The most effective drugs for anaphylaxis and should be given to patients with respiratory difficulty or hypotension is called the Adrenaline (epinephrine).

However, the treatment will not work if the adrenaline is delayed.

• In the management of anaphylaxis, it usually involves treatments using mainly epinephrine and histamine as a supplementary treatment. Treatment also involves post therapy which ensures that symptoms do not relapse.
  
  Dosage of epinephrine for adults in treatment is 0.3–0.5 mL of a 1:1000 dilution, while dosage for children is 0.01 mL/kg, up to a maximum 0.3 mL of a 1:1000 dilution.

• Epinephrine is injected in 5-15 minutes intervals until the symptoms of hyperandrealism show up on the patient. There are also intravenous epinephrine (1:10 000 dilution) but should only be used in extreme cases because of the potential to trigger tachrrhythmias.During treatment, the patient’s airways must be sufficiently opened and maintained while having oxygen tanks on standby for patients with anaphylactic reactions.
  
  
  
• Supplemtary treatment includes the use of H₁ and H₂ antihistamines like diphenhydramine, in which 25-50 mg is injected and ranitidine is taken orally 150mg each time or 50mg is injected.
  It is recommended to use these 2 treatments at the same time as H₁ and H₂ blockage is more effective than using H₁ blockage alone.

• Hypotensive patients should receive intravenous fluid support with crystalloid or colloid, and severe cases may require vasopressor agents such as dopamine or high-dilution epinephrine (1:10 000).

• Individuals who use ß-blockers (and possibly angiotensin-converting-enzyme inhibitors, although the evidence is incomplete) may not respond completely to epinephrine, in which case glucagon should be administered at a dose of 5–15 µg/min intravenously. Glucagon has inotropic, chronotropic and vasoactive effects that are independent of ß-receptors, and it also causes endogenous catecholamine release.

• The person may receive antihistamines, such as diphenhydramine, and corticosteroids, such as prednisone, to further reduce symptoms (after lifesaving measures and epinephrine are administered).

• Lastly, these patients require post-treatment observation to prevent relapse of anaphylaxis. Monitored settings of 24 hours are often optimal for most cases. Patients are often only discharged when the doctors can confirm he/she is not any life threatening situation.
  
  
  
• Prevention

Avoid known allergens. Any person experiencing an allergic reaction should be monitored, although monitoring may be done at home in mild cases.

Occasionally, people who have a history of drug allergies may safely be given the medication they are allergic to after being pretreated with corticosteroids (prednisone) and antihistamines (diphenhydramine).

People who have a history of allergy to insect bites/stings should carry (and use) an emergency kit containing injectable epinephrine and chewable antihistamine. They should also wear a MedicAlert or similar bracelet or necklace stating their allergy.

References:

Diagnosis and Management of anaphylaxsis - ellis and day 169(4):307 --canadian medical association ,Anne K. Ellis and James H. Day,(2003). retrived 6th Feb 2010 from:http://www.cmaj.ca/cgi/content/full/169/4/307#T123#T123