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25 Cards in this Set
- Front
- Back
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what are contraindications for emetics?
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dyspnea, hypoxia, seizures, coma, or abnormal pharyngeal reflexes, corrosive agents, volatile hydrocarbons, species that can't vomit
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gastric/rumen lavage?
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emesis is generally preferred over gastric lavage, contraindicated for cases in which caustic ingestions occur, occasionally recommended for cases in which massive ingestions (>LD50) occur, and emesis is unproductive, or delayed GI emptying is anticipated
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Activated Charcoal and cathartics
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medical grade activated charcoal contain large pore sizes and surface area which allow for the non-specific binding of many toxicants, charcoal tablets and 'universal antidote' (activated charcoal/magnesium hydroxide/tannic acid) are much less effective and are not recommended, repeated administration is commonly recommended for many toxicants (tricyclic antidepressants, digitoxin), may cause constipation which my be minimize this effect
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activated charcoal binding
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number of drug/toxin molecules that can be absorbed varies but sometimes is approximately proportional to molecular size of the xenobiotic and surface area of the activated charcoal, nonpolar large molecules are most rapidly absorbed, ionized solutes are less firmly absorbed than neutral solutes
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using activated charcoal
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most recent <6h ingestions, use a 10:1 activated charcoal-to-toxicant (mass) ratio, 1-4 g/kg (PO q4-6h), repeated administration of activated charcoal is commonly recommended for many toxicants, Cl in-caustic agent
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cathartics
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decrease GI transit time thereby decreasing absorption, saline cathartics-sorbitol (3ml/kg (PO) of a 70% solution), osmotic cathartic (magnesium sulfate, sodium sulfate, 250mg/kg PO)
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use of cathartics
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saline cathartics should not be administered if the ingested agent will have similar cathartic effects (eg laxative ingestions), combine with activated charcola as an aqueous suspension (10x vol), magnesium sulfate may induce CNS depression
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gastrotemy or gastric endoscopy
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rarely used, may be required in order to remove foreign bodies from the stomach (metal ingestions, large quantities of ingested drugs which form coalesced masses)
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measures to enhance elimination
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diruresis (increase urine production), ion trapping (reduce re-absorption of urine excreted agents by the urinary bladder)
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diuresis
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benefit only if compound has a significant plasma concentration, complications: pulmonary edema, cerebral edema, metabolic acidosis/alkalosis, electrolyte imbalances (hyponatremia, hypokalemia), cardiac arrhythmias
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ion trapping
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ionized compounds do not readily cross cell membranes, creates a pH difference from blood pH will favor trapping or reabsorption (weak acids - excreted faster in alkaline pH-anion form favored, weak basis - excreted faster in acidic pH - cation form favored, strong bases/acids tend to be already charged and are excreted by the kidney w/out further modifying the urine pH)
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ion trapping-acid urine
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ammonium chloride: requires monitoring of metabolic status, contraindicated with hepatic or renal insufficiency, severe rhabdomyolysis/myoglobinuria (nephrotoxicity of myoglobin is enhances in acid urine), ammonia intoxication can develop (CNS depression and coma), dose 100mg/kg in dog, 20mg/kg in cat BID PO
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ion trapping-alkaline urine
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drug = sodium bicarbonate, used to treat: EG, salicylate, phenobarbital, 2,4-dichlorophenoxyacetic acid (2,4D), 1-2mEga/kg, IV, q3-4h
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inter-lipid therapy
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intravenous lipid emulsion (ILE) or intravenous fat emulsion (IFE) - total (TPN) or partial parenteral nutrition (PPN), treatment for fat-soluble drug toxicity (local anesthesia overdoses in human medicine, verapamil, calcium-channel blockers & beta-blockers, others)
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inter-lipid therapy mechanism
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exact mechanism ILE works is unknown, potential hypotheses include: providing an energy substarte or calcium thereby improving cardiac performance, acting as a 'lipid sink' (sequestration of lipophilic compounds), increasing the overall fatty acid pool (overcomes bupivacaine inhibition of mitochondrial fatty acid metabolism)
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inter-lipid therapy use in vet med
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local anesthetics (bupivacaine, lidocaine), clomipramine, tricyclic antidepressants (TCA), propranolol, buproprion (wellbutrin, zyban), muscle relaxants (baclofen, flexeril), macrocylclic lactones (mosidectin, ivermectin)
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inter lipid therapy formulations
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lipidrescue 20%-marketed as an antidote for toxicities in human medicine, baxter 10 & 20% solutions, other
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inter lipid therapy dosing
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20% solution IFE dosing, administer 1.5ml/kg IV bolused over 1m, followed by 0.25 ml/kg/min for 30-69min. The initial bolus could be repeated 1-2 times if no response to the initial bolus is obtained, with a goalt to not exceed 8ml/kg/d
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inter lipid therapy side effects
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hypersensitivity reactions (people), phlebitis, fat emboli
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toxicant first 48h
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decrease absorption (repeated activated charcoal-cathartics), increase excretion (diuresis, ion trapping), antidotal therapies, surgical removal, life support
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antidotes
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atropine (OP, carbamate insecticides), pralidoxime (OP-insecticide toxicosis), vitamin K1 (anticoagulatn rodenticide ingestions), ethanol, 4-methylpyrazole (ethylene glycol, methanol), N-acetylcysteine (acetaminophen toxicosis), ascorbic acid (drug-induced methemoglobinemia), 2,3-dimercapto-1-propanol (As, Pb), calcium EDTA (Pb), penicillamine (Cu), desferrioxamine (Fe), sodium nitrite (cyanide)
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diagnosis of poisoning
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history of exposure to a possible poison, demonstration of an adverse efect compatible with the poison, confirmation of exposure/absorption of the poison by chemical analysis
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poisoning minimum database
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routine lab testing is recommended for suspected life-threatenting intoxications (CBC, serum electrolytes, serum glucose, BUN, creatinine, calcium, liver enzyme determinations, urinalysis), others (coag panel, electrocardiography, rads)
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forensic toxicology samples
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collect tissues for histologic and toxicologic examination: 10% buffered formalin, fresh frozen: submission pending histologic findings: urine 10ml (drug/pesticides), kidney 2-10g (heavy metals), liver 2-10g (best single tissue, mineral or organic chemical), vomitus/stomach/crop/intestinal contents 2-10g, suspected injection site 1g, brain (hemi or whole), fat 2-10g (fat soluble chemicals), bedding 100g, feed 100g and water 1L, whole blood 1ml or serum (lead/rbc)
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what does forensic toxicology do
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look for thousands of chemical compound with a high degree of specificity and sensitivity: gas chromatography-mass spectrometry (GC/MS), inductively coupled argon plasma emission spectroscopy (ICPAES), inductively coupled plasma mass spectrometry (ICP/MS)
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