Loratadine

BRAND NAMES

Agistam: It contains the active ingredient of loratadine. It is available in the form of tablets used to treat allergic conditions.

Claritin: It contains the active ingredients of loratadine. It is available in the form of tablets.

Clear-Atadine: It contains the active ingredients of loratadine. It is available in the form of tablets.

Dimetapp-ND: It contains the active ingredient of loratadine. It is available in the form of oral disintegration tablets used to treat cold and flu symptoms mainly.

Tavist ND: It contains the active ingredient of loratadine. It is available in the form of tablets to treat allergic symptoms.

Wal-itin: It contains the active ingredients of loratadine. It is available in the form of tablets.

MECHANISM OF ACTION

Loratadine works by blocking H1 histamine receptors. Loratadine binds to H1 histamine receptors on the surfaces of epithelial cells, eosinophils, neutrophils, airway cells, and vascular smooth muscle cells. H1 histamine receptors are part of the G-protein-coupled receptor family and exist in an equilibrium between active and inactive versions. Histamine binding to H1 receptors promotes cross-linking between transmembrane domains III and V, thereby maintaining the receptor's active form. 

PHARMACOKINETICS

Absorption

Loratadine is rapidly absorbed, reaching peak plasma levels in 1-2 hours, whereas its primary metabolite takes 3-4 hours.

Distribution

Loratadine has a volume distribution of 120L per kg.

Metabolism

CYP3A4 and CYP2D6 are primarily responsible for converting loratadine into descarboethoxyloratadine. This primary metabolite is four times as potent as loratadine. Furthermore, a study shows that descarboethoxyloratadine is first glucuronidated by UGT2B10 and subsequently hydroxylated by CYP2C8 to produce 3-hydroxydesloratadine. Further glucuronidation of 3-hydroxydesloratadine improves excretion.

Excretion

Loratadine is excreted in 40% of urine and 42% in feces.

PHARMACODYNAMICS

Loratadine, like other second-generation antihistamines, specifically targets peripheral H1 receptors. Loratadine does not effectively penetrate the central nervous system and has a low affinity for CNS H1 receptors. These characteristics result in the absence of CNS depressant effects such as sleepiness, sedation, and reduced psychomotor function.

ADMINISTRATION

Loratadine is available in three forms for oral administration: syrup, tablet, and rapidly dissolving tablet. It is often taken once per day, with or without food. Melt-in-the-mouth tablets melt on your tongue instantaneously without the need for a drink. 

DOSAGE AND STRENGTH

These tablets are available in the form of the following dosage forms

Syrup -5mg/ml

Tablets-10mg

Tablet chewable – 5mg

Tablet disintegrating mg and 10mg

Capsules -10 mg

DRUG INTERACTIONS

Loratadine may interact with the following drugs:

Amiodarone is a medicine used to treat low blood pressure and irregular heartbeat.

Antifungal  medications include ketoconazole

Antibiotic- erythromycin

 antihypertensives - Midodrine 

anti-HIV drug - Ritonavir 

Indigestion medicine- Cemitidine.

CONTRAINDICTIONS

Loratadine is contraindicated in individuals with known hypersensitivity to the formulation's component, as well as in children under the age of two because of its antihistamine qualities, which may trigger CNS stimulation or convulsions in young patients.

SIDE  EFFECTS

Loratadine may cause side effects, including

• Headache
• Dry mouth
• Nosebleed
• Sore throat
• Mouth sores
• Nervousness
• Weakness
• Stomach pain
• Red eyes

Loratidine severe side effects include

• Rash
• Hives
• Itching
• Swelling of the eyes, face, lips, tongue, throat, hands, arms, feet, ankles, or lower legs
• Hoarseness
• wheezing

OVERDOSE

Loratadine overdose symptoms may include gastrointestinal side effects such as agitation, drowsiness, tachycardia, and headaches. 

If you overdose on loratadine, you should get an ECG. 

TOXICITY

Loratadine-induced cardiotoxicity, such as cardiac arrhythmias and QT interval prolongation, is possible in patients, especially the elderly, who exceed the recommended 24-hour dose. Though uncommon, loratadine overdose can cause severe toxicity, including agitation and anticholinergic syndrome symptoms. Symptoms include mydriasis, urinary retention, tachycardia, and skin flushing.

STORAGE CONDITIONS

Keep out of reach of youngsters.

Store at room temperature 

Protect against wetness.

Discard any unused medication after its expiration date.