BACKGROUND AND GOAL OF STUDY

Many studies have evaluated the epidural pharmacokinetic and pharmacodynamic profiles in animal studies. Yaksh developed a study model in dogs. He threaded two catheters, one caudally around the cysterna magna into the intrathecal space and the other at the lumbosacral area upward into the epidural space to meet the two catheters at the same spinal level. However, in this method, some problems can occur such as bleeding and spinal cord damage due to the long trajectory of epidural catheter for adequate placement of epidural level.
Here we present a novel model, non-surgical and less invasive for the pharmacokinetic and pharmacodynamic analysis of epidural administered drugs.


MATERIALS AND METHODS

The study was conducted after institutional approval for animal experiment by the Korea University Institutional Animal Care and Use Committee. Twelve dogs weighing 21 kg (21 ± 2.77 kg; mean ± SD) were used.

Epidural catheterization
Epidural catheterization was performed at the upper level of vertebrae T1-T2 in lateral position. Epidural catheterization was performed with “the loss of resistance to air” technique in midline approach Using a C-arm. Tuohy needle was inserted midline between the first and second thoracic spinous process. The needle advanced slowly into the epidural space applying constant pressure to the plunger of the syringe with the thumb. A flexible catheter was then threaded cranially to the epidural space at C2–C3 level. The location of the catheter tip was verified fluoroscopically by injecting contrast medium into the catheter.
Intrathecal catheterization
In the lateral position, the external occipital protuberance, as well as both tips of the transverse processes of C1, was located using palpation; these three points formed the vertices of a triangle and the center of a triangle was a target point. Under local anesthesia, a 17G Tuohy needle was inserted into the cisterna magna region, checking the midline. A flexible catheter was then inserted caudated through the needle to the C2–C3 level; that is, to the same level as the epidural catheter.

RESULTS

In this study, we succeeded epidural and intrathecal catheterization all twelve dogs in sedation state. There were no side effects or complications associated with the new method of epidural and intrathecal catheterization.

CONCLUSIONS

A new model for the pharmacokinetic and pharmacodynamic analysis of epidural administered drugs in dogs is better than the Yaksh’s model.

A new model for the pharmacokinetic and pharmacodynamics analysis of epidural administered drugs in sedated dogs