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Exam #3 - Opioid (Narcotic) Analgesics & Antagonists
N/a
57
Pharmacology
Graduate
10/21/2009

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Term
Pain
Definition
a complex experience that consists of 2 components: as a physiological sensation and as an emotional & psychological reaction to a painful sensation
Term
Emotional & Psychological Component of Pain
Definition
the most important component of pain because it represents pain as "suffering"
Term
Places where morphine acts in the brain
Definition
limbic system, spinal cord, and thalamus
Term
Types of Pain Morphine is effective against
Definition
more effective against dull, constant visceral pain then against sharp, intermittent, somatic pain; a pt's ability to tolerate pain is markedly increased without altering perception of other sensations and does not cause loss of consciousness
Term
Morphine's actions at molecular & cellular level
Definition
agonist at receptors for endogenous opioid peptides (endorphins & enkephalins) and modifies processing of pain information in CNS & in periphery
Term
Mu receptors
Definition
opioid receptors found primarily in brainstem, spinal cord, & limbic areas & mediate supraspinal analgesia, some spinal analgesia, sedation, respiratory depression, euphoria, & dependence
Term
Kappa receptors
Definition
opioid receptors found mainly in brainstem & spinal cord; mediates some spinal analgesia, some supraspinal analgesia, meiosis, sedation, & dysphoria
Term
Delta receptors
Definition
opioid receptors that are located in brainstem & limbic system; mediates dysphoria & hallucinations & plays a role in development of tolerance to mu receptor agonists
Term
Morphine
Definition
strong agonist at mu receptors, moderate agonist at kappa receptors, and weak agonists at delta receptors
Term
pentazocine (Talwin)
Definition
strong agonists at kappa receptors, partial agonists or antagonists at mu receptors
Term
naloxone (Narcan)
Definition
antagonist at all types of opioid receptors
Term
Pharmacological Actions of Morphine
Definition
analgesia, sedation & mental clouding, relief of anxiety & apprehension, euphoria (usually) or dysphoria (occasionally), nausea, depression of respiration, constriction of pupils, antitussive effect, lowering of seizure threshold, endocrine disturbances, effects on smooth muscle, cardiovascular effects, skeletal muscle rigidity, immunosuppression (chronic use)
Term
Sedative & mental clouding aspect of morphine pharmacology
Definition
therapeutic doses provied a floating, dream-like state (easily woken up from); in OD situations, cause graded depreesion of cortical function which can lead to hypnosis/stupor to coma to death
Term
Dysphoria
Definition
unpleasant subjective effects that include fear, anxiety, restlessness, hallucinations, & nausea when taking morphine
Term
Nausea caused by morphine
Definition
due to stimulation of chemoreceptor trigger zone (CRTZ) in medulla; more common in ambulatory patients than hospitalized patients; tolerance does develop
Term
Depression of Respiration due to Morphine use
Definition
major toxic effect - usual cause of death in opioid poisoning; decreased sensitivity to CO2 at chemoreceptors in medulla; use with caution in pts with impaired respiratory function; may be used in treatment of pulmonary edema due to its frightening & unpleasant symptoms or air hunger
Term
Pin Point Pupils
Definition
tell-tale signs of opioid poisoning; due to severe constriction of pupils (meiosis)
Term
Effects of Morphine on Smooth Muscle
Definition
increased tone of circular smooth muscle, decrease in propulsive movements of longitudinal muscle; decreased intestinal motility (constipation), urine retention, bronchoconstriction, increased biliary pressure
Term
postural (orthostatic) hypotension
Definition
cardiovascular effect of morphine that is due to release of histamine & interference with hemostatic reflexes
Term
Cardiovascular Effects of Morphine
Definition
postural (orthostatic) hypotension, cutaneous vasodilation, increased CSF pressure (use with caution in pts with head injuries)
Term
Routes of Adminstration of Morphine
Definition
IM, SC, or oral (becoming more widely used); snorted = abuse
Term
Gold Standard Therapeutic Dose of Morphine
Definition
10 mg SC or IM
Term
Amount of morphine metabolized if taken orally under first pass effect
Definition
75% of dose is metabolized, reason why oral was generally not popular (can give high doses to provide a therapeutic oral dose)
Term
Duration of Analgesic Effect of Morphine
Definition
duration is usually 4-6 hrs, longer in elderly pts
Term
Major Drug Interactions with Morphine
Definition
additive effects of other CNS depressants; MAO inhibitors; abuse with amphetamines & cocaine ("speedballing"); enhanced analgesic effect when used in combinations with NSAIDs; certain antihistamines (hydroxyzine) enhance analgesic effects of opioids; tricyclic antidepressants enhance analgesic effects
Term
Triad Symptoms of Opioid Poisoning
Definition
CNS depression (stupor or coma); depressed depth & rate of respiration; pin point pupils (note: if ppt is severely hypoxic, pupils may be DILATED!)
Term
Treatment of Opioid Poisoning
Definition
support respiration; administer a narcotic antagonist like naloxone (NARCAN)
Term
Common Uses of Morphine
Definition
moderate-severe pain; treatment of chronic pain; adjuncts to surgical anesthesia; antitussive; antidiarrheals; dyspnea of left heart failure & pulmonary edema; abuse
Term
3 Important Developments in use of Morphine and related opioids
Definition
1) infusion & autoinjector systems; 2) PCA (patient controlled analgesia); 3) spinal analgesia
Term
morphine
Definition
oral, SC, IM, or IV; absorbed from GI tract but not as effective orally due to first pass metabolism; GOLD STANDARD Dose: 10 mg SC or IM or 10-30 mg PO; used for more severe pain
Term
codeine (phosphate of sulfate salt)
Definition
orally effective; 1/12th potency of morphine; common doses: 30-60 mg PO; used as analgesic for mild-moderate pain and as an antitussive; has only weak opioid agonist activity
Term
hydromorphone (Dilaudid)
Definition
similar to morphine but more potent
Term
oxycodone (Roxicodone, Percodan, Percocet, OxyContin)
Definition
a cross between morphine & codeine; used orally (alone or in combination with acetaminophen, ibuprofen) for moderate-severe pain; one is a sustained-release oral tab for management of severe chronic pain
Term
hydrocodone (Lortab, Lorcet, Vicodin, Norco)
Definition
similar to both codeine & oxycodone; used orally in combination with acetaminophen for mild-moderate pain and as an antitussive; one of most widely prescribed opioids
Term
meperidine (Demerol)
Definition
synthetic oral and parenteral administered drug with 1/10th potency of morphine; reported to have weaker effects on smooth muscle with less constipation & urine retention but studies show it does not; used for moderate to severe pain; commonly used in obstetrics; relatively short acting (1-3 hrs), not appropriate for chronic pain becuase of buildup of normeperidine which can cause seizures; falling into disfavor
Term
heroin (diacetylmorphine)
Definition
more potent & more euphoric than morphine; duration of action 4-6 hrs; not available for use in US; major drug of abuse; can be injected, snorted, or smoked
Term
methadone (Dolophine)
Definition
less euphoric & longer duration of action than heroin or morphine; used as an analgesic & in treating opioid addiction; dosing can be tricky, needs to be done carefully with close monitoring
Term
levo-alpha-acetylmethadol (ORLAAM)
Definition
newer drug approved for treatment of opioid dependence; similar to methadone except given every other day; can only be dispensed through approved drug abuse treatment programs
Term
propoxyphene (Darvon)
Definition
much less potent than other agents; has little analgesic activity; does have potential for serious toxicity at high doses; widely used but not a particularly good drug
Term
fentanyl (Sublimaze, Duragesic, Actiq)
Definition
very potent mu agonist (100x more potent than morphine); given parenterally to supplement surgical anesthesia; also has a transdermal patch for management of chronic pain; also comes in lozenge form for treatment of "breakthrough" pain
Term
fentanyl + droperidol (Innovar)
Definition
combination preparation that induces a state called neuroleptic analgesia --> various diagnostic or minor surgical procedures may be carried out even though patient might not completely lose consciousness; administering NO with this product will produce a state called neuroleptic anesthesia
Term
sufentanil (Sufenta) and alfentanil (Alfenta)
Definition
similar to fentanyl; used IV as adjuncts for surgical anesthesia
Term
pentazocine (Talwin, Talwin NX)
Definition
mixed agonist-antagonist with agonist effects dominant - kappa agonist, partial mu agonist(lower doses) & mu antagonist (high doses); less effective than morphine for severe pain; less sedation & respiratory depression than morphine; more CNS stimulation & hallucinations than morphine; can precipitate withdrawal symptoms in opioid addicts
Term
buprenorphine (Buprenex, Subutrex, Suboxone)
Definition
partial agonist at mu-receptors, very high doses cause mu-antagonist actions; abuse potential is much lower than morphine; reduces craving in heroin addicts, used in treatment of heroin addiction; one form also contains nalaxone and is designed for sublingual use; primary agent used for "office based" treatment of opioid addiction
Term
tramadol (Ultram)
Definition
newer drug used for mild to moderate pain; a weak mu agonist & inhibits synaptic reuptake of NE and SE; produces good analgesia with supposedly mild side effects; Side effects include: dizziness, sedation, nausea, constipation; claimed to have lower abuse potential but still has opioid-like abuse potential
Term
naloxone (Narcan)
Definition
pure opioid antagonist; drug of choice for opioid poisoning, can reverse respiratory depression of opioids; not effective orally, must be given parenterally; included in combination with oral narcotic analgesics to prevent abuse via injection; short duration of action (1-2 hrs); can precipitate withdrawal in addicts
Term
naltrexone (ReVia)
Definition
orally effective, long-acting antagonist (24 hrs); used in "immunizing" addicts (preventing high produced by opioid agonists); risk of hepatotoxicity; patient compliance is a major problem; opioid addict must first be detoxified (brought through withdrawal) before therapy can be initiated; decreases craving for alcohol in alcoholics, approved for use in treatment of alcoholism
Term
methylnaltrexone (Relistor)
Definition
quaternary salt used for treatment/prevention of opioid-induced constipation; must be given parenterally (subcutaneously); only appropriate for serious constipation resulting from opioid use in more severe types of pain
Term
Therapeutic Uses of Opioid Antagonists
Definition
treat opioid-induced overdose toxicity; diagnose opioid physical dependence; treat compulsive opioid abuseers; reduce cravings for alcohol in recovering alcoholics
Term
Physical Dependence
Definition
tolerance + withdrawal syndrome
Term
Characteristics of Acute Withdrawal Syndrome
Definition
craving for drug; anxiety, hostility, insomnia, yawning, rhinorrhea, hyperventilation; dilation of pupils; GI hypermotility (diarrhea, nausea, vomiting, cramping); hypertension; "goose flesh", chills
Term
Duration & Intensity of short acting drugs (i.e. heroin)
Definition
intense withdrawal symptoms, short duration (3-7 days)
Term
Duration & intensity of long acting drugs (i.e. methadone)
Definition
moderate withdrawal symptoms, long duration (1-2 weeks)
Term
treatment of dependence
Definition
quit "cold turkey"; weaning patient off drug; methadone (substitution or maintenance methods); buphenorphine; naltrexone; clonidine; anti-depressants
Term
Opioid dependence in medical setting
Definition
pts become dependent while chronically receiving opioids for medically valid reasons; they receive known doses of pure drug under strictly controlled conditions; usually, pts can be weaned off drug with minimal discomfort & little potential for continuing dependence
Term
Opioid Addiction in street setting
Definition
in this setting, drug abuser actively seeks illegal drug for its mind altering effects; pattern of addiction involves taking unknown doses of impure drugs under very unsanitary conditions; must often resort to crime or prositution to support their habit
Term
Health Hazards Associated with Street Use of Opioids
Definition
hepatitis, miscellaneous infections (abcesses, endocarditis, tuberculosis), AIDS
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