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 Rinafort [REPETABS Tablets]
Brand of dexbrompheniramine maleate and
pseudoephedrine sulfate
Antihistamine/Decongestant Tablets
DESCRIPTION
RINAFORT REPETABS Tablet is a smooth, uniform,
round, white to off-white, biconvex, lustrous coated tablet, free from
foreign matter. Each RINAFORT REPETABS Tablet contains 3 mg of
dexbrompheniramine maleate (antihistamine) and 60 mg pseudoephedrine sulfate
(nasal decongestant) in the outer coat for immediate action and 3 mg of
dexbrompheniramine maleate and 60 mg pseudoephedrine sulfate in the inner
core for a second or repeat dose. Inactive ingredients: Lactose, starch,
povidone, magnesium stearate, sucrose, calcium sulfate, calcium sulfate
anhydrous, talc, acacia, gum rosin, gelatin, zein, titanium dioxide, oleic
acid, soap, butylparaben, white wax and carnauba wax. Preservative:
Butylparaben.
RINAFORT REPETABS Tablets combine two medically recognized ingredients that
provide both rapid and sustained relief from symptoms of upper respiratory
mucosal congestion, such as in hay fever, nasal allergies, acute rhinitis,
sinusitis, rhinosinusitis and eustachian tube congestion. The antihistaminic
component of RINAFORT REPETABS Tablets provides relief of runny nose,
sneezing and watery, itchy eyes. The decongestant action reduces swelling of
mucous membranes, gently dries and clears nasal passages.
ACTIONS
RINAFORT REPETABS Tablets combine the antihistaminic
actions of dexbrompheniramine maleate with the decongestant properties of
pseudoephedrine sulfate.
PHARMACOLOGY
Dexbrompheniramine is the dextro isomer of
brompheniramine maleate, an alkylamine derivative. As its parent compound,
the uses and properties of dexbrompheniramine are similar to those of
histamine H1-receptor antagonists; these include antimuscarinic
effects and sedation.
Pseudoephedrine acts directly on both α- and to a lesser degree, β-adrenergic
receptors. It is believed that a-adrenergic effects result from the
inhibition of the production of cyclic adenosine-3',5'-monophosphate (AMP)
by inhibition of the enzyme adenyl cyclase, whereas β-adrenergic
effects result from stimulation of adenyl cyclase activity. Like ephedrine,
pseudoephedrine also has an indirect effect by releasing norepinephrine from
its storage sites.
Pseudoephedrine acts directly on α-adrenergic receptors in the mucosa
of respiratory tract producing vasoconstriction which results in shrinkage
of swollen nasal mucous membranes, reduction of tissue hyperemia, edema and
nasal congestion, and in an increase in nasal airway patency. Drainage of
sinus secretions is increased and obstructed eustachian ostia may be opened.
Pseudoephedrine may relax bronchial smooth muscle by stimulation of β2-adrenergic
receptors; however, substantial bronchodilation has not been demonstrated
consistently following oral administration of the drug.
Oral administration of usual doses of pseudoephedrine to normotensive
patients usually produces negligible effect on blood pressure.
Pseudoephedrine may increase the irritability of the heart muscle and may
alter the rhythmic function of the ventricles, especially in large doses or
after administration to patients such as those with cardiac disease who are
hypersensitive to the myocardial effects of sympathomimetic drugs.
Tachycardia, palpitation, and/or multifocal premature ventricular
contractions may occur.
Pseudoephedrine may cause mild CNS stimulation, especially in patients who
are sensitive to the effects of sympathomimetic drugs.
PHARMACOKINETICS
Dexbrompheniramine
Absorption - Dexbrompheniramine appear to be well absorbed from the
gastro-intestinal tract.
Following oral administration of a single 0.13 mg/kg dose of brompheniramine
maleate in healthy, fasting adults in one study, peak serum brompheniramine
concentrations of 7.7-15.7 ng/ml occurred within 2-5 hours; in most of these
individuals, a second lower peak, possibly secondary to enterohepatic
circulation, was also observed. The antihistamine effect of brompheniramine,
as determined by suppression of the wheal and flare response induced by
intradermal administration of histamine, appears to be maximal within 3-9
hours after a single oral dose of the drug, but suppression of the flare
response may persist for up to at least 48 hours; the antipruritic effect
appears to be maximal within 9-24 hours.
Following oral administration of 2 mg of dexbrompheniramine maleate every 4
hours in healthy adults, mean peak plasma concentrations of the drug were
about 22 ng/ml on the sixth and seventh days of dosing and mean trough
concentrations were about 17 and 18 ng/ml on the sixth and seventh days,
respectively. At steady state, 6 mg of dexbrompheniramine maleate every 12
hours as extended-release tablets (RINAFORT ) is reportedly bioequivalent to
4 mg of the drug every 2 hours as conventional tablets.
Distribution - Distribution of brompheniramine into human body
tissues and fluids has not been fully characterized, but the drug appears to
be widely distributed. Following oral administration of a single dose of the
drug in healthy adults, the apparent volume of distribution reportedly
averaged 11.7 L/kg.
Elimination - In healthy adults, the half-life of brompheniramine
reportedly ranges from 11.8-34.7 hours. The metabolic and excretory fate of
the drug has not been fully characterized.
Brompheniramine undergoes N-dealkylation to form
monodesmethylbrompheniramine and didesmethylbrompheniramine, and is
metabolized to the propionic acid derivative, which is partially conjugated
with glycine, and to other unidentified metabolites. Brompheniramine and its
metabolites are excreted principally in urine. About 40% of an oral dose of
brompheniramine is excreted in urine and about 2% in feces within 72 hours
in healthy individuals. In healthy individuals, about 5-10% of an oral dose
is excreted in urine as unchanged drug, 6-10% as
monodesmethylbrompheniramine, 6-10% as didesmethylbrompheniramine, small
amounts as the propionic acid derivative and its glycine conjugate, and the
remainder as unidentified metabolites.
In healthy adults, dexbrompheniramine reportedly has an elimination
half-life of about 22 hours.
Pseudoephedrine
Absorption - After oral administration
of 60 mg of pseudoephedrine hydrochloride as tablets or oral solution, nasal
decongestion occurs within 30 minutes and persists for 4-6 hours. Nasal
decongestion may persist for 8 hours following oral administration of 60 mg
and up to 12 hours following 120 mg of the drug in extended-release
preparations.
Distribution - Although specific information is lacking,
pseudoephedrine is presumed to cross the placenta and to enter CSF. The drug
may also be distributed into milk.
Elimination - Pseudoephedrine is incompletely metabolised in the
liver by N-demethylation to an inactive metabolite. The drug and its
metabolite are excreted in urine; 55-75% of a dose is excreted unchanged.
The rate of urinary excretion of pseudoephedrine is accelerated when urine
is acidified to a pH of about 5 by prior administration of ammonium
chloride. When the urine is alkalinized to a pH of about 8 by prior
administration of sodium bicarbonate, some of the drug is reabsorbed in the
kidney tubule and the rate of urinary excretion is slowed.
INDICATIONS AND USAGE
RINAFORT REPETABS Tablets are indicated
for the relief of symptoms of upper respiratory mucosal congestion, such as
in seasonal and perennial allergies, eustachian tube congestion, acute
rhinitis and rhinosinusitis. The decongestant temporarily relieves nasal
congestion due to the common cold, hay fever or other upper respiratory
allergies, and associated with sinusitis. Helps decongest sinus openings and
sinus passages. Reduces swelling of nasal passages and temporarily restores
freer breathing through the nose. The antihistamine alleviates runny nose,
sneezing, itching of the nose or throat, and itchy and watery eyes as may
occur in allergic rhinitis (such as hay fever).
DOSAGE AND ADMINISTRATION
Adults and children over 12 years :
One RINAFORT REPETABS Tablet every 12 hours; one in the morning and one at
bedtime. Following initial improvement, one RINAFORT REPETABS Tablet daily
may successfully control symptoms.
In exceptional cases, one
RINAFORT REPETABS Tablet every eight hours may be required to control severe
conditions. Dosage should be adjusted, once control is obtained, to one to
two RINAFORT REPETABS Tablets daily.
Do not exceed recommended dosage.
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