Complex regional pain syndrome is a debilitating chronic pain condition causing intense pain particularly in the arms, hands, legs, or feet. This syndrome is characterized by pain, swelling, vasomotor instability, limited range of motion, skin color changes and patchy bone demineralization. CRPS is often regarded to be caused as a result of malfunction of failure of peripheral and central nervous system and therefore also sometimes referred as reflex sympathetic dystrophy syndrome. Complex regional pain syndrome (CRPS) is classified into two similar forms termed as CRPS type 1 (Reflex Sympathetic Dystrophy or RSD) and CRPS type 2 (Causalgia). The former type mentioned has been used for individuals with confirmed nerve injuries while the latter type is used to refer patients without any confirmed nerve injury.
It is noteworthy to mention that the disease prevalence is very low and therefore classified as an orphan disease. Furthermore, since the sympathetic nervous systems affect several systems simultaneously, development of drugs for treating complex regional pain syndrome had been painstaking task for the researchers. However, the expanding knowledge base in neurology and medicine provides unique and underserved market opportunity for drugs and products in complex regional pain syndrome disease.
Presently there is no cure for the disease but drug therapies help in alleviating the pain associated with the disease as wells reduce the progression of the disease. Multimodal therapy is prescribed for the treatment of chronic regional pain syndrome which includes psychotherapy, rehabilitation therapy and drug therapy. Drug therapy for CRPS includes non-steroidal anti-inflammatory drugs (aspirin, ibuprofen, and naproxen) used to treat moderate pain while corticosteroids such as prednisolone and methylprednisolone are prescribed to treat inflammation and edema in the early stages of CRPS. Drugs effective in neuropathic pain are also administered to patients with CRPS.
These drugs include gabapentin, amitryptiline, nortryptiline and duloxetine. Other therapeutic drugs useful in complex regional pain syndrome (CRPS) include oxytocins, morphine, hydrocodone, vicodin, N-methyl-D-aspartate (NMDA) receptor antagonists (dextromethorphan) and botulinum toxin injections. Several emerging therapies are being evaluated for the treating CRPS which include intravenous immunoglobulin (IVIG), ketamine and hyperbaric oxygen therapy.