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
Test shows Spain nursing assistant clear of Ebola
A Spanish nursing assistant appears to have recovered from the...
medicalxpress.com
Metabolic genetics research paves way to treating diabetes and obesity
Breaking down complex conditions such as Type 2 Diabetes and...
medicalxpress.com
EM Nerd: Unclog the "Clogged Pipes" Model (CME/CE)
(MedPage Today) -- PCI is rarely helpful in ACS patients....
medpagetoday.com
Tear duct implant effective at reducing pain and inflammation in cataract surgery patients
The first tear duct implant developed to treat inflammation and...
medicalxpress.com
Experimental Ebola vaccine expected in Geneva Tuesday: hospital
Canada will start sending more than 1,000 doses of an...
medicalxpress.com
Many older people have mutations linked to leukemia, lymphoma in their blood cells
At least 2 percent of people over age 40 and...
medicalxpress.com
New insight that 'mega' cells control the growth of blood-producing cells
While megakaryocytes are best known for producing platelets that heal...
medicalxpress.com
Lab-developed intestinal organoids form mature human tissue in mice
Researchers have successfully transplanted "organoids" of functioning human intestinal tissue...
medicalxpress.com
Spike in ER Use Short-Lived After Medicaid Expansion
(MedPage Today) -- State budgets unlikely to take big hit,...
medpagetoday.com
Microbiome May Link Jet Lag to Obesity, Disease (CME/CE)
(MedPage Today) -- Circadian rhythms in intestinal microbes affect the...
medpagetoday.com
For many journalists Ebola's invisible threat scarier than war
You can't see shells falling, guns pointed or identify the...
medicalxpress.com
Children's genes affect their mothers' risk of rheumatoid arthritis
A child's genetic makeup may contribute to his or her...
medicalxpress.com
Nigeria expected to be declared Ebola-free
Nigeria is expected to be declared Ebola-free on Monday, just...
medicalxpress.com
Scientists identify mutation associated with cleft palate in humans and dogs
Scientists studying birth defects in humans and purebred dogs have...
medicalxpress.com
Women more likely to develop anxiety and depression after heart attack
Women are more likely to develop anxiety and depression after...
medicalxpress.com
Egg freezing: controversial new benefit in the US workplace
Free meals, four months of maternity leave and now egg-freezing:...
medicalxpress.com
Gene duplications associated with autism evolved recently in human history
Human geneticists have discovered that a region of the genome...
medicalxpress.com
Medical charity accuses US of pushing India to ease patent rules
Medical charity Medecins Sans Frontieres (MSF) on Saturday accused the...
medicalxpress.com
Tanzania launches giant measles vaccination drive
Tanzania on Saturday launched its biggest ever campaign against measles...
medicalxpress.com
Ebola monitoring inconsistent as virus spread
(AP)—The top administrator in Dallas County rushed to Texas Health...
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 +