- Uncommon but potentially fatal. Often chronic. Inorganic toxicity more common. Greater with tri- rather than penta-valent arsenic. Therapeutic use in acute promyelocytic leukaemia.
- As3 :
- Binds to many cell enzymes, inhibits cellular respiration & DNA replication/repair. Reactive O2 intermediates.
- Abs by GIT, skin & lungs. Distributes to kidney, liver then lungs, CNS/PNS and nails. Liver met. T½5d
- Rapid dev of metallic taste, hypersalivation & slight garlic odour, severe N&V & rice water diarrhoea±blood, abdo pain. Followed by encephalopathy, seizures, dysrhythmias, ARDS, RF, liver injury. Later marrow depression, alopecia & neuropathy.
- Insidious onset over years of constitutional symptoms, cutaneous lesions, nail changes, painful peripheral neuropathy and skin/bladder Ca.
- Screening: ECG, paracetamol, BSL
- Specific bloods:
- Spot (Norm<30µg/L or 4.0µmol/L) & 24hr (Norm<50µg/L or 6.65µmol/L) urinary arsenic, blood level if anuric, FBC, UEC, LFT, ABG, CXR/AXR
- Chronic intoxication can follow long-term drinking of artesian well water. Acutely <5mg → mild GIT symptoms, but >100–300mg (child <1mg/kg) potentially lethal.
Resus & Supportive Care
- Rarely req. Mannitol & dexamethasone if cerebral oedema.
- Fluid status.
- Remove source. Remove clothes & wash skin if dermal exposure.
- WBI if co-operative & ingested inorganic As trioxide (shown on AXR).
- Polythiol resin may reduce organic Hg enterohepatic circulation.
- Chelation therapy (see Antidotes)
- Depends on severity.
- inorganic (ground water, soil, industrial, traditional remedies)
- organic (fish: but in non-toxic forms, more toxic is trypanosomiasis Rx melarsoprol).