Overdose : מינון יתר

4.9 Overdose
In case of overdose or if a child has accidently swallowed the medicine, immediate visit to a doctor or a hospital emergency room with the package of the medicine is required.
Paracetamol& Codeine:
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, phe o ar ito e, phe ytoi , pri ido e, rifa pi i , St Joh ’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 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 overdosage.
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.
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) but results should not delay initiation of treatment beyond 8 hours after ingestion, as 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.
The effects of codeine in overdosage will be potentiated by simultaneous ingestion of alcohol and psychotropic drugs.
Central nervous system depression, including respiratory depression, may develop but is unlikely to be severe unless other sedative agents have been coingested, including alcohol, or the overdose is very large.
The pupils may be pin-point in size; nausea and vomiting are common. Hypotension and tachycardia are possible but unlikely.
Management should include general symptomatic and supportive measures including a clear airway and monitoring of vital signs until stable.
Consider activated charcoal if an adult presents within one hour of ingestion of more than 350mg or a child more than 5mg/kg. Give naloxone if coma or respiratory depression is present. Naloxone is a competitive antagonist and has a short half-life so large and repeated doses may be required in a seriously poisoned patient. Observe for at least 4 hours after ingestion.


Atropine:
There is considerable variation in susceptibility to atropine; recovery has occurred even after 1g, whereas deaths have been reported from doses of 100mg or less for adults and 10mg for children.
Symptoms of overdose: In overdose, the peripheral effects become more pronounced such as dilation of pupils, continuing blurred vision, or changes in near vision, severe dryness of mouth, nose or throat, dizziness and drowsiness. Other symptoms such as rapid respiration, increased respiratory rate, difficulty in breathing, increased heartbeat, hypertension, hyperthermia, fever, muscle weakness, inhibition of micturition, nausea and vomiting may occur. A rash may appear on the face, neck or upper trunk, and there may be unusual warmth, dryness or flushing of the skin.
Toxic doses also cause CNS stimulation marked by nervousness, restlessness, irritability, confusion, excitement, ataxia, incoordination, slurred speech, paranoid and psychotic reactions, hallucinations and delirium and occasionally seizures. In severe overdose, central stimulation may give way to CNS depression, coma, circulatory and respiratory failure and death.
Treatment of overdose: If a patient presents within an hour of an overdose of atropine by mouth, the stomach may be emptied (but only if a life-threatening amount has been ingested) or activated charcoal given to reduce absorption. Diazepam may be given to control marked excitement and convulsions. Hypoxia and acidosis should be corrected.
If metabolic acidosis persists despite correction of hypoxia and adequate fluid resuscitation consider correction with intravenous sodium bicarbonate. Antiarrhythmics are not recommended if arrhythmias develop. Phenothiazines should not be given as they may exacerbate antimuscarinic effects. Supportive therapy should be given as required.