Transcript
PAINTHERAPY AND CLINICAL ASPECTS
GUIDE – DR. L. S. PATILPRESENTER – Dr. DEEPAK R. CHINAGI
BLDE UNIVERSITY'S SBMPMC, VIJAYAPURA21-03-2017
Topics to be covered• Goals of therapy• Approach to a patient with pain• Nociceptive pain and neuropathic pain• NSAIDS• Opioid analgesics• Management of chronic pain• WHO Pain Ladder• TCAs and Anticonvulsants in the management of Chronic
Pain.• Pain as palliative care
GOALS OF THERAPY
• The ideal treatment for any pain is to remove the cause, and provide effective analgesia
• In certain painful conditions (post operative, burns, cancer, trauma), analgesics are the first line of treatment and hence practitioners should be familiar with the use of analgesic.
Approach to a patient with Pain
• International association for the study of pain Defined Pain as unpleasant sensory and emotionla experience associated with actual or potential tissue damage.
• Classification of pain according to etiology– Physiological– Inflammatory/Nociceptive– Neuropathic– Psychosomatic
• Classification by duration– Acute– Chronic
• A careful history will help in the diagnosis of underlying condition– History regarding site, distribution, character,
duration, rapidity of onset, severity of pain, aggravating or relieving factors,
• A detailed examination about the relevant systems involving musculoskeletal system , per abdomen, cardiovascular and respiratory system is made to find out the cause.
• An inflamed joint can be graded into following classes– Grade 1 : The patient says joint is tender– Grade 2 : The patient winces with pain– Grade 3 : The patient withdraws the affected part– Grade 4 : The patient will not allow the joint to be touched
• Measuring pain : Pain is a subjective experience and hence difficult to quantify.
• Either single dimension scales or Multidimension scales are used for quantifying pain.
Single dimension scale
• Visual analogue scale:– Patient is given a scale of 0 to 10 cm , with 0 being
no pain and 10 being the worst pain. And patient is asked to rate on the scale.
Multi dimension scale
• Mc Gill Pain Questionnare– Here multiple aspects of pain are analysed,
subjective quality of pain and emotiinal response to pain.
– Divided into Sensory pain rating, Affective Pain Rating, Visual Analogue scale and a sum of all 3 rating.
– Pain rating divides type of pain experienced into 3 grades(mild - 1, moderate - 2, severe - 3). Total scores are added to get final pain score.
Nociceptive pain and Neuropathic painNote Nociceptive pain Neuropathic Pain
Description of pain Aching, Localized, tooth like, sharp, Squuezing
Shooting, Radiating, Satbbing, Burning, Electric , Shock-like
Movement impact Associated with movement Independent
Physical examination Normal response Allodynia, Hyperalgesia, Vasomotor changes
Examples Injury, Post operative pain Peripheral neuropathy, shingles, Cancer pain
Treatment strategies Conventional analgesics Conventional and non- conventional (antidepressants, anticonvulsants)
NON STEROIDAL ANTI INFLAMMATORY DRUGS (NSAIDS)
• These drugs are effective in cases of mild to moderate headache and pain of musculo-skeletal origin.
• These drugs block the effect of both COX 1 and COX 2 enzymes. Cyclooxygenase 1 has protective role and action on gastro-intestinal mucosa, renal and platelet function. Cyclooxygenase 2 produces inflammatory prostaglandins at the site of inflammation.
• COX 1 blockade is undesirable effect of NSAIDs, which often leads to gastric irritation and ulceration. (e.g. Aspirin)
• Aspirin irreversibly inhibits platelet Cyclo-oxygenase, and interferes with platelet aggregation, hence it is used for this purpose.
• NSAIDs also affect renal prostaglandin synthesis at usual therapeutic dosage.
NSAIDs mediated renal injury
• Normally protective prostaglandins like PGE2 and PGI2 are secreted by the glomerulus in response to glomerular hypoperfusion. These prostaglandins act as vasodilators to maintain renal perfusion. Due to blockade of cyclooxygenase enzyme, these protective prostaglandins are not synthesized.
• Acute hypovolemia or hypotension should not receive NSAIDs.
Clinical aspects in the usage of NSAIDs
• For management of postoperative pain, COX2 selective inhibitors are useful. Non selective COX inhibitors are contraindicated postoperatively due to their unwanted effects on gastric mucosa, platelet function.
• COX 2 inhibitors are associated with increased risk of cardiovascular disease. Hence they are used with caution in patients with risk factors for cardiovascular disease.
OPIOID ANALGESICS• These drugs act directly on the pain transmission
pathway by activating pain inhibitory neuron. These drugs act on opiate receptors that are extensively distributed in brain and spinal cord as well as gastrointestinal tract.
• There are five types of opiate receptors, delta (DOR), kappa(KOR), mu(MOR), nociceptin (NOR), zeta(ZOR). Most of the drugs act on mu opiate receptor.
• These drugs are preferred for the control of acute severe pain and provide rapid pain relief by intravenous administration.
• Opioids are prone for respiratory depression(sedation and decreased respiratory rate). Hence close monitoring is required to prevent life threatening hypoxemia.
• Ventilator assistance is often required.
• Opioid antagonist Naloxone should be readily available and used whenever high doses of opioid are used or pulmonary function is compromised.
• Pain Controlled Analgesia (PCA devices): – It is a micropressor controlled infusion device that
can deliver a baseline continuous dose of an opioid drug and additional doses as and when required.
– It is used in management of post operative pain and pain due to cancer
• PCA devices deliver a small bolus of drug (1mg morphine or 0.2mg of hydromorphone or 10mcg of fentanyl). These devices have LOCKOUT period and dose limit per hour.
• New routes of administration: intrathecal morphine(0.1-0.3mg) low dose is sufficient to achieve required effect. This approach has been used during labor and post operative pain. Other routes of administration include intranasal, transdermal and rectal route.
Morphine
• It was first isolated by Freidrich Sertuner in 1803 from plant source poppy. (Morphium = Greek. God of Dreams)
• Pharmacokinetics : nearly 90 % of the drug is meatbolised in liver and excreted by kidney.
• Half life : 2 to 3 hours, Duration of action 4 – 6 hours.
• It is considered in the WHO list of essential drugs .
• It is used in the treatment of pain due to myocardial infarction, cancer pain and post operative pain control.
• Combination therapy : when opioids and COX inhibitors are used in combination, synergistic effect is seen and less chances of side effects.
• But the dose ratio combination can interfere with the rate of metabolism and excretion of each drug seperately.
WHO Analgesic Ladder
WHO Pain Ladder
• Step 1 : Mild to Moderate pain– Non Opioids(NSAIDs) are recommended. Adjuvant as
antidepressant or anticonvulsant.• Step 2 : Mild to Moderate pain not controlled by Non
Opioids– Weak opioid is added(e.g. hydrocodone) , adjuvants are
continued.• Step 3 : Moderate to Severe Pain– When pain is inadequately controlled by first 2 approaches,
a strong opioid is added. (e.g. Morphine , Oxycocodone)
Managing Chronic Pain
• Chronic Painful conditions like arthritis, chronic headache, chronic back pain, fibromyalgia, diabetic neuropathy and cancer require evaluation to assess emotional and organic factors before initiation of therapy.
• A multidisciplinary team is required for the management. Few of the approaches are counselling, physical therapy, nerve blocks and surgery, epidural injection of glucocorticoids.
• Other modalities like spinal cord electrode stimulation and intrathecal drug delivery system also have shown significant benefit.
• These procedures are generally reserved for those patients who do not get adequate analgesia with pharmacotherapy.
Tricyclic Antidepressant in Chronic Pain
• These drugs are useful in the management of chronic pain and provide relief of pain even at the lower dosages that are used for treating depression.
• These drugs potentiate opioid analgesia nad are used as adjuvant in the management of pain in cancer condition. They are also used to treat neuropathic painful conditions.
• Indications :– Post Herpetic Neuralgia– Diabetic Neuropathy– Tension Headache– Migraine– Rheumatoid Arthritis– Chronic Low Back pain– Cancer pain– Central post stroke pain
• Side effects :– Orthostatic Hypotension– Drowsiness– Cardiac Conduction Delay– Memory impairment– Constipation– Urinary Retention
Anticonvulsants and Antiarrythmics
• These drugs are primarily used for treating neuropathic pain with lancinating quality.
• Phenytoin and Carbamazepine are used for the treatment of trigeminal neuralgia.
• Gabapentin and Pregabalin are also advocated for the use in neuropathic pain.
Chronic Opioid Therapy
• Opioids provide prompt relief of pain, but their use for long term treatment is deferred due to its physical dependance.
• However the long term use of opioids in malignant disease is accepted. But for the long term use in non malignant conditions is controversial.
• Some animal studies have shown that long term opioid therapy may worsen pain in some individuals
Pain in Palliative Care
• Nearly 30 to 90 % of advanced cancer patients deal with pain, which occurs due to mechanical and chemical stimulation of nocicieptors.
• Interventions for pain in palliative care is done by WHO pain ladder(3 step approach).
• NSAIDs : drug of choice in palliative care is Ibuprofen 400mg q.i.d
• Weak opioids like codeine are used. Strong opioids like morphine 5 – 10mg/ 4th hrly.
• Ideally an antiemetic is added with opioid medication for initial week (e.g. metoclopramide)
Thank You
top related