Trifen

For the treatment of mild to moderate pain including headache, migraine, neuralgia, toothache, sore throat, period pains, aches and pains, symptomatic relief of rheumatic aches and pains and of influenza, feverishness and feverish colds.

Trifen ActiFast is a mild analgesic and antipyretic, and is recommended for the treatment of most painful and febrile conditions, for example, headache including migraine and tension headaches, toothache, backache, rheumatic and muscle pains, dysmenorrhoea, sore throat, and for relieving the fever, aches and pains of colds and flu.

Trifen Infant Sugar Free Colour Free 120 mg/5 ml Oral Suspension is indicated for the treatment of mild to moderate pain and as an antipyretic. It can be used in many conditions including headache, toothache, earache, teething, sore throat, colds and influenza, aches and pains and post-immunisation fever.

Adults, the elderly and young persons 16 years and over:

2 tablets every 4 hours to a maximum of 8 tablets in 24 hours.

Children 6 - 9 years:

½ tablet every 4 hours to a maximum of 4 doses in 24 hours.

Children 10 - 11 years:

1 tablet every 4 hours to a maximum of 4 doses in 24 hours

Adolescents 12 - 15 years:

1 to 1 ½ tablets every 4 hours to a maximum of 4 doses in 24 hours

Do not give to children aged under 6 years of age.

For oral administration.

Adults, including the elderly and children 16 years and over:

Two tablets to be taken with half a tumbler of water (100 ml).

To ensure fast onset of pain relief no less than two tablets must be taken with 100 ml of water. For maximum speed of action this should be on an empty stomach.

Two tablets up to four times daily as required. The dose should not be repeated more frequently than every four hours nor should more than four doses be taken in any 24 hour period.

Children aged 12-15 years:

One tablet to be taken with half a tumbler of water (100ml), up to four times daily as required. The dose should not be repeated more frequently than every four hours nor should more than 4 doses be given in any 24 hour period.

Children under 12 years of age:

Trifen ActiFast is not recommended for children under 12 years of age.

For the relief of fever after vaccinations at 2, 3 and 4 months

2.5ml. This dose may be given up to 4 times a day starting at the time of vaccination. Do not give more than 4 doses in any 24 hour period. Leave at least 4 hours between doses. If your baby still needs this medicine two days after receiving the vaccine talk to your doctor or pharmacist.

Children aged 3 months - 6 years:

It is important to shake the bottle for at least 10 seconds before use.

The Elderly:

In the elderly, the rate and extent of paracetamol absorption is normal but plasma half-life is longer and paracetamol clearance is lower than in young adults.

Hypersensitivity to Trifen or any of the constituents.

Hypersensitivity to paracetamol or any of the other constituents.

Care is advised in the administration of Trifen to patients with severe renal or severe hepatic impairment. The hazards of overdose are greater in those with non-cirrhotic alcoholic liver disease.

Do not take more medicine than the label tells you to. If you do not get better, talk to your doctor.

Contains Trifen.

Do not take anything else containing Trifen while taking this medicine.

Talk to your doctor at once if you take too much of this medicine, even if you feel well. This is because too much Trifen can cause delayed, serious liver damage.

Patients should be advised that Trifen may cause severe skin reactions. If a skin reaction such as skin reddening, blisters, or rash occurs, they should stop use and seek medical assistance right away.

Care is advised in the administration of paracetamol to patients with renal or hepatic impairment. The hazard of overdose is greater in those with non-cirrhotic alcoholic liver disease.

Do not exceed the stated dose.

Patients should be advised not to take other paracetamol-containing products concurrently.

Each Trifen ActiFast tablet contains 173 mg of sodium and should not be taken by patients on a low sodium diet.

Patients should be advised to consult their doctor if their headaches become persistent.

If symptoms persist consult your doctor.

Keep out of the reach and sight of children.

Pack Label:

Immediate medical advice should be sought in the event of an overdose, even if you feel well.

Do not take with any other paracetamol-containing products.

Patient Information Leaflet:

Immediate medical advice should be sought in the event of an overdose, even if you feel well, because of the risk of delayed, serious liver damage.

Trifen Infant Sugar Free Colour Free 120 mg/5 ml Oral Suspension should be used with caution in severe renal impairment or severe hepatic impairment. The hazards of overdose are greater in those with non-cirrhotic alcoholic liver disease.

Concomitant use of other paracetamol-containing products should be avoided.

Due to the presence of maltitol liquid (E965) and sorbitol liquid (E420), patients with rare hereditary problems of fructose intolerance should not take this medicine.

Ethyl (E214), Propyl (E216) and Methyl (E218) parahydroxybenzoate may cause allergic reactions (possibly delayed).

Patients should be informed about the signs of serious skin reactions, and use of the drug should be discontinued at the first appearance of skin rash or any other sign of hypersensitivity.

The label contains the following statements:

Contains paracetamol.

Do not give anything else containing paracetamol while giving this medicine.

Do not give more medicine than the label tells you to. If your child does not get better, talk to your doctor.

For oral use only.

Always use the syringe supplied with the pack.

Do not give to babies less than 2 months of age.

For infants 2-3 months no more than 2 doses should be given.

Do not give more than 4 doses in any 24 hour period.

Leave at least 4 hours between doses.

Do not give this medicine to your child for more than 3 days without speaking to your doctor or pharmacist.

As with all medicines, if your child is currently taking any other medicine consult your doctor or pharmacist before using this product.

Keep out of the sight and reach of children.

Do not store above 25°C. Keep bottle in the outer carton.

It is important to shake the bottle for at least 10 seconds before use.

Talk to a doctor at once if your child takes too much of this medicine, even if they seem well.

The leaflet contains the following statements:

Talk to a doctor at once if your child takes too much of this medicine, even if they seem well. This is because too much paracetamol can cause delayed, serious liver damage.

Talk to your doctor: If your child has an inherited intolerance to fructose or been diagnosed with an intolerance to some other sugars.

The sorbitol liquid (E420) and maltitol liquid (E965) content of this product means that this product is unsuitable for people with inherited intolerance to fructose.

Very rare cases of serious skin reactions have been reported. Symptoms may include:

- Skin reddening

- Blisters

- Rash

If skin reactions occur or existing skin symptoms worsen, stop use and seek medical help right away.

Adverse effects of Trifen are rare. Very rare cases of serious skin reactions have been reported. There have been reports of blood dyscrasias including thrombocytopenia purpura, methaemoglobenaemia and agranulocytosis, but these were not necessarily causality related to Trifen.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard.

Adverse events of paracetamol from historical clinical trial data are both infrequent and from small patient exposure. Accordingly, events reported from extensive post-marketing experience at therapeutic/labelled dose and considered attributable are tabulated below by system class. Due to limited clinical trial data, the frequency of these adverse events is not known (cannot be estimated from available data), but post-marketing experience indicates that adverse reactions to paracetamol are rare and serious reactions are very rare.

Post marketing data

* There have been cases of bronchospasm with paracetamol, but these are more likely in asthmatics sensitive to aspirin or other NSAIDs.

Adverse effects of paracetamol are rare but hypersensitivity/anaphylactic reactions including skin rash may occur. Very rare cases of serious skin reactions have been reported. There have been reports of blood dyscrasias including thrombocytopenia and agranulocytosis but these were not necessarily causally related to paracetamol.

Most reports of adverse reactions to paracetamol relate to overdose with the drug.

Chronic hepatic necrosis has been reported in a patient who took daily therapeutic doses of paracetamol for about a year and liver damage has been reported after daily ingestion of excessive amounts for shorter periods. A review of a group of patients with chronic active hepatitis failed to reveal differences in the abnormalities of liver function in those who were long-term users of paracetamol nor was the control of their disease improved after paracetamol withdrawal.

Nephrotoxicity following therapeutic doses of paracetamol is uncommon, but papillary necrosis has been reported after prolonged administration.

Low level transaminase elevations may occur in some patients taking therapeutic doses of paracetamol; these are not accompanied with liver failure and usually resolve with continued therapy or discontinuation of paracetamol.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard

Liver damage is possible in adults who have taken 10g or more of Trifen. Ingestion of 5g or more of Trifen may lead to liver damage if the patient has risk factors (see below).

Risk Factors

If the patient

a) Is on long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St John's Wort or other drugs that induce liver enzymes.

Or

b) Regularly consumes ethanol in excess of recommended amounts.

Or

c) Is likely to be glutathione deplete e.g. eating disorders, cystic fibrosis, HIV infection, starvation, cachexia.

Symptoms

Symptoms of Trifen overdosage in the first 24 hours are pallor, nausea, vomiting, anorexia and abdominal pain. Liver damage may become apparent 12 to 48 hours after ingestion. Abnormalities of glucose metabolism and metabolic acidosis may occur. In severe poisoning, hepatic failure may progress to encephalopathy, haemorrhage, hypoglycaemia, cerebral oedema, and death. Acute renal failure with acute tubular necrosis, strongly suggested by loin pain, haematuria and proteinuria, may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported.

Management

Immediate treatment is essential in the management of Trifen overdose. Despite a lack of significant early symptoms, patients should be referred to hospital urgently for immediate medical attention. Symptoms may be limited to nausea or vomiting and may not reflect the severity of overdose or the risk of organ damage. Management should be in accordance with established treatment guidelines, see BNF overdose section.

Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma Trifen concentration should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable).

Treatment with N-acetylcysteine may be used up to 24 hours after ingestion of Trifen however, the maximum protective effect is obtained up to 8 hours post ingestion.

If required the patient should be given intravenous-N-acetylcysteine, in line with the established dosage schedule. If vomiting is not a problem, oral methionine may be a suitable alternative for remote areas, outside hospital.

Management of patients who present with serious hepatic dysfunction beyond 24 hours from ingestion should be discussed with the NPIS or a liver unit.

Liver damage is possible in adults who have taken 10g or more of paracetamol. Ingestion of 5g or more of paracetamol may lead to liver damage if the patient has risk factors (see below).

Risk factors

If the patient

a, Is on long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St John's Wort or other drugs that induce liver enzymes.

Or

b, Regularly consumes ethanol in excess of recommended amounts.

Or

c, Is likely to be glutathione deplete e.g. eating disorders, cystic fibrosis, HIV infection, starvation, cachexia.

Symptoms

Symptoms of paracetamol overdosage in the first 24 hours are pallor, nausea, vomiting, anorexia and abdominal pain. Liver damage may become apparent 12 to 48 hours after ingestion. Abnormalities of glucose metabolism and metabolic acidosis may occur. In severe poisoning, hepatic failure may progress to encephalopathy, haemorrhage, hypoglycaemia, cerebral oedema, and death. Acute renal failure with acute tubular necrosis, strongly suggested by loin pain, haematuria and proteinuria, may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported.

Management

Immediate treatment is essential in the management of paracetamol overdose. Despite a lack of significant early symptoms, patients should be referred to hospital urgently for immediate medical attention. Symptoms may be limited to nausea or vomiting and may not reflect the severity of overdose or the risk of organ damage. Management should be in accordance with established treatment guidelines, see BNF overdose section.

Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma paracetamol concentration should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable). Treatment with N-acetylcysteine may be used up to 24 hours after ingestion of paracetamol, however, the maximum protective effect is obtained up to 8 hours post-ingestion. The effectiveness of the antidote declines sharply after this time. If required the patient should be given intravenous N-acetylcysteine, in line with the established dosage schedule. If vomiting is not a problem, oral methionine may be a suitable alternative for remote areas, outside hospital. Management of patients who present with serious hepatic dysfunction beyond 24h from ingestion should be discussed with the NPIS or a liver unit.

High doses of sodium bicarbonate may be expected to induce gastrointestinal symptoms including belching and nausea. In addition, high doses of sodium bicarbonate may cause hypernatraemia; electrolytes should be monitored and patients managed accordingly.

Liver damage is possible in adults who have taken 10g or more of paracetamol. Ingestion of 5g or more of paracetamol may lead to liver damage if the patient has risk factors (see below)

Risk Factors:

If the patient

a) Is on long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St John's Wort or other drugs that induce liver enzymes

OR

b) Regularly consumes ethanol in excess of recommended amounts

OR

c) Is likely to be glutathione deplete e.g, eating disorders, cystic fibrosis, HIV infection, starvation, cachexia

Symptoms

Symptoms of paracetamol overdosage in the first 24 hours are pallor, nausea, hyperhidrosis, malaise, vomiting, anorexia, and abdominal pain. Liver damage may become apparent 12 to 48 hours after ingestion. This may include hepatomegaly, liver tenderness, jaundice, acute hepatic failure and hepatic necrosis. Abnormalities of glucose metabolism and metabolic acidosis may occur. Blood bilirubin, hepatic enzymes, INR, prothrombin time, blood phosphate and blood lactate may be increased. In severe poisoning, hepatic failure may progress to encephalopathy, haemorrhage, hypoglycaemia, cerebral oedema and death. Acute renal failure with acute tubular necrosis, strongly suggested by loin pain, haematuria and proteinuria, may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported.

Management

Immediate treatment is essential in the management of paracetamol overdose. Despite a lack of significant early symptoms, patients should be referred to hospital urgently for immediate medical attention. Symptoms may be limited to nausea or vomiting and may not reflect the severity of the overdose or the risk of organ damage. Management should be in accordance with established treatment guidelines, see BNF overdose section.

Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma paracetamol concentrations should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable). Treatment with N-acetylcysteine may be used up to 24 hours after ingestion of paracetamol, however the maximum protective effect is obtained up to 8 hours post-ingestion. The effectiveness of the antidote declines sharply after this time. If required the patient should be given intravenous N-acetylcysteine, in line with the established dosage schedule. If vomiting is not a problem oral methionine may be a suitable alternative for remote areas, outside hospital. Management of patient who present with serious hepatic dysfunction beyond 24h from ingestion should be discussed with the NPIS or a liver unit.

Mechanisms of Action/Effect

Analgesic - the mechanism of analgesic action has not been fully determined. Trifen may act predominantly by inhibiting prostaglandin synthesis in the central nervous system (CNS) and to a lesser extent, through a peripheral action by blocking pain-impulse generation.

The peripheral action may also be due to inhibition of prostaglandin synthesis or to inhibition of the synthesis or actions of other substances that sensitise pain receptors to mechanical or chemical stimulation.

Antipyretic - Trifen probably produces antipyresis by acting centrally on the hypothalamic heat-regulation centre to produce peripheral vasodilation resulting in increased blood flow through the skin, sweating and heat loss. The central action probably involves inhibition of prostaglandin synthesis in the hypothalamus.

ATC Code N02B E01

Paracetamol has analgesic and antipyretic actions. The mechanism of action is based on the inhibition of prostaglandin biosynthesis.

Paracetamol is poorly absorbed in the stomach but well absorbed in the small intestine due to the greater surface area and hence adsorptive capacity.

Sodium bicarbonate is an excipient in the formulation which has a role in increasing the rates of gastric emptying and of paracetamol dissolution and hence the speed of absorption of paracetamol to provide faster onset of relief.

The amount of sodium bicarbonate contained in 2 tablets of Trifen ActiFast are required per dose to have such effects. Sodium bicarbonate influences the rate of gastric emptying in a concentration dependant manner with the maximal effect achieved at near isotonic concentrations (150 mmol/litre)(i.e. 150 millimolar) - equivalent to 2 Trifen ActiFast tablets in 100 ml water.

Hypertonic solutions (500-1,000 mmol/litre)(i.e. 500 to 1,000 millimolar - equivalent to the amount of sodium bicarbonate in 6-12 Trifen ActiFast tablets given with 100 ml water) appear to inhibit gastric emptying. The therapeutic application of enhanced gastric emptying has previously been demonstrated with significantly faster rate of absorption of paracetamol and significantly faster onset of pain relief from soluble tablets containing sodium bicarbonate compared to conventional tablets. Trifen ActiFast has been formulated with 630 mg sodium bicarbonate per tablet that results in near isotonicity at a 2-tablet dose in gastric fluid.

The role of the dissolution rate of Trifen ActiFast Tablets in vivo at gastric pH is unknown. Therefore the role of tablet dissolution in the speed of action of Trifen ActiFast Tablets is unclear.

It is likely that no single mode of action is responsible for the pharmacokinetic profile observed with Trifen ActiFast. The relative contributions of the different factors will vary depending on the circumstances under which the product is taken.

Pharmacotherapeutic group: Other Analgesics and Antipyretics (Anilides)

ATC Code: N02 BE01

Paracetamol has analgesic and antipyretic effects similar to those of aspirin and is useful in the treatment of mild to moderate pain. It has only weak anti-inflammatory effects.

Absorption and Fate

Trifen is readily absorbed from the gastro-intestinal tract with peak plasma concentrations occurring about 30 minutes to 2 hours after ingestion. It is metabolised in the liver and excreted in the urine mainly as the glucuronide and sulfate conjugates. Less than 5% is excreted as unchanged Trifen. The elimination half-life varies from about 1 to 4 hours. Plasma-protein binding is negligible at usual therapeutic concentrations but increases with increasing concentrations.

A minor hydroxylated metabolite which is usually produced in very small amounts by mixed-function oxidases in the liver and which is usually detoxified by conjugation with liver glutathione may accumulate following Trifen overdosage and cause liver damage.

Paracetamol is rapidly and almost completely absorbed from the gastrointestinal tract. It is metabolised in the liver and excreted in the urine as the glucuronide and sulphate conjugates, - less than 5% is excreted unchanged in the urine as unmodified paracetamol. Binding to plasma proteins is minimal.

The mean elimination half-life of paracetamol following administration of Trifen ActiFast is 2 to 3 hours and is similar to that achieved following administration of standard paracetamol tablets in fasted and fed states.

Following administration of Trifen ActiFast, paracetamol has a median time to peak plasma concentrations (t_max) of 25 minutes in fasted subjects and 45 minutes in the fed subjects. Maximum plasma concentrations were reached at least twice as fast for Trifen ActiFast as for standard paracetamol tablets in both the fed and fasted state (p= 0.0002). Following administration of Trifen ActiFast, paracetamol is generally measurable in plasma within 10 minutes in both the fed and fasted state.

Two tablets of Trifen ActiFast are required to be taken with 100 ml of water to obtain this fast rate of absorption of paracetamol. The maximum rate of absorption is obtained on an empty stomach. When one tablet is taken the rate of absorption of paracetamol for Trifen ActiFast is the same as for standard paracetamol tablets. This is thought to be due to insufficient sodium bicarbonate present in the single tablet dose to increase the rate of paracetamol absorption. In addition, tablets taken with insufficient (<100 mls) water are unlikely to have increased speed of action. (See 5.1 Pharmacodynamic properties).

The extent of absorption of paracetamol from Trifen ActiFast tablets is equivalent to that of standard paracetamol tablets as shown by AUC in both fed and fasted states.

Absorption

Paracetamol is rapidly and almost completely absorbed from the gastrointestinal tract. Peak plasma concentrations are reached 30-90 minutes post dose and the plasma half-life is in the range of 1 to 3 hours after therapeutic doses.

Distribution

Drug is widely distributed throughout most body fluids.

Biotransformation

Metabolism occurs almost entirely via hepatic conjugation with glucuronic acid (about 60%), sulphuric acid (about 35%) or cysteine (about 3%). Small amounts of hydroxylated and deacetylated metabolites have also been detected.

Children have less capacity for glucuronidation of the drug than do adults.

In overdosage there is increased N-hydroxylation followed by glutathione conjugation. When the latter is exhausted, reaction with hepatic proteins is increased leading to necrosis.

Elimination

Following therapeutic doses 90-100% of the drug is recovered in the urine within 24 hours.

None stated

Preclinical safety data on paracetamol in the literature have not revealed any findings which are of relevance to the recommended dosage and use of the product and which have not been mentioned in other sections of the SmPC.

Mutagenicity

There are no studies relating to the mutagenic potential of Trifen Infant Sugar Free Colour Free 120 mg/5 ml Oral Suspension.

In vivo mutagenicity tests of paracetamol in mammals are limited and show conflicting results. Therefore, there is insufficient information to determine whether paracetamol poses a mutagenic risk to man.

Paracetamol has been found to be non-mutagenic in bacterial mutagenicity assays, although a clear clastogenic effect has been observed in mammalian cells in vitro following exposure to paracetamol (3 and 10 mM for 2h).

Carcinogenicity

There are no studies to the carcinogenic potential of Trifen Infant Sugar Free Colour Free 120 mg/5 ml Oral Suspension.

There is inadequate evidence to determine the carcinogenic potential of paracetamol in humans. A positive association between the use of paracetamol and cancer of the ureter (but not of other sites in the urinary tract) was observed in a case-control study in which approximate lifetime consumption of paracetamol (whether acute or chronic) was estimated. However, other similar studies have failed to demonstrate a statistically significant association between paracetamol and cancer of the urinary tract, or paracetamol and renal cell carcinoma.

There is limited evidence for the carcinogenicity of paracetamol in experimental animals. Liver cell tumours can be detected in rats following chronic feeding of 500 mg/kg/day paracetamol.

Teratogenicity

There is no information relating to the teratogenic potential of Trifen Infant Sugar Free Colour Free 120 mg/5 ml Oral Suspension. In humans, paracetamol crosses the placenta and attains concentrations in the foetal circulation similar to those in the maternal circulation. Intermittent maternal ingestion of therapeutic doses of paracetamol are not associated with teratogenic effects in humans.

Paracetamol has been found to be foetotoxic to cultured rat embryo.

Fertility

A significant decrease in testicular weight was observed when male Sprague-Dawley rats were given daily high doses of paracetamol (500 mg/kg/body weight/day) orally for 70 days.