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:
- is on long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St. John's Wort or other drugs that induce liver enzymes, or
- regularly consumes ethanol in excess of recommended amounts, or
- 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, gastrointestinal bleeding 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.
Overdose of sodium bicarbonate may cause metabolic alkalosis. Patients with this acid-base disturbance may experience dyspnoea. While muscle weakness may occur as a result of potassium depletion, hypercalcaemic patients can develop twitching tetany. Severe overdoses may lead to convulsions and coma. Sodium overload can take two forms: hypernatraemia and iso-osmotic fluid retention. Treatment consists of appropriate correction of fluid and electrolyte balance and is otherwise supportive
The information below lists reported adverse reactions, ranked using the following frequency classification:
Very common (>1/10); common (>1/100 to <1/10); uncommon (>1/1,000 to <1/100); rare (>1/10,000 to <1/1,000); very rare (<1/10,000), not known (cannot be estimated from the available data).
Blood and lymphatic system disorders
Not known: blood dyscrasias including thrombocytopenia and agranulocytosis
Immune system disorders
Hypersensitivity including skin rash may occur.
Not known: anaphylactic shock, angioedema
Skin and subcutaneous disorders
Very rare cases of serious skin reactions such as Toxic Epidermal Necrolysis (TEN), Stevens-Johnson syndrome (SJS), acute generalised exanthematous pustulosis, fixed drug eruption have been reported.
Absorption of neutralised sodium bicarbonate can cause alkalosis - this is usually transient and clinically insignificant in people with normal renal function. The release of carbon dioxide from bicarbonate containing antacids can cause belching, occasional nausea, abdominal distension and flatulence.
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 Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.
Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, toxicity to reproduction and development.
Paracetamol Seltzer (Acetaminophen,Sodium Bicarbonate) is recommended for the relief of headache with upset stomach, dyspepsia or acid indigestion and will also help relieve the pain and discomforts of period pains, migraine, rheumatic pain, toothache, colds, flu and a sore throat. It is also effective in the symptomatic relief of fever.
ATC code: N02 B E 51
Paracetamol has analgesic and antipyretic effects and also weak anti-inflammatory effects.
Paracetamol is readily absorbed from the gastro-intestinal tract with peak plasma concentrations occurring within 30 to 90 minutes after oral administration. Paracetamol is distributed into most body tissues. It crosses the placenta and is present in breast milk. Plasma-protein binding is negligible at usual therapeutic concentrations.
Paracetamol is metabolised predominantly in the liver and execrated mainly in the urine mainly as glucuronide and sulphate conjugates. Less than 5% is excreted as unchanged paracetamol. The elimination half-life of paracetamol is between 2 to 3 hours in adults but is shorter for adolescents and children because of the extent of sulphate conjugation.
Administration of sodium bicarbonate by mouth causes neutralisation of gastric acid with the production of carbon dioxide. Any bicarbonate not involved in that reaction is absorbed and in the absence of a deficit of bicarbonate in the plasma, bicarbonate ions are excreted in the urine that is rendered alkaline and there is an accompanying diuresis.
Care is advised in the administration of paracetamol to patients with severe renal or severe hepatic impairment. The hazard of overdose is greater in those with non-cirrhotic alcoholic liver disease.
Do not exceed the recommended dose as excessive or prolonged use may lead to alkalosis.
Do not take with any other paracetamol-containing products.
If your symptoms persist for more than three days or worsen at any time, you should see your doctor.
Keep all medicines out of the reach and sight of children.
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.
Each tablet contains 388mg sodium which may be harmful to people on a low sodium diet e.g. patients with congestive heart failure or hypertension
Paracetamol Seltzer (Acetaminophen,Sodium Bicarbonate) has no influence on the ability to drive and use machines.
Posology
Do not take continuously for more than 3 days without consulting your doctor.
Adults, the elderly and children over 16 years:
Two tablets, to be dissolved in a glass of water, every 4 hours when necessary up to a maximum of 8 tablets in 24 hours.
Children aged 10 to 15 years:
One tablet every 4 to 6 hours when necessary to a maximum of four doses in 24 hours.
Paediatric population
Not recommended for children under 10 years of age.
Method of administration
For oral administration only, dissolved in water.
Not applicable.
