Iontophoresis of dexamethosone-phosphate into the equine tibiotarsal joint.
Abstract: In human rehabilitation medicine, dexamethasone-phosphate is theoretically iontophoresed to localized subcutaneous tissue where conversion to dexamethasone occurs. This delivery system has recently been introduced into veterinary medicine for the same purpose. However, the pharmacokinetic justification for parenteral delivery of this prodrug remains undocumented. Utilizing iontophoretic methods that are relevant to both human and veterinary clinical practice, the present investigation compared injection and iontophoresis of dexamethasone-phosphate into the equine tibiotarsal joint, also known as the tarsocrual joint. The tibiotarsal joints of seven horses were injected with 4 mL of 6 mg/mL dexamethasone-phosphate. With a similar drug concentration and over the same application site, six different horses underwent simultaneous cathodic iontophoresis (4 mA, 40 min) or passive application (0 mA, 40 min) on contralateral limbs. Following all applications, tibiotarsal joint synovium was collected. Local venous blood samples were also collected from the iontophoretic and passive application sites for analysis of plasma drug concentrations. Because of the potential for conversion of dexamethasone-phosphate to dexamethasone, an extraction and analysis protocol was developed for both chemicals. The technique demonstrated a linear range of detection (0.39-12 microg/mL) and a capability for measuring both chemicals in plasma and synovium. Conversion of dexamethasone-phosphate to dexamethasone occurred during synovial incubation (37 degrees C) and following freeze-thaw cycles. In contrast to the measurable synovial concentrations of dexamethasone-phosphate (2.3 +/- 0.96 mg/mL) and dexamethasone (0.27 +/- 0.07 mg/mL) following injection, neither drug was detected in the synovium or the local venous blood following iontophoretic or passive applications. In conclusion, these results do not confirm iontophoretic or passive delivery of measurable dexamethasone-phosphate into the tibiotarsal joint using current clinical methods.
Publication Date: 2000-12-07 PubMed ID: 11106997
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- Journal Article
Summary
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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.
Cite This Article
APA
Blackford J, Doherty TJ, Ferslew KE, Panus PC.
(2000).
Iontophoresis of dexamethosone-phosphate into the equine tibiotarsal joint.
J Vet Pharmacol Ther, 23(4), 229-236.
Publication
Researcher Affiliations
- Department of Large Animal Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville 37901, USA.
MeSH Terms
- Animals
- Anti-Inflammatory Agents / administration & dosage
- Anti-Inflammatory Agents / blood
- Anti-Inflammatory Agents / pharmacokinetics
- Chromatography, High Pressure Liquid / veterinary
- Dexamethasone / administration & dosage
- Dexamethasone / analogs & derivatives
- Dexamethasone / blood
- Dexamethasone / pharmacokinetics
- Drug Delivery Systems / veterinary
- Female
- Horses / metabolism
- Injections, Intra-Articular / veterinary
- Iontophoresis / veterinary
- Synovial Fluid / metabolism
- Tarsus, Animal / metabolism
Citations
This article has been cited 4 times.- Atalaia T, Prazeres J, Abrantes J, Clayton HM. Equine Rehabilitation: A Scoping Review of the Literature. Animals (Basel) 2021 May 22;11(6).
- Shaffer SM, Brismée JM, Sizer PS, Courtney CA. Temporomandibular disorders. Part 2: conservative management. J Man Manip Ther 2014 Feb;22(1):13-23.
- Draper DO, Coglianese M, Castel C. Absorption of iontophoresis-driven 2% lidocaine with epinephrine in the tissues at 5 mm below the surface of the skin. J Athl Train 2011 May-Jun;46(3):277-81.
- Coglianese M, Draper DO, Shurtz J, Mark G. Microdialysis and delivery of iontophoresis-driven lidocaine into the human gastrocnemius muscle. J Athl Train 2011 May-Jun;46(3):270-6.
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