The effects of intrathecal gabapentin on spinal morphine tolerance in the rat tail-flick and paw pressure tests

C Hansen, I Gilron, M Hong
Anesthesia and Analgesia 2004, 99 (4): 1180-4, table of contents
Analgesic tolerance to opioids has been described in both experimental and clinical conditions and may limit the clinical utility of these drugs. We have previously shown that systemic gabapentin (GBP), a non-opioid drug, prevents and reverses tolerance to systemic morphine in the rat. In this study, we investigated the effect of intrathecal GBP on spinal morphine tolerance. Studied rats were given 7 days of intrathecal injections with saline (10 microL), GBP (300 microg), morphine (15 microg), or a GBP-morphine combination, and analgesic testing using tail-flick and paw-pressure tests was conducted before and 30 min after the drug injection. On Day 8, an antinociceptive dose-response curve was constructed and the 50% effective dose (ED(50)) values for morphine (given alone) were calculated for each study group. Coinjection of GBP with morphine blocked the development of tolerance, as shown by the preservation of morphine analgesia over 7 days as well as by a concomitant decrease in ED(50) values on Day 8, as compared with the morphine-alone group. Although additive analgesia over Days 1-7 cannot be ruled out, ED(50) reductions in the GBP-morphine combination group indeed suggest some suppression of tolerance. These data support previous evidence that GBP prevents opioid tolerance and, more specifically, indicate that intrathecal GBP prevents the development of spinal opioid tolerance. Future studies are required to examine the respective roles of supraspinal and peripheral sites of GBP-morphine interaction and to investigate the mechanisms underlying the action of GBP on opioid tolerance.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"