Biological Standardization of Dermatophagoides Allergen Extracts in Allergic Patients Using Histamine Dihydrochloride and Sodium Chloride Controls

The primary objective of this study is the **biological standardization** of allergenic extracts derived from **Dermatophagoides pteronyssinus** and **Dermatophagoides farinae**. This is clinically relevant as it aims to ensure the consistency and efficacy of these allergen extracts, which are used in the diagnosis and management of **allergies**. Accurate standardization is crucial for the reliability of skin-prick tests, which are a common diagnostic tool for identifying specific allergen sensitivities in patients. No secondary objectives are specified for this study.

The clinical trial focuses on individuals diagnosed with **allergies** to Dermatophagoides pteronyssinus and Dermatophagoides farinae. The study population comprises both male and female participants aged between 18 and 50 years. Participants are required to reside in geographic areas where these allergens are prevalent, such as the Mediterranean coast, due to its humidity and mild temperatures. The trial does not include a vulnerable population. Participants must have a positive skin prick test and specific IgE test results indicating an IgE-mediated allergy to the specified allergens. The sponsor has not provided information regarding the total number of participants. The selection criteria ensure that participants are capable of understanding the study's purpose and have provided informed consent. Lifestyle factors such as diet and physical activity are not specified in the available data.

The clinical trial is designed to evaluate the **biological standardization** of allergenic extracts from **Dermatophagoides pteronyssinus** and **Dermatophagoides farinae**. This is a Phase IV, randomized, double-blind, controlled study aimed at determining the concentration of the extracts that produce a wheal size equivalent to that caused by a solution of **histamine dihydrochloride** at 10 mg/ml. The trial is expected to commence on January 15, 2025, and conclude by April 15, 2025, with an estimated duration of three months.

Participants will undergo a series of study visits, beginning with an inclusion visit where eligibility is confirmed based on specific criteria, such as residing in areas where the allergens are prevalent and having a positive **IgE-mediated allergy** diagnosis. The inclusion visit will involve a **skin prick test** to assess the wheal diameter, ensuring it meets the required threshold compared to a negative control. Follow-up visits will be scheduled to monitor the dose-response relationship and assess the safety of the extracts through descriptive analysis of any adverse reactions. The primary endpoint will be the area of the wheal at the cutaneous level, while secondary endpoints will focus on safety assessments.

The expected length of participant involvement is approximately three months, with conditions for early termination including withdrawal of consent or adverse reactions that compromise participant safety. The trial will utilize solutions for skin-prick tests, with administration routes including intradermal and intraepidermal use. The study will adhere to rigorous protocols to ensure the reliability and validity of the results, contributing to the understanding of allergenic extract standardization in patients with allergies.

The clinical trial involves the use of several **experimental medications** in the form of solutions for skin-prick tests. The first experimental medication is "Diagnóstico prick control positivo," which contains **histamine dihydrochloride** as the active substance. This solution is administered via subcutaneous use, with a maximum daily dose of 10 mg/ml. The administration is limited to a maximum treatment period of one day. This medication serves as a positive control in the trial.

The second experimental medication is "Diagnóstico prick control negativo," which contains **sodium chloride** as the active substance. This solution is also administered subcutaneously, with a maximum daily dose of 10 mg/ml and a treatment period of one day. It functions as a negative control in the study.

Another experimental medication is "Diagnóstico prick Dermatophagoides farinae," which contains an allergenic extract from the species **Dermatophagoides farinae**. This solution is administered intradermally, with a concentration of 1000 PNU/ml. The maximum daily dose is 10 PNU/ml, and the treatment period is one day. This medication is used to assess the biological standardization of the allergenic extract.

Similarly, "Diagnóstico prick Dermatophagoides pteronyssinus" contains an allergenic extract from the species **Dermatophagoides pteronyssinus**. This solution is also administered intradermally, with a concentration of 1000 PNU/ml. The maximum daily dose is 10 PNU/ml, and the treatment period is one day. This medication is part of the biological standardization process for the allergenic extract.

Additional experimental medications include variations of the "Diagnóstico prick Dermatophagoides farinae" and "Diagnóstico prick Dermatophagoides pteronyssinus" solutions, with different concentrations ranging from 5000 PNU/ml to 30000 PNU/ml. These solutions are administered intradermally or intraepidermally, with a maximum daily dose of 10 PNU/ml and a treatment period of one day. These variations are used to evaluate the dose-response relationship and standardize the allergenic extracts.

Throughout the trial, participant compliance is monitored to ensure adherence to the dosing schedules and administration routes. The trial aims to achieve biological standardization of the allergenic extracts of Dermatophagoides pteronyssinus and Dermatophagoides farinae, contributing to the understanding of their allergenic potential and therapeutic applications.

Efficacy in this clinical trial will be assessed through the primary endpoint, which involves measuring the area of the wheal (mm²) that occurs at the cutaneous level following the administration of allergenic extracts in a skin-prick test. This measurement will be used to calculate the primary endpoint, which includes the estimation of the dose/response relationship in each patient. A regression analysis will be conducted on the area values versus the concentration in PNU/ml to determine the theoretical concentration of extract that produces a papule equivalent to that produced by a solution of **histamine dihydrochloride** at 10 mg/ml.

The secondary endpoint focuses on the safety assessment, which will be conducted through a descriptive analysis of any adverse reactions that may occur during the study. The trial aims to biologically standardize allergenic extracts of **Dermatophagoides pteronyssinus** and **Dermatophagoides farinae**. The trial is designed to determine the concentration of the study extracts that elicit a wheal size equivalent to that produced by a histamine solution, ensuring the extracts' efficacy and safety in eliciting an appropriate immune response.