JPS63283652A - Electric circuit for iontophoresis - Google Patents

Abstract

PURPOSE:To reduce the change in a current or voltage with the elapse of time and to realize gentle current change effective for the permeation of drugs infiltrated in the electrode of a treatment part, by cyclically performing the charge and discharge of a condenser so as to allow the charge or discharge current of the condenser to flow to the output side of a circuit. CONSTITUTION:During the first definite time t0 when both switch mechanisms 3, 4 shortcircuit black spot sides, a condenser 6 is charged by a DC power source 1 through a variable resistor 2. After the elapse of the definite time t0, the charge of the condenser 6 charged during the time t0 is discharged to a human body through a variable resistor 7, a diode 8, a AC ammeter 9 and the treatment part electrode 10 bonded to the human body during the next time t1 (t1=t0) when both switch mechanisms 3, 4 shortcircuit white spot sides and, at the same time, a condenser 5 is charged by the DC power source 1 through the variable resistor 2. During the next time t2 (t2=t1) when the switch mechanisms 3, 4 shortcircuit the black spot sides, the condenser 5 is discharged and the condenser 6 is newly charged. On and after, the same operation is repeated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electric circuit for use in iontophoresis, and specifically, this electric circuit is connected to one electrode of the iontophoresis. .

[Conventional technology]

Iontophoresis has been used since the beginning of this century as a method for penetrating ionized drugs into epidermal tissue, and recently it has been used to administer lidocaine and epinephrine as local anesthesia, and fluoride iontophoresis has been attracting attention in the field of dentistry. There is.

Such iontophoresis is performed by a positive electrode and a negative electrode, at least one of which contains a drug, an electrical component that provides a desired potential difference between the two electrodes, and a power supply that drives the electrical component. It is configured.

As mentioned earlier, iontophoresis has been shown to be effective and safe for local treatment, but it has not received much attention as a therapeutic method with systemic effects, and the reasons for this are: It is difficult to set the optimal voltage waveform depending on the drug to be administered and individual differences, and skin irritation including burns cannot be ignored because electricity is applied to the same part of the skin for a long time. This capacitance component makes it difficult to introduce iontophoresis.

In general, the resistance and capacitance of human skin vary greatly from person to person, but are usually about 50Ω and 0.1 μF, respectively.Furthermore, in addition to these individual differences, there are also changes over time and due to current application associated with iontophoresis. There are changes depending on the state of sweating. Due to this capacitive component, the voltage waveform that can be expected to have a therapeutic effect is extremely distorted, and the current that should flow to the skin is obstructed.

Therefore, iontophoresis caused by direct current corresponds to charging the skin capacitance in a one-way manner without discharging it, and the apparent impedance of the skin also increases, so long-term continuous administration is not recommended. Difficult to apply.

Furthermore, although high-frequency power sources are appropriate from the point of view of lowering the polarization impedance of the skin, it has been confirmed that the movement of drugs cannot follow high-frequency waves, so high-frequency power sources are effective against iontophoresis. It's inappropriate.

Regarding pulse waves, as shown in Figure 1, there are basically only two voltages, high and low, so the pulse wave only instantaneously passes through the voltage value range (Zef in the diagram) that is most effective for drug penetration. The drawback is that it cannot be done.

Conventional iontophoresis can basically be divided into constant current method and constant voltage method. In the former case, the voltage increases because the skin resistance increases, and skin irritation, burns, redness, etc. are unavoidable. In the latter method using constant voltage pulses, the amount of electricity (ti) given by one pulse also varies due to changes in skin impedance.

In addition, the skin capacitor is charged when the pulse is generated, and discharge occurs from the skin capacitor when the pulse is paused, so drug permeation also stops at the same time as the pulse pauses, making it difficult to say that this is an efficient method. In this case, the intention is to lower the polarization impedance of the skin.
Although high frequency pulses of 0 kHz or higher have been used, since the skin is a living body, there is a limit to the drug permeation rate, and high frequencies may not be effective.

That is, considering that the potential difference effective for drug movement remains within a very small range, high-frequency pulse waves are not necessarily optimal.

Therefore, the purpose of the present invention is to solve the drawback of conventional iontophoresis, which is the change in current or voltage over time, and to make it effective for the actual permeation of the drug impregnated into the treatment area tm (electrode for iontophoresis). The purpose is to realize the slow current change that seems to occur.

[Means for solving problems]

The present invention is a circuit for connecting to one electrode of an iontophoresis device, which includes a power source and at least one capacitor connected to the power source, and after charging the capacitor with current, the circuit connects to one electrode of an iontophoresis device. The charging or discharging current of the capacitor is controlled so that the charging or discharging current of
The drawbacks of the prior art described above have been solved by an electric circuit for iontophoresis, which is characterized in that it is provided with a switching means for causing the discharge to occur periodically.

That is, the feature of the electric circuit of the present invention is that it utilizes the charging or discharging of a capacitor, which solves the problem of changes in current or voltage over time and is effective in actually permeating the drug impregnated into the treatment area electrode. It is possible to realize a slow current change that seems to be possible.

There are no particular limitations on the treatment area electrode to which the electric circuit of the present invention is connected and the corresponding ground electrode, and conventionally known electrodes may be used, such as capacitors, variable resistors, etc., which are also described in the Examples below. The element may also be a commercially available element.

〔Example〕

Hereinafter, the electric circuit for iontophoresis of the present invention will be explained based on the drawings.

FIG. 2 shows an electrical circuit of one embodiment, for example, an IO
A variable resistor 2 of Ω is connected to DC power supplies 1 and 10 to 20 of V. Furthermore, in Figure 0, a switch mechanism 3.4 having synchronization using a timer function is connected in parallel to this circuit. For a certain period of time (
For example, after 60 seconds have elapsed, the O side is short-circuited, and after 60 seconds, the - side is short-circuited again. Further, a capacitor 5.6 of, for example, 1000 μF is connected to each switch mechanism 3.4. -side of switch mechanism 3 and switch mechanism 4
A variable resistor 7 of 10 to 20 Ω, a diode 8 to prevent reverse current flow, and a DC ammeter 9 to monitor current changes are connected in series on the O side of the An impregnated treatment area electrode 10 is connected. In this electric circuit, variable resistor 2 and capacitor 5, variable resistor 7 and capacitor 5, or variable resistor 2
and capacitor 6, variable resistor 7, and capacitor 6 each form a time constant circuit.

With the above circuit configuration, the current obtained from the circuit and flowing through the human body has a waveform like that shown in Figure 3 (al), but in reality, the DC ammeter 9 has a response delay, so the current flowing through the human body is shown in the figure. In other words, in the circuit shown in Fig. 2, for a certain period of time (e.g. 60 seconds) when the switch mechanism 3.4 shorts both sides, the DC power source l causes the variable resistor to Capacitor 6 is charged via 2. After the fixed time t has elapsed, at the next fixed time t+ (t+-to) when the switch mechanism 3.4 both short-circuits the O side,
The electric charge of the capacitor 6 charged with to is transferred to the variable resistor 7,
A zero-order switch that discharges to the human body via a diode 8, a DC ammeter 9, and a treatment area electrode 10 that is attached to the human body, and simultaneously charges a capacitor 5 via a variable resistor 2 by the DC power supply 1. At time t*(Lx-L+), which is a short circuit on the side of mechanism 3.4, capacitor 5 is discharged,
Capacitor 6 is newly charged. After that, the same thing is repeated.

Here, the reason for using variable resistor 2.7 in the circuit will be described. As mentioned above, between the positive and negative electrodes of the iontophoresis device that connects the electric circuit of this invention, there is a capacitance component and a resistance component of the skin. Maximum current value at Mt. 1
The minimum current value of 1° is not necessarily constant over a long period of time, and may vary depending on the characteristics of the drug introduced in Figures 1 and 3.
Since the drug transfer effective area Zef shown in Figures 1 to 2 is also different, it is necessary to change I8. Therefore, the maximum current value 1) is proportional to the charge charged in the capacitor,
The slope of the discharge characteristic is determined by the variable resistor 7 forming a time constant circuit. Therefore, if the resistance value of the variable resistor 2 is lowered, the maximum current value 1) becomes higher, and the maximum current value 1) becomes higher.
When the resistance value of I is lowered, the minimum current value I becomes lower. By using the variable resistor 2.7 in this way, the maximum current value 1) and the minimum current value! 8 can be changed freely.

Also, the effective time T corresponding to the drug transfer effective area Zef
If it is desired to lengthen ef, it is necessary to change the cycle (to make the slope of the discharge characteristic gentler) as shown in FIG. 3 (C1), and this can be adjusted by the timer function of the switch mechanism 3.4.

Although the circuit configuration using the discharge characteristics of the two capacitors has been described above, the electric circuit of the present invention is not limited to this, and it is also possible to use a method in which the charging current of the capacitor is passed through the human body. However, capacitors of various capacities, such as 470 μF, 1000 μF, and 12200 μF, are installed in the circuit in advance, and a selection mechanism is added so that the capacitor with the desired capacity can be easily selected using a changeover switch or the like according to the drug. Good too.

When applying iontophoresis using such an electric circuit to a topical drug, both electrodes should be placed in the form of a film-like ultra-light sheet and placed in a place on the human body where it is easy to attach, such as the forearm. If a local effect is desired, the shape of the electrode containing the drug should be designed to match the local area, and the electrode should be attached to the application site and the electrical circuit should be connected to either the positive or negative electrode of the iontophoresis device. Bye.

In addition, as shown in Figure 2, by providing two variable resistors 2.7, the output current amount of the circuit can be adjusted arbitrarily depending on the skin resistance of the user, the type of drug to be introduced, the required amount of the drug, etc. In addition, the slope of current change can be controlled. Moreover, a major feature is that the state of the current change can be monitored one by one using the DC ammeter 9.

Furthermore, if a circuit that combines a circuit opening/closing mechanism and a timer mechanism that automatically opens or closes the circuit after a predetermined period of time has passed is provided on the output side of the DC power supply 1 in FIG. Overdosing can be prevented, drug administration can be started automatically after a certain period of time, and if an interval timer is used as a timer mechanism, it is also possible to administer and pause drugs intermittently. . In addition, upon discontinuation of drug administration, capacitor 5.
You may add a safety circuit to discharge 6.

In addition, if there is a particular need to control the amount of drug administered, a feedback mechanism is installed to automatically control the output current of the circuit while monitoring the amount of drug absorbed by the human body or the condition of the living body. There may be.

Experimental Examples Experimental examples using the electric circuit of the present invention are shown below.

The rat's skin was attached to a glass transmission cell so that the front side was in contact with an aqueous solution containing the drug (sodium salicylate) and the back side was in contact with physiological saline, and after 8 hours of electricity. The drug (sodium salicylate) that permeated into the physiological saline was quantified using high performance liquid chromatography.

In this case, current is applied by charging and discharging two capacitors each having a capacity of 1000 μF, and the current density to the rat's skin is set to 48 μA/aJ, which is the minimum current value (corresponding to It in Figure 3). Maximum current value (Figure 3 (b)
l (equivalent to D I + D) is 480I! It is changed to A/- at a cycle of 60 seconds.

As a result, drug permeation of 0.6 .mu./- or more was obtained.

Considering that the amount of permeation when left for 8 hours without applying electricity was less than 0.004 .mu./-, it can be said that transdermal absorption of the drug was significantly promoted.

〔Effect of the invention〕

As explained above, according to the iontophoresis using the electric circuit of the present invention, the transdermal absorption ability of drugs is further improved compared to the conventional ordinary iontophoresis. Since treatment can be performed while monitoring the current flowing to the human body, in addition to the basic treatment mode, you can freely set modes such as a mode that applies higher current for a shorter time, a mode that applies lower current for a longer time, etc. can. In other words, by specifying the capacitance and charging voltage of the capacitor, the charging rate per
Since the amount of discharge charge can be limited, sustained release of the drug can be achieved more easily. Furthermore, by using the electric circuit of the present invention for iontophoresis, there is no need for specialists such as doctors, there is no gastrointestinal disorder, and the liver
The drug is continuously absorbed into the blood without undergoing subsequent metabolism, and its intended pharmacological activity is achieved.

[Brief explanation of drawings]

FIG. 1 is a conceptual explanatory diagram for explaining the relationship between the pulse wave and the drug permeation effective area, FIG. 2 is a schematic circuit diagram showing an embodiment of the electric circuit of the present invention, and FIGS. C) is the waveform of the output current obtained by the circuit shown in FIG. l : DC power supply 2.7 : Variable resistor 3.4 z switch mechanism 5.6 : Capacitor 8 : Diode 9 : DC ammeter 10 : Treatment area electrode 1) : Ground t8i

Claims (2)

[Claims] (1) A circuit for connecting to one electrode of an iontophoresis device, comprising a power source and at least one capacitor connected to the power source, and after charging the capacitor, charging or An electric circuit for iontophoresis, comprising a switching means for periodically charging and discharging a capacitor so that a discharge current flows to the output side of the circuit. (2) The electric circuit for iontophoresis according to claim 1, characterized in that two capacitors are connected in parallel to the power source, and the switching means is connected to each capacitor.