Showing posts with label Toxicology. Show all posts
Showing posts with label Toxicology. Show all posts
Lead screening, levels and treatment in children
Current guidelines state that health-care professionals should use blood lead tests to screen children at ages 1 and 2 years. Older children should be screened in certain high risk situations.
The American Academy of Pediatrics policy statement recommends the use of venous samples for initial screening whenever possible. If capillary testing is performed and the lead concentration is greater than 10 mcg/dL, the lead concentration must be confirmed by a venous sample because capillary sampling is more likely to yield false-positive results due to contamination from skin.
Chelation therapy should be considered if lead concentrations are higher than 44 mcg/dL. The role of chelation is not clearly defined for children whose blood lead concentrations range from 20 to 45 mcg/dL. Levels below 20 mcg/dL can be monitored periodically.
Succimer is the drug of choice for children whose blood lead concentrations are > 45 mcg/dL. For levels >70 mcg/dL calcium-disodium EDTA can be added. The first dose always is succimer, followed 4 hours later by EDTA, because EDTA when given alone can worsen lead encephalopathy.
When to chelate for lead toxicity?
Indication:
Chelation therapy should be considered for lead toxicity if lead concentrations are higher than 44.0 mcg/dL. For levels between 10 and 44 frequent monitoring is recommended.
Drugs:
Succimer is the drug of choice for children whose blood lead concentrations are 45.0 to 100.0 mcg/dL . At values higher than 69.0 mcg/dL, a second drug, Calcium Disodium EDTA (Not to be confused with Sodium EDTA), is added. The first dose always is succimer, followed 4 hours later by EDTA, because children who present with lead encephalopathy may deteriorate when treated with EDTA alone.
Blood lead levels fall rapidly after chelation, but rebound within weeks, even if there is no further exposure to lead, due to release of lead from bone stores. These levels usually are not high enough to indicate chelation but if they do a second round of chelation may be needed.
Chelation therapy should be considered for lead toxicity if lead concentrations are higher than 44.0 mcg/dL. For levels between 10 and 44 frequent monitoring is recommended.
Drugs:
Succimer is the drug of choice for children whose blood lead concentrations are 45.0 to 100.0 mcg/dL . At values higher than 69.0 mcg/dL, a second drug, Calcium Disodium EDTA (Not to be confused with Sodium EDTA), is added. The first dose always is succimer, followed 4 hours later by EDTA, because children who present with lead encephalopathy may deteriorate when treated with EDTA alone.
Blood lead levels fall rapidly after chelation, but rebound within weeks, even if there is no further exposure to lead, due to release of lead from bone stores. These levels usually are not high enough to indicate chelation but if they do a second round of chelation may be needed.
Toxins and their specific antidotes.
| Drug | Antidote |
| Acetaminophen(TYLENOL)
| N- Acetylcysteine (MUCOMYST) |
| Anticholinergics | Physostigmine |
| Benzodiazepines | Flumazenil (ROMAZICON) |
| β-Blockers | Glucagon |
| Ca channel blockers | Calcium IV insulin in high doses with IV glucose |
| Carbamates | Atropine, Protopam |
| Digitalis glycosides (LANOXIN) | -specific Fab fragments |
| Ethylene glycol | Ethanol, Fomepizole |
| Heavy metals | Chelating drugs |
| Iron | Deferoxamine (DESFERAL) |
| Isoniazid (INH, NYDRAZID) | Pyridoxine (vitamin B6) |
| Methanol | Ethanol, Fomepizole (ANTIZOL) |
| Methemoglobin-forming agents (eg, aniline dyes, some local anesthetics, nitrates, nitrites, phenacetin, sulfonamides) | Methylene blue (UROLENE BLUE)
|
| Opioids | |
| Organophosphates | Atropine Some (ATROPEN
|
| Tricyclic antidepressants | NaHCO3 |
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