| Term | Definition |
|---|
| opioids | generic term for drugs with morphine-like activity that can reduce pain w/o loss of consciousness; induce tolerance and physical dependence |
| opiates | generic term for drugs with morphine-like activity DERIVED FROM OPIUM (e.g. morphine, heroin) |
| opiopeptins | endogenous peptides that have opioid-like activity; e.g. endorphins, enkephalins, dynorphins; derived from distinct polypeptide precursors (different gene products) |
| preproopiomelanocortin | polypeptide precursor that contains beta-endorphin |
| preproenkephalin | polypeptide precursor that contains met- and leu-enkephalin |
| preprodynorphin | polypeptide precursor that contains dynorphin A&B |
| mu, kappa, and delta receptors | localized in discrete areas of the CNS associated with pain modulation; also in GI tract, pituitary, other peripheral tissues |
| mu receptors | supraspinal/spinal analgesia, respiratory inhibition, euphoria, sedation; respond to B-endorphins |
| delta receptors | supraspinal/spinal analgesia; respond to enkephalins |
| kappa receptors | dysphoria, psychotomimetic actions; respond to dynorphins |
| inhibitory G proteins | linked to opioid receptors; activation results in inhibition of adenyl cyclase, decreased cAMP, protein phosphorylation (i.e. decreased cell activity!) |
| prejunctional Ca2+ channels | opioids close these to inhibit release of NTs |
| postjunctional K+ channels | opioids open these to hyperpolarize and inhibit activity of postjunctional neurons |
| mixed agonist-antagonists | these types of drugs are less effective than morphine; can precipitate withdrawal |
| buprenorphine | mu receptor partial agonist - long acting; used for moderate pain; can precipitate withdrawal |
| pentazocine | kappa receptor agonist and weak mu receptor antagonist; used for moderate pain; can precipitate withdrawal |
| spinal cord | opioids directly inhibit pain transmission from here to higher centers of the brain |
| CNS inhibitory pathways | opioids activate these DESCENDING processes to the spinal cord to inhibit pain transmission |
| reactivity to pain | this is decreased by opioid actions on the cortex, amygdala, and hippocampus |
| opioids | analgesics (for pre/post-op pain, pain of terminal illness) most effective on continuous, moderate to severe dull aching pain (visceral damage) |
| morphine | relieves anxiety, causes drowsiness/euphoria; increases pain threshold and decreases pain perception |
| myocardial infarction | morphine is useful to relieve the pain from this by producing venodilation -> decreasing the pre-load on the heart |
| diarrhea | codeine, diphenoxylate, loperamide used more than morphine to treat this (act at enteric NS and CNS) |
| dyspnea | morphine acts on this by 1)decreasing peripheral resistance, 2) depressing respiration, 3) relieving anxiety |
| dyspnea | associated with acute pulmonary edema secondary to acute LV failure; treated by morphine |
| cough | codeine, hydrocodone, and dextromethorphan suppress this reflex by direct action on this center in the brain |
| fentanyl | often used for preanesthetic or anesthesia supplement during surgery for analgesic, sedative, and anxiolytic effects |
| physical dependence | methadone, levomethadyl acetate, and buprenorphine used for initial and maintenance therapy |
| respiratory depression | side effect of opioids caused by direct inhibition in brain stem w/ decreased sensitivity to CO2 |
| head injuries | patients with these contraindicated for opioids b/c of cerebral vasodilation -> increased intracranial pressure |
| pregnancy | opioids contraindicated for this b/c of neonatal respiratory depression |
| chemoreceptor trigger zone | opioids stimulate this to activate the vomiting center; this is self limiting b/c of subsequent direct inhibition of vomiting center |
| tolerance | primarily cellular, takes several weeks; due to direct neuronal effect of opioids; degree varies; cross tolerance b/t opioid agonists |
| psychological dependence | compulsive drug use; at first drug use is reinforced by euphoria, then by avoidance of withdrawal |
| physical dependence | lacrimation, rhinorrhea, piloerection, diarrhea, muscle spasms, hyperalgesia are components of abstinent withdrawal; rarely results in opioid addiction! |
| miosis | opioids stimulate edinger-westphal nucleus -> this; mediated by ACh (blocked by atropine); occurs in the dark, diagnostic of overdose |
| postural hypotension | opioids inhibit vasomotor center in brain stem -> peripheral vasodilation, this |
| constipation | opioids cause this b/c of 1) decreased coordinated GI tract contractility, 2) increased anal sphincter tone, 3) inattention to defecation reflex |
| urine retention | opioids cause this by 1) decreased renal plasma flow, 2) decreased ureter/bladder contractility, 3) increased urethral sphincter tone, 4) inattention to urinary reflex |
| paradoxical pain | when opioids are used to treat kidney stones, biliary stones (increase tone, pressure) |
| codeine, methadone | opioids that have high oral:parenteral potency ratios (60%) |
| serotonin syndrome | occurs when opioids (esp. meperidine) are administered with SSRIs or MAOIs - hyperpyrexia, coma |
| meperidine | shorter duration of action than morphine, with less constipation, vomiting, fetal respiratory depression (used in obstetrics); no effect on cough reflex |
| meperidine | may cause CNS excitation and seizures due to formation of N-demethylated metabolite w/ no analgesic activity |
| meperidine | has weak anticholinergic activity -> mydriasis, tachycardia, dry mouth, blurred vision |
| fentanyl | more rapid onset, shorter duration of action than morphine; more potent; parenteral, patch, and lozenge (breakthrough pain) |
| fentanyl | used as preanesthetic, during labor, for "balanced anesthesia" with NO and halothane |
| fentanyl | minimal cardiac depression, may cause "truncal" rigidity |
| methadone | opioid substitute to treat dependence and for maintenance therapy; long duration of action -> less severe withdrawal syndrome |
| methadone | used for analgesic properties with good effects on cancer and neuropathic pain |
| heroin | schedule 1 drug; more lipid soluble and faster acting than morphine (gets to brain faster) |
| codeine | used for moderate pain; good antitussive at lower doses; good oral bioavailability |
| codeine | 10% gets converted to morphine; causes little resp. depression; overdose may cause seizures |
| propoxyphene | derivative of meperidine for mild pain; discourage use of this! |
| diphenoxylate | used to treat DIARRHEA; insolubility -> doesn't cross GI tract; minimal dependence liability or other centrally mediated opioid effects; combined with ATROPINE |
| loperamide | used to treat DIARRHEA; doesn't cross BBB; minimal dependence liability or other centrally mediated opioid effects |
| buprenorphine | may be effective for heroin detox and maintenance therapy; long duration of action, less severe withdrawal symptoms |
| ceiling effect | with pentazocine, buprenorphine - analgesic activity, respiratory depression limited |
| tramadol | for moderate (maybe neuropathic?) pain; mu receptor activity; blocks 5HT, NE reuptake |
| tramadol | less respiratory effect; more seizures, not for epileptics; anaphylaxis |
| naloxone | competitive antagonist at opioid receptors; can precipitate withdrawal; administered IV; treat opioid overdose/toxicity; short acting |
| naltrexone | competitive antagonist at opioid receptors; can precipitate withdrawal; administered orally; longer acting; used to treat opioid overdose/toxicity, diagnose dependence; reduces alcohol craving |
| dextromethorphan | non-opioid antitussive agent; less constipating than codeine; not analgesic, no dependence |
Combine with other sets
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