How does loratadine treat urticaria?

Loratadine is a relatively common antihistamine drug. It has a good therapeutic effect on allergic inflammation and has anti-inflammatory and analgesic effects. It is often used to treat allergic rhinitis, acute and chronic urticaria, etc. In addition, it also has a good therapeutic effect on allergic conjunctivitis and pollen disease. Of course, it belongs to the antihistamine drug class, so it has certain side effects and you should pay attention to it during use.

Pharmacokinetics: It is well absorbed orally, rapidly and extensively metabolized in the liver, and excreted via urine and feces. The drug takes effect quickly after taking it, and some patients show effects within 30 minutes. The tmax is 1.5 to 2 hours, and the elimination half-life is 8 to 14 hours. The half-life of the active metabolite descarboxymethylethoxyloratadine (DCL) is 17 to 24 hours. The half-life may be longer in the elderly and in patients with liver disease. The binding rate of loratadine to plasma proteins is 97% to 99%, and that of DCL is 73% to 76%. 24 hours after taking the medicine, about 27% of loratadine is excreted from the urine, and after 10 days, about 40% is eliminated from the urine and 42% is excreted from the feces. The secretion of this drug during breastfeeding is small, so it is safe to use during breastfeeding.

Adverse reactions (1) are rare. Occasionally there may be dry mouth, headache, etc. (2) Abnormal liver function, jaundice, hepatitis, and liver necrosis may occur occasionally. The dosage should be reduced for patients with impaired liver function. (3) Rare cases of erythema multiforme and systemic allergic reactions.

Note: 1. Use with caution in patients with severe liver or kidney damage, children under 2 years old, pregnant women, and lactating women. 2. If loratadine is used continuously for more than 1 month, the drug should be changed to prevent drug resistance. 3. When first using loratadine, drinkers or those who regularly take tranquilizers should pay close attention to whether there is an increase in drowsiness or other central nervous system depressant effects, and pay attention to adjusting the dosage, or stop drinking and taking diazepam-type drugs during the medication period. 4. Loratadine should be discontinued approximately 48 hours before the drug skin test, because antihistamines can prevent or reduce the positive reaction of the skin to the antigen used.