Biological Standardization of Blomia tropicalis Allergen Extract for Allergic Patients Using Skin-Prick Test with Histamine Dihydrochloride and Sodium Chloride Controls

The primary objective of this study is the **biological standardization** of the allergenic extract of **Blomia tropicalis**. This is clinically relevant as it aims to ensure the consistency and efficacy of the allergen extract used in skin-prick tests for diagnosing **allergies**. The standardization process is crucial for providing reliable diagnostic results, which can guide appropriate management and treatment strategies for patients with allergic conditions. No secondary objectives are specified for this study.

The clinical trial focuses on the **biological standardization** of the allergenic extract of Blomia tropicalis. The study population comprises individuals aged between 18 and 50 years, inclusive of both male and female participants. Participants are required to reside in geographic areas where Blomia tropicalis is prevalent and must have a confirmed diagnosis of IgE-mediated allergy to the Blomia tropicalis allergen. This diagnosis is validated through a skin prick test and a positive specific IgE in vitro diagnostic test. The trial does not include a vulnerable population. The sponsor has not provided information regarding the total number of participants. Participants' general health status and lifestyle considerations such as diet and physical activity are not specified. Key inclusion criteria include the ability to understand the study's purpose and scope, along with the provision of informed consent. The trial population was selected based on these specific criteria to ensure the relevance and accuracy of the study outcomes.

The clinical trial is designed to evaluate the **biological standardization** of the allergenic extract of **Blomia tropicalis**. This is a Phase IV, randomized, double-blind, controlled trial aimed at determining the concentration of the study extracts that elicit a wheal of a size equivalent to that produced by a solution of **histamine dihydrochloride** at 10 mg/ml. The trial will involve participants diagnosed with **IgE-mediated allergy** to **Blomia tropicalis**, residing in areas where this allergen is prevalent. The trial is expected to commence on July 15, 2025, and conclude by December 15, 2025, with an estimated duration of five months.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to confirm eligibility based on specific criteria, including a positive skin prick test and in vitro diagnostic test results. The trial will involve the administration of allergenic extracts via **intraepidermal use** to assess the primary endpoint, which is the area of the wheal (mm²) formed at the cutaneous level. The secondary endpoint will focus on the safety assessment through the descriptive analysis of any adverse reactions. Follow-up visits will be scheduled to monitor the dose/response relationship and to perform regression analysis of area values versus concentration in PNU/ml. The end-of-study visit will conclude the participant's involvement, ensuring all data is collected and any adverse events are addressed.

Participant involvement is expected to last for the duration of the trial, with conditions for early termination including withdrawal of consent, non-compliance with study procedures, or the occurrence of significant adverse events. The trial will utilize a **solution for skin-prick test** containing **Blomia tropicalis** and control solutions of **sodium chloride** and **histamine dihydrochloride** to ensure accurate and reliable results. The trial's methodology and design are structured to provide robust data on the allergenic extract's efficacy and safety, contributing to the understanding and management of **allergies** related to **Blomia tropicalis**.

The clinical trial involves the use of several **experimental medications** in the form of solutions for skin-prick tests, primarily focusing on the allergenic extract of **Blomia tropicalis**. The first experimental medication is "Diagnóstico prick Blomia tropicalis," which contains an allergenic extract of Blomia tropicalis at a concentration of 500 PNU/ml. This solution is administered via **intraepidermal use**. The dosage is standardized at 10 mg/ml, with a maximum daily and total dose of 10 mg/ml, administered over a maximum treatment period of one day.

Another experimental medication, "Dignostico prick Blomia tropicalis," contains the same active substance, Blomia tropicalis, but at a higher concentration of 30,000 PNU/ml. This solution is also administered via intraepidermal use, with the same dosage and treatment period as the previous medication.

The third experimental medication, also named "Diagnóstico prick Blomia tropicalis," contains Blomia tropicalis at a concentration of 10,000 PNU/ml. The administration route remains intraepidermal, with a dosage of 10 mg/ml and a maximum treatment period of one day.

The fourth experimental medication, "Diagnóstico prick Blomia tropicalis," contains Blomia tropicalis at a concentration of 2,000 PNU/ml. It follows the same administration and dosage guidelines as the other Blomia tropicalis solutions.

In addition to the experimental medications, the trial includes a **positive control** solution, "Diagnóstico prick control positivo," which contains **histamine dihydrochloride**. This solution is used for subcutaneous administration, with a dosage of 10 mg/ml and a maximum treatment period of one day. The histamine dihydrochloride serves as a chemical control to ensure the accuracy of the skin-prick test results.

The trial also employs a **negative control** solution, "Diagnóstico prick control negativo," containing **sodium chloride**. This solution is administered subcutaneously, with the same dosage and treatment period as the positive control. Sodium chloride acts as a physiological serum to provide a baseline for evaluating the skin-prick test responses.

The efficacy of the clinical trial will be assessed through the primary endpoint, which involves measuring the area of the wheal (mm²) that occurs at the cutaneous level after the administration of the allergenic extracts in the 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 of area values versus concentration in PNU/ml will be conducted 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.

Secondary endpoints will focus on the safety assessment through a descriptive analysis of adverse reactions that could occur during the course of the study. The trial aims to biologically standardize the allergenic extract of **Blomia tropicalis** by determining the concentration of the study extracts that elicit a wheal of a size equivalent to that produced by a histamine solution. The trial is categorized as a Phase IV clinical trial, with an estimated recruitment start date of July 15, 2025, and an estimated end date of December 15, 2025.