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27 Cards in this Set
- Front
- Back
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Tolerance
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when standard drug dose, if repeatedly administred progressively produce less effect, and increasing dose is required.
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Cross tolerance
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tolerance to the effects of other opiates that act on the same type of opiate receptors (ie mu receptor).
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Physical dependance
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condition where normal physiological function requires continued presence of the drug- in its absence, causes withdrawal or abstinence syndrome.
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Cross-dependance
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when another opiate can supress withdrawal of an opiate ie. using methadone to supress heroin withdrawals.
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Addiction
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overall PATTERN of drug use-- compulsive use, securing supply, and tendency to replase after withdrawal. Addiction may be present in individuals showing NO SIGNS of withdrawal or dependance on opiates.
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The very first dose of an opiate experience
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in healthy individuals, it's averseive; nausea, emesis etc.
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If it's so nasty, why do people end up becoming addicted?
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social pressure, the 'rush', subsequent mood elevation with sedation (escaping external demands for upto 4 hours). It also fills psychological need (feeling normal)
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Consequence of opiate addiction
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no real physiologic consequence only if opiate taken regularly in a sterile fashion (about 2 or more doses per day).
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The consequence of opiate addiction in the REAL world?
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OD due to impurities, infections, skin ulcers, endocarditis, emboli, hepatitis, psych and social conseq.
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How's withdrawal precipitated?
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use opiate antagonists such as Naloxone
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How's withdrawal suppressed?
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give more heroin or another opiate.
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how to make dx of drug-dependant state?
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give small dose of Naloxone, which would then precipitate brief, mild withdrawal syndrome.
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What are the withdrawal characteristics
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6-12 hrs: lacrimation, rhinorrhea, yawning.//
12-24 hrs: restless sleep// 16-96 hrs: dilated pupils, gooseflesh, muscle spasm, CNS stimulation (EJACULATION or ORGASM), dehydration, ketosis. |
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Are withdrawals fatal?
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No, unless pt previously ill or something. Max severity at 48-72 hrs. //
cravings will continue for months to years.// |
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Withdrawal: Time course vs. length of drug action
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long last opiate (methadone) will give long lasting (10-14 days) BUT mild withdrawal.//
Meperidine, short-acting will have more intense sx first 24 hrs but decline within 4-5 days.// |
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What's Conditioned withdrawal syndrome?
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return to an environment in which drugs have previously been used may induce intense cravings.
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Opiate withdrawals in newborn
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If mother heroin-addict-- sx less severe.//
If mother was on methadone, then sx more severe.// Tx: put on opiates and gradualy tapper off to smaller doses progressively.// |
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What's the Mech for Tolerance to opiates?
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the neurons become LESS SENSITIVE but NO DOWNREGULATION of receptors. Also, alterations in expression of some neural genes.//
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What's the Mech of dependance?
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neurons adapt to function normally despite presence of drug e.g by increasing enzymes inhibited by drug.
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Mech of withdrawal?
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the adaptations to drugs decay slower than opiate excretion, therefore resulting in excitability.
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Mech of addiction and 'reward'?
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Opiates reduces release of GABA, causing disinhibtion of DA and enhanced DA release in Nucleus accumbens, and ventral tegmental area.//
Noloxone blocks effects of opiate drugs in nuc. accumbens.// |
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Tx of addiction with Methadone
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spreads withdrawal over 3-6 weeks, intense cravings report but other sx mild. INPATIENT use only.
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Tx of addiction with Clonidine
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alpha-2 R agonist, acts centrally, reduces severity of withdrawals.//
decrease NE firing, which otherwise increases during withdrawal, in Locus Ceruleus.// Not useful in heavy drug addicts. Side effects dry mouth, sedation and euphoria.// |
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Methadone maintainance?
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long half-life, give complete cross-tolerance, daily oral administration. INPATIENT only.
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Buprenorphine maintainanace
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a partial agonist, high rate of retention. Given orally with naloxone (poorly absorbed antagonist), so buprenorphine produces mild agonist effects. //
approved for OUTPATIENT settings.// |
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How about using antagonists to treat?
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They cause brief but severe withdrawal, therefore retention rate is low. NOT recommended.
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Px for heroin addicts?
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go through several cycles of addiction. 80% relapse in 6 mo to a year.//
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