Iontophoresis of dexamethosone-phosphate into the equine tibiotarsal joint.

This research focused on the effectiveness of delivering dexamethasone-phosphate, a drug used for pain and inflammation, to the joint of horses via iontophoresis, a process involving the use of electric current to deliver medication. The authors tested this method in two groups of horses and took samples to check the presence of the drug and its active form, dexamethasone. The results suggested that this way of delivery could not be confirmed as the drug presence remained undetectable in the joints and blood.

Introduction and Goals

• The research focused on evaluating a method known as iontophoresis for delivering a drug, dexamethasone-phosphate, to the tibiotarsal joint (tarsocrual joint) in horses.
• This technique involves sending medication via electric current and has been introduced in both human and veterinary medicine.
• The authors wanted to verify the efficiency of this delivery method, as there was no previous documented justification for its use.

Methods

• The study involved seven horses, where the tibiotarsal joints were treated with an injection of 4 mL of 6 mg/mL dexamethasone-phosphate.
• In a control group of six different horses, the same procedure was performed, but via iontophoresis (4 mA, 40 min) or passive application (0 mA, 40 min) on contralateral limbs.
• The researchers collected tibiotarsal joint synovium (the joint’s connective tissue) and local venous blood samples for later analysis.
• The measurement protocols were developed due to the potential for dexamethasone-phosphate to convert into dexamethasone.

Results and Conclusion

• The study found that, in contrast to the considerable amounts of dexamethasone-phosphate and dexamethasone present after injection, neither drug was detectable in the synovium or the local venous blood after iontophoretic or passive applications.
• Therefore, the results did not support the iontophoretic or passive delivery of measurable dexamethasone-phosphate into the tibiotarsal joint using the clinically relevant procedures tested.
• Overall, this study questions the effectiveness of iontophoresis for delivering certain drugs into specific local sites, noting that alternative delivery methods may be more efficient.