Efficacy of Co-administration of an NSAID With a Dopamine Agonist In Healthy Subjects
Status:
Withdrawn
Trial end date:
2015-01-01
Target enrollment:
Participant gender:
Summary
Findings from the investigator's lab and others' show the involvement of the brain's
mesolimbic circuitry in pain perception and evaluation, as well as during the transition from
acute to chronic pain states in both humans and animals. Dopamine (DA) is one of the main
neurotransmitters in this circuitry, and it is possible it could have an intimate role in
pain processing, chronicity, and related anatomical and functional neuroplasticity. In this
study, the investigators first need to know if the combination of l-dopa and Naproxen is safe
and efficacious in humans with acute pain, and if so, at what doses. For the present study,
healthy pain-free participants will be injected with a small bolus of capsaicin
subcutaneously to induce acute cutaneous inflammatory pain. Capsaicin is ideal for this study
because it causes a characteristic inflammatory response that is almost always accompanied
with pain, has a well-validated dose-response curve, and has effects that will go away
completely in a few hours after administration, causing no permanent damage to study
subjects. Effects of capsaicin will be measured by changes (decreases) from baseline in
thermal and tactile thresholds, as well as by verbally reported cutaneous pain levels (on a
scale from 0-10). Participants will also be given study medication in the form of a placebo,
one drug, or a combination of drugs before capsaicin injection to allow for any analgesic
effects to peak before pain onset. For those receiving active medication, they will either
receive Naproxen with placebo or the combination of naproxen and l-dopa (the latter of which
will be in one of two different doses). This will allow the investigators to investigate (1)
whether co-administration of naproxen and l-dopa has analgesic effects in low levels of acute
pain in humans, (2) if this combination is pain-alleviating, whether it is equally as or more
efficacious than naproxen, which is the clinical standard of treatment, and finally (3) what
dose provides the most analgesia.
Phase:
Phase 2
Details
Lead Sponsor:
Northwestern University
Collaborators:
National Institute of Dental and Craniofacial Research (NIDCR) National Institutes of Health (NIH)
Treatments:
Carbidopa Carbidopa, levodopa drug combination Dopamine Dopamine Agonists Levodopa Naproxen