grass pollens allergen extract

Action and Spectrum

Actions and Spectrum: 

grass pollen allergen extracts are commonly used in allergy testing and immunotherapy. These extracts contain proteins derived from various types of grass pollen, which can trigger allergic reactions in susceptible individuals.  

Action: 

• Allergen Sensitization: grass pollen extracts are used to identify individuals sensitized to specific grass pollen allergens. Sensitization occurs when a person’s immune system recognizes the grass pollen proteins as foreign and produces specific IgE antibodies. 
• Allergic Reactions: When a sensitized individual comes into contact with grass pollen, the allergenic proteins in the extract can trigger an allergic reaction. This reaction can range from mild symptoms like sneezing, itching, and watery eyes to more severe symptoms such as asthma attacks or anaphylaxis. 

Spectrum:  

grass pollen allergen extracts typically contain a mixture of proteins from different grass species, as people can be allergic to various types of grass pollen. The specific grass species included in the extract may vary depending on geographical location and the prevalent grasses in that area. Common grasses that contribute to pollen allergies include: 

• Timothy grass (Phleum pratense): One of the most critical grasses associated with allergies worldwide. Timothy grass pollen extract is frequently included in allergen extracts used for testing and immunotherapy. 
• Bermuda grass (Cynodon dactylon): Commonly found in warm regions, Bermuda grass is a significant cause of allergies, particularly in southern parts of the United States. 
• Ryegrass (Lolium perenne): This grass species is prevalent in many parts of the world and is known to produce significant allergenic pollen. 
• Kentucky bluegrass (Poa pratensis): Another common grass found in lawns and sports fields, Kentucky bluegrass can cause allergic reactions in sensitized individuals. 
• Orchard grass (Dactylis glomerata): Orchard grass is widespread in meadows and can contribute to grass pollen allergies. 

Drug Interaction

Adverse Reaction

Frequency defined 

>10% 

Throat irritation (22%) 

Oral pruritus (25.1%) 

1-10% 

Adults 

Ear pruritus (8.4%) 

Mouth edema (8.2%) 

Tongue pruritus (7.9%) 

Cough (7.3%) 

Oropharyngeal pain (5.1%) 

Lip edema (4.4%) 

Paraesthesia, oral (4.3%) 

Abdominal pain (4.2%) 

Dyspepsia (3.9%) 

Pharyngeal edema (3.8%) 

Tongue edema (2.7%) 

Urticaria (2.3%) 

Hypoesthesia, oral (2.2%) 

Stomatitis (2.1%) 

(Children or adolescents) 

Atopic dermatitis (3.2%) 

Dysphonia (2.6%) 

URI (3.9%) 

Tonsillitis (5.8%) 

Lip pruritus (3.2%) 

Asthma (7.1%) 

Black Box Warning

Black Box Warning: 

Allergic reactions: Allergenic extracts, including those derived from grass pollens, can potentially cause allergic reactions in sensitive individuals. These reactions may vary in severity, and healthcare providers need to assess the individual’s medical history, conduct proper testing, and closely monitor patients during immunotherapy or other treatments involving allergenic extracts. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

• Severe or Uncontrolled Asthma: Individuals with severe or uncontrolled asthma may be at an increased risk of experiencing severe allergic reactions during immunotherapy. Therefore, grass pollen allergen immunotherapy may be contraindicated in these cases. However, an allergist or healthcare professional should make the final decision following a thorough assessment of the individual’s condition. 
• Immunodeficiency Disorders: Individuals with certain immunodeficiency disorders may have a compromised immune system, which can affect the safety and effectiveness of immunotherapy. grass pollen allergen immunotherapy may be contraindicated in these cases or require careful evaluation and monitoring. 
• Unwillingness or Inability to Comply: Immunotherapy involves a series of regular injections or sublingual tablets over an extended period. It may not be recommended if an individual is unable or unwilling to comply with the treatment regimen. 
• Pregnancy: The safety of grass pollen allergen immunotherapy during pregnancy is not well established. It is generally recommended to avoid starting or initiating immunotherapy during pregnancy, although maintenance doses may be continued in some cases. Individual assessment and consultation with a healthcare professional are essential for determining the appropriate action. 
• Uncontrolled Allergic Reactions: If an individual has a history of severe allergic reactions to previous immunotherapy or allergic reactions to the allergen extract, it may be contraindicated or require careful consideration. 

Caution 

• Allergic Reactions: grass pollen allergen extracts can potentially cause allergic reactions ranging from mild-severe. It is essential to closely monitor patients for any signs of an allergic response during and after administration. Healthcare professionals should be prepared to manage and treat any adverse reactions promptly. 
• Concurrent Medications: Some medications, such as beta-blockers and angiotensin-converting enzyme (ACE) inhibitors, can affect the response to allergen immunotherapy. They may increase the risk of adverse reactions or interfere with the effectiveness of the treatment. It is vital to inform the healthcare professional about the patient’s medications before starting immunotherapy. 
• Respiratory Conditions: Individuals with pre-existing respiratory conditions, such as chronic obstructive pulmonary disease or bronchial asthma, may be at higher risk of experiencing respiratory symptoms during immunotherapy. Particular caution and monitoring are necessary in these cases to ensure the safety and effectiveness of the treatment. 
• Concurrent Infections or Illness: During periods of acute illness or infection, postponing allergen immunotherapy to avoid potential interactions and complications is generally recommended. The immune system may already be compromised during these times, and starting or continuing immunotherapy may not be advisable. 
• Children and Elderly: grass pollen allergen immunotherapy may require particular caution and adjustment in dosage for children and elderly individuals. Close monitoring and evaluation of their needs and responses are necessary to ensure safety and effectiveness. 
• Severe Local Reactions: grass pollen allergen injections can occasionally cause severe local reactions at the injection site. Patients should be educated about the potential for such reactions, and the injection site should be carefully monitored during and after administration. 

Pregnancy / Lactation

Pregnancy consideration:  

AU TGA pregnancy category: B2
US FDA pregnancy category: B 

Lactation:   

Excreted into human milk: Not known. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

The pharmacology of grass pollen allergen extract involves its interaction with the immune system in individuals sensitized to grass pollen. When administered through immunotherapy, the extract stimulates the immune system, producing allergen-specific IgG antibodies. These antibodies help modulate the immune response by reducing the production of allergen-specific IgE antibodies responsible for triggering allergic reactions.

Over time, the gradual increase in the allergen extract dose during immunotherapy induces immunological tolerance and a shift from Th2 (allergic) to Th1 (non-allergic) immune response, resulting in decreased allergic symptoms upon subsequent exposure to grass pollen. The extract’s pharmacological action aims to desensitize the immune system, reduce allergic reactivity, and provide long-term relief from grass pollen allergy symptoms. 

Pharmacodynamics: 

Mechanism of action: The mechanism of action of grass pollen allergen extract involves modulating the immune response in individuals sensitized to grass pollen.  

• Sensitization: Sensitization occurs when an individual’s immune system recognizes grass pollen allergens as foreign substances and produces specific IgE antibodies. This sensitization process typically happens through prior exposure to grass pollen. 
• Immunotherapy Initiation: grass pollen extract is administered subcutaneously or sublingually as part of allergen immunotherapy. The extract contains allergenic proteins derived from grass pollen. 
• Immune Modulation: The allergen extract interacts with immune cells, like dendritic cells and B cells, which process and present the allergenic proteins to T cells. This interaction leads to the activation of allergen-specific T cells. 
• Tolerance Induction: The activated T cells play a crucial role in shifting the immune response from a Th2 (allergic) dominant response to a Th1 (non-allergic) dominant response. This shift involves the production of immunomodulatory cytokines, such as interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β). These cytokines promote the generation of regulatory T cells (Tregs) and the suppression of Th2 responses, reducing the production of allergen-specific IgE antibodies. 
• Desensitization and Long-term Tolerance: The immune system becomes desensitized to grass pollen allergens through the gradual increase of allergen extract dose during immunotherapy. A decreased reactivity to grass pollen characterizes this desensitization, reduced allergic symptoms upon subsequent exposure, and improved quality of life. Long-term tolerance may develop in some cases, meaning the immune system no longer exhibits allergic responses to grass pollen. 

Pharmacokinetics: 

Absorption 

When administered subcutaneously as allergen immunotherapy, the grass pollen allergen extract is directly injected into the subcutaneous tissue. This allows for direct contact with immune cells and initiates an immune response. When administered sublingually, the extract is absorbed through the mucous membranes under the tongue, where it comes into contact with immune cells and elicits an immune response. 

Distribution 

Once absorbed, grass pollen allergen extracts distribute locally at the injection site (subcutaneous) or mucous membranes (sublingual). They interact with immune cells, such as dendritic and T cells, initiating an immune response and promoting immunological changes associated with desensitization. 

Metabolism 

grass pollen allergen extracts are composed of proteins derived from grass pollen. Once the extract is administered, these proteins are recognized by the immune system and processed by antigen-presenting cells (APCs), such as dendritic cells. APCs process the proteins into smaller peptide fragments, then present them to T cells, triggering an immune response. 

Elimination and Excretion 

The grass pollen allergen extract does not undergo traditional excretion pathways. After administration, the extract is gradually eliminated or broken down within the body as part of the normal immune response processes and clearance of foreign substances. 

Adminstartion

Administration: 

Subcutaneous/Sublingual administration 

Administered grass pollen allergen extract can be done through two main routes: subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT).  

Subcutaneous Immunotherapy (SCIT): 

• Preparation: grass pollen allergen extracts used for SCIT are typically available as a liquid formulation. The extract is prepared by diluting the concentrated allergen extract to a specific concentration suitable for administration. 
• Administration: The allergen extract is injected subcutaneously using a syringe and a small needle. Injections are usually given in the upper arm. The initial phase of SCIT involves increasing the dose gradually over several weeks or months until reaching the maintenance dose. 
• Schedule: SCIT involves regularly administering allergen injections during the build-up phase, typically once or twice a week. The build-up phase can last several months until the maintenance dose is reached. Once the maintenance dose is achieved, the frequency of injections is reduced to every two to four weeks, depending on the individual’s response and the specific treatment protocol. 

Sublingual Immunotherapy (SLIT): 

• Preparation: grass pollen allergen extracts used for SLIT are available as tablets or drops. The extract is prepared by dissolving the tablets or placing drops under the tongue. 
• Administration: The patient places the tablet or drops under the tongue, allowing it to dissolve or be absorbed. The extract is held in the mouth for a specific period before swallowing, usually a few minutes. 
• Schedule: SLIT involves daily administration of the grass pollen allergen extract. Treatment is typically initiated a few months before the grass pollen season and continues throughout. The duration of SLIT can vary depending on the individual’s response and the specific treatment plan. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: grass pollens allergen extract 

Why do we use grass pollen allergen extract? 

grass pollen allergen extracts have several uses in allergy diagnosis and treatment.  

• Allergy Testing: grass pollen allergen extracts are commonly used in allergy testing, specifically in skin prick tests or blood tests (specific IgE). These tests help identify individuals who are allergic to grass pollen. Small amounts of the allergen extract are applied to the skin or added to a blood sample to measure the presence of specific IgE antibodies. Positive test results indicate sensitization to grass pollen. 
• Allergen Immunotherapy: grass pollen extracts are a crucial component of allergen immunotherapy, also known as allergy shots or desensitization therapy. Immunotherapy involves administering gradually increasing doses of the allergen extract over time to reduce or eliminate the allergic response. It can treat allergic rhinitis (hay fever) and asthma caused by grass pollen allergies. 
• Desensitization: grass pollen extracts are used in allergen immunotherapy to desensitize individuals with grass pollen allergies. The treatment aims to modify the immune response by gradually exposing the patient to increasing amounts of the allergen extract. This helps the immune system build a tolerance to grass pollen, reducing allergy symptoms and decreasing the risk of severe reactions upon future exposure. 
• Symptom Relief: In addition to immunotherapy, grass pollen allergen extracts can be used to provide temporary relief of allergy symptoms. These extracts are sometimes formulated as sublingual tablets or drops that can be taken during the grass pollen season. They help reduce sneezing, nasal congestion, itchy eyes, and other allergic reactions.