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33 Cards in this Set
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- Back
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Mechanism of Action of Opioids
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Interact with mu, kappa, and delta opiopeptin receptors in the CNS, GI tract and pituitary. Receptors are linked to inhibitory G-proteins (Gi), whose activation leads to inhibition of adenylyl cyclase with decreased intracellular levels of cAMP and decreased protein pohophorylation.
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Opioid receptor activation inhibits neurotransmission. Close voltage gated Ca2+ channels on prejunctional nerve terminals to inhibit the release of pain neurotransmitters (substance P, ACh, glutamate). Open K+ channels to hyperpolarize and inhibit activity of postjunctional neurons.
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Used extensively for pre and postoberative pain and pain of terminal illness. Relieves anxiety, causes euphoria, drowsiness, VENODILATION (benefit for use in MI), and most effective for continuous, moderate to severe dull aching type of pain associated with visceral damage.
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Morphine
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Causes Dyspnea, respiratory depression
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Opioids (3) used for tx of diarrhea.
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Codeine, Diphenoxylate and Loperamide.
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Given in subanalgesic doses. The latter two are over the counter.
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Opioid indicated for tx of Dyspnea associated with pulmonary edema secondary to acute left ventricular heart failure.
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Morphine (decreases TPR, Depresses respiratory center, relieves anxiety).
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Antitussive opioid (1) and non-opioid (1)
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Codeine and Dextromethorphan (Benadryl)
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Adverse Effects and Contraindications for Opioids
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Respiratory Depression (emphysema, COPD), Patients with high ICP, Sedation and Drowsiness, N/V (stimulates CETZ, but eventually self limits by inhibiting the CETZ), Tolerance (Psychological Dependence, Physical Dependence). Stimulates EW Nucleus to constrict the pupils. Constipation and Urine retention. Pain from Biliary Spasm in the sphincter of Oddi. Pruritis.
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Physical dependence rarely results in addiction to opioids. Morphine 6-glucoronide has analgesic activity.
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Strong opioid agonist with a short DOA. Produces less constipation, commonly used in OB (moreso than morphine), can cause CNS excitation in overdose and has NO effect on the cough reflex.
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Meperidine (Demerol)
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Metabolite is normeperidine. Has weak anticholinergic activity.
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Strong opioid agonist used as a preanesthetic medication for pain and for balanced anasthesia. May cause severe muscle rigidity. Available as a transdermal patch or lozenge to control breakthrough pain.
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Fentanyl
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Opioid substitute to treat opioid dependence and use for maintenance therapy. Less severe withdrawal in addicts, and has good effects on neuropathic pain.
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Methadone
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Weak Opioid Agonist used for moderate pain. Little respiratory depression. OD may cause seizures.
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Codeine (Oxycodone, Hydrocodone, Dihydrocodeine)
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Often used in combination with other analgesics: hydrocodone + acetominophen = vicodin, oxycodone + acetaminophen = percocet, oxycodone + aspirin = percodan.
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Mixed agonist-antagonists/ Partial Agonists. One has agonist activity at k-receptors and weak antagonist activity at u-receptors. Another has partial agonist activity at the u-receptor. Both are used for moderate pain due to a ceiling in their analgesic activity. Resistant to naloxone reversal. Ceiling for respiratory depression.
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Buprenorphine (k-agonist, u-antagonist) and Pentazocine (u-agonist)
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SE: dysphoria, hallucinations and depersonalization
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Miscellaneous agent used for moderate pain. Has m-receptor activity and also weakly enhances serotonin and NE neurotransmission by blocking transporters for reuptake.
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Tramadol
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Special use in the tx of neuropathic pain. Associated with an increased risk of seizures.
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Antagonists at opioid receptors. One is administered IV, one is adminstered orally. They have three specific uses for treatment.
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Naloxone (Narcan, IV), Naltrexone (oral and IV), Methylnaltrexone
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Naloxone is used to treat acute opioid overdose and toxicity. Naltrexone is used to reduce craving for alcohol. Methylnaltrexone is used to treat constipation in late-stage advanced illness.
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The two types of local anesthetics and their prototypes.
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Esters with Procaine (Novocain), and Amides with Lidocaine (Xylocaine)
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Potency and duration of this local anesthetic, an amide, is greatly increased due to its fat solubility and protein binding affinity.
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Bupivacaine (due to it's butyl group at the amine terminus).
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Addition of what to a local anesthetic preparation adds alpha-1-mediated local vasoconstriction to aid with delivery and prolong DOA?
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Epinephrine.
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Mechanism of action of local anesthetics.
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Blocade of voltage gated sodium channels INSIDE the pore of the channel near the cytoplasmic opening. Has Frequency Dependence meaning that the anesthetic gains access to the channel from the cytoplasm during depolarization, when the channel population is in the open configuration.
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The differential nerve block associated with local anesthetics results in certain types of nerves receiving analgesia first. This is the order...
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(1) Small Diameter fibers first, (2) more rapidly firing nerves and nerves with longer AP's, (3) Myelinated fibers, (4) outer fibers of a nerve bundle
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Fast acting inhalation anesthetic. Little respiratory or BP change. Increases TPR. Indicated for minor surgery. Does NOT cause Malignant Hyperthermia
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Nitrous Oxide
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SE: Vitamin B12 deficiency. N/V
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Slow acting, inhalation anesthetic. Has very little effect on TPR. Used to maintain anesthesia. Most widely used PEDIATRIC anesthetic. Pleasant odor.
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Halothane
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SE: Arrhythmia and Hepatotoxicity
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Fast acting inhalation anesthetic. Used for outpatient anesthesia. Very pungent, and irritates the airway of asthmatics. Little change in contractility.
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Desflurane
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CI in asthmatics
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Fast acting inhalation anesthetic. Used for outpatient anesthesia, especially for children. Inhalation induction, sepecially in children. Nonirritating vapor. Fast recovery.
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Sevoflurane
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Drug of choice for prevention and treatment of Malignant Hyperthermia.
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Dantrolene
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Skeletal muscle relaxant that blocks calcium release from the sarcoplasmic reticulum.
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Malignant Hyperthermia is triggered by these types of agents (with examples)
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Halogenated volatile anesthetics (Halothane, Isoflurane, Sevoflurane, Deflurane). There has to be genetic predisposition alongside the trigger.
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IV anesthetics do not appear to trigger MH.
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Slow Acting inhalation anesthetic. Used to maintain anesthesia. The MOST WIDELY USED anesthetic in adults. Gives a stable cardiac rhythm. Has a pungent odor.
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Isoflurane
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CI for asthmatics due to airway irritation.
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IV anesthetic used to induce unconsciousness (usu in 30 seconds). Barbiturate given as a single dose that lasts 5-8 mninutes.
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Thiopental
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Rapidly redistributes, which accounts for the termination of its action. SE: Respiratory and Cardiovascular Depression. Hangover and Accumulation.
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IV anesthetic used to sedate and reduce anxiety. Produces anterograde amnesia. Used with opiate agonists in cardiac patients. slow onset, long duration of hypnosis. Undergoes demethylation in the liver. PHLEBITIS!
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Diazepam
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Most widely used IV anesthetic benzodiazepine drug. Minimal respiratory or cardiovascular depression. NO MAJOR ADVERSE EFFECTS!
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Midazolam
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Structurally related to LSD. Produces a hypnotic state distinct from other anesthetics. Major use is in ASTHMATICS because it's the only fast acting IV anesthetic which is a bronchodilator.
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Ketamine
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Increases sympathetic outflow. Less of a hallucination effect in children.
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Anesthetic induction of patients at risk for hypotension and or myocardial ischemia. Causes SUBSTANTIAL PAIN on injection. Has minimal CV and respiratory depression.
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Etomidate
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IV anesthetic used for induction and maintenance in outpatient surgery. Hypnotic. Most commonly used IV anesthetic in the US. Rapidly eliminated. Recovery is not delayed after prolonged infusion, thus it can be used as a continuous infusion.
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Propofol
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An opiate receptor agonist that causes minimal cardiac depression. It's major effect is to decrease vascular resistance from direct effects and by histamine release. Has a dose related respiratory depression.
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Morphine
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Has replaced morphine for high dose opiate anesthesia for cardiac patients due to its minimal cardiovascular depression. Need controlled ventilation during anesthesia.
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Fentanyl
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