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DESCRIPTION
Diphtheria antitoxin is a sterile, nonpyrogenic solution of
refined and concentrated protein ( mainly immunoglobulins ) containing
antitoxic antibodies. The solution is prepared from the plasma or
serum of healthy equines hyperimmunized against diphtheria toxin.
Diphtheria antitoxin injection contains 
0.25% phenol as preservative.
Diphtheria antitoxin occurs as a transparent or slightly opalescent
liquid and has slight odour because of the preservative.
USES AND ADMINISTRATION
Diphtheria Antitoxin is used in the treatment of diphtheria and
rarely as prophylactic of diphtheria in asymptomatic, non-immunised
individuals who have been exposed to diphtheria. Diphtheria
antitoxin neutralizes the toxin produced by Corynebacterium
diphtheriae locally at the site of infection and in the
circulation.
Diphtheria antitoxin is used for passive immunization in suspected
cases of diphtheria and should be given without waiting for
bacteriological confirmation of the infection. An antibacterial
agent such as erythromycin or benzylpenicillin is usually given
concomitantly. Diphtheria Antitoxin is generally not used for the
prophylaxis of diphtheria because of the risk of provoking a
hypersensitivity reaction. Contacts of a diphtheria case should be
promptly investigated, given a prophylactic course of erythromycin
and active immunization with a suitable diphtheria containing
vaccine as appropriate and keep under observation.
A test dose of diphtheria antitoxin should always be given to
eliminate hypersensitivity. For the treatment of diphtheria of
mild or moderate severity, doses of 10,000 to 30,000 units of
diphtheria antitoxin may be given intramuscularly, doses of 40,000
to 100,000 units may be given in severe cases. Higher doses have
been used in some countries. Doses of more than 40,000 units
should be given intravenously about 0.5 to 2 hours after the
initial portion of the dose has been given intramuscularly.
TREATMENT OF DIPHTHERIA
In the treatment of diphtheria, diphtheria antitoxin should be
administered as soon as the clinical evidence of the disease
appears; administration of the antitoxin should not await
bacteriologic confirmation of the diagnosis since the condition of
the patient with diphtheria can deteriorate rapidly.
PROPHYLAXIS OF DIPHTHERIA
Diphtheria antitoxin is rarely used for the prophylaxis of
diphtheria. Chemoprophylaxis with an anti-infective agent ( i.e. a
7 to 10 day course of oral erythromycin or a single IM dose of
penicillin G benzathine) and active immunization with a diphtheria
toxoid preparation is the recommended therapy for prophylaxis of
respiratory or cutaneous diphtheria in asymptomatic, non-immunised
household or intimate contacts.
Diphtheria antitoxin is administered by IM injection or slow IV
infusion. Sensitivity testing must be performed prior to the
administration of diphtheria antitoxin ( See Sensitivity Testing
and Desensitization ) Diphtheria antitoxin and diphtheria toxoid
should not be given in the same syringe nor injected at the same
site since neutralization of the vaccine may occur.
Specimens for bacteriologic culture should be obtained before and
after treatment or prophylaxis of diphtheria. For the treatment of
diphtheria, diphtheria antitoxin should be administered by IM
injection or IV infusion as soon as clinical evidence of the
disease appears; administration of the antitoxin should not await
bacteriologic confirmation of the diagnosis. In patients with
severe infections, the antitoxin preferably should be administered
by slow IV infusion to neutralise the toxin as rapidly as
possible.
For IV infusion, the appropriate dose of diphtheria antitoxin
should be diluted with an appropriate volume of 0.9 % sodium
chloride injection or 5 % dextrose injection to provide a 1 : 20
dilution of the antitoxin.
The solution may then be infused directly into a vein at a rate
not exceeding 1 ml/minute.
ADVERSE EFFECTS
AND PRECAUTIONS
Reactions are liable to occur after the injection of any serum of
animal origin. Anaphylaxis ( type I hypersensitivity reaction ) may
occur with hypotension, dyspnoea, urticaria and shock. A history of
evidence of sensitivity of equine serum, asthma or other allergies
should be obtained prior to administration of diphtheira antitoxin,
however, sensitivity testing should be performed in all individuals
regardless of allergic history or a history of prior administration
of preparation containing equine serum (see Dosage and
Administration : Sensitivity Testing and Desensitization).
Diphtheria antitoxin should be used with extreme caution in
individuals with a history of allergic disorders and/or who have
exhibited previously sensitivity to equine serum.
Epinephrine and other supportive measures should be available for
immediate management of an anaphylactic reaction if it occurs.
SENSITIVITY TESTING AND DESENSITIZATION
Prior to the use of diphtheria antitoxin, an intradermal or scratch
skin test and a conjunctival test for serum sensitivity should be
performed. Whenever possible, both the conjunctival test and the
intradermal or scratch skin test should be performed. The
intradermal skin test procedure consists of intradermal injection of
0.1 ml of a 1:100 dilution of diphtheria antitoxin in 0.9% sodium
chloride injection : the intradermal skin test is read after 20
minutes. When the patient has a history of allergy, 0.05 ml of a
1:1000 dilution should be used for preliminary intradermal skin
testing. A control test using 0.9% sodium chloride injection
facilitates interpretation of the results. A positive intradermal
skin test reaction consists of an urticaria wheal, with or without
pseudopods, surrounded by a zone of erythema. Alternatively, a
scratch skin test for sensitivity may be performed. The scratch skin
test procedure consists of placing 1 drop of a 1:100 dilution of
diphtheria antitoxin on the skin and then making a 0.64-cm
(1/4-inch) scratch through the drop; the scratch skin test is read
after 20 minutes. A control test using 0.9% sodium chloride
injection facilitates interpretation. A positive scratch skin test
reaction consists of an urticaria wheal, with or without pseudopods,
surrounded by a zone of erythema. The conjunctival test procedure
consists of placing 1 drop of a 1:10 dilution of diphtheria
antitoxin into the lower conjunctival sac of one eye; the test is
read after 15 minutes. A control test using 0.9% sodium chloride
injection that is placed on the other eye facilitates interpretation
of the results. A positive conjunctival test reaction consists of
itching, burning redness and lacrimation: these signs and symptoms
can be relieved by placing 1 drop of an ophthalmic solution of
epinephrine on the affected eye. A negative intradermal, scratch or
conjunctival sensitivity test is usually considered reliable but
does not completely rule out systemic sensitivity. When the skin or
conjunctival test is positive or a doubtful reaction occurs, the
risk of administering diphtheria antitoxin should be weighed against
the risk of withholding it, If diphtheria antitoxin must be used,
desensitization should be performed.
The procedure for desensitization consists of subcutaneous injection
of the following doses of diphtheria antitoxin at 15 minutes
intervals; 0.5 ml of a 1:20 dilution, 0.1 ml of a 1:10 dilution,
0.3ml of a 1:10 dilution, 0.1 ml of undiluted diphtheria antitoxin,
and 0.2 ml of undiluted diphtheria antitoxin; after 15 minutes,
0.5ml of undiluted diphtheria antitoxin is administered IM. If an
immediate sensitivity reaction occurs at any time during the
desensitization procedure, a tourniquet should be applied proximal
to the sites of injection and epinephrine administered proximal to
the tourniquet. After 1 hour, the procedure may be continued by
injecting the last dose of antitoxin that did not produce a
reaction. If no reaction occurs after 0.5 ml of undiluted diphtheria
antitoxin has been administered, the remaining usual dose may be
administered IM or IV. (See Dosage and Administration : Dosage.) An
allergist, immunologist, and / or other experts should be consulted
for advice on treatment of patients who develop signs or symptoms of
impending anaphylaxis despite desensitization.
STORAGE AND STABILITY
Diphtheria antitoxin injection should be stored in the dark between
2°-8°C.
DO NOT FREEZE.
PRESENTATION
1000 IU ( 1ml ) x 50 ampoules box
2000 IU ( 2 ml ) x 50 vials box
10,000 IU ( 10ml ) x 25 vials box
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