Overview

• Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma is a lung condition characterized by:
  • Airway hyperresponsiveness (due to release of mediators, e.g., histamine)
  • Variable airway obstruction Airway obstruction Airway obstruction is a partial or complete blockage of the airways that impedes airflow. An airway obstruction can be classified as upper, central, or lower depending on location. Lower airway obstruction (LAO) is usually a manifestation of chronic disease, such as asthma or chronic obstructive pulmonary disease (COPD). Airway Obstruction (due to bronchoconstriction and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation)
  • Airway inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation (due to recruitment of inflammatory cells)
• Goals of asthma management:
  • Preventing/reversing bronchoconstriction:
    • β-agonists (e.g., albuterol)
    • Methylxanthines (e.g., theophylline)
    • Muscarinic agonists (e.g., ipratropium)
  • Preventing mast cell degranulation:
    • Anti-IgE (immunoglobulin E) monoclonal antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins (e.g., omalizumab)
    • Chromones or cromoglycates (e.g., cromolyn)
  • Preventing the release of inflammatory mediators:
    • Corticosteroids
    • Antileukotrienes (e.g., montelukast, zafirlukast, zileuton)
    • Antibodies (e.g., mepolizumab)

Bronchodilators: β2-Agonists

Types and administration

• SABA: 
  • Albuterol (inhalation, oral)
  • Levalbuterol (inhalation)
  • Terbutaline (oral, intravenous (IV))
• LABA:
  • Salmeterol (inhalation)
  • Formoterol (inhalation)
  • Vilanterol (inhalation)

Mechanism of action and effects

• Drug binds the β-2 receptor.
• Effect: stimulates cAMP in smooth muscle cells → smooth muscle relaxation → dilation of bronchioles
• SABA: duration of 4–6 hours and onset within 5 minutes
• LABA: duration of up to 12 hours

Clinical uses

• SABA:
  • Rapidly acting bronchodilator, used in acute asthma exacerbation 
  • Oral form not recommended for acute exacerbation (longer onset of action, less effective bronchodilation)
• LABA: 
  • Used only with inhaled corticosteroids, not as a monotherapy
  • Combined inhaled CS and LABA (low-dose inhaled CS-formoterol): can be used as acute symptom reliever (Global Initiative for Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma guidelines)
  • Used for exercise-induced bronchoconstriction and prevention of nocturnal symptoms

Side effects

• β2-mediated skeletal muscle tremors (most common side effect)
• Other effects: 
  • Tachycardia (cardiac β receptor stimulation)
  • Hyperglycemia
  • Hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia

Precautions

• Use with caution in cardiovascular disease (arrhythmia, heart failure, coronary artery disease).
• May increase glucose in diabetics
• May elevate intraocular pressure in glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma

Bronchodilators: Muscarinic Antagonists

Types and administration

• SAMA: ipratropium bromide (inhalation)
• LAMA: tiotropium bromide (inhalation)

Mechanism of action and effects

• Competitively block muscarinic receptors, thereby preventing vagal-induced bronchoconstriction
• ↓ cyclic guanosine monophosphate (cGMP) → ↓ smooth muscle contraction Smooth muscle contraction Smooth muscle is primarily found in the walls of hollow structures and some visceral organs, including the walls of the vasculature, GI, respiratory, and genitourinary tracts. Smooth muscle contracts more slowly and is regulated differently than skeletal muscle. Smooth muscle can be stimulated by nerve impulses, hormones, metabolic factors (like pH, CO2 or O2 levels), its own intrinsic pacemaker ability, or even mechanical stretch. Smooth Muscle Contraction and ↓ mucus secretion
• No anti-inflammatory effect

Clinical uses

• Less effective than β2-agonists for acute exacerbation but with additive benefit
• Long-term maintenance treatment in children > 6 years of age and adults with severe symptomatic asthma uncontrolled with inhaled CS
• Also used in chronic obstructive pulmonary disease Chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)

Side effects

• Few systemic effects because of poor absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption into the circulation
• Minor atropine-like effects with high doses

Precautions

• Use with caution in patients with narrow-angle glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma (can increase intraocular pressure).
• Bladder neck obstruction/prostatic hyperplasia (may cause urinary retention)

Bronchodilators: Methylxanthines

Types and administration

• Theophylline (oral, IV)
• Theobromine (found in cocoa) and caffeine (found in coffee) are also methylxanthines.

Mechanism of action and effects

• Blockage of receptors for adenosine (which provokes smooth muscle contraction Smooth muscle contraction Smooth muscle is primarily found in the walls of hollow structures and some visceral organs, including the walls of the vasculature, GI, respiratory, and genitourinary tracts. Smooth muscle contracts more slowly and is regulated differently than skeletal muscle. Smooth muscle can be stimulated by nerve impulses, hormones, metabolic factors (like pH, CO2 or O2 levels), its own intrinsic pacemaker ability, or even mechanical stretch. Smooth Muscle Contraction and histamine release) 
• Inhibition of phosphodiesterase (which degrades cyclic adenosine monophosphate (cAMP)) → smooth muscle relaxation
• Overall, results in bronchodilation and reduced inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation

Clinical uses

• Nonpreferred alternative for asthma that is uncontrolled with inhaled CS
• Decreases exacerbations; has similar effect as increasing the dosage of the inhaled CS
• Modest anti-inflammatory action
• Narrow therapeutic index and serum concentration must be monitored regularly.
• Despite disadvantages, theophylline is used in some countries due to low cost.

Side effects

• Gastrointestinal symptoms (nausea, vomiting), tremor, headache
• Toxic doses:  hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, cardiac arrhythmias, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, and possibly death

Precautions

• Limited use due to significant side effects and life-threatening toxicity
• Use with caution in patients with seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, cardiac arrhythmias, hepatic impairment, peptic ulcer disease Peptic ulcer disease Peptic ulcer disease (PUD) refers to the full-thickness ulcerations of duodenal or gastric mucosa. The ulcerations form when exposure to acid and digestive enzymes overcomes mucosal defense mechanisms. The most common etiologies include Helicobacter pylori (H. pylori) infection and prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs). Peptic Ulcer Disease, and hyperthyroidism Hyperthyroidism Thyrotoxicosis refers to the classic physiologic manifestations of excess thyroid hormones and is not synonymous with hyperthyroidism, which is caused by sustained overproduction and release of T3 and/or T4. Graves' disease is the most common cause of primary hyperthyroidism, followed by toxic multinodular goiter and toxic adenoma. Thyrotoxicosis and Hyperthyroidism.

Corticosteroids

Types and administration

• Inhaled corticosteroids (ICS): beclomethasone, budesonide, fluticasone, mometasone, triamcinolone  
• Systemic corticosteroids:
  • Oral CS: prednisone, prednisolone 
  • IV CS: hydrocortisone, methylprednisolone

Mechanism of action and effects

• Blocks the release of arachidonic acid (via phospholipase A2 inhibition), consequently halting the release of inflammatory mediators
• Effects: 
  • ↓ airway hyperresponsiveness
  • ↓ airway mucosal edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • ↓ capillary permeability
  • ↓ leukotriene release

Clinical uses

• ICS: generally, the most effective anti-inflammatory agent for the treatment of asthma
• Drug of choice for long-term control of persistent asthma
• Short-term oral CS treatment (< 7 days) of acute severe exacerbations
• Tapering required if oral CS > 2 weeks

Side effects

• ICS:
  • Less severe and fewer than those of systemic CS
  • Local effects:
    • Dysphonia: less common with devices that produce smaller-sized particles 
    • Thrush: can be avoided by a large-volume spacer with metered-dose inhalers (MDIs); rinsing of the oropharynx and spacer after inhalation also helps
  • Much less common:
    • Deceleration of growth velocity in children
    • Adrenal suppression
    • Cataracts
• Systemic CS side effects: adrenal suppression, weight gain, diabetes, hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, immune suppression, osteoporosis Osteoporosis Osteoporosis refers to a decrease in bone mass and density leading to an increased number of fractures. There are 2 forms of osteoporosis: primary, which is commonly postmenopausal or senile; and secondary, which is a manifestation of immobilization, underlying medical disorders, or long-term use of certain medications. Osteoporosis, and depression

Antileukotriene Agents

Types and administration

• Leukotriene receptor antagonists (LTRAs): zafirlukast, montelukast (oral)
• 5-lipoxygenase inhibitor: zileuton (oral)

Mechanism of action and effects

• Zileuton: selective inhibition of 5-lipoxygenase (thus preventing conversion of arachidonic acid to leukotrienes)
• Zafirlukast and montelukast: inhibit leukotriene (LT)-D4 receptors and LTE4 receptors
• Effects (by targeting leukotriene): 
  • ↓ smooth airway contraction
  • ↓ vascular permeability and mucus secretion
  • Reduced activation of inflammatory cells

Clinical uses

• Exercise-induced bronchospasm
• Mild persistent asthma + allergic rhinitis Rhinitis Rhinitis refers to inflammation of the nasal mucosa. The condition is classified into allergic, nonallergic, and infectious rhinitis. Allergic rhinitis is due to a type I hypersensitivity reaction. Non-allergic rhinitis is due to increased blood flow to the nasal mucosa. Infectious rhinitis is caused by an upper respiratory tract infection. Rhinitis
• Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma and aspirin-exacerbated respiratory disease
• Additive benefit for moderate-to-severe persistent asthma
• Considered in patients with difficulty with compliance or inhaler technique (e.g., children)

Side effects

• Common: headaches, fatigue, dyspepsia 
• Neuropsychiatric adverse effects: behavior and mood-related changes (especially montelukast) 
• Zafirlukast and zileuton: 
  • Potentially hepatotoxic, requiring liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver function test monitoring
  • Drug interactions (including increased warfarin effect)
• Eosinophilic granulomatous polyangiitis can develop when antileukotrienes are given to patients with steroid-dependent asthma.

Precautions

• Zafirlukast and zileuton: 
  • Contraindicated in liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver disease/hepatic impairment
  • Monitor for mood and behavioral changes
• Montelukast: 
  • Monitor for mood and behavioral changes
  • Contains phenylalanine (not recommended for patients with phenylketonuria)

Mast Cell Stabilizers (Chromones)

Types and administration

• Cromolyn (nebulization)
• Nedocromil (not available for asthma treatment in the United States)

Mechanism of action and effects

• Prevents the degranulation of mast cells, thereby preventing local inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation 
• Prevents early and late inflammatory effects

Clinical uses

• For prevention of exercise-induced bronchospasm 
• Alternative long-term asthma maintenance therapy
• Less effective and more expensive than CS
• Rarely used (metered-dose inhaler not available in the United States)

Side effects

• Throat irritation
• No significant toxicity due to minimal systemic absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption

Antibodies: Anti-IgE

Type(s) and administration

Omalizumab (subcutaneous)

Mechanism of action and effects

• Monoclonal antibody that binds circulating IgE
• IgE plays a central role in immediate bronchoconstriction and the influx of inflammatory cells.

Clinical use

• For persistently uncontrolled allergic asthma despite high-dose ICS and ≥ 1 other controller(s)
• For patients with:
  • Age ≥ 6 years
  • An elevated IgE level (30–700 IU/mL)
  • Positive allergen skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin test or specific IgE tests to a perennial allergen
• Reduces CS requirements

Side effects

• Urticaria Urticaria Urticaria is raised, well-circumscribed areas (wheals) of edema (swelling) and erythema (redness) involving the dermis and epidermis with associated pruritus (itch). Urticaria is not a single disease but rather is a reaction pattern representing cutaneous mast cell degranulation. Urticaria (Hives), injection site reaction
• Headache

Precautions

• Anaphylaxis/severe hypersensitivity reaction is a contraindication.
• Monitor for parasitic infections (helminth).
• Cerebrovascular events have been reported.

Antibodies: Anti-IL-5 and Anti-IL-5 Receptor

Types and administration

• Mepolizumab (subcutaneous)
• Reslizumab (intravenous)
• Benralizumab (subcutaneous)

Mechanism of action and effects

• IL-5 is a pro-eosinophilic cytokine contributing to eosinophilic inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation.
• Mepolizumab, reslizumab: monoclonal antibody to IL-5
• Benralizumab: cytotoxic monoclonal antibody against IL-5 receptor alpha

Clinical use

• For severe eosinophilic asthma
• Mepolizumab: 
  • For blood eosinophil count ≥ 300 cells/μL
  • Patient age: > 12 years
• Reslizumab: 
  • For blood eosinophil count ≥ 400 cells/μL 
  • Patient age: > 18 years
• Benralizumab: 
  • For blood eosinophil count ≥ 300 cells/μL
  • Patient age: > 12 years

Side effects

• Mepolizumab: herpes zoster Herpes Zoster Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Shingles (also known as herpes zoster) is more common in adults and occurs due to the reactivation of VZV. Varicella-Zoster Virus/Chickenpox (may give varicella vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination ≥ 1 month before)
• Reslizumab: oropharyngeal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
• Benralizumab: headache, pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis

Precautions

• Anaphylaxis/severe hypersensitivity reaction is a contraindication.
• Helminth infection needs to be treated prior to initiation.

Antibodies: Anti-IL-4 Receptor

Types and administration

• Dupilumab (subcutaneous)

Mechanism of action and effects

• Blocks IL-4 receptor
• Through receptor blockage, IL-4 and IL-13 with other cytokines are inhibited.

Clinical use

• For severe eosinophilic asthma or oral-steroid asthma
• Inadequately controlled asthma with eosinophil count ≥ 150 cells/μL 
• Patient age: > 12 years
• Other uses: atopic dermatitis Atopic Dermatitis Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema), rhinosinusitis with nasal polyposis

Side effects

• Injection site reaction
• Transient eosinophilia

Precautions

• Anaphylaxis/severe hypersensitivity reaction is a contraindication.
• Monitor for eosinophilia and vasculitis.
• May cause worsening eye symptoms ( conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis and keratitis)
• Helminth infection needs to be treated prior to initiation.

Clinical Relevance

Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma medications are also used for the following conditions:

• Chronic obstructive pulmonary disease ( COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)): a common chronic disease of the airways characterized by airflow limitation. Obstructive inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation is noted in the small airways, lung parenchyma, and pulmonary vasculature. Patients usually present with dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea and chronic cough. Bronchodilators and corticosteroids are part of the regimen for treating COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD).
• Eosinophilic granulomatous polyangiitis (EGPA): vasculitis characterized by necrotizing granulomas, eosinophilia, and eosinophilic tissue infiltration. The vasculitis affects small- and medium-sized arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries. Multiple organs can be affected, including the pulmonary, renal, gastrointestinal, cardiovascular, and nervous system Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. General Structure of the Nervous System. Among the treatments is mepolizumab.
• Allergic rhinitis Rhinitis Rhinitis refers to inflammation of the nasal mucosa. The condition is classified into allergic, nonallergic, and infectious rhinitis. Allergic rhinitis is due to a type I hypersensitivity reaction. Non-allergic rhinitis is due to increased blood flow to the nasal mucosa. Infectious rhinitis is caused by an upper respiratory tract infection. Rhinitis: a condition characterized by rhinorrhea, sneezing, and itching of nose Nose The nose is the human body's primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Anatomy of the Nose, eyes, and palate Palate The palate is the structure that forms the roof of the mouth and floor of the nasal cavity. This structure is divided into soft and hard palates. Oral Cavity: Palate. Allergens trigger an allergic nasal response where nasal mast cells release histamine and other mediators. Corticosteroid nasal sprays are commonly prescribed. Other less-used therapies available include cromolyn nasal spray, ipratropium nasal spray, and montelukast.