PDA opoids Flashcards
What is analgesia?
a state in which no pain is felt despite the presence of normally painful stimuli
What is teh ascending pain pathway?
A-delta fiber mediate sharp localized pain to dorsal horn of spinal cord
C fibers mediate dull diffuse aching pathway
activate secondary nerons that form spinothalamic tract
What is the descending pain pathway?
originate in periaqueductal gray region of midbrain and nuclei of rostro-ventral medulla
descend in dorsolateral funiculus to dorsal horn
releaase norepi and serotonin
What are the mu receptor endogenous ligands opioid?
Endogenous ligands: enkephalins, Beta-endorphin
What are the endogenous ligands of kappa receptor opioid?
dynorphins
What ar ehte delta recepor for opioid endogenous ligands?
enkephalins, beta-endorphin
What is the mechanism of action of morphine?
binds receptor that is a Gi decreases camp opens potassium channel decrease release of neurotransmitter calcium entry block leads to decreased release
What are the localization of opoids?
periaquaductal gray, dorsal horns of spinal cord, medulla and hypothalamus. Gi system and heart
What receptors in limbic area for opioid receptors are responsible for drug dependence?
Mu and delta receptors in limbic areas may be involved in drug dependence
What opioid receptor in limbic structure hat may be involved in dysphoric actions?
kappa agents and kappa receptors
What si teh onset of action of opioids determined by?
lipophilicity
What are opioids metabolized by?
metabolized by liver, to more polar and less active metabolites
What is the chemical structure of heroin and what is it converted to?
diacetylmorphine converted to monoacetyl-morphine
What are the effects of opioids?
Analgesia-full agonists cough suppression antidiarrheal effect euphoria sedation respiratory depression nausea endocrine effects pupillary constriction-miosis
What opioid is not a full agonist for analgesia?
codeine and propoxyphene
What opioids suppress cough and not necessarily by opioid receptor but by brainstem cough receptors?
codeine and dextromethorphan
What are the endocrine effects of opioids?
Decreased LH release-Mu effect
Increased ADH secretion-mu
decrease ADH- Kappa
What opioids effects don’t cause tolerance?
pupillary constriction
Constipation
What is the structure of Heroin and basic information?
diacetyl morphine
more lipophilic than morphine
high abuse potential
Codeine and Oxycodone information about structure and basic info?
mild to moderate paiin
morphine like efficacy not achievable at codeine
some metabolized to morphine
oxycodone is more efficacious and useful in moderate to severe pain
oxycodone is availabe as a sustaine release oral prep
major abuse problem
What is basic infor about meperidine?
phenylpiperidine
shorter duration of annalgesia than morphine
forms toxic metabolite that can accumulate
interaction with MAO inhibitor
What is basic information behind methadone and structure?
phenylheptylamine
mu agonist
equipotent with morphine; has good oral availability
longer duration of action
used in tx of opioid abuse and chronic pain
What is basic structure and function fentanyl?
meperidine mu agonist 100 times as potent as morphine short acting 1 to 1.5 hours available injectable and transdermal patches
What type of pain is codeine for?
mild to moderate pain
morphine-like efficacy is not achievable at any dose
