The Effects of Apomorphine on Experimental and Clinical Pain in Patients With Chronic Radicular Pain

Rambam Health Care Campus

Status and phase: Completed; Phase 4

Conditions: Chronic Low Back Pain

Treatments: Drug: Apomorphine; Drug: Normal Saline

Study type: Interventional

Funder types: Other

Identifiers

NCT02969629

0234-11-RMB

Details and patient eligibility

About

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.

Full 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.

Enrollment: 59 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Triple Blind

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59 participants in 2 patient groups, including a placebo group

apomorphine

Experimental group

Description:

1.5 mg apomorphine, administered subcutaneously

Treatment:

Drug: Apomorphine

Normal saline

Placebo Comparator group

Description:

saline, administered subcutaneously

Treatment:

Drug: Normal Saline