Clinical trial NCT02969629: The Effects of Apomorphine on Experimental and Clinical Pain in Patients With Chronic Radicular Pain
Official title: The Effects of the Dopamine Agonist (Apomorphine) on Experimental and Clinical Pain in Patients With Chronic Radicular Pain: a Randomized, Double-blind, Placebo-controlled, Cross-over Study
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Chronic Low Back Pain
Lead sponsor: Rambam Health Care Campus
Sponsor class: OTHER
First posted: 2016-11-21
Enrollment: 59
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: The study aimed to explore the effect of the dopamine agonist apomorphine on spontaneous pain intensity and evoked cold clinical and experimental pain in patients with lumbar radicular neuropathic pain (NP). Patients received either apomorphine or placebo in a randomized double-blinded manner.

Detailed description: Although evidence suggests that dopaminergic systems are involved in pain processing, the efficacy of dopaminergic interventions in reducing pain remains questionable. This randomized, double blinded, placebo-controlled, cross-over study was aimed to explore the effect of the dopamine agonist apomorphine on spontaneous pain intensity and evoked cold clinical and experimental pain in patients with lumbar radicular neuropathic pain (NP).

Data was collected from 35 patients (18 men, mean age 56.2±13.1 years). The following five pain measures were tested before (baseline) and 30, 75 and 120 min subsequent to subcutaneous injection of 1.5 mg apomorphine or placebo in two separate sessions: spontaneous pain intensity, threshold and tolerance to cold pain in the most painful site in the affected leg and in a remote healthy site in the dominant hand.

Eligibility criteria: Inclusion Criteria:

1. Presence of radicular pain for at least 3 months;
2. Average pain level during the last week prior to enrollment \> 40 (0-100);
3. No use of a new analgesic drug within 30 days prior to entry to the study and
4. Adults who were capable of understanding the purpose and instructions of the study and signing an informed consent.

Exclusion Criteria:

1. Pregnancy or breastfeeding;
2. Presence of Parkinson's disease or any other extra-pyramidal diseases;
3. History of allergy to the investigational drugs: Apomorphine or Domperidone;
4. History of polyneuropathy and
5. Respiratory depression, dementia, psychotic diseases or hepatic insufficiency

Primary outcomes:
measure: Experimental and clinical cold pain tolerance measured in seconds
timeFrame: Up to 120 minutes after drug administration
Secondary outcomes:
measure: Experimental and clinical cold pain threshold measured in seconds
timeFrame: Up to 120 minutes after drug administration
measure: Spontaneous clinical pain intensity measured on a numeric pain scale (NPS, 0-100)
timeFrame: Up to 120 minutes after drug administration
Other outcomes:
Locations:
city: Haifa
country: Israel
facility: Rambam Health Care Campus
Study officials:
affiliation: Rambam Health Care Campus
name: Elon Eisenberg, MD
role: PRINCIPAL_INVESTIGATOR
References: