Pregabalin effects on Cardiovascular Responses to Pain and Fatigue in Fibromyalgia
Fibromyalgia syndrome (FM) is characterized by widespread pain in muscles, joints, and deep connective tissues for at least three months. FM patients represent a heterogeneous population of chronic pain patients, making them challenging to diagnose and to treat successfully. It has been noted that exercise therapy showed the reduced pain ratings with increased function in FM patients. However, because many FM patients experienced post-exertional worsening of pain, physical fatigue and mental fog, the dropout rate of FM patients from exercise programs was high.
Pregabalin has been reported to be an approved or effective treatment for fibromyalgia with decreased sympathetic nervous system (SNS) activity. It inhibits sympathetically maintained pain but effects on exercise responses have not been reported yet.
To evaluate the exercise effects, a randomized double-blind cross over design was conducted of 5 weeks with Pregabalin on acute cardiovascular and subjective responses to moderate exercise in 19 FM patients. In the trial, blood pressure (BP), heart rate and ratings of perceived exertion (RPE) during exercise and ratings of pain, physical fatigue and mental fatigue before, during and for 48 hours after exercise were compared in patients on pregabalin versus placebo and also versus 18 healthy controls.
After evaluation, in placebo, exercise RPE and BP were significantly higher in FM patients than controls. Pregabalin responders had significantly lower exercise BP, HR and RPE on pregabalin versus placebo but no longer differed from controls. Cardiovascular responses of non-responders were not altered by pregabalin. However, pregabalin improved ratings of fatigue and pain but negative effects on pain in responders and fatigue were seen in non-responders.
Findings suggested that the pregabalin might normalize cardiovascular and subjective responses to exercise in many FM patients. Nonresponders to pregabalin had normal exercise BP and HR responses on placebo, and these responses were not altered by pregabalin. In addition to expected benefits on pain and sleep quality, FM patients who were pregabalin responders demonstrated significant reductions in multiple fatigue-related symptoms, and presence of comorbid CFS was not associated with nonresponse to pregabalin. Whereas, future research to determine whether pre-treatment of FM patients with pregabalin could reduce initial post-exertional symptoms and enhance success in completing an exercise training program is recommended.