Toxicology Heavy Metals Flashcards
A ____ is something that can cause harm, _____ is the chance of it happening
Hazard, Risk
Most drugs are eliminated through ____ order kinetics, but at high concentrations saturation is reached and elimination then becomes _____ order
1st
Zero
*Prolong half life when saturated as well as increase unbound free fractions
The apparent volume in which a substance is distributed is called volume of Distribution, is a large or small Vd more easily accessed?
Small
*Larger Vds are not good candidates for hemodialysis
________ is the accumulation of a toxic agent across time whereas _____ is accumulation through the food chain
Bioaccumulation
Biomagnification
Naturally occurring elements with high atomic weight and a density 5-times greater than water are called?
Heavy Metals
What are the three most toxic heavy metals?
1-Lead
2-Mercury
3-Arsenic
*based on prevalence and severity
Both children and pregnant women absorb more lead because their bodies have a greater demand for what?
Calcium and Iron
*50% ingestion rather than 10-15%
Leads half life is 1-2 months and cause what 3 main symptoms?
1-Headaches
2-Neurocognitive deficits
3-Kidney damage
*substitutes for Ca in bone
Dark lines on the gingiva are cause by what heavy metal?
Lead
*called Burtonian Lines
What are 5 ways lead interferes with the body?
1-Interferes with Ca++ use
2-Causes anemia
3- Immunosuppression
4-Binds sulfhydryl groups on any enzymes and co-factors
5-Crosses BBB and concentrates in gray matter, can cross placenta
Treatment for lead toxicity is to remove the exposure which is done principally with which chelator?
- Edetate Calcium disodium (EDTA)
- Followed by Succimer
*can cause rebound intoxication as the bone re-equilibrates
Found as a liquid at room temperature what are three main ways we are exposed to mercury?
1-Fish
2-Dental Amalgam
3-Thermometers
Mercury is highly reactive with which essential dietary element?
Selenium
*needed to prevent reverse oxidative damage
Acute intoxication of mercury can effect the gingiva how?
Gingivostomatitis
Chronic mercury intoxication can cause neurological and psychiatric problems historically common to which profession?
Hatter (used mercury in leathers to make hats)
*Mad Hatter’s Disease
Mercury toxicity is treated using which two chelators?
1-Dimercaprol (if acute, can cause renal issues)
2-Succimer
What are two main exposure sources of Arsenic?
1-Industrial contamination
2-Groundwater contamination
*absorbed through respiratory and GI tracts. Keratinized tissues act as a depot
What are 4 consequences of arsenic toxicity?
1-Hyper pigmentation
2-Peripheral neuropathy
3-Carcinogenic in lungs, skin and bladder
4-Hemolytic effect on RBC
*increases ROS
Chelators are useful for _____ arsenic intoxication but not for ______
Acute
Chronic (irreversible damage to several vital organs)
*Chelators also ineffective in acute arsine inhalation
The longer the half-life of a heavy metal the ______ effective chelation will be
Less
*treat as early as possible
Which FDA approved mono therapy chelator is used for Arsenic and Mercury but not lead?
Dimercaprol
*can be used in combination for lead
Dimercaprol is not water soluble and has a narrow therapeutic index and has consequently been largely replaced by what two chelators?
Succimer and unithiol
Which water soluble derivative of dimercaprol is not FDA approved and increases renal excretion of mercury, arsenic and lead?
Unithiol
*orall or IV
Which chelator is a water soluble dimercaprol and is FDA approved for children and adults with lead, arsenic and mercury poisoning?
Succimer
Which drug is FDA approved and indicated as the 1st line treatment for chelation of lead but is contraindicated in anuric patients?
EDTA (Edetate Calcium Disodium)
*nephrotoxicity when used 5+ days
What are the 4 criteria for biocompatible dental materials?
1-Not harm pulp/soft tissue
2-No toxic diffusible substance
3-Free of sensitizing agents
4-Not carcinogenic
The greatest amount of mercury is released during which dental procedure?
Dry polishing of amalgam restorations
To prevent pulpitis caused by unpolymerized monomers in resin composite _____ the recommended time of curing exposure and ____ place should be done
twice
Incremental
How can zinc phosphate cement exposure be limited?
Proper mix or use of a resin-modified glass ionomer cement
Though it is not a heavy metal, how does cyanide poison?
inhibits cytochrome C oxidase
What is the antidote for cyanide poisoning?
Hydroxycobalamin
