In vivo iontophoretic delivery of calcium ions through guinea pig skin enhanced by direct and pulsating current

Development of natural calcium- and phosphate-donating microparticles and a new iontophoretic apparatus for the topical treatment of local osteoporosis. Preliminary in vitro and in vivo studies

AIM

We wished to develop a new iontophoretic device suitable for the treatment of local bone loss such as after fractures or in osteodystrophy.

METHODS

The new iontophoretic apparatus consists of two parts. The first part consists of two natural-based, chemically modified particles as potential medicines, while the other part is a 3-electrode electrophoretic device based on a new principle. This device 'knocks out' Ca²(+) and PO₄ ³⁻ ions from the particles with its impulse-like positive and negative charges transmitted through its electrodes placed on the skin. The current and the voltage of the electrodes can be adjusted separately in both leads. Subsequently, these 'knocked out' ions are channelled into the porotic bones with the help of the 3rd-reference-electrode.

RESULTS

In our preliminary in vitro studies, we used porcine tissues to test their calcium and phosphate content after iontophoresis; with or without using molecules. This preliminary analysis revealed that both calcium and phosphate ions became incorporated into the bone. Some in vivo data are also presented. Iontophoretic treatment increased speed of sound (SOS) as determined by ultrasonography in ovariectomized rats.

CONCLUSION

Our results suggest that topical iontophoresis may be suitable to treat local osteoporosis or bone defects.