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
Use of frozen material for fecal transplant successfully treats C. difficile infection
A pilot study by Massachusetts General Hospital (MGH) investigators may...
medicalxpress.com
Pregnancy complications may be more common in immigrants from certain regions
Pregnant immigrants from Sub-Saharan Africa, Latin America and Caribbean islands...
medicalxpress.com
Death rates from pancreatic cancer predicted to rise in Europe in 2014
Pancreatic cancer is the only cancer for which deaths are...
medicalxpress.com
Genetics explain why some boys and girls are bigger than others
The influence of genetic factors on differences between children's Body...
medicalxpress.com
Bioethicists use theatrical narratives to bridge the gap between society and science
A pair of bioethics experts have added "playwright" to their...
medicalxpress.com
The best toxicology lab: a mouse with a human liver
A few years ago, Stanford pharmacogenomic expert Gary Peltz, MD,...
scopeblog.stanford.edu
How Great the Breast Ca Risk After Radiation as Child?
(MedPage Today) -- Women who survived childhood cancers treated with...
medpagetoday.com
Income Tax Fraud Appears to Target Docs
(MedPage Today) -- Hundreds of doctors across several states and...
medpagetoday.com
Stem cells in circulating blood affect cardiovascular health, study finds
New research suggests that attempts to isolate an elusive adult...
medicalxpress.com
Rural microbes could boost city dwellers' health
The greater prevalence of asthma, allergies and other chronic inflammatory...
medicalxpress.com
FDA Considers Ban on 'Aversive' Shock Devices
(MedPage Today) -- An FDA advisory committee will consider on...
medpagetoday.com
Big Data in Biomedicine technical showcase to feature companies’ innovations related to big data
In an effort to spark collaboration among thought leaders across...
scopeblog.stanford.edu
People with mild cognitive impairment may die at higher rate than people without condition
Mayo Clinic research studying the relationship between death and the...
medicalxpress.com
Marijuana use may increase heart complications in young, middle-aged adults
Marijuana use may result in cardiovascular-related complications—even death—among young and...
medicalxpress.com
People with more education may recover better from traumatic brain injury
People with more years of education may be better able...
medicalxpress.com
Iron consumption can increase risk for heart disease, study says
A new study from the Indiana University School of Public...
medicalxpress.com
Cyber buddy is better than 'no buddy'
A Michigan State University researcher is looking to give exercise...
medicalxpress.com
Study Suggests Heart Risk From Smoking Pot (CME/CE)
(MedPage Today) -- A French study provided support for an...
medpagetoday.com
Pollutants from coal-burning stoves strongly associated with miscarriages in Mongolia
Burning coal for domestic heating may contribute to early fetal...
medicalxpress.com
ASTRO issues guideline on the role of postoperative radiation therapy for endometrial cancer
The American Society for Radiation Oncology (ASTRO) has issued a...
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 +