Treatment Of Anaphylaxis

1. Exposure to the offending agent should be terminated.
2. Adrenaline has actions opposite to those of histamine and thus acts as a physiological antagonist. It may be given by SC or IM route.
3. Hypotension should be corrected with the infusion of intravenous fluids.
4. Corticosteroids are occasionally used.
5. Other supportive measures include administration of oxygen and artificial respiration if necessary.

N.B. Antihistaminic drugs are not able to counteract the hypotension and brochospasm characteristic of anaphylactic shock.

Antihistaminc Drugs

These drugs competitively block histamine receptors and are of two types:

1. H₁ receptor antagonists
2. H₂ receptor antagonists (used in the treatment of acid-peptic disease)

H₁ Receptor Antagonists

Classification of H1 recepror antagonists:

1. Potent and sedative: such as diphenhydramine and promethazine.
2. Potent but less sedative: such as cyclizine and chlorpheniramine

• Less potent and less sedative: such as pheniramine
• Non-sedative: such as terfenadine, loratadine, and cetrizine.

The newer generation agents are relatively free of central depressant effects. These agents may also possess anti-emetic effects.