**2. Analgesic (painkiller)**

analgesic effects has recently gained popularity worldwide because of their natural origin and fewer side effects [1]. Moreover, medicinal plant extracts and their fractions are used by 80% of the world population for their simple health care necessities. They are the significant source of natural drug molecules and secondary metabolites which can be used in modern medicine for the cure of various diseases. Throughout history, people relied on an old‐style traditional system of medicine to cure diseases and disorders, which with time has gained popularity and global significance. Present approximations suggest that in numerous devel‐ oping countries, a large proportion of the population seriously trusts traditional specialists and local healers in addition to trusting medicinal plants and medicinal plants‐derived drugs to cure diseases, though modern drugs may be accessible in these countries. However, herbal

Native people and early civilizations tested different plants and animal parts to determine what effect they have. Using trial and error methods, local healers and shamans found that particular plants or parts had therapeutic activity. These indicated the first crude drugs and this knowledge was passed down through the generations and arranged similar to the old‐ style Chinese medicine as well as Ayurveda [2, 3]. Many traditional medicines have actual and useful effects, and extracts of these medicines have led to the discovery of bioactive mol‐

Recently, several people in developed countries have turned to complementary treatments including the use of therapeutic herbs [2]. In this context, the term Ayurvedic medicine has been introduced which is mainly in the form of a crude extract that consists of a mixture of several compounds; however, when the active agents are isolated and purified, they individu‐ ally fail to give the desired activity. Therefore, pharmacological data on several medicinal plants and isolated compounds are required to regulate active compounds with the desired biological potency. Furthermore, modern methods of production, purification, and standard‐ ization should be followed to obtain plant‐derived materials of high quality [3]. In ancient times, humans extracted chemicals from plants for treatment of various diseases, and kept records of useful properties and uses of medical plants, such as willow bark and *Papaver som‐ niferum*, used as a pain killers. It is now documented that willow bark contains acetylsalicylic

Due to its frequent occurrence, pain is a public health problem with considerable socioeco‐ nomic effects. It is an indication of several illnesses and it is predicted that about 80–100% of the population will experience, for example, back pain once in life [4]. Pain treatment requires analgesics including, anti‐inflammatory medicines, which at maximum doses have analgesic properties. In this respect, inhibition of nitric oxide (NO) and prostaglandin E2 production has been reported as a potential therapy for different inflammatory disorders [5]. Though several anti‐inflammatory and analgesics drugs exist on the shelves, current drug therapy is related to certain adverse effects such as gastrointestinal irritation [6], bronchospasm, fluid retention, and extension of bleeding time. Consequently, it is necessary to discover new drugs with fewer adverse effects. Accordingly, people resort to medicinal plants for discovery and development of new drugs [7]. In addition, scientists discovered that extracts from medicinal plants can be a significant source of natural and safer new drugs for the treatment of inflam‐

medicines must be approved by local authorities before being prescribed.

ecules and to the growth of current chemically active pure drug discovery [3].

acid, the active ingredient in aspirin [3].

340 Pain Relief - From Analgesics to Alternative Therapies

mation and pain [8, 9].

Analgesics drugs include paracetamol (acetaminophenol), in addition to the nonsteroidal anti‐ inflammatory drugs (NSAIDs) such as salicylates, and morphine and oxycodone isolated from opium. There are many classes of drugs available for treatment of pain. Each class has a dis‐ similar history of uses for treatment of different types of pain and in different types of people.

Analgesic selection is governed by the type of pain. For example, for neuropathic pain, tra‐ ditional analgesics are less effective, whereas drugs that are not normally mentioned as anal‐ gesics, such as tricyclic antidepressants and anticonvulsants medicine, are more effective as pain killers [10]. In general, pain killers are not used if there have other serious side effects. For pain relief, drugs are classified based on either their chemical structures or on their uses for different classes of medical illnesses. Moreover, some drugs are arranged according to the requirements of people who use them. In other cases, these drugs are listed based on acces‐ sibility in a geographical zone, possibly to stop obtaining drugs which are prohibited there.
