**3. Conclusion**

wide array of drugs for pain alleviation. SNRIs are commonly used in conjunction with opioids (especially tapentadol and tramadol) with greater success in pain relief. This is the case of chronic pain syndromes, which usually require the use of this "adjuvant analgesics." The treatment of neuropatic pain has changed with time. At the beginning it included tricyclic antidepressants and anticonvulsants such as carbamazepine. Nowadays, the arsenal has spread with the use of gabapentinoids and SNRI antidepressants, such as duloxetine which in recent years has acquired approved indications for pain. For migraine pain, anticonvulsants such as valproic acid and topiramate are also used [34, 35]. And last but not least the T-type calcium channel blockers have also been included in pain treatment protocols in animals and

When Western medicines seem not to be effective, many people restore to nontraditional or alternative medicine. There is some evidence that some treatments using alternative medicine can relieve some types of pain more effectively than placebo [40, 41]. Medicinal plants (MPs) have been used for centuries by many cultures to treat pain and this knowledge has been embraced by the pharmaceutical industry which has used it to synthesize and elaborate analgesics commonly used in traditional Western treatments. The scientific verification process of this tradition is ongoing. The natural origin of MPs may lead to the false impression of innocuity and ample safety [42, 43], but despite presenting a wide therapeutic range, MPs are not exempt of adverse effects and interactions [44]; phytovigilance should be performed as for conventional medicines and should be sustained on a scientific basis regarding their toxicity and its allergenic potential [44]. Despite all this evidence, MPs use should not be discouraged, because for certain population, they are not only the adequate option but may be the only one

As it has been stated that the two main systems addressed in pain treatment are the routes involving COXs enzymes and opioids receptors and lately the inhibition of monoamines reuptake. Seeking for other options, lately, the endocannabinoid/vanilloid systems have also been studied regarding their effect on pain alleviation [45–47]. Although cannabis has proved to be useful in pain alleviation, there are two drawbacks for this option. First, cannabis is still a prohibited plant in many countries and second, as with many other plants, it is troublesome to identify the substance responsible for the action. To make matters worse, what raises concerns in this case is that tetrahydrocannabinol (THC) which is responsible for pain alleviation is also responsible for the psychoactive effects of marijuana. THC is not the only natural occurring substances capable of agonizing the endocannabinoid receptors and efforts are being made to find synthetic derivatives with a safer profile. The entourage effect is also a problem when extracting substances from biological matrixes, as sometimes the final effect of a treatment depends on a group of substances and not just

Local anesthetics have also proven to be a useful tool in acute and chronic pain relief; lidocaine presents good results in this regard because of the rapid alleviation obtained after administration, though cardiovascular adverse effects should also be taken into consideration [48, 49].

human models [36–39].

4 Pain Relief - From Analgesics to Alternative Therapies

available or affordable.

an isolated one.

**2.2. Other targets and techniques for pain alleviation**

It has been clearly stated that pain treatment is a challenge difficult to face. Health care teams have to articulate the resources available and patients' needs in a particular scenario where previous experiences are sometimes difficult to extrapolate. This book intends to give those involved in pain management a proper idea of the tools available for pain relief, comprising pharmacological ones and adjuvant techniques, as well as presenting late research on analgesics, their benefits and security profile.
