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59 Cards in this Set
- Front
- Back
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What is type of drug that is most commonly overdosed?
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Analgesics (APAP, ASA, NSAIDS)
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What type of drug is the number one cause of death due to pharmaceutical ingestions?
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sedatives
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Salicylates
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is easily dialyzable, weak acid, 2-4 hour half life in normal dosing ( may increase in overdose). elimination is first order by 5 pathways and varies with plasma concentration. switches to zero MM kinetics in overdose.
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what is the mechanism of Salicylate toxicity?
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bind to alpha ketogluterate dehydrogenase which interferes with the krebs cycle. also interfere with proton pumps in mitochondria
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What can salicylates do in overdose?
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uncouple oxidative phosphorylation. oxygen consumption , CO2 production, and tissue glycolysis can lead to hyperglycemia ( can see hypoglycemia in kids).
*other complications include hypoprothombinemia, increase capillary fragility, decreased platelet adhesiveness, thrombocytopenia |
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What is an important antidote in Salicylate overdose?
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vitamin K
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Do salicylates cross the placenta?
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yes. is listed as a class D drug which means it can possibly harm fetus. May cause metabolic acidosis in fetus because of slow metabolism, possible teratogenic effects. contraindicated in 3rd trimester.
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what is used to treat metabolic acidosis
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sodium bicarbonate. also excellent antidote for sodium channel blockers. used to alkalinize urine which enhances renal excretion of the drug. also used to decrease crystallization of hemoglobin in renal tubules
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is acetaminophen acidic or basic?
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acidic
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what are the normal doses of acetaminophen in adults and children?
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adults - 625-1000mg
children- 10-15 mg/kg |
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what happens to acetaminophen if ingested with narcotics?
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when ingested with narcotics or other drugs that slow GI motility peak plasma levels of acetaminophen are delayed
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how is acetaminophen metabolized?
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glucuronidation (60%), sulfation(30%), CYP450 2E1 (10%)... produces toxic metabolite NAPQI
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what detoxifies acetaminophen in the body?
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N-acetylcysteine (NAC)
*very effective if given within 8 hours of tox. helps the production of glutathione among other mechanisms of action |
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what structure is in NAC?
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has a sulfhydryl group which is an antioxidant
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what determines risk of developing hepatotoxicity with acetaminophen ?
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depends on hours after ingestion and plasma concentration
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what are NSAIDs?
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salicylates, Propionic acids (ibuprofen) , Acetic acids, oxicams, pyazolones, fenamates
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what are common symptoms in NSAID overdose?
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- CNS depression
- respiratory depression - metabolic acidosis - renal insufficiency |
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what are the dose risks of NSAIDs?
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200mg or less - well tolerated
200-400mg - need to clear gut with ingested charcoal greater than 400mg - serious toxicity |
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what is the mechanism of cyclic anti depressant toxicity/therapeutic effectiveness?
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they block the reuptake of NE into presynaptic vesicles
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what can CAD overdose lead to?
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- excessive NE reuptake blockade
-direct quinidine like effect - central plus peripheral anticholinergic effects |
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what is the mechanism of CADs?
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they are direct inward fast sodium channel and potassium rectifier channel blockers. which allows more calcium to enter the cell causing contraction
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overdose of CAD symptoms?
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NE excess effects ( tachycardia...) give way to NE depletion effects after metabolism by COMT
- arrhythmias, bradycardia, hypotension, collapse |
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what is the treatment of CAD overdose?
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alkalization with sodium bicarbonate , sodium bolus to overcome sodium channel blockade, cautious GI contamination, arrhythmia and seizure control in ICU
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What is the mechanism of iron overdose toxicity?
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free iron catalyzes redox reactions causing free radical formation
* causes tissue hypoperfusion and lactate formation *disruption of oxidative phosphorylation |
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What are symptoms of iron overdose?
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hypotension, hypovolemia,
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what is the antidote for iron overdose?
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deferoxamine - chelates iron
adverse effects - can cause hypotension and acute lung injury if given too quickly. anaphylaxis |
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what is the MAJOR adverse affect with deferoxamine?
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chronic use can cause hearing and visual loss. also associated with yersinia sepsis and mucomycosis
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What are some anticonvulsants?
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carbamazepine, valporic acid, phenobarbital, phenytoid
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how can carbamazepine toxicity occur?
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drug drug interaction with erythromycin
* nystagmus, ataxia, convulsions |
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what two drugs are important to realize that they may cause faulty drug screens?
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impramine and CBZ have structural similarities , can cause cross drug reactivity on drug screens.
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symptoms of overdose in anticonvulsants (CBZ)
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Respiratory depression, apnea, decreased GI motility , delayed aborbtion
* crosses placenta *major metabolite is epoxide but may not peak until 24 hours after exposure |
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what effects do CBZ have on fetuses
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folate deficiency effects
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can activated charcoal help in the case of CBZ overdose?
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yes
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what are the mechanisms of toxicity for the different anticonvulsants?
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CBZ - sodium channel blocker
Valproic acid - enhances GABA Phenytoin - sodium channel blocker Phenobarbital- enhances GABA |
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what are opiates?
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*naturally occurring alkaloids form opium poppy ( morphine and codeine)
*semi synthetics - heroin, oxycodone, hydrocodone *synthetics - propoxyphene, meperidine, methadone |
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what are the antidotes to anticonvulsant overdose?
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CBZ - activated charcoal (MDAC)
Valproic acid - carnitene to affect mitochondrial fatly acid oxidation Phenytoin - supportive care may result in arrhythmias phenobarbital - MDAC?? maybe |
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what does overdose of opiates result in?
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CNS depression, seizures, miosis, respiratory depression, pulmonary edema, hypotension, bradycardia, circulatory collapse, cardiac arrest
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what drug is useful in heroin overdose?
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naloxene
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Cocaine characteristics?
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derivative if erythroxylon coca
CNS stimulent; blocks reuptake of NE and promotes release of NE, blocks presynaptic monoamine transporters, slow sodium channel blocker, fast potassium rectifier channel blocker |
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do seizures occur with cocaine overdose?
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yes, especially in children
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overdose of cocaine symptoms?
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CNS hemorrhage, myocardial infarction, pulmonary edema, pneumothorax, seizures, rhabdomyolysis
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what is cocaine metabolized by?
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cholinesterase
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why is the ratio of BE to cocaine significant?
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if greater than 100 fold then it shows that the cocaine was used more than 10 hours prior
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what are the two primary mechanisms of psychostimulant toxicity?
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1. releasers; amphetamines (disrupt vesicle pH gradient allowing vesicular dopamine to redistribute into the cytoplasm)
2. uptake blockers; cocaine and methylphenidate |
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Amphetamine metabolism
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allow the release of dopamine and NE and serotonin from presynaptic terminals.
*highly lipophilic, large Vd * lack catechol structure ... sooo they can resist COMT metabolism giving them longer half lives. *metabolized by CYP2D6 |
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why is the dose important in amphetamine toxicity?
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at low doses DA is released from cytoplasmic pool
* at high doses amphetamines diffuse across presynaptic terminal membrane , alkalinize vesicles and permit dopamine release |
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symptoms of amphetamine overdose
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tachycardia, hypertension, hyperthermia, agitation, seizures, CNS hemorrhage, rhabdomyolysis
* compared to cocaine , less likely to cause seizures, arrhythmia, myocardial ischemia |
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Phencyclidine (PCP)
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- antagonizes glutamate at NMDA receptor by binding with ion channel and blocking calcium influx
*abused by smoking , or ingesting *mix of CNS stimulant and depression |
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substance dependance
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1. tolerance with increased need
2. diminished effect of drug 3. withdrawal 4. substance taken in large amounts 5. great amount of time spent to obtain substance 6. social actiities given up 7. substance abuse is continued despite of knowledge of harm |
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what are some SSRIs?
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fluoxetine, paroxetine, sertaline, fluvoxamine
*less toxic than CADs |
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what is the toxicity of barbiturates?
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GABA excess, CNS and respiratory depression
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what is the toxicity of benzodiazepines?
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increase GABA tone
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what is Flumazenil?
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competitive inhibitor of benzodiazepine activity at the GABA receptor complex. can't be used if there is any mixed ingestion! seizures may occur
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what are atypical antipsychotics?
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have low incidence of extra pyramidal symptoms compared to flumazenil
* hypotension, tachycardia, prolonged qt, widened qrs |
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what is a serious side effect of clozapine ( atypical antipsychotic)
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drug induced agranulocytosis
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Aripiprazole
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atypical antipsychotic - stabilizing effect on dopamine levels
prolonged qt are NOT seen |
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digoxin
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cardia glycosides in overdose, poisons the sodium potassium pump, leads to excessive calcium levels intracellularly, treatment with correction of electrolytes and FAB antibodies (digifab), vomiting, altered color vision
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beta blockers
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very lipid soluble, can cause CNS depression and seizures , hypoglycemia
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warfarin toxicity (anticoagulant)
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treat with vitamin K
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