Dimetapp PE Sinus Pain +
Allergy Tablets
Phenylephrine Hydrochloride, Paracetamol &
Chlorpheniramine Maleate
PRODUCT INFORMATION
Product description
Dimetapp PE Sinus Pain + Allergy tablets are pink coloured round tablets with break-line on one
side.
Each tablet contains:
Phenylephrine hydrochloride 5mg, Paracetamol 500mg and Chlorpheniramine maleate 2mg.
The tablet also contains cellulose-microcrystalline, magnesium stearate, starch-pregelatinised
maize, povidone, crospovidone, erythrosine CI 45430 and water-purified.
Refer to presentation for a complete description of the dosage form.
Pharmacology
Dimetapp PE Sinus Pain + Allergy tablets contain phenylephrine, a synthetic sympathomimetic
amine, which acts directly on alpha adrenergic receptors; paracetamol, a p-aminophenol derivative
that is thought to produce analgesia through a central inhibition of prostaglandin synthesis; and
chlorpheniramine, a sedating antihistamine which competes with histamine at central and peripheral
histamine1-receptor sites.
Pharmacokinetics:
Phenylephrine has low oral bioavailability owing to irregular absorption and first-pass metabolism
in the gastrointestinal tract and liver by the enzyme monoamine oxidase (MAO). Following oral
administration nasal decongestion may occur within 15 or 20 minutes and may persist for 2-4 hours.
The half-life of phenylephrine is 2-3 hours.
Paracetamol is readily absorbed from the gastrointestinal tract with peak plasma concentrations
occurring about 10 to 60 minutes after oral administration. Paracetamol is distributed into most body
tissues. Paracetamol crosses the placenta and is present in breast milk. Plasma-protein binding is
negligible at usual therapeutic concentrations but increases with increasing doses. The elimination
half-life of paracetamol varies from 1 to 3 hours.
Paracetamol is metabolised predominantly in the liver and excreted in the urine mainly as the
inactive glucuronide and sulfate conjugates. Less than 5% is excreted as unchanged paracetamol.
The metabolites of paracetamol include a minor hydroxylated intermediate, which has hepatotoxic
activity. This intermediate metabolite is detoxified by conjugation with glutathione, however, it can
accumulate following paracetamol overdosage (more than 150mg/kg or 10g total paracetamol
ingested) and if left untreated can cause irreversible liver damage.
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Paracetamol is metabolised differently by premature infants, newborns, infants and young children
compared to adults, the sulfate conjugate being predominant.
Chlorpheniramine is absorbed relatively slowly from the gastrointestinal tract, with peak plasma
concentrations occurring about 2.5 to 6 hours after oral administration. Chlorpheniramine appears to
undergo considerable first-pass metabolism. Bioavailability is low, values of 25 to 50% having been
reported. About 70% of chlorpheniramine in the circulation is bound to plasma proteins. There is
wide inter-individual variation in the pharmacokinetics of chlorpheniramine; half-life values ranging
from 2 to 43 hours have been reported. Chlorpheniramine is widely distributed in the body and
enters the central nervous system (CNS).
Chlorpheniramine is metabolised extensively. Metabolites include desmethyl- and
didesmethylchlorpheniramine. Unchanged drug and metabolites are excreted primarily in the urine;
excretion is dependent on urinary pH and flow rate. Only trace amounts have been found in the
faeces.
A duration of action of 4 to 6 hours has been reported; this is shorter than may be predicted from
pharmacokinetic parameters.
More rapid and extensive absorption, faster clearance, and a shorter half-life have been reported in
children compared to adults.
Pharmacodynamics/Mechanism of action:
Phenylephrine has direct sympathomimetic activity and is an effective decongestant in the upper
respiratory tract. It elicits a response in the effector tissue by directly stimulating alpha adrenergic
adrenoreceptors.
Sympathomimetic agents are used as nasal decongestants to provide symptomatic relief. They act
by causing vasoconstriction resulting in redistribution of local blood flow, which reduces oedema of
the nasal mucosa, thus improving ventilation, drainage and nasal stuffiness.
Paracetamol is a p-aminophenol derivative that exhibits analgesic and antipyretic activity. It does
not possess anti-inflammatory activity. Paracetamol is thought to produce analgesia through a
central inhibition of prostaglandin synthesis.
Chlorpheniramine competes with histamine at central and peripheral histamine1-receptor sites,
preventing the histamine-receptor interaction and subsequent mediator release.
Chlorpheniramine is a highly lipophilic molecule that readily crosses the blood-brain barrier.
Chlorpheniramine is highly selective for histamine1-receptors but has little effect on histamine2 or
histamine3 receptors. Chlorpheniramine also activates 5-hydroxytryptamine (serotonin) and αadrenergic receptors and blocks cholinergic receptors.
Indications
Relief from the symptoms of sinus headache, sinus pain, nasal and sinus congestion. Symptomatic
relief from colds and flu including headaches, body aches and pains. Reduces fever. It also relieves
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CDS: PE 5.0; Chlor. Mal 5.0 Page - 2
runny nose, sneezing, itching of nose or throat, itchy watery eyes due to cold, flu, hay fever or
allergic rhinitis.
Contraindications
Dimetapp PE Sinus Pain + Allergy tablets are contraindicated for use in patients:
• with known hypersensitivity or idiosyncratic reaction to phenylephrine, paracetamol,
chlorpheniramine or any of the other ingredients in the product
• with severe hypertension or coronary artery disease
• taking or have taken in the last two weeks a monoamine oxidase inhibitor (MAOI)
• with narrow-angle glaucoma
• with stenosing peptic ulcer
• with symptomatic prostatic hypertrophy
• with bladder neck obstruction
• with pyloroduodenal obstruction
Do not use in children under 12 years.
Precautions
Dimetapp PE Sinus Pain + Allergy tablets should be used with caution in patients with:
• cardiovascular disease (including ischaemic heart disease, hypertension, bradycardia,
tachycardia, arteriosclerosis and coronary artery disease)
• thyroid disease
• diabetes mellitus
• glaucoma
• prostatic hypertrophy
• epilepsy
• impaired hepatic function
• impaired renal function
• breathing problems or chronic lung disease (such as chronic bronchitis, asthma or emphysema)
Dimetapp PE Sinus Pain + Allergy tablets may cause drowsiness or sedation and may increase the
effects of alcohol. Drowsiness may continue the following day. Those affected should not drive or
operate machinery; alcohol should be avoided.
Patients should not exceed recommended dosage.
Patients should not take this product if symptoms get worse or lasts longer than few days, unless
directed by a doctor.
This product should not be taken with another cough and cold medicine unless directed by a doctor.
This product should be kept out of reach of children.
Use in children and elderly
Children and the elderly may experience paradoxical excitation with chlorpheniramine in Dimetapp
PE Sinus Pain + Allergy tablets. The elderly are more likely to have CNS depressive side effects,
including confusion.
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Use in pregnancy
Category B2: The active ingredient of Phenylephrine in Dimetapp PE Sinus Pain + Allergy tablets
has been taken by only a limited number of pregnant women or women of childbearing age, without
an increase in the frequency of malformation or other direct or indirect harmful effects on the human
fetus having been observed. Studies in animals are inadequate, or may be lacking, but available
data shows no evidence of an increased occurrence of fetal damage. Safety in pregnancy has not
been established, therefore Dimetapp PE Sinus Pain + Allergy tablets should not be used in
pregnant women, or those likely to become pregnant, unless the potential benefits to the patient are
weighed against the possible risk to the foetus.
Use in lactation
Paracetamol is excreted in small amounts (<0.2%) in breast milk, chlorpheniramine is excreted in
breast milk and it is not known whether phenylephrine is distributed into breast milk. Therefore
Dimetapp Sinus Pain + Allergy tablets are not recommended for breastfeeding mothers unless the
potential benefits to the patient are weighed against the possible risk to the infant.
Interaction with other medicines
The following interactions with Phenylephrine/Paracetamol/Chlorpheniramine have been noted:
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Monoamine oxidase inhibitors (MAOIs) and antidepressant medication eg tricyclic
antidepressants - may cause a serious increase in blood pressure or hypertensive crisis
Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs) - may prolong and
intensify the anticholinergic and CNS depressive effects
Other sympathomimetic agents, such as decongestants, appetite suppressants and
amphetamine-like psychostimulants – may cause an increase in blood pressure and additive
effects
Methyldopa and β-blockers – may cause an increase in blood pressure
Anticoagulant drugs (warfarin) – dosage may require reduction if paracetamol and
anticoagulants are taken for a prolonged period of time
The risk of paracetamol toxicity may be increased in patients receiving other potentially
hepatotoxic drugs or drugs that induce liver microsomal enzymes such as alcohol and
anticonvulsant agents
Paracetamol absorption is increased by substances that increase gastric emptying, e.g.
metoclopramide
Paracetamol absorption is decreased by substances that decrease gastric emptying e.g.
propantheline, antidepressants with anticholinergic properties and narcotic analgesics
Paracetamol may increase chloramphenicol concentrations
Paracetamol excretion may be affected and plasma concentration altered when given with
probenecid
Colestyramine reduces the absorption of paracetamol if given within1 hour of paracetamol
CNS depressants (including alcohol, sedatives, opioid analgesics, hypnotics and tranquillizers)
may increase the CNS depressant or sedation effects
Chlorpheniramine when taken concomitantly with phenytoin may cause a decrease in phenytoin
elimination
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Adverse reactions
The following adverse reactions may be associated with the use of
Phenylephrine/Paracetamol/Chlorpheniramine containing products:
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Blood and lymphatic system – Agranulocytosis, haemolytic anemia, hypoplastic anemia,
thrombocytopenia, haematological reactions
Cardiac disorders – Palpitations, tachycardia, bradycardia, extrasystoles
Eye disorders – Vision blurred, visual disturbance
Gastrointestinal disorders – Nausea , vomiting, constipation, diarrhea, dry mouth
General disorders and administration site conditions – Fatigue, malaise
Immune system disorders – Hypersensitivity, anaphylactic shock
Nervous system disorders – Dizziness, headache, psychomotor hyperactivity, tremors,
hallucinations, coordination abnormal, impaired performance, sedation, somnolence, appetite
stimulation, activation of epileptogenic foci
Psychiatric disorders – Excitability, insomnia, irritability, nervousness, restlessness, anxiety,
confusional state, euphoric mood
Renal and urinary disorders – Dysuria, urinary retention
Respiratory, thoracic and mediastinal disorders – Dry throat, nasal dryness
Skin and subcutaneous tissue disorders – Rashes, urticaria, drug eruption, photosensitivity
reaction. Very rare cases of serious skin reactions (including severe cutaneous reactions such
as Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis, and Acute Generalized
Exanthematous Pustulosis) have been reported
Vascular disorders – Increased blood pressure, hypertension
Children and the elderly are more likely to experience adverse effects than other age groups.
Dosage
Adults and children 12 years and over:
Take 2 tablets swallowed whole with water. Repeat dose if necessary every 4-6 hours.
Do not exceed 8 tablets in 24 hours.
Adults should not take this product for more than a few days at a time except on medical advice.
Children should not use for more than 48 hours, except on medical advice.
Do not use in children under 12 years.
Overdosage
The following signs or symptoms may be associated with an overdose of
Phenylephrine/Paracetamol/Chlorpheniramine:
Cardiac disorders
Bradycardia, palpitations, tachycardia
Eye disorders
Vision blurred
PI-Dimetapp PE Sinus Pain + Allergy_2015-03-09R
GMA Approved: 02 Mar 2012
CDS: PE 5.0; Chlor. Mal 5.0 Page - 5
Gastrointestinal disorders
Nausea, vomiting, dry mouth, abdominal discomfort
General disorders and administration site conditions
Fatigue, hyperpyrexia, hyperthermia
Investigations
Heart rate abnormal
Nervous system disorders
Convulsions, dizziness, tremor, ataxia, depressed level of consciousness, coma, convulsion,
somnolence, lethargy, sedation
Psychiatric disorders
Anxiety, irritability, nervousness, restlessness, insomnia, agitation, delirium, excitability,
hallucinations, psychotic disorder
Respiratory, thoracic and mediastinal disorders
Apnea, dyspnea, dry throat, nasal dryness, respiratory arrest, respiratory failure
Vascular disorders
Increased blood pressure, hypertension, circulatory collapse, flushing, hypotension, pallor
In case of overdose, immediately contact the Poisons Information Centre (in Australia, call 13 11 26;
in New Zealand call 0800 764 766) for advice, or go to a hospital straight away even if you feel well
because of the risk of delayed, serious liver damage.
Overdosage with paracetamol if left untreated can result in severe, sometimes fatal liver damage
and rarely, acute renal tubular necrosis.
Presentation
Dimetapp PE Sinus Pain + Allergy tablets are pink coloured round tablets in blister pack.
Pack sizes:
Australia: 10’s, 20’s, 24’s & 30’s (Marketed); 30’s (Marketed)
New Zealand: 30’s (Registered and Marketed)
Storage
Store below 25°C.
Poison Schedule
Dimetapp PE Sinus Pain + Allergy tablets are:
Pharmacy Medicine (S2): 10’s, 20’s, 24’s & 30’s.
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Name and Address of Sponsor
Pfizer Australia Pty Limited
38-42 Wharf Road
West Ryde, NSW 2114 Australia
Australia ☎Toll Free 1800 555 057
Web: www.dimetapp.com.au
Pfizer New Zealand Ltd
Level 3, Pfizer House
14 Normanby Road
Mt Eden, Auckland
New Zealand
New Zealand ☎Toll Free 0800 447 400
Web: www.dimetapp.co.nz
Date of TGA Approval:
25 Aug 2010
Date of Last Amendment:
09 Mar 2015
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CDS: PE 5.0; Chlor. Mal 5.0 Page - 7