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By K K Jain MD

A wide variety of methods are used in the management of pain. Details are given in management of specific types of pain and painful diseases. Management of neuropathic pain is a challenge and requires an improved understanding of pain mechanisms as well as a personalized approach (Jain 2008). Biomarkers will facilitate the development of novel pain therapies. Molecular approaches to neuropathic pain, including cell and gene therapies as well as RNAi-based treatments, will play an important role in the future. Management of chronic pain is multidisciplinary.

A list of drugs used for the management of pain is shown in Table 3 and nonpharmacological approaches are listed in Table 4.

Table 3. Drugs Used for the Treatment of Pain

  • Non-steroidal antiinflammatory drugs
    • Acetaminophen
    • Acetyl salicylic acid
    • COX-2 inhibitors
    • Ibuprofen
    • Ketoprofen
    • Meclofenamate
    • Nabumetone (Relifex)
    • Naproxen
  • Opioid analgesics
    • Codeine
    • Dihydrocodeine
    • Fentanyl
    • Hydromorphone
    • Levorphanol
    • Methadone
    • Morphine
    • Oxycodone
    • Tramadol
  • N-methyl-D-aspartate receptor antagonists
  • Ketamine
  • Antidepressants
  • Anticonvulsants
  • Local anesthetics
  • Other drugs
    • Capsaicin
    • Corticosteroids
    • Free radical scavengers: N-acetylcysteine, dimethylsulfoxide
    • Neuroleptics
    • Mexiletine

Table 4. Nonpharmacological Approaches to Management of Pain

  • Physical therapy
  • Application of ultrasound, microwave, laser, heat, cold
  • Mobilization, manipulation, and massage
  • Noninvasive procedures
  • Acupuncture
  • Transcutaneous electrical nerve stimulation
  • Psychological approaches
  • The placebo response
  • Behavioral approaches
  • Virtual reality therapy
  • Cell therapy (Jain 2008a)
  • Gene therapy (Jain 2008b)
  • Neurosurgery
    • Spinal cord and brain stimulation
    • Sensory cortex stimulation
    • Peripheral nerve and ganglia surgery
    • Implantation of intrathecal pumps for analgesics
    • Dorsal rhizotomy
    • Spinothalamic tractotomy
    • Mesencephalic tractotomy
    • Thalamotomy

Personalized management of pain. There is a trend toward the development of personalized pain therapy in the postgenomic era (Jain et al 2015a). Genetic factors have been implicated in pain thresholds or predisposition to neuropathic pain. Polymorphisms of some genes and changes in protein expression may be associated with some chronic painful conditions. Correlation of polymorphisms and gene expression profile obtained by microarrays with neurologic features may be helpful in developing novel therapeutic intervention and tailoring the therapeutics to the specific pain syndrome.

Advances in pharmacogenomics, particularly those relevant to the action of analgesics, will facilitate personalized management of pain. Genes related to the opioid receptors, ATP-binding cassette subfamily B, catechol-O-methyltransferase (COMT), cytochrome 2D6, interleukin-1 receptor antagonist, and the melanocortin-1 receptor show promise in helping to predict the gene phenotype (Fernandez Robles et al 2012). Catecholamines are involved in the modulation of pain and are partly metabolized by the COMT enzyme. Genetic variability in the COMT gene may, therefore, contribute to differences in pain sensitivity and response to analgesics. Genetic variation in the COMT gene can influence the efficacy of morphine and can explain differences in morphine requirements in individual cancer patients with pain (Rakvag et al 2008). Brain imaging studies have been conducted to develop an fMRI-based measure for predicting pain intensity at the level of the individual person (Wager et al 2013).

Genetic polymorphisms linked with musculoskeletal pain are found in genes contributing to serotonergic and adrenergic pathways. The study of the biological mechanisms by which these biomarkers contribute to the perception of pain in these patients will enable the development of better diagnostic methods and more effective drugs to facilitate personalized management of pain (Diatchenko et al 2013).

In This Article

Clinical manifestations
Pathogenesis and pathophysiology
Differential diagnosis
Diagnostic workup
Special considerations
References cited