Basics of antihistamines and asthma drugs | MPO training 21
If you're planning to become a Medical Promotion Officer (MPO), understanding
the basics of antihistamines and asthma drugs is a must. This article explains
these medicines in a way that’s easy to grasp, even if you're just starting
your career. You'll learn how they work, when they are used, and why every MPO
should know them.
Whether you're new or experienced, this topic is vital. It helps you speak
confidently with doctors and healthcare professionals. By reading this, you’ll
be one step closer to becoming a successful MPO.
Table of contents: Basics of antihistamines and asthma drugs
Check out the table of contents of the article-
Basics of antihistamines and asthma drugs
What are the basics of antihistamines and asthma drugs?
Antihistamines help reduce allergic symptoms by blocking histamine, while
asthma drugs help open airways and control breathing. Both types of medicine
are essential for Medical Promotion Officers (MPOs) to understand.
This article breaks down the basics of antihistamines and asthma drugs in
simple terms, helping you explain their use to healthcare professionals. If
you're aiming for an MPO job, this is key knowledge for success.
What are respiratory diseases?
Respiratory diseases are illnesses that affect the lungs and other parts of
the respiratory system, such as the trachea, bronchi, and alveoli. They can
be caused by infections, environmental factors, or chronic conditions.
Now we will gradually discuss the basics of respiratory diseases—
- The basics of antihistamines and
- The basics of antiasthmatic drugs
The basics of antihistamines
What is Histamine?
Histamine is a substance found in virtually all animal body cells. It is
produced from the amino acid-Histidine, which causes the dilation of
blood vessels, increased secretion of acid by the stomach, smooth muscle
constriction (e.g. in the bronchi), mucus production, tissue swelling
and itching (during allergic reactions).
What is Antihistamine?
An antihistamine (or histamine antagonist) is an agent that inhibits the
actions of histamine by blocking histamine receptors.
H₁ antihistamines are used as the treatment for symptoms of allergies,
such as sneezing, runny nose, watery eyes, itching etc.
Note:
- H₁ antihistamines are generally used for allergies.
- H₂ antihistamines are used to reduce stomach acid.
Mode of action of all antihistamines
H₁-antihistamines work by binding to histamine H₁ receptors in mast cells,
smooth muscle, and endothelium in the body. Antihistamines that target the
histamine H₁-receptor are used to treat allergic reactions.
This diagram is a flowchart that explains the mode of action of all
antihistamines.
Step-by-step explanation:
1. Allergen (Dust, Pollen, etc.)
- → Allergens (like dust and pollen) enter the body.
2. Mast Cell
- → The allergen activates the mast cell.
3. Histamine
- → Histamine is released from the mast cell.
4. Then, there are two possible pathways:
-
Histamine + H₁ Receptor → Allergic Reaction
- → This combination causes an allergic reaction.
-
Anti-Histamine + H₁ Receptor → No Allergic Reaction
- → If antihistamines occupy the H₁ receptor, the allergic reaction does not occur.
The diagram mainly shows how antihistamines block the action of histamine
to prevent allergic reactions.
Terminology
Allergen: A substance that is capable of producing an allergic
reaction.
Allergic rhinitis: Allergic rhinitis more commonly referred to as
hay fever, is an inflammation of the nasal passages caused by allergic
reaction to airborne substances. Allergic rhinitis may be seasonal,
perennial & occupational. The symptoms include nasal congestion,
clear runny nose, itching in nose, sneezing etc.
Mast cells: The allergy causing cells that release chemicals like
histamine. They are very close to basophil granulocyte (a WBC) and are
widely found in skin, lung mucosa, digestive tract, mouth, conjunctiva
& nose.
Drug rash: A skin eruption (redness or spotting), usually an
allergic reaction, that is caused by a particular drug. Generally a drug
rash that is a sensitivity reaction does not occur the first time the
drug is taken, but the effect is observed with subsequent uses.
Hay fever: An acute allergic reaction to pollen that is usually
seasonal and is marked by sneezing, nasal discharge & congestion,
itching and watering of the eyes.
Anticholinergic: Inhibiting or blocking the physiological action
of acetylcholine at a receptor site used to control intestinal spasm.
Anticholinergics can increase the heart rate, dilate the pupils for
examination of the eyes, dry mouth etc.
Idiopathic: Of, relating to, or designating a disease having no
known cause.
Prophylaxis: Prevention of or protective treatment for disease.
Pruritus: An itching sensation or feeling that makes a person
scratch.
Sedative: A drug that can produce sedation (relaxed, often sleepy
state).
Dizziness: A sensation of faintness or an inability to maintain
normal balance in a standing or seated position.
Drowsiness: A state of impaired awareness associated with a
desire to sleep.
Vasomotor rhinitis: Inflammation of the nose (rhinitis) due to
abnormal neuronal (nerve) control of the blood vessels in the nose.
Vasomotor rhinitis is not allergic rhinitis.
ACME's Antihistamines
| Brand | Generic |
|---|---|
| Rhitin | Ebastine |
| Histalex | Chlorpheniramine |
| Mebolin | Mebhydrolin |
| Cetizin | Cetirizine |
| Orin | Loratadine HCl |
| Phenadryl | Diphenhydramine |
| Orinex | Desloratadine |
| Ketifen | Ketotifen Fumarate |
| Alanil | Fexofenadine Hel |
| Rupastin | Rupatadine Fumarate |
| Bilan | Bilostin |
The basics of antiasthmatic drugs
What is Asthma?
- The term "asthma" comes from the Greek meaning, "to breathe hard." Asthma is a chronic obstructive inflammatory disease of the airways that causes acute bronchospasm and dyspnea.
- A chronic inflammatory disorder of the airways.
- Inflammation (swelling) of the lining of the airways.
- Bronchoconstriction (tightening of the bands of smooth muscles surrounding the airways) which reduces the width of the airways.
- Excess mucus production that further narrows the airways.
Symptoms of Asthma
- Dyspnea
- Chest Tightness
- Wheezing
- Night Awakening
- Coughing
Types of Asthma
1. Allergic Asthma: Allergic asthma is caused by allergen
substances capable of causing an allergic reaction.
2. Intrinsic asthma: Not likely to develop in children; its
typical onset occurs after age 40.
3. Nocturnal Asthma: Nocturnal, or sleep-related, asthma affects
people when they are sleeping.
4. Occupational Asthma: Occupational asthma occurs directly as a
result of breathing chemicals, wood dust, or other irritants over long
periods of time.
5. Juvenile asthma: Juvenile asthma is a type of breathing
problem that occurs in children and teenagers, where the airways become
narrow and inflamed. It causes coughing, shortness of breath, and chest
tightness.
Triggering Factors of Asthma
The most common triggers of asthma are:
- Viral respiratory infections, such as influenza (the flu) or bronchitis.
- Bacterial infections, including sinus infections.
- Allergic rhinitis.
- Irritants, such as pollution, cigarette smoke, perfumes, dust, or chemicals.
- Sudden changes in either temperature or humidity, especially exposure to cold air.
- Allergens, for people with allergies.
- Emotional upsets, such as stress.
- Exercise etc.
Treatment & Management of asthma
Asthma cannot be cured, but it can be controlled with proper asthma
management.
Medications: There are seven major classes of asthma
medications-
1. Beta-agonists
- a. Short acting bronchodilator (SABA)
- b. Long acting bronchodilator (LABA)
2. Steroidal anti-inflammatories drugs
3. Non-steroidal anti-inflammatories Drugs
4. Xanthines
5. Anticholinergics
6. Leukotriene receptor antagonists Ex: Montelukast (Monas by ACME)
7. Anti-allergic (Antihistamines)
Note:
- SABA = Short-Acting Beta-2 Agonist
- LABA = Long-Acting Beta-2 Agonist
These are classes of bronchodilators used to treat asthma and other
respiratory conditions:
- SABA (e.g., salbutamol/albuterol) provides quick relief by relaxing airway muscles — often used as a rescue inhaler.
- LABA (e.g., salmeterol, formoterol) provides long-term control and is used as maintenance therapy, not for immediate symptom relief.
Some Terminology
Bronchitis: Bronchitis is inflammation of the mucous
membranes of the bronchi, the airways that carry airflow from the
trachea into the lungs.
Bronchospasm: Bronchospasm or a bronchial spasm is a sudden
constriction of the muscles in the walls of the bronchioles.
Bronchoconstriction: Bronchoconstriction is the constriction
of the airways in the lungs due to the tightening of surrounding
smooth muscle, with consequent coughing, wheezing, and shortness of
breath.
COPD: Chronic obstructive pulmonary disease (COPD) is the
co-occurrence of chronic bronchitis and emphysema, a pair of
commonly co-existing diseases of the lungs in which the airways
become narrowed.
Emphysema: Emphysema is a lung condition that causes
shortness of breath. In people with emphysema, the air sacs in the
lungs (alveoli) are damaged. Over time, the inner walls of the air
sacs weaken and rupture.
ACOS: ACOS means Asthma and COPD happening together. It
causes breathing difficulty, cough, and wheezing. It usually occurs
in older people or smokers with lung problems. Proper use of
inhalers and medicines can help control it.
- ACOS = Asthma and COPD Overlapping Syndrome.
Types of Inhalers
- MDI: Metered Dose Inhaler
- DPI: Dry Powder Inhaler
MDI (Metered Dose Inhaler): This is a pressurized inhaler
that delivers a specific amount of medication with each puff. It
releases the medicine in the form of aerosol mist, and the user
must coordinate pressing the inhaler and inhaling at the same
time. It's commonly used for asthma and other respiratory
conditions.
DPI (Dry Powder Inhaler): This type of inhaler delivers
medication in a dry powder form. The patient needs to inhale
deeply and forcefully to draw the medicine into the lungs. It
doesn’t use any propellant, making it breath-actuated and often
easier to use for some patients.
Both types are effective for delivering medicine directly to the
lungs, and the choice depends on the patient's condition and
ability to use the device properly.
Cough Preparations
A cough, is a voluntary or involuntary act that clears the throat and
breathing passage of foreign particles. microbes, Imitants, fluids, and
mucus; it is a rapid expulsion of air from the lungs. Coughing can be
done deliberately or as part of a reflex.
Cough Types: Basically 2 Types
- a. Wet cough, also called a productive cough, is a cough that typically brings up mucus.
- b. Dry cough is a cough that doesn't bring up mucus. It may feel like you have a tickle in the back of your throat triggering your cough reflex, giving you hacking coughs.
What causes a cough?
A cough can be caused by several conditions, both temporary and
permanent.
a. Clearing the throat
Coughing is a standard way of clearing your throat. When your
airways become clogged with mucus or foreign particles such as smoke
or dust, a cough is a reflex reaction that attempts to clear the
particles and make breathing easier.
Usually, this type of coughing is relatively infrequent, but
coughing will increase with exposure to irritants such as smoke.
b. Viruses and bacteria
The most common cause of a cough is a respiratory tract infection,
such as a cold or flu.
Respiratory tract infections are usually caused by a virus and may last
from a few days to a week. Infections caused by the flu may take a
little longer to clear up and can sometimes require antibiotics.
c. Smoking
Smoking is a common cause of coughing. A cough caused by smoking is
almost always a chronic cough with a distinctive sound. It's often known
as a smoker's cough.
d. Asthma
A common cause of coughing in young children is asthma. Typically,
asthmatic coughing involves wheezing, making it easy to identify.
Asthma exacerbations should receive treatment using an inhaler. It's
possible for children to grow out of asthma as they get older.
e. Medicines
Some medications will cause coughing, although this is generally a rare
side effect. Angiotensin-converting enzyme (ACE) inhibitors, commonly
used to treat high blood pressure and heart conditions, can cause
coughing.
Two of the more common ones are:
- Zestril (lisinopril)
- Vasotec (enalapril)
The coughing stops when the medication is discontinued.
f. Other conditions
Other conditions that may cause a cough include:
- damage to the vocal cords
- postnasal drip
- bacterial infections such as pneumonia, whooping cough, and croup
- serious conditions such as pulmonary embolism and heart failure
Another common condition that can cause a chronic cough is
gastroesophageal reflux disease (GERD). In this condition, stomach
contents flow back into the esophagus. This backflow stimulates a reflex
in the trachea, causing the person to cough.
Some important definition
1. Mucus: Mucus is a slippery secretion of the lining of the
mucous membranes in the body. It is a viscous colloid containing
antiseptic enzymes (such as lysozyme) and immunoglobulin. Mucus is
produced by goblet cells in the mucous membranes that cover the surfaces
of the membranes. It is made up of mucins and inorganic salts suspended
in water.
2. Phlegm: Phlegm is sticky fluid produced by the respiratory
system, excluding that from the nasal passages, and particularly that
which is expelled by coughing (Sputum). In the mouth it mixes with
saliva (spit) to become sputum, which is then expectorated: phlegm plus
saliva equals sputum, which is commonly studied by doctors to give signs
of what is happening in the lungs.
3. Chesty cough: In chesty coughs a patient will expel phlegm and
mucus when coughing.
4. Sputum: Sputum is matter that is coughed up from the
respiratory tract, such as mucus or phlegm mixed with saliva and then
expectorated from the mouth.
5. Expectorant: This helps when one has thick chest congestion,
which he is unable to cough up. It loosens thick mucus, making it easier
to cough up. They increase the volume and decrease the thickness of
secretions in the airways.
6. Mucolytic agent: Mucolytic agent is any agent, which
dissolves thick mucus usually used to help relieve respiratory
difficulties. (Hydrolyzing, glycosaminoglycans: tending to break
down/lower the viscosity of mucin-containing body
secretions/components). The viscosity of mucous secretions in the lungs
is dependent upon the concentrations of mucoprotein, the presence of
disulfide bonds between these macromolecules and DNA.
7. Allergic rhinitis: Allergic rhinitis, more commonly referred
to as hay fever, is an inflammation of the nasal passages caused by
allergic reaction to airborne substances.
Allergic rhinitis may be seasonal, perennial & occupational. The
symptoms include nasal congestion, clear runny nose, itching in nose,
sneezing etc.
8. Antitussive: An agent which is capable of relieving or
suppressing coughing.
9. Decongestant: A decongestant or nasal decongestant is a type
of drug which is used to relieve nasal congestion.
10. Edema: It is the swelling of soft tissues as a result of
excess fluid accumulation.
11. Expectorant: A medication that helps to bring up mucus and
other material from the lungs, bronchi, and trachea. (Ex-out of +
Pectus-chest)
12. Mucopolysaccharide: A group of polysaccharides which contain
hexosamine in their structure. Mucopolysaccharides form many of the
mucins when dispersed in water. (Mucin is a glycoprotein).
13. Phlegm: It is the thick, sticky, stringy mucus secreted by
the mucous membrane of the respiratory tract, as during a cold or other
respiratory infection.
14. Pneumoconiosis: Any disease of the lungs caused by chronic
inhalation of dust, usually mineral dusts of occupational or
environmental origin. The principal agents include coal, cotton, sand,
and asbestos (a fibrous incombustible magnesium & calcium silicate).
15. Sputum: Matter coughed up and usually ejected from the
trachea, bronchi & lungs through the mouth. (Saliva + Phlegm/Mucus =
Sputum).
16. Vasomotor rhinitis: Inflammation of the nose (rhinitis) due
to abnormal neuronal (nerve) control of the blood vessels in the nose.
Vasomotor rhinitis is not allergic rhinitis.
Cough Preparations by ACME and Their Generics
| ACME Brand | Generic Name |
|---|---|
| X-Cold | Ambroxol Hydrochloride |
| A-Cold | Bromhexine Hydrochloride |
| A-Cof | Dextromethorphan + Pseudoephedrine + Triprolidine |
| Cofrid | Guaifenesin + Dextromethorphan + Menthol |
| Butacite | Butamirate Citrate |
| Cintos | Guaifenesin + Levomenthol + Diphenhydramine |
FAQs
1. What is the difference between first-generation and
second-generation antihistamines?
First-generation antihistamines often cause drowsiness and sedation,
while second-generation antihistamines are less likely to cause these
side effects. Second-generation antihistamines are commonly preferred
for allergy treatment.
2. How do bronchodilators work in asthma treatment?
Bronchodilators relax the muscles around the airways, helping to open
them up and improve airflow to the lungs. They provide quick relief from
asthma symptoms and are often used in rescue inhalers.
3. What are the symptoms of respiratory diseases?
Symptoms of respiratory diseases vary but can include cough, shortness
of breath, wheezing, chest tightness, fatigue, and increased mucus
production. Severe cases may lead to respiratory failure.
4. What is the role of the lungs in respiratory diseases?
The lungs are responsible for oxygenating blood and expelling carbon
dioxide. Respiratory diseases often impair lung function, leading to
difficulty in breathing, reduced oxygen levels, and other complications.
5. What is the difference between restrictive and obstructive lung
diseases?
Restrictive lung diseases, like pulmonary fibrosis, reduce lung
expansion, leading to less air intake. Obstructive diseases, like asthma
and COPD, block airflow, making it harder to exhale.
6. How is respiratory disease diagnosed?
Respiratory diseases are diagnosed through physical exams, patient
history, chest X-rays, CT scans, pulmonary function tests (PFTs), and
blood tests to assess lung function and oxygen levels.
Conclusion
To sum up, learning the basics of antihistamines and asthma drugs is not
just about knowing medicines—it’s about being confident in your role as
a Medical Promotion Officer (MPO). This knowledge helps you build trust
with doctors and ensures you represent your company with clarity.
Whether you are new to the field or preparing for an MPO job, this
article gives you a strong foundation. Keep learning and applying—your
success depends on it.
Sarwar Hossain Himel
I am Sarwar Hossain Himel — a sports-loving person. Education: I have obtained a BBA and MBA degree in Accounting. Profession: Currently, I am working as a Medical Promotion Officer (MPO). In addition, I have over 5 years of experience in teaching. Freelance Work: I work as a Google Blogger and Article Writer in freelancing. Passion: I love doing web design and digital marketing. Especially, web design is one of my passions.