Antihistamines Research Paper
Histamines and Antihistamines Neurotransmitters are chemical compounds that are central nervous system stimulants that mainly transmit nerve impulses with another cell or muscle. They are released in the synapse which chemically help signal one neuron to the next. One of the nerve cells that influence neurotransmitter release and stimulate the central nervous system pathway are histamines. It is specifically located in the nerve cells of the hypothalamus. All neurotransmitters structurally contain amines and are synthesized from amino acids in our diet. They are typically ionized, which means they undergo some positively charged chemical functionality. Histamine is an organic molecule chemically generated from the amino acid
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histidine, which includes a positively charged nitrogen known as an ammonium ion and a carboxylate group that is removed and converted to carbon dioxide. When the immune system responds to an allergen, it becomes hypersensitive, thus activating mast cells and creating an allergic reaction from more histamine that is being released. Researchers think nasal allergies affect about 50 million people in the United States. Allergies are increasing. They affect as many as 30 percent of adults and 40 perfect of children (1).
Although histamine is part of the human body’s defense mechanism, it causes a range of allergic reactions. Many people suffer from allergies, which often result in serious problems or death. When histamine combines with histamine receptors, it causes allergic reactions, which may include inflammation, watery eyes, itchy skin, and hay fever. Histamine can also cause smooth muscle constriction, such as the closing of the trachea in persons allergic to shellfish (2). In addition, histamine dilates blood vessels, increases the permeability of the cells, and causes redness and swelling (3). The most fatal allergic reaction is anaphylactic shock because it involves severely affecting two or more organs. Symptom reports from questionnaires were categorized into 5 organic systems: (1) respiratory, increased breathing rate, cough, wheeze, chest tightness, throat itching, and/or hoarse voice; (2) skin and subcutaneous tissue, including itching, rash, hives, eye swelling, lip swelling, or tongue swelling; (3) gastrointestinal, including cramps, abdominal pain, vomiting, and/or diarrhea; (4) neurologic, including feelings of uneasiness and/or sudden behavioral change (in young children); and (5) cardiovascular, including dizziness, loss of consciousness, low blood pressure, and/or loss of bladder or bowel control (4). One of the foods that can cause this fatal reaction are peanuts. 1.5 million Americans are allergic to peanuts . . . resulting in 50 to 100 deaths a year and thousands of hospital visits (5). The most common triggers reported were medications (34%), foods (31%), and insect stings (20%) (4).
People take medications to block the action of histamine, known as antihistamines that control or inhibit allergy symptoms that are caused by foreign pathogens. Allergic reactions are reduced or stopped when antihistamine bind to the histamine receptors, therefore preventing histamine from combining with those receptors. Some antihistamines include Benadryl, Zantac, and Tagamet. Using an antihistamine such as diphenhydramine helps reduce the effects of histamine (3). Some of the alternatives to help stop or reduce histamine activity are steroid hormones and systematic desensitization. Adrenal cortical steroids may be used to decrease the reaction. Desensitization (the process of making the patient able to tolerate the antigen without having a reaction) may be accomplished by giving injections of antigen, first in minute doses and then in gradually increasing doses as tolerance builds up (6). Another alternative that helps combat histamine release is caffeine consumption. Researches have found that in rats caffeine can block acute allergic reactions such as anaphylactic shock (7). They have discovered that caffeine alleviates some severe allergic reactions because it reduces the amount of histamine being released from the mast cells. The most effective treatment for anaphylactic shock is injecting adrenaline, also known as epinephrine.
Studying the activity of histamines and how they are opposed by antihistamines has been one of the major efforts the medical community for many years and a strong understanding has since emerged. So much more so that the costs and figures of allergies. In 2010, Americans with nasal swelling spent about $17.5 billion on health costs. They have also lost more than 6 million work and school days and made 16 million visits to their doctor. Food allergies cost about $25 billion each year (8). In addition, skin and blood testing for allergies are highly expensive and health insurance may or may not pay for them. There are people who also struggle financially because they do not have health insurance. A skin allergy test can cost $60 to $300. A blood test can cost $200 to $1,000 (9). However, people have found relief without a prescription by purchasing affordable and generic over-the-counter medicine. When it comes to price, there is a big difference between generic and brand name drugs. On average, the cost of a generic drug is 80 to 85 percent lower than the brand name product. In 2010 alone, the use of FDA-approved generics saved $18 billion, an average of $3 billion every week (10).
Antihistamines are generally classified into three generations depending on their side effects and vector of treatment.
First generation antihistamines include, brompheniramine (Dimetane), hydroxyzine (Vistaril), chlorpheniramine (Aller-Chlor), clemastine (Tavist), and diphenhydramine (Benadryl). Most of the first-gen medications are recommended less often due to their side effects. They are capable of moderately to severely impairing a person depending on dosage. This is because all first generation antihistamines are highly lipophilic and that enables them to easily pass through a blood-brain barrier. So while they are effective at reducing allergy symptoms, it also affects their central nervous system. This makes the person much more susceptible to the sedating effects and why there are so many warnings against taking allergy medications with alcohol. The second generation antihistamines are regarded as less sedating because they have been designed to be hydrophobic and to not cross the blood-brain barrier. Second generation Antihistamines include loratadine (Claritin), cetirizine (Zyrtec), and levocetirizine (Xyzal). In addition to causing less severe side effects, this class of medications have longer half lives than their predecessors. This is a great benefit to patients since dosages could be dropped from several times a day to just one or two per day. Third generation antihistamines are a refined version of their
first
histidine, which includes a positively charged nitrogen known as an ammonium ion and a carboxylate group that is removed and converted to carbon dioxide. When the immune system responds to an allergen, it becomes hypersensitive, thus activating mast cells and creating an allergic reaction from more histamine that is being released. Researchers think nasal allergies affect about 50 million people in the United States. Allergies are increasing. They affect as many as 30 percent of adults and 40 perfect of children (1).
Although histamine is part of the human body’s defense mechanism, it causes a range of allergic reactions. Many people suffer from allergies, which often result in serious problems or death. When histamine combines with histamine receptors, it causes allergic reactions, which may include inflammation, watery eyes, itchy skin, and hay fever. Histamine can also cause smooth muscle constriction, such as the closing of the trachea in persons allergic to shellfish (2). In addition, histamine dilates blood vessels, increases the permeability of the cells, and causes redness and swelling (3). The most fatal allergic reaction is anaphylactic shock because it involves severely affecting two or more organs. Symptom reports from questionnaires were categorized into 5 organic systems: (1) respiratory, increased breathing rate, cough, wheeze, chest tightness, throat itching, and/or hoarse voice; (2) skin and subcutaneous tissue, including itching, rash, hives, eye swelling, lip swelling, or tongue swelling; (3) gastrointestinal, including cramps, abdominal pain, vomiting, and/or diarrhea; (4) neurologic, including feelings of uneasiness and/or sudden behavioral change (in young children); and (5) cardiovascular, including dizziness, loss of consciousness, low blood pressure, and/or loss of bladder or bowel control (4). One of the foods that can cause this fatal reaction are peanuts. 1.5 million Americans are allergic to peanuts . . . resulting in 50 to 100 deaths a year and thousands of hospital visits (5). The most common triggers reported were medications (34%), foods (31%), and insect stings (20%) (4).
People take medications to block the action of histamine, known as antihistamines that control or inhibit allergy symptoms that are caused by foreign pathogens. Allergic reactions are reduced or stopped when antihistamine bind to the histamine receptors, therefore preventing histamine from combining with those receptors. Some antihistamines include Benadryl, Zantac, and Tagamet. Using an antihistamine such as diphenhydramine helps reduce the effects of histamine (3). Some of the alternatives to help stop or reduce histamine activity are steroid hormones and systematic desensitization. Adrenal cortical steroids may be used to decrease the reaction. Desensitization (the process of making the patient able to tolerate the antigen without having a reaction) may be accomplished by giving injections of antigen, first in minute doses and then in gradually increasing doses as tolerance builds up (6). Another alternative that helps combat histamine release is caffeine consumption. Researches have found that in rats caffeine can block acute allergic reactions such as anaphylactic shock (7). They have discovered that caffeine alleviates some severe allergic reactions because it reduces the amount of histamine being released from the mast cells. The most effective treatment for anaphylactic shock is injecting adrenaline, also known as epinephrine.
Studying the activity of histamines and how they are opposed by antihistamines has been one of the major efforts the medical community for many years and a strong understanding has since emerged. So much more so that the costs and figures of allergies. In 2010, Americans with nasal swelling spent about $17.5 billion on health costs. They have also lost more than 6 million work and school days and made 16 million visits to their doctor. Food allergies cost about $25 billion each year (8). In addition, skin and blood testing for allergies are highly expensive and health insurance may or may not pay for them. There are people who also struggle financially because they do not have health insurance. A skin allergy test can cost $60 to $300. A blood test can cost $200 to $1,000 (9). However, people have found relief without a prescription by purchasing affordable and generic over-the-counter medicine. When it comes to price, there is a big difference between generic and brand name drugs. On average, the cost of a generic drug is 80 to 85 percent lower than the brand name product. In 2010 alone, the use of FDA-approved generics saved $18 billion, an average of $3 billion every week (10).
Antihistamines are generally classified into three generations depending on their side effects and vector of treatment.
First generation antihistamines include, brompheniramine (Dimetane), hydroxyzine (Vistaril), chlorpheniramine (Aller-Chlor), clemastine (Tavist), and diphenhydramine (Benadryl). Most of the first-gen medications are recommended less often due to their side effects. They are capable of moderately to severely impairing a person depending on dosage. This is because all first generation antihistamines are highly lipophilic and that enables them to easily pass through a blood-brain barrier. So while they are effective at reducing allergy symptoms, it also affects their central nervous system. This makes the person much more susceptible to the sedating effects and why there are so many warnings against taking allergy medications with alcohol. The second generation antihistamines are regarded as less sedating because they have been designed to be hydrophobic and to not cross the blood-brain barrier. Second generation Antihistamines include loratadine (Claritin), cetirizine (Zyrtec), and levocetirizine (Xyzal). In addition to causing less severe side effects, this class of medications have longer half lives than their predecessors. This is a great benefit to patients since dosages could be dropped from several times a day to just one or two per day. Third generation antihistamines are a refined version of their
first