396 Section 11/ Chelating Agents & Treatment of Poisoninggiven immediately after exposure to the
metal.
It is given by parenteral route (deep IM
injection) and has short plasma half life.
Adverse effects include increased
blood pressure, burning sensation in lips,
mouth and throat; nausea, vomiting,
sweating, pain in chest, throat or hands;
painful sterile abscess at site of injection;
haemolytic anaemia in patients with G-6-
PD enzyme deficiency; hypertension,
tachycardia, salivation, lacrimation and
conjunctivitis.
It is indicated in metallic intoxication
due to arsenic, mercury, gold, bismuth,
lead, nickel, thallium and antimony; in
conjunction with sodium calcium edetate
for lead poisoning. It is also useful in
hepatolenticular degeneration (Wilson’s
disease). It is contraindicated in iron and
cadmium poisoning.
Dose: BAL; 2.5 to 5.0 mg/kg QID
depending upon the severity of the
poisoning.
D-PENICILLAMINE
It is a monothiol, prepared by alkaline
hydrolysis of benzyl penicillin and
chemically it is beta-dimethylcysteine.
It acts as a chelating agent which helps
in elimination of heavy metal ions by
forming stable soluble complexes which
can be easily excreted by the kidneys.
It is used in poisoning due to copper,
mercury and lead; Wilson’s disease,
cystinuria, scleroderma and rheumatoid
arthritis.
Adverse effects include skin rash,
proteinuria, bone marrow depression,
nausea and loss of taste sensation.
Dose: CILAMIN; 0.5-1 g/day in
divided dose.DESFERRIOXAMINE
It is a iron chelating agent, available for
intramuscular, subcutaneous and
intravenous administration.
When injected, it forms a stable water-
soluble iron complex (ferrioxamine) that
prevents the iron from entering into
further chemical reactions and is readily
excreted in the urine giving the urine a
characteristic reddish colour. Some of it is
also excreted in the faeces via the bile. It
can also chelate aluminium and thus is
useful in aluminium overload. It is
primarily a chelator used in acute iron
poisoning and chronic iron overload as in
thalassemia patients needing multiple
transfusions.
Adverse effects include flushing,
urticaria, hypotension, shock, tachypnoea,
hypoxaemia, tachycardia, cardiac
arrhythmias, convulsions, erythema,
swelling, GIT disturbances, dysuria, fever,
allergic skin rashes. Leg cramps on long term
therapy and reversible ocular and auditory
disturbances have also been reported.DESFERAL
Acute iron intoxication: Initially 1 g IM
followed by 500 mg every four hours for
two doses. Subsequent doses of 500 mg are
given 4 to 12 hourly depending on response,
maximum 6 g in 24 hours.
Patients with cardiovascular collapse: IV
infusion 50 mg/kg/hour up to a maximum
of 80 mg/kg in 24 hours.