Generality
Pain therapy (also referred to as analgesic therapy or pain medicine) aims to recognize, evaluate and treat chronic pain in the most appropriate way.
The type of drug to be used may vary depending on the origin, nature and intensity of the painful stimulus that is intended to be treated. Therefore, before illustrating the categories of drugs most used in this "field, it is useful to understand how" is chronic pain and what are the causes that can trigger it.
Causes of Chronic Pain
According to the definition provided by the "International Association for the Study of Pain (IASP), pain represents "an unpleasant" sensory and emotional experience associated with actual or potential tissue damage, or described in terms of damage. It is an "individual and subjective experience, to which purely sensory components converge (nociception), relating to the transfer of the painful stimulus from the periphery to the central structures, and experiential and affective components, which modulate what is perceived in an important way".
Basically, three different types of pain can be distinguished: acute, chronic and procedural.
Chronic pain, the target of analgesic therapy, persists over time, is highly debilitating and is capable of causing not only physical, but also psychological, social and economic damage to the patients who are afflicted by it. For this reason, chronic pain is considered a real pathology.
Very often, it is believed that chronic pain is a peculiarity of neoplastic pathologies. However, tumors are not the only possible cause capable of triggering the aforementioned form of pain. In fact, the cause may not be of an oncological type, but may be, for example, a neuropathic type, or associated with degenerative pathologies of various nature.
Drugs used
The choice of the type of drug to be used in pain therapy depends above all on the intensity and type of pain afflicting the patient.
The main classes of drugs used in analgesic therapy will be briefly described below.
NSAIDs
NSAIDs (non-steroidal anti-inflammatory drugs) are used in the treatment of pain when the latter is mild or moderate.
Generally, these medicines complement the analgesic activity also with an anti-inflammatory and antipyretic action.
Their mechanism of action involves the inhibition of the cyclooxygenase enzyme, with consequent inhibition of the synthesis of prostaglandins responsible for mediating painful responses and inflammatory processes.
Among the active ingredients most used in pain therapy, we mention ketoprofen, diclofenac, naproxen and nimesulide.
To obtain more information about the properties and the mechanism of action of NSAIDs, we recommend reading the dedicated articles "NSAIDs: History, Mechanism of action, Indications" and "NSAIDs: Side effects and contraindications".
Opioid analgesics
Opioid analgesics, widely used in pain therapy, are particularly indicated when the pain stimulus is moderate to severe.
These drugs carry out their antinociceptive action through the stimulation of the opioid receptors present throughout our organism. In fact, these particular receptors are located on the pain pathways and their task is precisely to mediate and transmit painful stimuli.
Among the opioid analgesics most used in pain therapy we find codeine, tramadol, buprenorphine, fentanyl, oxycodone, methadone, hydromorphone and morphine.
Although they can be used in the treatment of pain of various origins and nature, the aforementioned active ingredients are considered as the most important drugs in the treatment of chronic cancer pain.
In any case, to obtain more information about the characteristics of this class of drugs, please refer to the "dedicated article" Opioid drugs ".
Antidepressants
Although their main therapeutic indication is the treatment of depression, some active ingredients belonging to the classes of tricyclic antidepressants (or TCAs) and serotonin and norepinephrine reuptake inhibitors (or NSRIs) have proved very useful in the therapy of neuropathic pain. and can be used either alone or in combination with opioid analgesics.
Among the TCAs most used in this field, we mention amitriptyline and clomipramine.
Among the NSRIs, on the other hand, we remember duloxetine, an active ingredient that has been shown to be particularly effective in the treatment of diabetic neuropathic pain.
Anticonvulsants
Some types of anticonvulsant drugs have also been shown to be quite effective in the treatment of neuropathic pain. In particular, gabapentin and pregabalin are among the active principles most used in this field.
These drugs, in fact, through the interaction with the voltage-dependent calcium channels present in the central nervous system, are able to reduce the release of neurotransmitters involved in the modulation and transmission of the painful stimulus, such as substance P and peptide related to the calcitonin gene.
Local anesthetics
Among the local anesthetics most used in the treatment of chronic pain we find lidocaine.
More specifically, lidocaine is able to reduce and block the transmission of the painful stimulus through the inhibition of the voltage-gated sodium channels present on cell membranes.
Non-drug therapy
To the classic pain therapy carried out with medicinal specialties, it is possible to combine a non-pharmacological pain therapy.
Of course, the type of approach you decide to take varies according to the type of chronic pain that needs to be treated.
These different approaches include radiotherapy, cryotherapy, thermotherapy, massage and physiotherapy.
Finally, it is now known that the psychological component also plays a certain role in the perception and possible worsening of chronic pain. For this reason, in some cases, approaches based on psychological behavioral or cognitive techniques may be useful, as it may prove to be the use of relaxation and imagination techniques and distraction techniques is useful.
