Efficacy of pain treatment may be seen on MRI

Treatment of pain with analgesics may be measured through the use of MRI, which could assist with drug development, according to recently published research.

“We believe that neuroimaging techniques, such as [functional MRI] FMRI, can provide objective evidence that can be used as outcome measures in early drug development to enhance the efficiency of the drug development process,” study coauthor Vishvarani Wanigasekera, DPhil, clinical post-doctoral research fellow at Nuffield Division of Anaesthetics, University of Oxford, England, said in a press release from the American Society of Anesthesiologists.

Wanigasekera and colleagues studied images collected from 24 healthy individuals who underwent capsaicin-induced mechanical punctate hyperalgesia. Three study visits 1 week apart were conducted during which participants were screened and received either placebo, 1,200-mg gabapentin or 600-mg ibuprofen after a 6-hour fast. Food was provided, and 1% capsaicin cream was applied on the anteromedial aspect of the right lower leg in a 4 cm-by-4 cm area 14 cm above the medial malleolus. Dynamic mechanical allodynia and hyperalgesia were elicited in an area 2 cm below the area treated with capsaicin. Allodynia was induced with a soft brush over 10 minutes with 6-second stimuli applied to area. Pain was measured on a VAS.

A 3T MRI scanner was used 150 minutes following the dose of medication or placebo. During the elicitation of hyperalgesia and allodynia, scans were obtained sequentially in blocks, followed by an arterial spin labeling sequence and a resting-state, echo planar sequence.

A venous blood sample was collected following the scan administration about 200 minutes following dosage, and drug levels were analyzed for 22 patients.

Analysis showed the pain intensity of hyperalgesia and unpleasant responses were reduced in participants who received gabapentin, but not in participants who received either ibuprofen or placebo.

“Many potential pain relieving drugs identified in preclinical research fail to reach the market because of a lack of early objective evidence that shows whether a drug is effectively reaching target pain receptors in the body and regulating chronic pain mechanisms,” Wanigasekera said. “We have used noninvasive FMRI to successfully obtain such evidence that we hope can help to prevent the premature discarding of potentially effective pain relievers, as well as avoid exposing patients to ineffective ones.” – by Shirley Pulawski



Disclosure: The researchers report no relevant financial disclosures.

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