TOX 7 - Arsenic

Question 1

Arsenic compounds

Answer 1

Elemental is basically harmless

forms which enter the body:

• Inorganic arsenic salts:
• Trivalent arsenite- highly toxic, poor solute, but can be absorbed through skin
• Pentavalent - less toxic, more soluble
• or arsenates

Question 2

Pharmacodynamics

Answer 2

Binds to SH groups (sulfhydryl ) and inhibits enzymes–> interfering with oxidative phosphorylation

Strong capillary poison

Possible carcinogenic

Question 3

Acute intoxication symptoms

Answer 3

initial - nausea, vomiting, dizziness

mid - latency period

late - severe vomiting and diarrhoea (rice water stool) -> severe dehydration

• gastroenteritis, hematemesis, severe diarrhea → hypovolemic shock; arrhythmias,
• CNS symptoms (encephalopathy, delirium, coma), pancytopenia
• weeks later – ascending peripheral neuropathy (may result neuromuscular respiratory failure)
• month later - transverse white striate on the nails

Question 4

Treatment of acute intox

Answer 4

Gastric lavage

Chelation therapy (dimercaprol)

Supportive treatment

Question 5

Chronic intoxiaction

Answer 5

Skin change, anorexia, cachexia, GI problems etc -> death

• weakness,
• peripheral neuropathy (socking-glove pattern),
• anemia,
• liver and kidney damage,
• skin changes - hyperkeratosis, hyperpigmentation, general cachexia

Question 6

Arsine gas poisoning (ASH3)

Answer 6

Very powerful haemolytic agent - fever, icterus, renal damage

Supportive treatment

Question 7

Most frequent source of intoxication- arsenic

Answer 7

1. industry,
2. agriculture (herbicides, insecticides),
3. wood, preservatives,

Question 8

Major route of absorption - arsenic

Answer 8

1. respiratory and
2. GI tract

Question 9

distribution of arsenic

Answer 9

Distribution

1. soft tissues,
2. first of all liver and kidney,
3. later skin, hair, nail

Question 10

Arsenic poisoning mechanism

Answer 10

Interferes with over 200 enzymes in the body

• ATP depletion
• Carcinogenic: Interfere with base and nucleotide excision repair –> cancer risk increases
• Oxidative stress
• Disrupts signal transduction pathways
• Atherosclerosis
• Diabetes
• Acute lethal dose: 70 – 200mg or 1 mg/kg/day

Question 11

arsenic acute lethal dose

Answer 11

• Acute lethal dose: 70 – 200mg or 1 mg/kg/day

Question 12

arsenic poisoning diagnosis

Answer 12

Diagnosis:

• Measurement of arsenic in blood, urine, hair and fingernails
• Symptoms
• Drinking water measurements

Question 13

treatment of arsenic poisoning

Answer 13

Treatment:

• Supportive treatment
• Chelation:  Dimercaprol  Dimercaptosuccinic acid
• Calcium sodium edetate