Analgesics PDF

Analgesics Opioids - Affect MU and Kappa Receptors - MU receptors are found throughout the body and are incorporated in to all steps of the pain pathway - Makes them Ideal for pain management as they have the most profound effect across entirety of pain pathway - Kappa r...

Analgesics Opioids - Affect MU and Kappa Receptors - MU receptors are found throughout the body and are incorporated in to all steps of the pain pathway - Makes them Ideal for pain management as they have the most profound effect across entirety of pain pathway - Kappa receptors can cause or influence mild to moderate sedation - Common disadvantages with opioids - Hypersalivation - Nausea and vomiting due to the histamine releasing capabilities which can affect the CRTZ (emetic center) - Can cause respiratory and cardiovascular depression - May cause Pupillary changes - Decreased GI motility and ileus - Opioids have a high abuse potential and are a controlled drug - All opioids are derived from Morphine which comes from the poopy - Potency is measured in strength of effect in relation to morphine Morphine - MU agonist - Low Kappa agonist - Can be given IV, SQ, IM, epidural - Given IV produces less emesis effect as it reaches the emetic center faster - Class 1 narcotic - Advantages - Good for visceral pain - Low dose euphoria Hydromorphone - Pure MU agonist - Strongest analgesic - Some sedation so anesthetic sparing - 5x the potency of morphine - Reversible via naloxone - Can be given IV, SQ, IM - Advantages - Minimal CV effects - Low histamine release so less chance of vomiting - Disadvantages - Hyperthermia Fentynal - MU agonist - 100x the potency of morphine - Can be given IV, CRI, transdermal - Advantages - Profound analgesia - Very short acting (30 min to 2 hr) - Little vomiting and histamine release - Disadvantages - Dysphoria - Patch instructions - Shave and clean surface of animal and warm patch - Takes 12-24 hours to take affect - Will last for up to 72 hours - Client must be educated about the fentynal patch - Do not touch it - Keep animal away from children or other pets - Pet must wear a cone, or some other for of restraint to ensure patch is not eated or licked Meperidine - Short acting and has high CV depressant effects - Not the ideal opioid - It is a weak MU agonist - Potency is only 0.1x morphine - Better option s Butorphanol - Aka torbugesic - Partial MU antagonist, Kappa agonist - Is transported by G-glycoprotein in dog brains - Mild analgesia effect - Partially reversible via naloxone - Can be given SQ, IM, IV - 2-5x as potent as morphine - Advantages - Good for GI compromised patients as the MU receptors are not full effected meaning less GI motility issues and Illeus - Can help as a cough suppressant - Disadvantages - Ceiling effect - Cannot be used with other opioids as it blocks MU receptors - Short duration 60min in dogs up to 90 in cats Buprenorphine - Partial MU agonist - Kappa antagonist - Can be given SQ, IM, IV, Transmucosal (cats) - Moderate analgesia - Slow onsent - Partially reversible - Advantages - Mild sedation - Less adverse effects - Good for moderate to sever pain - Disadvantages - Ceiling effects - Cannot be given with a pure MU Methadone - MU agonist - Also binds NMDA receptors - Profound analgesia - Can be given IV and IM - Advantages - Short onset - No histamine release - Disadvantages - Bradycardia - Reparatory depression - Ileus and nausea Opioid derivatives These come from opioids but have different MOA Tramadol - Requires metabolization to work - M1 metabolite is an MU agonist - Prevents the reuptake of serotonin and acetylcholine receptors - Given PO - Analgesic - Cannot be given with serotonin reuptake inhibitors - Better option for cats as not well metabolized by dogs Apomorphine - Dopamine agonist - Can be given SQ, IV, transmucosal and PO - It is used to induce emesis