Analgesic Effect of Oxytocin Receptor Modulation

What Was Tested

This registered not phased trial tested Carbetocin.

Carbetocin is a synthetic analogue of the hormone Oxytocin and is routinely used in obstetric anesthesiology to control uterine bleeding after cesarean section.

As an incidental finding, women who received carbetocin had less pain after cesarean section than women who had received Oxytocin.

Carbetocin may therefore have an analgesic effect.

It had two arms (groups): Carbetocin first (active comparator) and Placebo first (active comparator).

The registry classes the interventions as drug.

More on the Plan

Background Chronic pain is still a largely unresolved issue, causing suffering, disability and high social costs.

A recent study on postpartal bleeding came to the accidental finding of a possible analgesic action of the oxytocin agonists carbetocin.

Oxytocin is a well known nonapeptide synthesized in the hypothalamus, acting as neurohormone during parturition and the milk ejection reflex.

In addition to GABAergic hyperpolarisation, models of oxytocin selectively blocking A-delta and C-fibers have been published.

Who Took Part

The registry lists 25 actual participants took part.

It was open to men only aged from 18 years up to 65 years.

Healthy volunteers could join, not only people with the condition.

Examples of who could join: Written informed consent.

The full record lists 3 inclusion and 16 exclusion criteria; among the exclusions: chronic pain; acute pain at time of testing; sign or suspicion of neurological dysfunction at the tested sites.

How the Study Was Run

The set-up was randomized, crossover and triple-blind.

Random assignment meant chance, not the researchers, decided who got Carbetocin and who got the comparison, which limits bias.

In the crossover set-up each of the participants took both Carbetocin and the comparison in turn, acting as their own control.

Neither the participants nor the staff measuring them knew who was on Carbetocin, so expectations could not easily colour the readings.

Those kept unaware of assignments: participant, investigator and outcomes assessor.

It started in 2013-07 with completion listed for 2014-12.

It ran at 1 site in Switzerland.

Its stated primary purpose is basic science.

What Was Measured

The main thing measured (primary outcome): Change in intramuscular electrical pain threshold compared to baseline (time frame: 10, 60 and 120 minutes after carbeoticin administration).

It also tracked 7 secondary outcomes, for example Capsaicin-induced area of hyperalgesia and allodynia, Nociceptive withdrawal reflex thresholds of the foot, Single cutaneous electrical pain thresholds, Repeated cutaneous electrical pain thresholds, Single intramuscular electrical pain threshold and Heat pain detection threshold.

What This Means in Plain Language

Put simply, this is a not phased, randomized trial of Carbetocin in 25 people.

Its size is small, so on its own it can only give an early look.

The trial is marked completed; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Carbetocin compound page, all human trials.