the iontophoresis is periodically switched by a timer mechanism and a switch mechanism. 1 / 5〜1
It can be shortened to / 20, and a large transdermal absorption can be obtained even with a short energization time, and a treatment with less possibility of burns can be realized for a longer time.

In addition, if the electric circuit of the present invention is miniaturized using an IC or the like, it is not necessary to use a specialist such as a doctor, and the drug can be sustained without causing gastrointestinal disorders and receiving primary liver metabolism. It can be absorbed into the blood to achieve its intended pharmacological activity, while also suggesting its potential use as a systemic drug.

Furthermore, by changing the energization and pause time,
Different types of drugs or different administration times can be accommodated.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram of an embodiment of the electric circuit of the present invention, and FIG.
FIG. 3 is a diagram showing energization and short circuit times in the electric circuit shown in FIG. 1, FIG. 3 is a graph showing a relationship between time and energization and short circuit current in the electric circuit in FIG. 1, FIG.
(B) is a schematic circuit diagram for explaining the principle of energization and short circuit in the electric circuit of the present invention, and FIG. 5 is a schematic circuit diagram for explaining the principle of continuous energization in the conventional iontophoresis. 1: Positive electrode for iontophoresis 2: Negative electrode for iontophoresis 3: Human skin 4: Switch mechanism 5: DC constant current power supply 6: Diode 7: DC ammeter for monitor

Claims (1)

(57) [Claims] 1. A circuit for connecting to an electrode of an iontophoresis used for drug administration, comprising: a current-carrying circuit having a DC power supply for current supply for periodically performing current supply and suspension thereof; An electricity for iontophoresis, comprising: a rest-side circuit for allowing a drug to permeate by a current flowing in a direction opposite to a conduction current, which is generated by short-circuiting or lowering impedance of both electrodes of the iontophoresis. circuit.