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ANALGESICS

ANALGESICS. Pain Management. What is pain ? A protective mechanism to warn of damage or the presence of disease Part of the normal healing process. Managing pain can be a challenge. ANALGESICS. I. Opioid ( narcotic ) analgesics

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ANALGESICS

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  1. ANALGESICS

  2. Pain Management What is pain? • A protective mechanism to warn of damage or the presence of disease • Part of the normal healing process

  3. Managing pain can be a challenge.

  4. ANALGESICS I.Opioid (narcotic) analgesics 1.Agonists of opioid receptors – morphine hydrochloride, promedol, omnopon, fentanyl, codeine; 2.Agonists – antagonists and partial agonists of opioid receptors – pentazocin, buprenorphine. II.Non-opioid analgesics and non steroidal anti-inflammatory drugs - NSAIDs acetylsalicylic acid, paracetamol, analgin, indometacin, butadion, ibuprofen, pyroxicam, diclofenac-sodium, ketorolac, ketoprofen. III.Substances with mixed mechanism of action(opioid and non-oioid components) tramadole

  5. The structures that take part in perception of pain: thalamus, hypothalamus, reticular formation, limbic system, occipital and frontal areas of cortex System which conducts and perceives pain-nociceptive

  6. System which protects organism from pain – antinociceptive

  7. Classification of Pain By Onset and Duration • Acute pain • Sudden in onset • Usually subsides once treated • Chronic pain • Persistent or recurring • Often difficult to treat

  8. Major Sources of Pain

  9. OPIOIDANALGESICS

  10. History of Opioids Opium is extracted from poppy seeds (Papaver somniforum) Used for thousands of years to produce: Euphoria Analgesia Sedation Relief from diarrhea Cough suppression

  11. History cont’d Used medicinally and recreationally from early Greek and Roman times Opium and laudanum (opium combined with alcohol) were used to treat almost all known diseases

  12. Morpheus is the Greek god of dreams and sleep. Friedrich Wilhelm Adam Sertürner, a German pharmacist, isolated Morphine from opium, in 1805.

  13. History and Background Invention of the hypodermic needle in 1856 produced drug abusers who self administered opioids by injection Controlling the widespread use of opioids has been unsuccessful because of the euphoria, tolerance and physiological dependence that opioids produce

  14. Opioidreceptors • group of G-protein coupled receptors with opioids as ligands. • The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. Subtypes of opiod receptors: mu, delta, kappa, epsilon, sigma

  15. Opiod Receptor Activation

  16. Morphine CNS Depressant effects Stimulate effects CTZ (nausea, vimiting) Edinger Wesphal nucleus (III nerve –producing miosis) Vagal centre (bradycardia) Certain cortical areas and hippocampal • Analgesia • Indifference to surroundings • Mood and subjective effects • Depression of respiration • Cough centre • Temperature regulating centre • Vasomotor centre

  17. Morphine can be used as an analgesic to relieve: • pain in myocardial infarction • pain associated with surgical conditions, pre- and postoperatively (pre-anesthetic medication, balanced anesthesia, surgical analgesia) • pain associated with trauma, burns • severe chronic pain, e.g., cancer • pain from kidney stones, renal colic, ureterolithiasis, etc (pain may be valuable for diagnosis: should not be relived by analgesic unless proper assessment of the patient has been done) • traumas of thorax accompanied by cough(morphine depresses central links of coughing reflexes)

  18. Acute left-ventricular cardiac failure (cardiac asthma) • Reduce preload on heard due to vasodilatation • Tending to shift blood from pulmonary to systemic circuit; relieves pulmonary congestion and edema • Allays air hunger by depressing respiratory centre • Cuts down sympathetic stimulation by calming the patient • ,

  19. Narcotic (opioid) analgesics are extremely effective in reducing acute dental and postoperative pain. The narcotic analgesics have established a niche for the treatment of pain in those situations where the NSAIDs are less effective. Hydrocodone, oxycodone, codeine, and occasionally meperidine are the narcotics used to treat dental pain. Applications in Dentistry

  20. MORPHINE HYDROCHLORIDE routes of administration • subcutaneously and intramuscularly (analgesic action after 10-15 min) • oral administration – presystemic elimination ( 20-60 % enters general blood circulation) • sublingually – quick absorption • i.v. is indicated even in emergency • Epidural or intrathecal ( into the spinal canal ) injection produces segmental analgesia lasting 12 hours without affecting other sensory, motor or autonomic modalities Duration of analgesic action – 4-6 hours Maximum single dose of morphine is 0,02 g, maximum daily dose – 0,05 g

  21. Side effects of morphine • Respiratory depression • Vomiting (excitation of starting zone of vomiting center) • bradycardia(increasing of tone of n. vagus nuclei) • spasm of sphinctersof gastro-intestinal tract accompanied by constipations • increasing of tone of smooth musculature of urinary and bile-excreting tracts (retentions of urination, bile stasis) • Decreasing of BP

  22. CONTRAINDICATIONS FOR ADMINISTRATION OF MORPHINE • acute respiratory depression • renal failure (due to accumulation of the metabolites morphine-3-glucuronide and morphine-6-glucuronide) • chemical toxicity (potentially lethal in low tolerance subjects) • raised intracranial pressure, including head injury (risk of worsening respiratory depression) • Biliary colic Precauntation • painthat accompanies chronic inflammatory pain • childrenbefore the age of 2 years

  23. Tolerance Tolerance is a diminished responsiveness to the drug’s action that is seen with many compounds Tolerance can be demonstrated by a decreased effect from a constant dose of drug or by an increase in the minimum drug dose required to produce a given level of effect Physiological tolerance involves changes in the binding of a drug to receptors or changes in receptor transductional processes related to the drug of action This type of tolerance occurs in opioids

  24. Addiction Physical dependence Physiological dependence Withdrawal reactions

  25. Tolerance and Dependence

  26. Withdrawl Reactions Acute Action Analgesia Respiratory Depression Euphoria Relaxation and sleep Tranquilization Decreased blood pressure Constipation Pupillary constriction Hypothermia Drying of secretions Reduced sex drive Flushed and warm skin Withdrawl Sign Pain and irritability Hyperventilation Dysphoria and depression Restlessness and insomnia Fearfulness and hostility Increased blood pressure Diarrhea Pupillary dilation Hyperthermia Lacrimation, runny nose Spontaneous ejaculation Chilliness and “gooseflesh”

  27. OMNOPON • containsmixture if opium alkaloids (48-50% morphine) • does not cause spasms of smooth musculature, as it contains alkaloids of isoquinoline raw • isused for analgesia according to all the indications of morphine hydrochloride, for example, colics

  28. Promedol (trimeperidine) produces similar effects to other opioids, such as analgesia and sedation, along with side effects such as nausea, itching, vomiting and respiratory depression which may be harmful or fatal. duration of analgesic action- 3-4 hours moderatespasmolytic influence on smooth musculature of internal organs stimulationof rhythmic contractions of uterus can be used for analgesia in case of pain syndrome connected with spasms of smooth musculature

  29. Fentanyl synthetic opioid analgesic of short action analgesic activity is 300 times higher than of morphine analgesiceffect after intravenous introduction– after 1-3 min,lasts for15-30 min used with neuroleptic droperidol (complex drug– “talamonal”) for neuroleptanalgesia

  30. fentanyltransdermal system • should be used for long-term (chronic) pain requiring continuous narcotic pain • Is designed to release the drug into the skin at a constant rate ranging from 25 to 100 micrograms/h,

  31. Codeine • opium alkaloid • analgesic action is not strong, but anticough effect is considerable • administered as an anticough drug of central action • combination with non opiod analgesics (eg. Paracetamol) is supra-additive

  32. Pentazocin • agonist-antagonist of opioid receptors • comparatively with morphine, it is a bit less dangerous in the aspect of addiction development • indicated in case of pain of medium intensity in such conditionslike other opioid analgesics. In case of strong pain its administration is limited as in case of increasing of dose of the drug excitation appears • itcan cause increasing of blood pressure and tachycardia that’s why it’s not advised to use in case of acute myocardium infarction • if it is administered for people with narcotic addiction manifestations of abstinence develop

  33. Buprenorphine Partly agonist of mu-opioid receptors Acts longer than morphine (approximately 6 hours) Analgesic activity is higher than of morphine, that’s why it’s used in doses of 0,3-0,6 mg In case of breathing depression, which it causes, naloxon is less effective since buprenorphine is slowly released from the connection with mu-receptors Indicated for pain decreasing in the same situations as other narcotic analgesics May be used for detoxication and supporting treatment of individuals who is addicted to heroine

  34. Acute poisoning with opioid analgesics Respiratory Depression Euphoria Relaxation and sleep Tranquilization Decreased blood pressure Constipation Pupillary constriction Hypothermia Drying of secretions Flushed and warm skin

  35. Triad in case poisoning with morphine Acute miosis(Pinpoint pupils) Cheyne Stokes respiration deep tendon reflexes increased

  36. Treatment of acute poisoning • Naloxon(antagonist of opioid receptors) intravenously - 0,4-1,2 mg general dose of naloxon should not overcome10 mg • stomach lavage (for morphine enterohepatic circulation is typical) with 0,05-0,1% solution of potassium permanganate and 0,5 % tannin solution • suspension of 20-30 g of activated charcoal • saltlaxative agents (sodium sulfate) • forceddiuresis • atropine sulfate • inhalation of carbogen(5-7 % СО2and 93-95 % O2)

  37. NON-OPIOID ANALGESICS

  38. Pharmacodynamic Effects • Analgesic • Antipyretic • Anti-inflammatory (except paracetamol)

  39. Mechanism of action of non-opioid analgesics depression of cyclooxygenases activity decreasing of prostaglandins synthesis in peripheral tissues and in central nervous system decreasingof sensitivity of nervous endings and depression of transmission of nociceptive impulses on the level of CNS structures pain-relieving action of non-opioid analgesics is partly connected with their anti-inflammatory activity

  40. Effects of COX Inhibition by Most NSAIDS NSAIDs : anti-platelet—decreases ability of blood to clot

  41. COX Enzyme:Prostaglandin Effects

  42. Indications for administration of non-narcotic analgesics • headache • toothache • backache • neuralgias • pulled muscles • joint pain • dysmenorrhea for potentiating of their action – combinations paracetamol with codeine, metamizol with dimedrol, metamizol with codeine

  43. Applications in Dentistry Toothache Post extraction pain Periodontitis Neuritis Stomatitis Arthritis Local usage as keratoplatic agents for hyperkeratosis, hyperesthesia

  44. Paracetamol (Acetaminophen) • analgesic and antipyretic drug • maximal effect if the drug is introduced orally–after 2 hours, lasts approximately for 4 hours • in case of durable administration of big doses–damaging of liver and kidneys, production of met-hemoglobin

  45. Paracetamol (Acetaminophen)N-Acetyl-P-Aminophenol Classification: analgesic, antipyretic, misc. not an NSAID Mechanism: inhibits prostaglandin synthesis via CNS inhibition of COX (not peripheral)- doesn’t promote ulcers, bleeding or renal failure; peripherally blocks generation of pain impulses, inhibits hypothalamic heat-regulation center

  46. Paracetamol Tablets Suppositories Syrups Soluble tablets Capsules

  47. PARACETAMOL

  48. Pharmacokinetics: paracetamol Metabolism: major and minor pathways Half-life: 1-3 hours Time to peak concentration: 10-60 min Treatment for overdose: Acetylcysteine

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