Brand Name: Grastek
Generic Name: Timothy Grass Pollen Allergen

Drug Class: Allergen extract, Immunotherapy
Similar Drugs: Ragwitek (Short Ragweed Pollen Allergen Extract), Oralair (Sweet Vernal, Orchard, Perennial Eye, Timothy, and Kentucky Blue Grass Mixed Pollens Allergen Extract.
Manufacturer: MercK Sharp & Dohme Corp.

What is Grastek and how does it work?

Grastek is a sublingual (placed under the tongue) tablet that is made up of extractions from Timothy grass pollen. Grastek is a treatment option for people between the ages of 5-65 years who suffer from grass pollen allergies with or without conjunctivitis (eye swelling or inflammation). The immune system is designed to protect the body from foreign substances which pose a threat to our health. The immune system in allergy sufferers is easily activated by a generally non-harmful substance such as grass pollen and causes significant misery. Allergy immunotherapy treatments such as Grastek decrease the immune response to non-harmful substances such as Timothy grass pollen.  

The exact mechanism of how Grastek works to treat and prevent allergy symptoms is unknown. Scientists think that by providing our bodies with small amounts of the allergen regularly, over time tolerance is developed. With continued use our immune system gets used to the allergen and is activated less often, allowing patients to experience symptoms less frequently and symptoms are less severe. Grastek helps patients manage their allergy symptoms and may also prevent symptoms with continued use.

What does Grastek treat?

Grastek is used to treat allergic rhinitis caused by Timothy grass and other related grass pollens. Although not native to North America, today Timothy grass is widely grown in the US as hay and pasture grass. Most grasses begin to grow in early spring and start to release their pollen by late spring or early summer. The pollen released by Timothy grass is the cause of asthma or allergy symptoms in millions of allergy sufferers. Allergic rhinitis affects approximately 30 million people in the United States and significantly impacts quality of life. 

Symptoms of allergic rhinitis include:

• Nasal congestion
• Runny nose
• Sneezing
• Sore throat
• Itchy throat
• Red/itchy/watery eyes

Before treatment with Grastek doctors perform a skin or lab test to confirm that symptoms are caused by Timothy grass or other related grass pollens.

How effective is Grastek?

The following clinical trials were conducted to measure the effectiveness of treatment with Grastek. The end points measured were the daily symptom score (DSS) and the daily medication score (DMS). DSS is the number and severity of allergy symptoms experienced by patients per day while the DMS score corresponds to the number of allergy medications used by patients per day to manage their symptoms. All trials showed that Grastek was superior to placebo in decreasing both DSS and DMS measurements.

Grastek was compared to placebo (sugar pill) in patients between the ages of 5 and 65 years over a period of 24 weeks. Patients taking Grastek had a DSS of 2.49 versus 3.13 in the placebo group. The DMS in the Grastek treated group was 0.88 versus 1.36 in the placebo group.

Grastek was compared to placebo in pediatric patients between the ages of 5 and 17 years over a period of 24 weeks. The DSS and DMS in the treatment group was 3.71 and 0.91 respectively, compared to 4.91 and 1.33 in the placebo treated group.

Grastek was compared to placebo in patients 18 years and older for a period of 5 years. Patients were treated with either Grastek or placebo daily for 3 consecutive years followed by 2 years of observation with no treatment. Patients treated with Grastek experienced a decrease in their daily symptoms and daily use of allergy medications throughout the pollen season during the 3 years of active treatment. These benefits were sustained during the 1st year without treatment but not in the 2nd year. 

What are interesting facts about Grastek?

• Grastek does not provide immediate relief from your allergy symptoms.
• Grastek may cause severe allergic reactions that may be life threatening. Patients are advised to stop taking Grastek and seek medical attention immediately if they experience difficulty breathing, throat swelling, difficulty swallowing or talking, fainting, severe stomach pain, severe vomiting or diarrhea, or severe skin flushing or itching.
• Due to the risk for severe allergic reactions, patients who are taking Grastek at home should be prescribed auto injectable epinephrine that can be used if a severe allergic reaction does occur.
• Grastek may also be used for prevention of Timothy grass and other pollen related allergies. In a clinical study it was shown that patients who took Grastek for 3 consecutive years continued to experience the benefits of the medication for 1 year after stopping treatment.
• Grastek is the first sublingual allergy immunotherapy approved for children as young as 5 years of age.

What is the dosage of Grastek?

Grastek is only available as sublingual tablets of 2800 Bioequivalent Allergy Units (BAUs). 

Grastek is taken once daily. Patients should start treatment at least 12 weeks before the start of the pollen season and continue treatment throughout the season. Patients can take Grastek once daily for 3 years to experience sustained benefits for one grass pollen season after stopping treatment.

How to take Grastek?

All patients must be given their first dose of Grastek in their doctor’s office. The patient is observed for at least 30 minutes for signs or symptoms of a severe allergic reaction.  If the patient does not have any problems with the first dose, the patient can then be given a take home prescription of Grastek. 

Grastek is available as a sublingual tablet that should be placed under the tongue. Patients should not swallow their saliva for at least 1 minute. The tablet should be handled with dry hands and it’s important to wash hands after handling the tablets.  Grastek should not be taken with food and up to 5 minutes after eating or drinking.

What are the possible side effects of Grastek?

Common: swelling under the tongue, throat irritation, and itching of the mouth, lips, or tongue.

Severe: difficulty breathing, throat swelling, difficulty swallowing or talking, dizziness, rapid or weak heart rate, severe stomach pain, severe vomiting or diarrhea, and severe flushing or itching of the skin.

Who should not take Grastek?

Grastek should not be used by the following people who fit the following criteria:

Severe, unstable or uncontrolled asthma

A history of eosinophilic esophagitis

A history of any type of severe systemic allergic reactions

A history of any type of severe reaction to sublingual allergen immunotherapy

Hypersensitive to any ingredient contained in the product

Pregnancy:  Category B.  There was no indication of harm to the fetus due to Grastek in animal studies. However, GRATEK should be used in pregnancy with caution as adverse reactions associated with immunotherapy during pregnancy may be poorly tolerated.

Nursing mothers: It is unknown if Grastek is excreted in breast milk.  Due to the lack of safety evidence, Grastek should be used cautiously in nursing mothers.

What is the cost of Grastek?

The average wholesale price per tablet of Grastek is $9.90. The estimated cost of a 30 day supply of Grastek (30 tablets) is $300.

How to obtain prescription assistance for Grastek

For prescription assistance visit Merck and obtain Grastek coupons.

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Reference

Grastek Full Prescribing Information (PI)