|
Drug Information
Pharmacokinetics
| Indication
& Dosage | Action
| Interactions
Adverse
Effect & Precautions |
Brands available in Market
Pharmacokinetics
Loratadine is
rapidly absorbed from the gastrointestinal tract after oral
administration, peak plasma concentrations being attained in about one
hour. Bioavailability is increased and time to peak plasma
concentrations is delayed when administered with food. Loratadine
undergoes extensive metabolism. The major metabolite,
descarboethoxyloratadine (desloratadine), has potent antihistamine
activity. Reported mean elimination half-lives for loratadine and
descarboethoxyloratadine are 8.4 and 28 hours respectively. Loratadine
is about 98% bound to plasma proteins; descarboethoxyloratadine is less
extensively bound. Loratadine and its metabolites have been detected in
breast milk, but do not appear to cross the blood-brain barrier to a
significant extent. Most of a dose is excreted equally in the urine and
faeces, mainly in the form of metabolites.
Indication
& Dosage
Oral
SEASONAL AND PERENNIAL ALLERGIC RHINITIS, SKIN ALLERGIES INCLUDING
ALLERGIC DERMATITIS AND URTICARIA, OCULAR ALLERGY: Adult and Children over
30kg: 10mg once daily. Children under 30kg or 5 yrs: 5mg once daily. In
patients with liver failure: Start with 10mg on alternate days.
Binds selectively to peripheral histamine H1 receptors. Also has mast cell stabilising effect. Does not cross blood-brain barrier and has no effect on sleep patterns or REM sleep. Antihistamine action quick onset and long duration.
Loratadine
is metabolised by cytochrome P450 isoenzymes CYP3A4 and CYP2D6.
Therefore concomitant administration of other drugs that inhibit
or are metabolised by these hepatic enzymes may result in changes
in plasma concentrations of either drug and, possibly, adverse
effects. Drugs known to inhibit one or other of these enzymes
include cimetidine, erythromycin, ketoconazole, quinidine,
fluconazole, and fluoxetine.
Ketoconazole also appears to be able to inhibit the metabolism of
loratadine and at therapeutic doses, is approximately 3 times more
inhibitory than erythromycin. (3) However, the concentrations of
ketoconazole required are reported to be much higher than those
required to inhibit the metabolism of astemizole or terfenadine.
Cimetidine also appears to have an inhibitory effect on the
metabolism of loratadine and all 4 drugs also attenuate the
clearance of its active metabolite descarboethoxyloratadine
although no clinically significant consequences were observed in
these studies.
Adverse
Effect & Precautions
Fatigue,
headache, nausea.
Precaution: Neonates, Infants
Pregnancy: Use with caution.
Breast Feeding: Contraindicated.
Man: May be used in reduced dose.
