U5.2 : HEAVY METALS AND CHELATORS Flashcards
U
Heavy Metal
Storage batteries, ammunition, metal alloys, solder, glass, plastics, pigments (in paints), Ceramics
Lead
Heavy Metal
No useful purpose in the human body
Lead
Heavy Metal (Pharmacokinetics)
absorbed slowly but consistently via respiratory and gastrointestinal tract
Lead
Heavy Metal
Lead affects _____ due to industrial exposure
Respiratory tract
Heavy Metal
Lead affects _____ due to non-industrial exposure
Intestinal tract
Heavy Metal
Up to 50% absorbed in children; Up to 10-15% absorbed in adults
Lead
Heavy Metal
may cause low dietary calcium, iron deficiency and ingestion on an empty stomach increases absorption
Lead
Heavy Metal
Distributed to the bone marrow, brain, kidney,
liver, muscle and gonads; then bones
Lead
Heavy Metal
Half-life of Lead
1-2 months
Heavy Metal
In Lead, 70% excreted in the _____
Urine
Heavy Metal
Multiple mechanism of actions of ______ include inhibition of enzyme functions, interference with action of essential cations, and oxidative stress generation
Lead
Heavy Metal
Multiple mechanism of actions of _______ gene expression changes, cell signaling alteration, and disruption of membrane integrity
lead
Heavy Metal
Major forms of Lead Intoxication
- Inorganic Lead Poisoning
- Organic Lead Poisoning
Heavy Metal (Lead)
Inorganic Major Routes
GI, Respiratory
Heavy Metal (Lead)
Organic Major Routes
Skin, GI, Respiratory
Heavy Metal (Lead)
Inorganic Distribution
Soft Tissues; redistributed to skeleton
Heavy Metal (Lead)
Organic Distribution
Soft Tissues (esp liver and CNS)
Heavy Metal (Lead)
Major Clinical Findings
CNS deficits; peripheral neuropathy; anemia; nephropathy; hypertension; reproductive toxicity
Inorganic
Heavy Metal (Lead)
Major Clinical Findings
- Encephalopathy
Organic
Heavy Metal (Lead)
Mechanism of Action
- Inhibits enzymes
- interferes with essential cations
- alters membrane structure
Inorganic
Heavy Metal (Lead)
Mechanism of Action
Hepatic dealkylation (fast) -> Trialkyl metabolites (slow) -> dissociation to lead
Organic
Heavy Metal (Lead)
Metabolism and Elimination
- Renal (major)
- feces and breast milk (minor)
Inorganic
Heavy Metal (Lead)
Metabolism and Elimination
- Urine and feces (major)
- Sweat (minor)
Organic
Heavy Metal
Treatment includes immediate termination of exposure, supportive
care and chelation therapy
Lead
Heavy Metal
Treatment
Chelate it using Intravenous
edetate calcium disodium (CaNa2EDTA) at a dosage of 30-50 mg/kg/d by continuous infusion for up to 5 days only
Lead
Heavy Metal
Semiconductors in our devices , wood, preservatives, nonferrous alloys, glass, turf herbicide monosodium methane arsonate (MSMA)
Arsenic
Heavy Metal
- Well-absorbed via respiratory and GI tract
- Percutaneous absorption is limited
Arsenic
Heavy Metal
T/F Arsenic is metabolized in the liver and excreted in the urine (major), sweat and feces
T
Heavy Metal
Multiple mechanism of actions
- Inhibition of enzyme functions
- Oxidative stress generation
- Gene expression changes
- Cell signaling alteration
Arsenic
Heavy Metal
Major Route of Arsenic Intoxication
GI, Respiratory
Heavy Metal
Distribution of Arsenic Intoxication
Predominantly soft tissues (highest in liver and kidney). Tightly bound to skin, hair and nails
Heavy Metal
Major Clinical Findings
- Cardiovascular: shock, arrythmias
- CNS: Encephalopathy, Peripheral Neuropathy
- Others: Gastroenteritis, Pancytopenias, Cancer
Arsenic
Heavy Metal
Mechanism of Action Arsenic
Multiple
Heavy Metal
Metabolism and Elimination
- Methylation
- Excreted via Urine (major)
- Sweat and Feces (minor)
Arsenic
Heavy Metal
- “Raindrop pattern”
- Hyperpigmentation and hyperkeratosis involving hands and
feet
Arsenic
Heavy Metal
Treatment
- Immediate termination of exposure, supportive
care and chelation therapy
Arsenic
Heavy Metal
Treatment
Acute Poisoning: Chelation with Unithiol 3-5
mg/kg every 4-6 hours or Dimercaprol every 4-6 hour
Arsenic
Heavy Metal
Quicksilver or liquid metal
Mercury
Heavy Metal
Electrolytic production of chlorine and caustic soda;
electrical equipment, thermometer, instruments, fluorescent lamps; dental amalgams; artisanal gold production
Mercury
Heavy Metal
an organomercurial preservative that are now removed from almost all vaccines
Thimerosal
Heavy Metal
T/F Environmental release of mercury from burning of fossil fuels contributes to bioaccumulation in fishes
T
Heavy Metal
Absorption varies depending on chemical form
Mercury
Heavy Metal
Absorbed from the lungs, GI tract, and percutaneous
route
Mercury
Heavy Metal
Distributed well into tissues (most concentrated in
kidneys)
Mercury
Heavy Metal
Mercury is excreted via
urine and feces
Heavy Metal : Type of Mercury
Major Route : Respiratory Tract
Elemental Mercury