There are several classes of drugs that can be usefully employed in the treatment of pain.
The choice of medication or drugs more effective is to be based on characteristics of the pain, the cause of pain and characteristics of the patient. Drugs can be administered by local or systemic (oral, rectal, intramuscular, intravenous).
WHO METHOD
Approach to THREE STEPS
1) Drugs not opioids (Mild pain)
2) Oppioidi weak + or-other (+ Moderate pain mild)
3) Oppioidi strong + or-other (Severe pain)
In any steps can be added drugs audiovanti: Steroids, anticonvolsivanti and psychotropic
Drugs by local
We can recall the local anesthetics such as lidocaine and bupivacaina that can be used successfully in fibromyalgia. In this disease that primarily affects women are areas fibromialgiche called trigger points that are characterized by inducing pain that can be located at the trigger point or irradiated at a distance. If these trigger points are infiltrated with a modest amount of local anesthetic, there is often the disappearance of both the local and pain that radiated.
Drugs systemically
The first group of medicines antalgici to consider is that of NSAIDs.
Main categories of NSAIDs:
Derivatives salicilici
Salicylates sodium
Acetylsalicylic acid
Diflunisal
Derivatives pirazolonici
Aminopirina
Of pirone
Derivatives paraaminofenolo
Fenacetina
Paracetamol
Derivatives indolici
Indometacina
Etodolac
Derivates propionic
Ibuprofen
Ketoprofene
Derivatives acetic acid
Diclofenac
Ketorolak
Derivatives ossicamici
Piroxicam
Tenoxicam
The use of NSAIDs is fundamental in somatic pain and visceral, modest or moderate intensity, such as those that occur daily observation of the doctor. You can treat rheumatic pains in the broadest sense, some types of headaches, those muscolo-tensive, and the visceral pain that is often erroneously considered little sensitive to NSAIDs. The action on visceral pain for example is particularly evident and peculiar to the dipiridone, effective in pain type cholic thanks to his action antispastica. The pain tumor, if treated early, for a long time may be sensitive to NSAIDs or association FANS-oppioidi.
The second group of medicines antalgici to consider is that of opioids. Opioid drugs are substances that, once introduced in the body, tend to bind with specific receptors called for opiate receptors that are normally employed by other compounds normally produced and secreted by S. N. C, known as endogenous opioids. The endogenous opioids are about 20, some of these are active and others are not, but all are derived from only three parents (Proopiomelanocortina, Proenkefalina, Prodinorfina) per share of peptidases. The most active endogenous opioids are basically four:
Endorfina
Met- enkefalina
Leu- enkefalina
Dinorfina
With regard to these opioid receptors are protein nature and have a structure similar to the somatostatina.Si receptor on the cell membrane place with three components:
Intramembranale
Extracellular
Intracellular
They were discovered, according to the presence of specific ligands, endogenous or exogenous able to stick to them different subtypes of receptors for opioids:
Receptors m (divided into m1 and m2)
Receptors k (divided into k 1, k 2 k 3)
D receptors (divided into d 1 and 2)
Receptors s
The factors that determine the effect of opioids are:
Biodisponibilità (related to the route of administration)
The passage of BEE
The affinity for the receptor
The type of action that the receptor plays
The inherent power of drug
The passage of BEE favorite:
Low molecular weight
Lipophilicity
Low degree of ionization
Low degree of protein binding
Regarding affinity receptor that is "the ability of a oppioide to bind to its receptor" molecules that distinguish have a high affinity where almost all molecules bind (morphine) and low-affinity molecules in which only a small portion molecules binds (d-propoxyphene). With regard to the type of interactions with receptors are: pure agonists: a ceiling receptor activation (morphine), no effect roof, but by increasing the dose of medicine is a linear increase of partial agonists: activation sub-ceiling receptor, which have a limit to submit an action-roof (codeine).
Agonisti- antagonists: act on multiple receptors, as a kind agonists and antagonists as a more (buprenorphine).
Blockers: bind to the receptor blocking activity or scalzando an agonist that is working Are drugs for the treatment of overdose.
Analgesic Effects
The endogenous opioids are able to reduce and modulate the transmission of nociceptive messages. The morphine and other opiate drugs, exercise their effects mimando (often more efficiently) the physiological mechanism normally exercised by endogenous opioids. In the circuit of pain opioids act at various levels: you have the activation of the system descending modulation of pain and a direct inhibition presinaptica and postsinaptica level spinal cord that prevents the progression of stimulus algogeno towards centers integration talamica and cortical.
Review of the main opioid drugs
Morfina
Alcaloide of plant origin, is the main derivative instead of (papaver somniferu m). Agonista pure action with the main receptor µ, σ, κ. It ranks with the strong opioids, is the main analgesic severe pain, especially in chronic cancer pain. It is absorbed quickly for each route of administration and undergoes intestinal and hepatic metabolism: in the liver is conjugated with glucuronic acid to form its main metabolites: morfina-3- glicuronide and morfina- 6-glicuronide. There is bound to plasma proteins in 36%. Elimination: primarily by renal excretion and only in small part by bile, with the possibility of resorption circle entero- liver.
The main routes are:
Oral
Inhalation
Sublingual
Intravenous
Subcutaneous
Intramuscular
Rectal
Peridurale
Codeine
Alcaloide instead of with power farmacologica1 / 10 of morphine. Good gastrointestinal absorption ensures that bioavailability of 60%. Metaboliti: codeina- 6-glucuronide, norcodeina, morphine, morfina- 3-glucuronide, morfina- 6-glucuronide. Performs its action on prevailing µ receptors. Clinical Properties: Action antitussigena, analgesic (especially in combination with NSAIDs or paracetamol).
Methadone
Oppioide summary basic lipophilic. It is a receptor agonist µ ek while acts antagonist of NMDA-receptors Methadone is a racemic mixture analgesic effect is linked all'isomero levogiro. Good gastrointestinal absorption with a bioavailability of 90% After 30 ' After an oral dose is present in plasma, the peak plasma concentration is 4 hours. Rapid passage in the CNS because of the more lipophilic morphine.
Buprenorphine
Derived synthetic tebaina. It is a partial agonist-receptor µ 30 times more potent than morphine. It has a roof high doses (> 1 - 2 mg) is highly fat-soluble and thus can easily cross the barrier ematoencefalica.Essendo most powerful can antagonizzare the effects of the drug-receptor agonist µ and also having a roof will effectively. Less so that patients already treated with opioids can cause a crisis of abstinence. The overdose is not antagonizzato by naloxone.
Tramadol
Medication property with synthetic opioids and non opioids. The tramadol and its metabolite (demetil-tramadolo) has an affinity for the µ receptors for opioids. He also inhibitory action on the re-uptake presinaptico of serotonin and noradrenaline. It is considered at low risk of respiratory depression and naloxone antagonises only partially by the analgesia tramadol.
Fentanyl
Powerful oppioide agonist, derived fenilpiperidina. It has a power pharmacology 100 times the morphine. More fat-soluble compared to morphine, and the effect is reversible with the use of Naloxone.
It is mainly eliminated by the liver. Other drugs that can be taken into consideration are oxycodone, idromorfone, meperidine, and pentazocina.
