Loratadine: Uses, Interactions, Mechanism Of Action
Loratadine is a second-generation antihistamine that is used as a medication for managing allergy of symptoms such as sneezing, running nose, itchy and watery eyes. It can also be used to treat itch and rash associated with chronic idiopathic urticaria.
USES
Allergic Rhinitis: Loratadine is commonly used to control symptoms of seasonal allergic rhinitis which are sneezing, stuffy nose, itchy eyes and runny nose. It can also be useful for aggravating relief from perennial allergic rhinitis which is a condition that comes all year round, manifested by sensitiveness to dust as well as mould.
Chronic Urticaria (Hives): Loratadine is useful in management of urticaria which is a recurrent hives of uncertain origin. This results in itching and formation of welts on the skin and the medicine assists in minimising them.
Other Allergic Conditions: In addition to allergic rhinitis and hives, loratadine can be used for managing symptoms of other allergic conditions, such as allergic conjunctivitis or mild allergic reactions caused by insect bites, foods, or environmental allergens.
Off-Label Uses: Other uses of loratadine include management of the symptoms of other allergies such as allergic conjunctivitis and other mild allergic reactions elicited by insects' stings, certain foods, or contact with certain environmental stimuli.
Mechanism Of Action
Loratadine is a selective histamine H1 receptor antagonist. Histamine is a chemical released by the body in response to allergens, and it binds to H1 receptors in various tissues, triggering allergic symptoms like itching, sneezing, and increased mucus production. By blocking the H1 receptors, loratadine prevents or eliminates the allergy symptoms. Unlike first-generation antihistamines, loratadine is less likely to cause sedation since it does not easily cross the blood-brain barrier. It was approved for medical use in 1993 and is available as an over-the-counter drug
Interactions
CYP450 Inhibitors: Loratadine is primarily metabolised in the liver. Drugs that inhibit these enzymes can lead to increased levels of loratadine in the blood, potentially increasing the risk of side effects like drowsiness.
Other Antihistamines: Loratadine should not be combined with other antihistamines unless advised by a healthcare provider as this can increase the risk of side effects like dry mouth, dizziness, or drowsiness.
Alcohol: Although loratadine itself does not typically cause sedation, consuming alcohol while taking the drug may enhance the CNS depressant effects, leading to increased drowsiness or impaired coordination.
Central Nervous System Depressants: Caution is advised when using loratadine with other CNS depressants because of the potential for enhanced sedative effects, even though loratadine is not typically sedating on its own.
Side Effects
Loratadine is generally well-tolerated, but like all medications, it can cause some side effects, particularly when taken at higher-than-recommended doses or in certain individuals.
Headache: This is one of the most commonly reported side effects, though it is usually mild.
Fatigue: Although loratadine is less sedating than first-generation antihistamines, some individuals may still experience mild fatigue or drowsiness, particularly at higher doses.
Dry Mouth: Antihistamines can reduce saliva production, leading to dry mouth.
Dizziness: Some patients may experience dizziness, though this is less common with loratadine than with older antihistamines.
Nervousness or Insomnia: Rarely, loratadine may cause excitability or difficulty sleeping, especially in children or sensitive individuals.
Rash: In rare cases, allergic reactions to loratadine itself can occur, manifesting as a rash, itching, or swelling.
Tachycardia (Fast Heartbeat): In rare instances, loratadine has been associated with an increased heart rate, which can be more common in patients with pre-existing heart conditions.
Loratadine: Uses, Interactions, Mechanism Of Action
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