|
Cetrizet D
Composition
Each film coated tablet of Cetrizet D contains:
Cetirizine Hydrochloride BP
.................... 5mg
Pseudoephedrine Hydrochloride BP
........ 120mg
(As extended release)
Product Description
A yellow coloured, circular, film coated tablet with break line marked on
one side and plain on the other side.
Description
Combination of antihistamine and decongestant used to relieve allergic
rhinitis.
ACTION AND MODE OR MECHANISMS OF ACTION
Pharmacodynamic
Cetirizine is a potent antihistamine with a low potential for drowsiness at
pharmacologically active doses and with additional anti-allergic properties.
It is selective H,-antagonist with negligible effects on other receptors and
so is virtually free from anti-cholinergic and antiserotonin effects. At
pharmacologically active doses, it induces neither sedation nor behaviour
changes. This may be explained by the fact that cetirizine does not cross
the blood-brain barrier.
It was shown in human pharmacology studies that cetirizine inhibits certain
effects produced by exogenous histamine. This activity appears rapidly.
Cetirizine also inhibits the effects produced by endogenous histamine
released in vivo by any agent. It also inhibits the cutaneous reaction
induced by VIP (Vasoactive Intestinal Polypeptide) and substance P,
neuropeptides, which are believed to take part in the allergic reaction.
Cetirizine inhibits the histamine-mediated 'early' phase of the allergic
reaction and also reduces the migration of inflammatory cells and the
release of mediators associated with the 'late' allergic response.
Cetirizine markedly reduces bronchial hyper-reactivity to histamine in the
asthmatic patient. It also reduces the allergic reaction induced by specific
allergens. These effects are obtained without any central effects being
demonstrated either by psychometric tests or by quantified EEG.
Pseudoephedrine has direct and indirect sympathomimetic activity and is an
orally effective upper respiratory tract decongestant. Pseudoephedrine is
substantially less potent than ephedrine in producing both tachycardia and
elevation in systolic blood pressure and considerably less potent in causing
stimulation of the central nervous system.
Pharmacokinetic
Cetirizine
After oral administration, cetirizine is rapidly and almost completely
absorbed. Under fasting conditions, Cmax is about 1 hour. The
extent of absorption is not reduced by food; however, the rate of absorption
is reduced and the peak levels are expected about 3 hrs after dosing.
Cetirizine does not undergo any appreciable first-pass metabolism. After
repeated oral administration, the daily urinary excretion of unchanged
cetirizine is approximately 65% of the dose. The absorption and the
elimination of cetirizine are independent of the dose. Inter and infra
subject variations are low. The plasma half-life of cetirizine is
approximately 9 hours. This value is increased in patients with reduced
renal function. Cetirizine is strongly bound to plasma proteins.
Pseudoephedrine
Pseudoephedrine is rapidly and completely absorbed after oral
administration. Pseudoephedrine, given as a sustained-release formulation,
provides maximum plasma levels 8 hrs after administration. About 1/4-1/2 of
the administered dose of pseudoephedrine is transformed by the liver into
inactive metabolite through N-de-methylation. This metabolite and the remaining non-metabolized
pseudoephedrine are excreted via the kidneys.
The rate of urinary excretion is increased when the urine is acidic, and
reduced in case of alkalinization of urine. The absorption of
pseudoephedrine is not affected by fatty meals. After repeated oral
administration (every 12 hrs), the steady state is obtained within 6 days
and the effective half-life is estimated to 15 hrs.
There was no evidence for a relevant pharmacokinetic interaction between
cetirizine and pseudoephedrine.
Indications
Treatment of symptoms associated with seasonal allergy or hay fever,
perennial allergic rhinitis and common cold e.g., nasal congestion,
sneezing, rhinorrhea, nasal and ocular pruritus.
Cetrizet-D should be administered when both the antiallergic properties of
cetirizine HCI and the nasal decongestant activity of pseudoephedrine HCI
are desired.
Recommended Dosage, Dosage Schedule
Adult and children ≥ 12 years:
The recommended dosage is 1 tablet, twice daily. Do not take more often than
one tablet every twelve hours.
The tablet should preferably be swallowed with some liquid and should not
chewed.
Treatment should normally not exceed the symptomatic period. When adequate
relief from nasal symptoms is obtained, treatment with an antihistaminic
drug should be continued, if appropriate.
Symptoms and Treatment For Overdosage
Cetirizine hydrochloride
Drowsiness can be a symptom of overdosage, occurring from administration of
50 mg of Cetirizine dihydrochloride as a single dose. In the case of massive
overdosage, gastric lavage should be performed together with the usual
supportive measures. To date, there is no specific antidote. Apart from the
usual supportive measures, all vital parameters have to be monitored
regularly.
Pseudoephedrine Hydrochloride
Symptoms of overdosage include irritability, restless, tremor, convulsions,
palpitations, hypertension, difficulty in micturition, tachycardia,
arrhythmia, signs of CNS depression (sedation, apnea, unconsciousness,
cyanosis and cardiovascular collapse) or stimulation (insomnia,
hallucination, tremor, seizures) which can be fatal.
Treatment preferably in a hospital setting, should be symptomatic and
supportive, taking into account any concomitantly ingested medication.
Necessary steps should be taken to maintain the support respiration and
control convulsions. Gastric lavage should be performed if indicated. After
vomiting, the drug still remaining in the stomach can be absorbed using a
suspension of charcoal in water. Apart from the usual supportive measures,
all vital parameters have to be monitored regularly. There are no known
antidotes. Catheterisation of the bladder may be necessary. If desired, the
elimination of pseudoephedrine can be accelerated by acid duress or by
dialysis. Sympathomimetic amines should not be used.
Hypertension can be controlled with alpha-blockers and tachycardia with
beta-blockers. Seizures can be treated with 10mg of IV diazepam or 0.5mg/kg
of diazepam given rectally in the case of children.
Mode of Administration
Oral
1
2 |
