desloratadine

Action and Spectrum

Actions and Spectrum: 

desloratadine is an antihistamine medication that is used to relieve symptoms of allergic rhinitis (hay fever) and chronic idiopathic urticaria (hives). It works by blocking the action of histamine, a substance in the body that causes allergic symptoms.  

The medication is available as a tablet, oral solution, and disintegrating tablet. Its peak effect is usually seen within 1-2 hours after taking it and the duration of action is 24 hours.  

desloratadine is a non-sedating antihistamine, meaning it is less likely to cause drowsiness than some other antihistamines. 

Drug Interaction

Adverse Reaction

Frequency Defined  

>10%  

Irritability (12%)  

Fever (12%)  

Diarrhea (15%)  

Cough (11%)  

Headache (14%)  

Upper respiratory infection (11%)  

1-10%  

Somnolence (2%)  

Fatigue (2%)  

Dizziness (4%)  

Macupopular rash (3%)  

Erythema (2%)  

Black Box Warning

Black Box Warning 

desloratadine, a medication used to treat allergic rhinitis and chronic idiopathic urticaria, carries a black box warning regarding the risk of suicidal thoughts and behavior. The warning states that patients, particularly children and adolescents, should be closely monitored for any signs of suicidal thoughts or behavior while taking desloratadine. 

Contraindication / Caution

Contraindication/Caution: 

desloratadine is contraindicated in patients with known hypersensitivity to desloratadine, loratadine, or any of the excipients in the formulation. 

Caution should be exercised in patients with hepatic impairment, as desloratadine is metabolized by the liver and may have increased plasma concentrations in these patients. Additionally, caution should be used in patients with renal impairment, as desloratadine is eliminated primarily by the kidneys. 

Pregnancy / Lactation

Pregnancy warnings:     

US FDA pregnancy category: N/A 

Lactation:   

Excreted into human milk is known  

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were lack of studies on pregnant women and no evidence of risk to the foetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology:  

desloratadine is a non-sedating antihistamine that belongs to the class of drugs known as second-generation antihistamines. It works by blocking the action of histamine, a chemical produced by the body that causes symptoms of allergies such as sneezing, runny nose, and itching. 

Pharmacodynamics:  

It works by binding to the histamine H1 receptor, preventing the binding of histamine and reducing the symptoms of allergic reactions. 

Desloratadine has a high binding affinity for the H1 receptor, with a dissociation constant (Kd) of 0.3 nM. This means that it binds strongly to the receptor and has a long duration of action. It also has a low potential for sedation, as it does not have significant binding to the H2 receptor, which is responsible for sedation with first-generation antihistamines. 

Pharmacokinetics:  

Absorption  

desloratadine is rapidly and well absorbed after oral administration. The maximum plasma concentration (Cmax) is reached within 1-2 hours. The bioavailability of desloratadine is approximately 70-80%.  

Distribution  

It is widely distributed in the body and reaches peak concentrations in the blood within 1-2 hours. The protein binding of desloratadine is approximately 50%.  

Metabolism  

It is metabolized by the liver, mainly by the enzyme CYP3A4. The main metabolite of desloratadine is 3-hydroxydesloratadine, which is also active.  

Elimination and Excretion  

desloratadine and its metabolites are mainly excreted in the urine, with a small amount excreted in the feces. The elimination half-life of desloratadine is approximately 27 hours.

Adminstartion

Administration:  

orally administration: 

desloratadine administered orally and is rapidly and well absorbed after oral administration. The maximum plasma concentration (Cmax) is reached within 1-2 hours. The bioavailability of desloratadine is approximately 70-80%.  

Patient Information Leaflet

Patient information leaflet 

Generic Name: desloratadine 

Why do we use desloratadine? 

desloratadine is used in the treatment of Perennial Allergic Rhinitis and Chronic Idiopathic Urticaria. It is an Antihistamines, 2nd Generation drug works by blocking the action of histamine, a chemical produced by the body that causes symptoms of allergies such as sneezing, runny nose, and itching.