HEAVY METAL POISIONING

Arsenic poisoning

Acute poisoning symptoms:

1.       Burning sensation

2.       Thirst

3.       Difficulty in swallowing

4.       Inflammation of gums and mouth

5.       Abdominal pain

6.       Vomiting and diarrhoea

Treatment:

1.       Removal of patient from source of poison

2.       Removal of unabsorbed poison ( emesis, gastric lavage, mgso4)

3.       Antidote: a. Dimercaprol injection   b. Egg and albumin

4.       Symptomatic treatment: replacement of fluids by i.v. drips

5.       Peripheral vasoconstrictor should be injected

6.       Morphine is used for severe pain

Chronic poisoning symptoms :

1.       Skin rashes

2.       Loss of hair and finger nails

3.       Weakness

4.       Loss of weight

Treatment:

1.       Removal of patient from further exposure to poison

2.       Dimercaprol injection helps to improve peripheral neuritis

3.       General nutrition must improve

Mercury poisoning

Acute poisioning: symptoms

1.       Metallic taste

2.       Choking of throat

3.       Burning sensation in abdomen associated with diarrhoea

4.       Thrombocytopenia and bone marrow depression

5.       Whiteness of mucus membrane of mouth with change in voice

6.       Appearance of blood in the vomiting and urine may occur

Treatment:

1.white albumin of egg +glucose+ nahco3 is introduced into stomach to convert the mercury into insoluble mercury albuminate

2. Dimercaprol injection should be given to form non toxic complex with unabsorbed mercury

3. Antidote- penicillamine is used

4. Symptomatic treatment – use of morphine, demulcents, i.v. Glucose, cardiac stimulants.

Chronic poisoning: symptoms

1.       Nausea, vomiting

2.       Loss of appetite

3.       Abdominal pain

4.       Swollen and inflamed gums

5.       Skin eruptions and paralysis of speech muscles

Treatment:

1.       Avoid further  exposure to poison

2.       Regular antiseptic e.g. Borax powder is used

3.       A course of dimercaprol/ penicillamine should be given.

lead poisioning

Acute  poisioning: symptoms

1.       loss of appetite  and sleep

2.       2. Metallic taste, thrist

3.       3. Nausea , vomiting and abdominal pain

4.       4. If large amount of lead has been absorbed a shock like syndrome

5.       5. Pain, paresthesias and muscle weakness

6.       6. Acute hemolysis sometimes leading to hemoglobinuria, oliguria and kidney damage

7.       7. feeling of pain in the joints and muscles

Chronic poisioning: symptoms

1.       On git: metallic taste, anorexia,  chronic contipation, abdominal pain

2.       Neuromusculareffect: muscular weakness, increased fatigability leading to paralysis.

3.       Cns: lead encephlopathy, ataxia, vertigo, headache, insomnia, irritability (common in children), delirium, lethargy, convulsions.

4.       Hematologic: hypochromic microcyte anemia

5.       Renal damage

6.       blue lining on the gums

7.       in female it cause menstrual disturbance and abortion

Treatment of lead poisioning:

1. in acute phase supportive measures are given.

2. Fluid and electrolyte balance must be maintained.

3. It must be ensured that there is no further exposure

4. Convulsions if present are treated with diazepam

5. Concentration of lead in blood is estimated prior to chelation therapy

6. If blood lead concentration is more than 50-60 micro gram /dl  then chelators are administrated.

6. The chelators are commonly used:edetate calcium disodium, dimercaprol and d-penicillamine

7.for lead encephalopathy edetate calcium disodium (5 mg/kg/day) and dimercaprol (4 mg/kg/day) used.

calcium gluconate is given if abdominal pain persists

magnesium sulphate given for chronic constipation

Heavy metal antagonists

1.       Dimercaprol:

also known as BAL ( BRITISH ANTI LEWISITE)

M.o.a.-

Dimercaprol forms chelation comlex with sulfhydryl groups and metals (PB, arsenic, antimony, copper, mercury, gold , bismuth).

It works best in 2:1 complex

Dose:

usually 100 mg every 4 hours for 48 hours, then 100 mg eight hourly for 8-10 days.

In wilson disease, it is given in a dose of 300 mg daily for 10 days.

Uses:

In poisoning of  pb, arsenic, antimony, copper, mercury, gold , bismuth.

It is also used as an adjuvant to ca- edta in lead poisoning

Adjuvant to penicillamine in copper  poisoning

Contraindications: in fe and cd poisoning fe- dimercaprol complex and cd- dimecaprol complex  itself toxic.

Adverse effects:

Increased bp, tachycardia

Vomiting, tingling

Burning sensation, conjuctivitis, lacrimation, rhinorrhea

Sweating of  hand and forhead, muscle pain.

2.       Disodium edetate

Chelator of calcium

Used for emergency control of hypercalcaemia

Causes tetany on rapid i.v. Injection

3.       Calcium disodium edetate

It binds to lead , zinc, cadmium, manganese, copper and also some radioactive metals.

M.o.a.- it exchanges the calcium ( of calcium disodium edetate) with excess of heavy metals.

It is excreted through urine

It is given i.v.

Uses: in lead poisoning

In zinc, cd, cu, mn poisoning

Not used in hg poisoning

Adverse effect

It might cause kidney damage and necrosis of pct of the kidney

Cause acute febrile reaction which is characterised by chills, urticaria, anaphylaxis, myalgia, dermatitis.

4.       Penicillamine-

Strongly bind to Cu

It is obtained as a degradation product of penicillin

It has very strong copper chelating property

It also bind with hg, pb  and zn

It is known to occur in two isomers

D (+) isomer- can be used therapeutically for chelating property

Uses: in Wilson’s disease

In copper poisoning

Hg, pb, and zn poisoning

In cysteine stones

In scleroderma (excessive fibrosis of the muscles and skin, wooden body

Rheumatoid arthritis

Adverse effect:

Cutaneous vasoconstriction

Renal and haematological problems

Aplastic anemia, lupus erythematosus, leucopenia.

5.       Deferoxamine:

It is isolated as iron chelate from streptomyces pilosus

Dose: the 500 mg injection is continued at four or 12 hour but the total amount of drug should not exceed 6 g in24 hours.

Adverse effect: pruritis, rashes, anaphylaxis, neurotoxicity, diarrhoea, fever, leg cramps, hepatic failure.

Uses: in iron poisoning

6.       Acetyl d- penicillamine

A weak chelator but less toxic drug. It has been shown to be highly effective in mercury poisoning.

It is administered 1 g daily in three or four divided dose for 10 days

7.       Succimer

Succimer is chemically similar to dimercaprol.

It is effective in lead poisoning.

Succimer is less toxic than dimercaprol

Adverse effect

Nauses, vomiting, diarrhoea, loss of appetite