Quantcast Mechanism of Action of Antihistamines - Pharmacology V

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
e. Anaphylactic Shock. Anaphylactic shock is the most serious type of allergic
reaction. The antigen that produces the response can range from a bee sting toxin to
an antibiotic. Again, this response is produced by an antigen-antibody reaction
characterized by the sudden overwhelming release of histamine in the body. Therefore,
one would expect the effects of histamine on the body to be demonstrated. Two main
effects of anaphylactic shock on the body are severe drops in blood pressure and
impaired respiration. The drastic drop in blood pressure develops from the severe
peripheral vasodilation and the increased permeability of the capillaries. The impaired
breathing arises from bronchoconstriction. The anaphylactic reaction occurs very
rapidly after the introduction of the antigen into the patient. Unless prompt action is
taken by medically trained personnel, the patient will die in a matter of minutes.
f. Prevention or Control of Symptoms of Allergic Reactions. It is possible
to decrease or even prevent the symptoms of an allergic reaction. For a very severe
allergic reaction like anaphylactic shock, a drug that will stop the effects of histamine on
the body must be used. Moreover, the drug must produce positive physiological effects
on the body. The drug used for anaphylactic shock is epinephrine.
g. Desensitization. In some instances, it may be advantageous to prevent an
allergic reaction from occurring. Since the production of abnormal antibodies by the
plasma cells is the real beginning of the potential allergic reaction, it makes sense that if
the abnormal antibodies were not produced, a reaction would not occur when the
antigen again enters the body. The answer would then be to have only complete
(divalent) antibodies produced in the body. This is the basis of treatment to prevent an
allergic reaction. The treatment is referred to as desensitization. Here, extracts of
substances such as pollen or drugs are given to the patient in small, but increasing
doses. In time, the body produces complete antibodies, and the allergic reaction does
not occur.
4-6.
MECHANISM OF ACTION OF ANTIHISTAMINES
a. Antihistamines are drugs that compete with histamines for their receptor sites,
known as H1 and H2 receptor sites. These receptor sites are found in tissue cells, with
H1 receptors located throughout the body and H2 receptor sites found in the gastric
mucosa. The majority of available antihistamines are H1 antagonists.
b. H1 antagonists are believed to act not by opposing but by preventing the
physiologic action of histamine. This occurs because anti-histamine molecules are
chemically similar to histamine molecules. When the antihistamine binds itself to the H1
receptor site, it prevents histamine from doing the same, which effectively eliminates
histamine action.
MD0808
4-6



Medical News
Asian-language smoking quitline successful nationwide
(HealthDay)—An Asian-Language Smokers Quitline (ASQ) reaches Chinese, Korean, and Vietnamese...
medicalxpress.com
Could insulin pills prevent diabetes? Big study seeks answer
For nearly a century, insulin has been a life-saving diabetes...
medicalxpress.com
Prescription drug monitoring programs offer multiple benefits
(HealthDay)—Prescription Drug Monitoring Programs (PDMPs), frequently utilized by emergency medicine...
medicalxpress.com
Americans' risk of dying from cancer is falling, CDC finds
(HealthDay)—The risk that any one American will die from cancer—the...
medicalxpress.com
Many Americans trying to cut their salt intake: CDC
(HealthDay)—Worried about links between high daily salt intake, high blood...
medicalxpress.com
Summer danger: BBQ grill brush wires causing big health woes
(HealthDay)—Before you bite into that burger on Independence Day, you...
medicalxpress.com
How to avoid July Fourth allergy flare-ups
Fireworks, picnics and parades are favorite Fourth of July traditions...
medicalxpress.com
One death reported from salmonella outbreak at US restaurant
State health officials say one person has died in connection...
medicalxpress.com
WATCHMAN heart device gives patients alternative to blood thinners and reduces stroke risk
MedStar Heart & Vascular Institute now offers patients with irregular...
medicalxpress.com
Gene therapy for cystic fibrosis shows encouraging trial results
A therapy that replaces the faulty gene responsible for cystic...
medicalxpress.com
Millions of children's lives saved through low-cost investments
More than 34 million children's lives have been saved since...
medicalxpress.com
Cystic Fibrosis: New Hope for Gene Therapy? (CME/CE)
(MedPage Today) -- Early results suggest stabilization in lung function...
medpagetoday.com
Rapid response to kids' stroke symptoms may speed diagnosis
An emergency room rapid response plan for children can help...
medicalxpress.com
Stroke Rounds: Fast Call IDs Zebras vs. Horses in ER (CME/CE)
(MedPage Today) -- Stroke rapid response alerts speeds pediatric stroke...
medpagetoday.com
FDA OKs Cystic Fibrosis Combination
(MedPage Today) -- Drug combo targets most common root cause...
medpagetoday.com
Purdue Pulls New OxyContin Application, and Questions Follow
(MedPage Today) -- FDA disavows previous requirement for study of...
medpagetoday.com
Walking on sunshine: How to celebrate summer safely
Normally, I spend the Fourth of July on the shores...
scopeblog.stanford.edu
The Craziness of ICD-10
(MedPage Today) -- This vast expansion of diagnosis codes isn't...
medpagetoday.com
When RA Patients Are Poor, DMARDs Often Delayed (CME/CE)
(MedPage Today) -- End result: greater joint damage and worse...
medpagetoday.com
Washington woman's measles death is first in US since 2003
Washington state health officials say measles caused the death of...
medicalxpress.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +