Beroende Flashcards
Vad är tolerans? Diskutera vad som menas med tolerans på farmakokinetisk och farmakodynamisk nivå.
Generellt:
tolerans där man behöver större mängder av drogen för att uppnå den avsedda effekten
Farmakokinetik (vad händer med LM i kroppen): Tolerans
Farmakodynamik (vad gör kroppen med LM-mekanismer): Tolerans
Pharmacokinetic(metabolic) tolerance[edit]
Pharmacokinetics refers to the absorption, distribution, metabolism, and excretion of drugs. All psychoactive drugs are first absorbed into the bloodstream, carried in the blood to various parts of the body including the site of action (distribution), broken down in some fashion (metabolism), and ultimately removed from the body (excretion). All of these factors are very important determinants of crucial pharmacological properties of a drug, including its potency, side effects, and duration of action.
Pharmacokinetic tolerance (dispositional tolerance) occurs because of a decreased quantity of the substance reaching the site it affects. This may be caused by an increase in induction of the enzymes required for degradation of the drug e.g. CYP450 enzymes. This is most commonly seen with substances such as ethanol.
This type of tolerance is most evident with oral ingestion, because other routes of drug administration bypass first-pass metabolism. Enzyme induction is partly responsible for the phenomenon of tolerance, in which repeated use of a drug leads to a reduction of the drug’s effect. However, it is only one of several mechanisms of tolerance
Pharmacodynamic tolerance[edit]
Tolerance is a reduced response to repeated administration of the same dose or increase in the dose are required to produce the same magnitude of response. Liver damage can lead to dramatic loss of drug tolerance. For example chronic alcoholics at a late stage of alcoholism can get drunk on just a few drinks due to death of liver cells
Pharmacodynamic tolerance (reduced responsiveness) is when the response to the substance is decreased by cellular mechanisms. This may be caused by a reduced receptor firing rate in response to receptor agonists (receptor desensitization), a reduction in receptor density (usually associated with receptor agonists), or other mechanisms.[4] Pharmacodynamic tolerance to a receptor antagonist involves the reverse, i.e., increased receptor firing rate, an increase in receptor density, or other mechanisms.
Tolerance is mediated by neural changes at the synaptic level that are induced by frequent drug use. These may include changes in number of postsynaptic receptors, receptor desensitization, or depletion of neurotransmitters. For example chronic ingestion of alcohol (a GABA agonist) eventually leads to down-regulation of inhibitory GABA receptors, as postsynaptic cells compensate for too much GABA-receptor-mediated inhibition. This process is called neural adaptation and it is also the basis of the withdrawal symptoms that can occur in chronic alcoholics and heroin addicts.
One example of pharmacodynamic tolerance occurs with cocaine. Heavy use of cocaine temporarily depletes axon terminals of neurotransmitters such as dopamine and serotonin, thus cocaine has much less of a mood-elevating effect after several successive doses than it did initially.
Definiera begreppet abstinens.
abstinenssymtom som innebär mer eller mindre kraftigt obehag då man slutar använda drogen!!
Abstinens är de tecken kroppen visar när det finns ett su/behov av en drog där tolerans har skapats.
Symptom —> Inom ett dygn efter senaste heroinintag: Svettning, snuva, ökat tårflöde
Muskelvärk
Rastlöshet, sömnlöshet
Illamående, diarré
Behandling
Värktabletter och lugnande mediciner Buprenorfin (Subutex / Suboxone)
Majoriteten av beroendeframkallande medel ökar dopaminerg transmission i mesolimbiska dopaminsystemet, vilket anses ha betydelse för att skapa ett sug (”wanting”) efter drogen. Beskriv med hjälp av figuren nedan hur olika beroendeframkallande medel som amfetamin, kokain, opiater och nikotin ökar dopaminerg transmission.
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Vilken är dödsorsaken vid överdos av heroin? Fundera över varför risken för överdosering med heroin ökar efter en tids drogfrihet.
Trauma… + reversibel toleransutveckling /frånvaro av signalsubstanser….
Redogör för vilka läkemedel som finns tillgängliga för behandling av alkoholberoende, samt deras
verkningsmekanismer och något om deras kliniska effekter.
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Vilket symptom vid alkoholabstinens kan vara livshotande? Vilka läkemedel används vid behandling av alkoholabstinens och delirium tremens?
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Metadon och buprenorfin används vid behandling av opiatberoende. Vad har de för verkningsmekanism och hur verkar de vid opiatberoende?
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Diskutera vilka övergripande effekter man kan uppnå med farmakologisk behandling av beroende som kompletterar en psykologisk behandling.
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