Pharmacotherapy of pain
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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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Pharmacotherapy of pain

Pharmacotherapy of pain


Types of pain 1

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


Types of pain 2

Types of pain 2

  • Nociceptive

    • somatic

      • superficial

      • deep

    • visceral (diffuse)

  • Neuropatic

    • central

      • deafferentational

    • peripherial

      • neuropaties

  • Idiopatic

  • Psychogenic


Therapy of pain

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)


Non opioid analgesics

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.))


  • Pharmacotherapy of pain

    Analgesics/antipyretics


    Paracetamol

    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.


    Metamizole

    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.


    Pharmacotherapy of pain

    Non-steroidal anti-inflammatory drugs

    (NSAIDs)


    Pharmacotherapy of pain

    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


    Non steroidal anti inflammatory drugs

    Non-steroidal anti-inflammatory drugs

    Division according to COX selectivity:


    Effects of nsaids

    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 ...


    Pharmacotherapy of pain

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


    Adverse effects of nsaids

    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...


    Gastrointestinal adrs

    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


    Kidney adrs

    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%


    Cardiovascular adrs

    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


    Opioid analgesics

    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


    Pharmacological effects

    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


    Adverse effects of opioids

    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


    Morphine

    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


    Fentanyl

    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


    Tramadol

    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.


    Pharmacotherapy of pain

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


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