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Pharmacotherapy of pain

Pharmacotherapy of pain. Acute pain preventive function localised has vegetative sympthomatology and doesn´t cause severe psychological changes clearly defined beginning and ending analgesics are usually effective in treatment. Chronic pain without preventive function lasts 3-6 months

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Pharmacotherapy of pain

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  1. Pharmacotherapy of pain

  2. Acute pain preventive function localised has vegetative sympthomatology and doesn´t cause severe psychological changes clearly defined beginning and ending analgesics are usually effective in treatment Chronic pain without preventive function lasts 3-6 months often associated with severe psychological changes without clearly defined beginning malignant (caused by cancer)or non-malignant Types of pain 1

  3. Types of pain 2 • Nociceptive • somatic • superficial • deep • visceral (diffuse) • Neuropatic • central • deafferentational • peripherial • neuropaties • Idiopatic • Psychogenic

  4. Therapy of pain • Analgesics and co-analgesics • Non-opioid analgesics • Analgesics/antipyretics • Non-steroidal anti-inflammatory drugs (NSAIDs) • Opioid analgesics • Natural (morphine, dihydrocodeine) • Synthetic (fentanyl, buprenorphine) • Co-analgesics(Antidepressants, Anxiolytics, Myorelaxants, Anticonvulsives, Neuroleptics, Glucocorticoids, Anesthetics, 2 sympaticomimetics, H1 antihistamines)

  5. Non-opioid analgesics • Analgesics/antipyretics • aspirin (acetylsalicylic acid- ASA) • paracetamol (USA- acetaminophen) • metamizole (textbooks from the US say it´s an NSAID) • Non-steroidal anti-inflammatory drugs (NSAIDs) • Non-selective inhibitors of COX-1 and COX-2 (ibuprofen, diclofenac, ASA) • Preferential inhibitors of COX-2 (nimesulide, meloxicam) • Selective inhibitors of COX-2 (celecoxib, rofecoxib (dereg.))

  6. Analgesics/antipyretics

  7. Paracetamol Derivate of anilin • Mechanism of action – unknown, possibly inhibition of COX-3 (variant of COX-1) in CNS • Good absorption from GIT • Biological half life - 1,5-3 h  • Only a small percentage of the drug binds on plasma proteins (10%) • Elimination – through the kidnies in the form of glukuronides and sulfates • In doses over 5 g/day can cause hepatal damage • In the world, approximately 200 different preparates containing paracetamol are being used.

  8. Metamizole Derivate of pyrazolone • Synonyms Noramidopyrín, Dipyrón • has spasmolytic properties. • Serious adverse effect is depression of bone marrow leading to agranulocytosis. • Good absorption in the case of both peroral and rectal administration. • More than 50 % binds onto plasmatic proteins • Plasmatic halflife is short (i.v. metamizole - 14 min) • Elimination- mostly through kidnies.

  9. Non-steroidal anti-inflammatory drugs (NSAIDs)

  10. Properties Cyklooxygenase 1 Cyklooxygenase 2 Localisation cytoplasmatic in ER perinuclear Regulation constitutional inducable / constitutional Presence intissues GIT mucosa, renal parenchyma, endothelium, Tr Mf, Mo, CNS, kidneys, uterus, seminiferous Predicted function Integrity of stomach mucosa, kidney perfusion, Tr function Patogenesis of inflammation andgenesis of pain

  11. Non-steroidal anti-inflammatory drugs Division according to COX selectivity:

  12. Effects of NSAIDs • Analgesic effect • Antipyretic effect • Antiflogistic effect (mainly higher doses) • Antiaggregatory effect (not every NSAID, most important is ASA because of irreversible blocade of COX-1- be careful with combination of ASA for anti-aggregation and other NSAIDs- mostly ibuprofen) • Other effects- for example reduced incidence of some tumors (for example colorectal carcinoma), uricosuric effekt ...

  13. NSAIDs– oneofthe most widelyuseddruggroups→theirADRsrepresent a seriousmedical / publichealth / economicalproblemthere are big differencesbetweenvariousNSAIDsin thelevel risk ofparticularpossibleADRs

  14. Adverse effects of NSAIDs • GIT- erosions and ulcersofthegastricmucosa (also in otherlocalisationsinthe GIT), nausea, vomitus, meteorism, diarrhoea, constipation... (mainlyinhibitionof COX-1) • kidney-reductionofglomerularfiltration, retentionof Na and fluids, edema, hyperkaliemia, kidneyfailure, interstitialnephrits...(inhibitionof COX-1 and 2) • CVS-thromboticevents, increaseofbloodpressure, heartfailure...(mainly COX-2 (mostly in thromboticevents)) • CNS- cephalea, weakness, sleapdisorders, dizziness, epilepticseizures... • other- hepatotoxicity, bleeding, provocationofasthmaticattack, Ray´ssyndrom, prolongedchildbirth, urticaria, decreasednumberofwhitebloodcells...

  15. Gastrointestinal ADRs most serious – ↓ productionofprostaglandins in thegastricmucosa→ pepticulcer(most often in thestomach and duodenum; themucosacan get damaged by NSAIDsalso in otherplacesinthe GIT) roughly 25 % ofchronic NSAID usersmightdeveloperosions and ulcers, in 2-4 % perforation or bleedingcanoccure

  16. Kidney ADRs Decreasedproductionofprostanoids→negativeeffect on theperfusionofthekidneys, glomerularfiltration, excretionofsodium and waterand on productionofrenin→circulationoverload, oedemas, hypertension ; hyperkalemia; in severe casessymptomsofacutekidneyfailure seriouscomplication– interstitialnephritis(immunologicalreasons) IncidenceofkidneyADRsispoughly 18%, severe cases- roughly 1%

  17. Cardiovascular ADRs • Increasedbloodpressure- mostly in hypertensivepatientstreatedwithantihypertensives (mainlyACEIs, ARBs, beta blockers), there are big differencesbetweenvariousNSAIDs • Development/worseningofheartfailure- the risk ishighestduringthefirstweeksoftreatment, mainly in patientswithpreexistingcongestiveheartfailure; possibly 19% ofallcasesofcongestiveheartfailurecouldbecaused (atleastpartially) by NSAID therapy • Thromboticevents- acutemyocardialinfarction, stroke, thromboembolicdisease

  18. Opioid analgesics • Strong agonists: morphine, fentanyl Weak agonists: tramadol, codeine Partial agonists: buprenorphine Agonists/antagonists: butorfanol, pentazocine Antagonists: naloxone, naltrexone • Dampen strong somatic and visceral pain – strongest analgesics, without roof effect, can cause addiction • Dampen algognostic (perception and localisation) and algotymick(psychical and emotional) part of pain

  19. Depressory Analgesia Depression of breathing Antitussive effect Decreased secretion and motility in the GIT – constipation Sedation Stimulatory Vomiting Miosis Increased tonus of smooth muscles, sphincters Induction of histamine release Euphoria Pharmacological effects

  20. Adverse effects of opioids Neuropsychiatric • Sedation, clouded consciousness, euphoria, sleep disorders Cardiopulmonal • Depression of breathing, Bronchoconstriction (high doses) Orthostatic hypotension, Bradycardia (high doses) Gastrointestinal • Nausea, vomiting, constipation, gastrointestinal or gallbladder colics Urinary system • Retention of urine Endocrine • Decreased levels of testosterone, problems with menstrual cycle Allergic and immunologic • Pruritus, immunosupression

  21. Morphine Prototypical opioid • Isolated from sap from unriped skulls of poppy (1803) • Fast resorption after p.o. application, bioavailabilityis only 30% (significant first pass effect) • Most common adverse effects- nausea, vomiting, constipation, gallbladder and uretral spasms • Depression of breathing is the most common cause of death in case of intoxication. • Most common signs of intoxication – unconstiousness, bradypnoea a miosis

  22. Synthetic derivate of phenylpiperidine Strong agonist of  receptors 80-100 times more potent than morphine Lipophilic character – rapid onset of action, but the effect lasts only for a short time Contraindicated in pregnancy Derivates of fentanyl- sufentanyl and alfentanyl are used in anesteziológii Big advantage – availability of fentanyl in the form of transdermal patches – „Durogesic“ The second most widely used opioid Fentanyl

  23. Tramadol Atypical opioid • Intermediate analgesic effect • High bioavailability is an advantage. • In therapeutic doses lacks most of the adverse effects of opioids. • The most common adverse effects are sweating, nausea and dry mouth. • Suitable for treatment of mild to severe pain in adults and children. • Available in different drug forms. • It is cheap.

  24. In case of long term treatment, analgesics should be administered regularly, not only when the patient feels pain.

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