Chinanews.com, Shanghai News, April 24 (Tang Yanjun) The season of sunshine and sunshine, but being "pasted" by the willow catkins flying everywhere has come as scheduled! With it, there are also the troubles of patients with various allergic diseases: sneezing, nasal congestion, nasal itching, and ...... In order to alleviate the symptoms, many patients with allergic rhinitis have taken out "loratadine tablets", so that the keyword "loratadine" once appeared on the hot search.
What kind of drug is loratadine, what diseases can it be used to treat, and what are the precautions? Today, I will explain to you the incomprehensible "relationship" between allergies and loratadine.
How do allergies occur?
Allergies are actually a kind of immune response of the human body, which is a self-protection mechanism that occurs when the body fights against external substances. But for people with some constitutions, this protective mechanism may be abnormal, which can lead to allergic reactions. To put it simply, common allergic reactions are mainly caused by the secretion of "histamine" in the human body. When the immune system encounters an allergen, it releases certain chemicals that trigger various allergic reactions. Histamine is one of the more important substances. But allergies aren't just caused by "histamine". If histamine is to cause allergies, it must bind to the "H1 receptor" in the body. It's like an office worker has to sit at their own "desk" in order to work properly.
Therefore, the most common category of anti-allergic drugs is "antihistamines", generally speaking, the role of this type of drug is to "preemptively" bind to the receptor, preempting the "station" of histamine, and histamine can no longer cause allergic reactions. Our common loratadine is a classic "antihistamine".
The past and present life of loratadine
Antihistamines first appeared in the forties and fifties of the 20th century, when Italian pharmacologist Daniel Bovet discovered the first synthetic compound with antihistamine effects. After more than 70 years, there are generally two generations of common antihistamines.
First-generation antihistamines include diphenhydramine, chlorpheniramine, ketotifen, etc. Useful, but the drawbacks are also obvious. Its lipophilicity can easily penetrate the blood-brain barrier to cause drowsiness, and the receptor selectivity is relatively poor, and it is also easy to cause adverse reactions such as dry mouth, tachycardia, and gastrointestinal dysfunction. After years of research, the second generation of antihistamines was born, and one of the most representative drugs is "loratadine". In addition to the anti-allergic and anti-inflammatory effects, loratadine has the characteristics of poor fat solubility and low penetration of the blood-brain barrier, strong receptor selectivity and specificity, and a significant reduction in central inhibition. To put it simply, loratadine is an ingredient that moves very accurately in the process of seizing the histamine "station", does not "occupy the space" and rarely runs around, and the adverse reactions such as drowsiness are greatly reduced.
In 1988, loratadine (Claritine®) was approved for marketing in Europe. Just a few years later, loratadine entered the Chinese market as an imported drug under the trade name Clarityne®. After several years of development, in 2005, due to its excellent anti-allergic effect and good safety, the State Food and Drug Administration officially approved both loratadine tablets and syrup to enter the OTC catalog as over-the-counter drugs. Loratadine is gradually becoming widely used worldwide, becoming one of the most common anti-allergy drugs and a household medicine for many people. Take, for example, the label indications for loratadine reference (Claritin), which is more common on the market: it can be used to relieve symptoms related to allergic rhinitis. It is also suitable for relieving the signs and symptoms of chronic urticaria, pruritic skin diseases and other allergic skin diseases.
Generally speaking, loratadine can generally be used to relieve symptoms caused by allergies, such as sneezing, runny nose, nasal itching, nasal congestion, itching and burning sensation around the eyes, skin itching, wheals, red rashes, etc.
Although loratadine is an over-the-counter drug, it is still "evidence-based" for which diseases should be used and whether it should be used first. These evidences are generally the conclusions of more professional studies such as "clinical trials", "meta-analyses", "observational studies", etc., and the more sufficient the evidence, the higher the recommendation level in the diagnosis and treatment guidelines of related diseases. So which diseases recommend second-generation antihistamines represented by loratadine in these professional guidelines?
The 2022 Guidelines for the Diagnosis and Treatment of Allergic Rhinitis recommend second-generation antihistamines for allergic rhinitis and the Clinical Practice Guidelines for the diagnosis and treatment of allergic rhinitis in children. It is recommended that the prevention and treatment of allergic rhinitis in children should adopt a "stepwise treatment mode", and syrups are preferred for children under 5 years old. Guidelines for the diagnosis and treatment of urticaria in China 2018 Edition: second-generation antihistamines are recommended as the first choice for the treatment of acute and chronic urticaria, and Guidelines for the Diagnosis and Treatment of Atopic Dermatitis in China 2020 Edition: used as an adjuvant treatment for itching in atopic dermatitis, especially for patients with allergic comorbidities such as urticaria and allergic rhinitis, the use of second-generation non-sedating antihistamines is recommended, and the dose can be doubled if necessary.
It can be seen that whether it is "self-medication" or treatment under the guidance of a doctor, second-generation antihistamines represented by loratadine can effectively alleviate some common allergy symptoms, and are generally safer.
What are the precautions for loratadine use?
Of course, the effectiveness and safety of any drug are relative, and it is still necessary to find the right cause and use the right symptomatic medication to achieve the best effect. So what problems need to be paid attention to when using loratadine for "self-medication"?
1. The second-generation antihistamine represented by loratadine cannot eradicate allergens, but only relieve symptoms and avoid allergens is still very important;
2. For those who know that they are allergic to specific allergens, they can take prophylactic medication during the allergy season or before exposure to allergens under the guidance of a doctor;
3. Use according to the instructions or doctor's guidance, it is not recommended to increase or decrease the dosage or stop eating and eating without authorization, the guidelines recommend that for allergic rhinitis and skin allergies, it should be used continuously for at least 2 weeks;
4. In general, avoid long-term use of loratadine "self-medication", generally should not exceed 1 month, and seek the advice of a professional doctor in time if necessary;
5. It is not recommended to drink alcohol or alcoholic beverages immediately after taking the drug, so as not to increase the risk of adverse reactions such as drowsiness;
6. When choosing a dosage form, it is necessary to choose the appropriate type according to different age groups. Pregnant women, lactating women, and special populations with severe liver and kidney insufficiency should also be cautious, and it is recommended to consult a professional doctor or pharmacist. (ENDS)
Editor: Tang Yanjun