Arsenic Mechanism of Action * Arsenic reversibly combines with sulphydrl enzymes. It blocks Krebs cycle and interrupts oxidative phosphorylation causing depletion of ATP and death of cell. * It also inhibits transformation of thiamine into acetyl CoA and Succinyl -CoA resulting in thiamine deficiency. * It replaces the phosphorus in the bones * Arsenic is incorporated into hair, nails and skin. * It causes increased permeability of small blood vessels with inflammation and necrosis of intestinal mucosa thus causing manifestation of hemorrhagic gastroenteritis. Clinical Features Acute poisoning A patient with acute arsenic consumption may present in 1. Fulminant type: collapse and circulatory failure 2. Gastroenteritis type-constriction of throat,difficulty in swallowing,rice water stools,hepatic fatty infiltration,headache,veigo,hypehermia 3. Narcotic form * Metallic taste * Garlicky odour * Nausea and vomiting * Colicky abdominal pain * Profuse diarrhea resembling rice water stool of cholera. * Circulatory failure * Intense thirst * Oliguria * Uremia * Ventricular tachycardia * Headache * Veigo * Tremors * Convulsions * Formication * Delirium * Tenderness in muscle * Paralysis * Hyperpyrexia * QT prolongation, tachyarrhythmia including torsades de pointes may develop within first 24 hours after ingestion. Chronic Arsenic Poisoning Skin - generalized or localized fine mottled pigmentation of skin (Rain drop pigmentation) Nails - become brittle and show Mees' line. Mees' line are white transverse lines over nails Hairs - dry and may fall off; patchy or diffuse alopecia Arsenic dust - flexor eczema, painless perforationof nasal septum. Liver enlarged (hepatomegaly) and cirrhotic Weakness of muscle and atrophy - extensor muscles more commonly affected resulting in wrist drop and foot drop CNS-polyneuritis,optic neuritis Eyes-congestion,watering of eyes,photophobia GIT-cirrhosis of liver,nausea,vomiting,abd cramp,diarrhoea,salivation CVS-cardiac failure,dependent edema Hematologic-* Leukopenia * Thrombocytopenia * Mild eosinophilia * Karyorrhexis - manifested by bizarre nuclear forms * Megaloblastic anemia * Basophilic stippling RS-cough,hemoptysis REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO 305