Thea Sinensis

Green Tea Leaf, derived from Camellia sinensis, is utilized clinically as a non-standardized allergenic extract for the diagnosis and treatment of specific plant and food-based sensitivities, belonging to a class of diagnostic and therapeutic biologicals.

Dosage for Green Tea Leaf allergenic extracts is not standardized by a universal potency unit (like milligrams). Instead, it is typically expressed in Weight/Volume (w/v) ratios or Protein Nitrogen Units (PNU) per milliliter (mL).

Diagnostic Testing

• Skin Prick Test (SPT): Usually, a drop of the 1:10 or 1:20 w/v extract is applied to the skin. A sterile lancet is used to prick the skin through the drop. A positive control (histamine) and negative control (saline) are used simultaneously.
• Intradermal Testing: If the SPT is negative but an allergy is still suspected, a 0.02 mL to 0.05 mL dose of a much more dilute extract (e.g., 1:1000 w/v) may be injected intradermally.

Immunotherapy

• Build-up Phase: Treatment starts with a very low dose (e.g., 0.1 mL of a 1:100,000 w/v dilution) administered subcutaneously once or twice a week. The dose is gradually increased until the maintenance dose is reached.
• Maintenance Phase: Once the effective dose is reached, the frequency of injections is usually decreased to once every 2 to 4 weeks.

Green Tea Leaf allergenic extracts may be used in children; however, the dosage must be carefully individualized. Children are often more sensitive to allergens, and the risk of systemic reactions must be weighed carefully.

• Infants: Testing is generally avoided unless symptoms are severe and unavoidable.
• Children (Age 2 and older): Diagnostic testing procedures are similar to adults, though fewer tests may be performed in a single session to minimize discomfort and systemic risk.

Renal Impairment

No specific dosage adjustments are required for patients with renal impairment, as the systemic load of the extract is extremely low. However, the patient's overall health should be stable before testing.

Hepatic Impairment

No dosage adjustments are defined for hepatic impairment. The metabolic clearance of allergenic proteins does not rely on hepatic enzyme pathways.

Elderly Patients

Elderly patients may have reduced skin reactivity (false negatives) during diagnostic testing. Furthermore, these patients are at higher risk if a systemic reaction occurs due to underlying cardiovascular disease. Healthcare providers may use lower starting doses for immunotherapy in this population.

Green Tea Leaf allergenic extracts are not for self-administration. They must be administered by a healthcare professional in a clinical setting.

• Preparation: The skin (usually the forearm or back) is cleaned with alcohol and allowed to dry.
• Administration: For diagnostic testing, the extract is applied topically or injected intradermally. For immunotherapy, it is injected subcutaneously (usually in the upper arm).
• Observation: Patients must remain in the medical office for at least 30 minutes after any administration of the extract to monitor for signs of a systemic allergic reaction or anaphylaxis.
• Storage: Extracts must be stored in a refrigerator at 2°C to 8°C (36°F to 46°F). They should never be frozen.

In the context of immunotherapy, a missed dose can disrupt the desensitization process.

• If a dose is missed by a few days, the provider may continue with the planned dose.
• If a dose is missed by several weeks, the provider may need to reduce the dose to ensure safety before building back up to the maintenance level.

An overdose of Green Tea Leaf extract occurs if too much is administered or if the concentration is too high for the patient's sensitivity level.

• Signs: Severe local swelling, hives (urticaria), swelling of the throat (angioedema), wheezing, or a drop in blood pressure.
• Emergency Measures: Immediate administration of epinephrine (Adrenalin), oxygen, intravenous fluids, and antihistamines.

> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance.

Most patients receiving Green Tea Leaf allergenic extracts will experience some form of localized reaction. These are generally expected and indicate that the extract is interacting with the immune system.

• Local Wheal and Flare: A small, itchy, raised white bump (wheal) surrounded by a red area (flare) at the site of the skin test. This typically peaks at 15-20 minutes and resolves within a few hours.
• Local Swelling and Redness: During immunotherapy, the injection site may become swollen, red, and warm. This is a common delayed-type reaction that can last 24 to 48 hours.
• Pruritus (Itching): Intense itching at the site of administration is very common.

Green Tea Leaf allergenic extracts are potent biological materials. They are intended only for use by physicians experienced in the diagnosis and treatment of allergic diseases. Patients must be informed of the risks and benefits before starting treatment. The most significant risk is a systemic allergic reaction, which can occur even in patients who have previously tolerated the extract well.

No specific FDA black box warning exists specifically for 'Green Tea Leaf' as a standalone product, but it falls under the general regulatory warnings for Allergenic Extracts. These warnings emphasize that systemic reactions are a constant risk and that the physician must be prepared to treat anaphylaxis with epinephrine and other emergency measures.

• Allergic Reactions / Anaphylaxis Risk: This is the primary concern. The risk is highest during the build-up phase of immunotherapy or when switching to a new vial of extract (which may be more potent than the previous one).

• Beta-Adrenergic Blockers (Beta-Blockers): Medications like propranolol, atenolol, or metoprolol are generally contraindicated for patients receiving allergenic extracts. If the patient has a severe allergic reaction (anaphylaxis) to the Green Tea Leaf extract, the beta-blocker will prevent epinephrine (the life-saving treatment) from working effectively. This can lead to a fatal outcome.

• ACE Inhibitors: Drugs like lisinopril or enalapril may increase the risk of systemic reactions or make the reactions more severe. They can also interfere with the body's natural compensatory mechanisms during an allergic event.
• MAO Inhibitors (MAOIs): Medications used for depression (e.g., phenelzine) can increase the effects of epinephrine, potentially leading to a dangerous spike in blood pressure if epinephrine is needed to treat a reaction to the extract.

• Severe, Uncontrolled Asthma: Patients whose asthma is not well-managed are at an unacceptably high risk of fatal bronchospasm if a systemic reaction to the extract occurs. This is an absolute contraindication for both testing and immunotherapy.
• Recent Myocardial Infarction (Heart Attack): Patients who have had a heart attack within the last 3 to 6 months should not undergo allergy testing or immunotherapy, as their heart may not be able to handle the stress of an allergic reaction or the administration of epinephrine.
• History of Severe Anaphylaxis to the Specific Extract: If a patient has already had a near-fatal reaction to Green Tea Leaf extract, further use is strictly contraindicated unless in an extremely controlled hospital desensitization setting.

Green Tea Leaf allergenic extracts are categorized as FDA Pregnancy Category C. This means that animal reproduction studies have not been conducted, and it is not known whether the extract can cause fetal harm or affect reproduction capacity.

• Risk Summary: The primary risk during pregnancy is not the extract itself, but the potential for a systemic reaction (anaphylaxis) in the mother. Anaphylaxis can cause a sudden drop in blood pressure, leading to decreased blood flow to the placenta and fetal distress or death.
• Clinical Recommendation: Healthcare providers typically do not start new allergy testing or immunotherapy during pregnancy. If a woman becomes pregnant while on a stable maintenance dose of immunotherapy, the treatment may be continued, but the dose is usually not increased.

It is not known whether the allergenic proteins from Green Tea Leaf extract are excreted in human milk. However, since these are proteins that are naturally present in the diet (via tea consumption), they are generally considered to be of low risk to the nursing infant. The decision to continue immunotherapy while breastfeeding should be made after a risk-benefit analysis by the physician.

Green Tea Leaf extract functions as a diagnostic and therapeutic biological agent. Its primary molecular mechanism involves the Type I Hypersensitivity pathway. The extract contains specific protein antigens (e.g., CsP proteins) that are recognized by the immune system of sensitized individuals.

Upon exposure, these antigens bind to IgE antibodies that are bound to the high-affinity IgE receptor (FcεRI) on mast cells and basophils. This binding causes the receptors to cluster, triggering an intracellular signaling cascade involving tyrosine kinases (like Syk). This leads to the influx of calcium and the release of pre-formed mediators like histamine and the synthesis of new mediators like leukotrienes. This is the basis for the diagnostic skin reaction.

In immunotherapy, the mechanism shifts toward immunological tolerance. Repeated exposure to increasing doses of the extract induces the production of Regulatory T-cells (Tregs) and the secretion of IL-10. It also promotes a shift from a Th2 (allergic) immune response to a Th1 response and stimulates B-cells to produce IgG4 antibodies