Researchers from the Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA, characterized the α2-adrenergic control of motor and sensory functions of gastrointestinal tract and colon.
To do this, they studied the dose-related effects of clonidine (placebo or up to 0.3 mg po) by random assignment in 55 healthy humans.
Gastrointestinal transit was measured in all subjects.
In 35 individuals, colonic compliance, tone, and sensations of gas and pain during phasic distensions were assessed.
The team found that clonidine did not significantly alter gastrointestinal or colonic transit. However, it increased colonic compliance and reduced fasting tone without altering colonic response to a meal.
Clonidine significantly reduced aggregate sensation to distensions overall. It had significant linear dose-related sensory effects at 8- and 24-mmHg distensions.
| Clonidine at doses as low as 0.05 mg may be beneficial in humans.
| American Journal of Physiology - Gastrointestinal and Liver Physiology |
Effect on pain (including dose-response relationship) was due to 0.3-mg dose for distensions at 24 mmHg.
Blanca E. Viramontes, of the Gastroenterology Research Unit at the Mayo Clinic, said on behalf of fellow authors, "We have confirmed that clonidine relaxes fasting colonic tone and reduces the sensation of pain.
"In this study, gut transit was not altered by clonidine, and novel dose-response characteristics and clonidine's effect on gas sensation are provided."
"Doses as low as 0.05 mg may be effective and potentially useful in reducing colonic tone and gas sensation," it was concluded.