Chronic Poisoning Flashcards
(27 cards)
Pathophysiology of Lead
It has a strong affinity for sulfhydryl and electron donor groups thus, lead ends up bound to and affecting a wide range of proteins
Neuronal S&S of Lead
Cognitive deficits and behavioural changes (children) Peripheral neuropathy (adults) Seizures and coma
Haematology S and S of Lead
Anemia by interfering with the function of enzymes involved in heme synthesis (↓ production of RBCs) and enzymes involved in maintaining RBC cell membrane integrity (↑ destruction of RBCs)
Renal S and S of Lead
induce a proximal tubule dysfunction leading to a Fanconi-like syndrome
competes with uric acid for excretion leading to ↑ serum urate, which gets deposited as urate crystals in joints causing “saturnine gout”.
Diagnosis of Lead
Measurement of lead levels in capillary or whole blood.
There are no safe levels of lead in blood
Treatment of Lead
Elimination of lead source
Cheating for kids with encephalopathy
Chela ting for adults with symptoms plus PbB>70
Chelating drugs for Lead
Contain sulfhydryl groups that bind lead.
Oral chelating agents for Lead
Succimer and Penicillamine
Parenteral chelating agents for Lead
Dimercaprol and CaNa2EDTA
Forms of mercury
Elemental from thermometers, etc
Inorganic salts from disc battery ingestion
Organic compounds from contaminated sea food, paint etc. MOST DEADLY is METHYLMERCURY
Pathophysiology of Mercury
Mercury binds to sulfhydryl groups and interrupt cellular enzymes and protein systems.
Inactivates Na/K ATPase which leads to membrane depolarisation and cell death.
Excretion of Mercury
Elemental and inorganic salts
Mainly through kidneys and minimally thorough GIT
Total half life 30-60 days
Organic mercury
Mainly fecal. Enterohepatic recirculating leading to longer half life (~70days)
Neuronal Symptoms of Mercury
Psychiatric issues Visual loss Hearing loss Ataxia Neuropathy
Renal Symptoms of Mercury
Nephrotic syndrome
Proteinuria
Pulmonary Symptoms of Mercury
Cough
Respiratory distress and failure
GIT Symptoms of Mercury
Nausea
Diarrhoea
Metallic taste
Salivation
Diagnosis of Mercury
Blood and urine analysis are required.
Blood 7.1
Urine 5
Treatment of Mercury
Removal of mercury source Acute treatment Gastric lavage Activated charcoal Whole bowel irrigation Chelating agents Haemodialysis
Chelating agents for Mercury
Succimer
Acute and chronic toxicity. First line and fewer S/E
D-penicillamine
Acute or chronic
Not used in renal failure
Dimercaprol
Preferred for mercury salts
Action of antidotes
Preventing absorption of poison
Binding and neutralising poison
Antagonising organ effect of poison
Inhibiting conversion of toxin to more toxic metabolites
Non specific binding agents
Activated charcoal
Lipid sink therapy
Enhancing elimination
Specific antidotes
Chelating agents for heavy metal poisoning
Digi-Fab for digoxin overdose
Hydroxycobolamine for cyanide poisoning
Action on toxin binding site
Receptor level
Flumazenil
Naldo one for opioids
Decreasing toxic metabolites
Binding
NAC
Convert to less toxic form
Sodium thiosulphate
