Docstoc

ANALGESICS

Document Sample
ANALGESICS Powered By Docstoc
					ANALGESICS
The treatment of Pain Relief of pain without loss of consciousness
Opioids
       Pain
       Diarrhoea
       Cough
       Pulmonary edema (Morphine)
Non opioids
       Non steroidal anti-inflammatories (NSAIDs)
              Pain
              Fever
              Inflammation
              Coagulation (Aspirin)
       Anti-pyretics
              Pain
              Fever
       Corticosteroids
              Inflammation
       Autacoids and autacoid antagonists

Migraine
Gout
Arthritis

Opioid receptors
Mu receptor ()
Kappa receptor ()
Delta receptor ()
Sigma receptor ()

All opioid receptors are coupled to inhibitory G proteins that inhibit adenylyl cyclase
causing hyperpolarization that impedes neuronal firing and transmitter release.

OPIOIDS
Opioid agonists
Strong agonists
               Morphine
               Pethidine
               Methadone
               Fentanyl –   Alfentanil
                            Remifentanil
                            Sufentanil
Mixed opioid agonist-antagonist
              Buprenorphine
              Pentazocine



                                                                                          1
Opioid antagonists
              Naloxone
              Naltrexone


Strong agonists
Morphine
      Analgesia         pain threshold
                       alter brain perception
       Euphoria        only during pain
                       lack – dysphoria
       Respiration     depression
                       common cause of death
       Anti-tussive
       Miosis          diagnosis
       Emesis          chemoreceptor trigger zone
       GIT             anti-diarrhoeal agent
       CVS             no direct effect
                       vasodilatation + hypotension
        cerebral fluid pressure
       Histamine release       urticaria
                               sweating
                               vasodilatation
       Hormonal actions        various actions
                                anti-diuretic hormone
                               urinary retention
       IM, IV, Subcutaneous         Not orally – first pass metabolism
       Kinetics
       Least lipophilic – low concentration in brain
       Duration of action – 4–6 hours
       Drug interaction
                       Phenothiazides                   MAOI
                       Tricyclic antidepressants
                       Amphetamine             Hydroxyzine
       Adverse effects                 hypotension
               sedation                constipation
               nausea                   vomiting
               urinary retention       highly addictive
               severe respiratory depression
       Contra – indications
               asthma          renal failure
               labour+ pregnancy
                intracranial pressure
               chronic obstructive pulmonary disease          (COPD)
Pethidine



                                                                         2
              as morphine except no miosis
       Kinetics
              orally – more often IM injections
              duration of action 2-4hours
       Drug interactions
                      CNS drugs      MAOI
       Adverse effects
              tremors                muscle twitches
              convulsions (rare)
              hypotension highly addictive

      Preferred during labour
Methadone
              same as morphine except
              less euphoric – controlled withdrawal of    addicts
              orally         longer duration of action
Fentanyl
              mainly used as a anaesthetic
              rapid onset            short duration

Moderate agonists
Propoxyphene
      mild analgesic addiction is low
      orally Peak in 1 hour
      combination + aspirin + paracetamol
      Adverse effects
             anorexia
             resp depression only at high doses
             also convulsions hallucinations confusion

       Drug interaction
              alcohol sedatives
              Severe CNS and resp depression
              cardiotoxicity death

      Use Naloxone
Codeine
      moderate addiction
      orally
      combination + aspirin + paracetamol

Mixed opioid agonist - antagonists
Pentazocine
Buprenorphine
Agonist      kappa receptors       Antagonist      mu and delta receptors




                                                                            3
Do not use with agonists will block their effect

Pentazocine
      Adverse effects
              blood pressure and work of heart in        angina          tachycardia
             hallucinations nightmares
             dizziness            renal flow
             low addiction

Buprenorphine
       Partial agonist mu receptor
       Kinetics
               injection
               long duration of action
       Adverse effects
               dizziness
                blood pressure
Antagonists
Naloxone
               antagonist mu, kappa and delta receptors
               reverse coma + respiratory depression      within 30 sec
               Half life 60-100 minutes
               addicts – opiate withdrawal
Naltrexone longer duration of action
       not available in RSA

NON STEROIDAL ANTI-INFLAMMATORIES
Salicylates
Aspirin       Uses:
              anti-inflammatory
              anti pyretic
              analgesic
              anti coagulant
       Kinetics
       Oral 2x325mg           analgesia
                      3,6 – 6g       inflammation
                      160mg anti platelet effects
       Drug interactions
              antacids               anti coagulants
              gout + preparations
       Adverse effects
       GIT epigastric distress, nausea, microscopic bleeding, vomiting
              Take with food, large volumes of water or misoprostal!
       Blood poor clotting
              bone murrow dysfunction
              low platelet, white blood cell and neutrophil counts



                                                                                        4
      Respiratory depression        bronchoconstriction
              respiratory and metabolic acidosis
      Urticaria       edema
      High doses      Hyperthermia
                               Uric acid retention
      Reye’s syndrome                  FATAL
              children 16 years and under
              viral infection present
      Symptoms
              cerebral edema
              disorientation           confusion
              Liver damage/failure
              Fatty infiltration in brain/liver
      Drug intolerance         within 3 hours
      Symptoms                 acute urticaria angioedema
                               bronchospasm rhinitis
                               shock
      Drug toxicity
      Symptoms                 vomiting        hyperthermia
                               respiratory failure lead to death
                               delirium        hallucinations
                               convulsions coma
      Treatment
               urinary pH clearance 4X if pH >8
              correct fluid + electrolyte imbalance
              glucose
              potassium
              lavage emesis activated charcoal

Others
Ibuprofen
               anti-inflammatory
               analgesic
               anti pyretic
Other examples: Naproxen Fenoprofen Ketoprofen
                 Flurbiprofen Oxaprozin
Indomethacin not for children
       anti-inflammatory
       analgesic
       anti pyretic
Other examples:        Sulindac            Etodolac
Lornoxicam
       cyclo oxygenase 2 selectivity (COX2 )
        alternative to misoprostal use
       less GIT effects
Others Meloxicam, Piroxicam



                                                                   5
Mefenamic acid
      analgesic
      Toxic side effects - diarrhea
      not used more that week
      not in children
Ketoralac
      injectable NSAID (IM)
      mild to moderate postsurgical pain
      not before or during surgery - bleeding

ANTI PYRETIC ANALGESICS
Paracetamol (acetaminophen)
      analgesic
      anti pyretic
      oral
      drug of choice in children
      no significant adverse effects
      Overdose
              Children – pleasant syrups
              Renal tubular necrosis
              Hypoglycemic coma
              Hepatic necrosis
              Death in 3 days
              N-acetylcysteine in 10 hrs – binds toxic metabolites
CORTICOSTEROIDS
–Glucocorticoids      - anti-inflammatory action
–Mineralocorticoids


All corticosteroids can be administered orally

Glucocorticoids
Hydrocortisone      (topical,IM)
Cortisone
Prednisone
Prednisolone
Methylprednisolone
Beclomethasone (aerosol, topical, IM)
Dexamethasone (topical, IM)

Glucocorticoids
Anti-inflammatory action: reduce inflammation response and suppress immunity
dramatically
Block release of arachidonic acid
↑ neutrophils



                                                                               6
↓lymphocytes, eosiniophils, basophils, monocytes
↓ release of histamine



DRUGS FOR GOUT

Allopurinol
       interfere with uric acid synthesis
Colchicine
       inhibit leukocyte entry (inflammation)
Probenecid
Sulfinpyrazone
        uric acid excretion
NSAIDs – Ibuprofen, Indomethacin

DRUGS FOR RHEUMATIC ARTHRITIS

Slow acting anti-inflammatory drugs.

Chloroquine
–Slow erosive bone lessions
–Serious side effects


Gold salts (auranofin)
–prevent further injury
Leflunomide

Methotrexane
–Slows new erosions within joints
–Side effects : mucosal ulceration, nausea


D-Penicillamine
–Slows bone destruction
–Side effects: dermatologic problems, nephritis, aplastic anaemia




                                                                    7
                                 BDS III

          Worksheet 1: Dental pain - Report
1.   It is a fact that if you prescribe 6 drugs the chances of drug interaction is 80%.

2.   Myprodol is a combination of Paracetamol + Codeine + Aspirin, in some of
     the prescriptions this is combined with Ibuprofen. Is this necessary? If yes
     then why when Aspirin is a more than effective anti-inflammatory agent.

3.   Please read the latest on Warfarin – Paracetamol interaction.




                                                                                      8