Role of pharmacist in treatment of poisoning

Poisoning:-

          

Poisoning occurs when any substance interferes with normal body functions after it is swallowed, inhaled, injected, or absorbed. The branch of medicine that deals with the detection and treatment of poisons is known as toxicology.

Unintentional poisonings:-

                    Community pharmacists can promote poison prevention by encouraging all consumers to use child resistant packaging and to keep all medications out of reach of children.

Specific prevention information can be targeted to those picking up prescriptions for opioids, cardiovascular medications, and sedative-hypnotic agents.

Grandparents can be reminded to keep their medicines out of sight and reach and to remove their medications from purses and luggage when visiting the grandchild’s home.

Parents and caregivers must be reminded that child-resistant packaging is not “childproof.”

While legislation requires child-resistant packages to prevent at least 80% of children younger than five years of age from opening them within a specified time, 20% of young children are able to open child-resistant containers.

Parents, grandparents, and caregivers should keep the phone number of the local poison control centre with other emergency numbers, and know basic first aid in case a poisoning occurs.

Community pharmacists can increase awareness by distributing poison prevention pamphlets and poison control centre phone numbers.

Intentional poisonings and overdoses:-

                                Anyone who expresses the hint of suicide should be taken seriously. Poison prevention in this patient population will involve working with other health care professionals, agencies, and family members.

The community pharmacist can limit the number of pills provided at one time to a suicidal or depressed patient and monitor the intervals between refills to ensure appropriate use and prevent drug hoarding.

Pharmacists must protect the patient’s right to confidentiality, but this may be breached when failure to disclose information could place the patient in serious danger.

Before confidentiality is compromised, the pharmacist should consult with other health professionals involved with the patient. Intentional poisoning also occurs when someone abuses medication for recreational purposes.

Patterns of drug abuse differ by region, vary with time, and are often inventive.

Community pharmacists must be knowledgeable about local drug abuse trends to address adverse effects, potential interactions, drug diversion issues, and overdose management.

Poison control centres, drug information centres, local law enforcement agencies, and internet sites can provide insight into local drug abuse patterns.

Awareness of local drug abuse practices can also help pharmacists enhance patient care by identifying patients at risk for drug overdose and misuse.

General management of poisoning and

overdosage:

The mainstay of management for poisoned patients is providing symptomatic and supportive care.Antidotes for specific poisoning agents will also be used where appropriate. As for any seriously ill patient, a systematic and thorough approach to treatment is required, including the following aspects of care:

●      Initial “ABC” (airway, breathing, circulation) assessment and resuscitation if necessary

●      A secondary survey for infection or trauma (of the head and cervical spine if a patient’s mental status is abnormal) and metabolic derangements

●      Supportive care with continuous assessment and monitoring

●      Case-specific management such as preventing further absorption, using antidotes or enhancing the elimination of the toxic agent

Because of the serious nature of some poisonings, early treatment and supportive care may often proceed rapidly without extensive investigations being carried out or an apparent diagnosis being made. Attention must be given to assessing a patient’s vital signs and to providing immediate treatment of life- threatening conditions such as hypotension, hypertension, bradycardia, tachycardia, car- diac arrhythmias, hyperthermia, hypothermia and respiratory depression.

Arrhythmias and conduction defects require cardiac monitoring and prompt treatment. Arterial blood gas measurements can be useful to assess ventilation and oxy- genation and also to identify metabolic derangements (eg, metabolic acidosis caused by toxic alcohols such as ethylene glycol or in salicylate poisoning). Where appropriate, blood samples should be sent for a full blood count, and to measure hepatic and renal function, electrolytes and blood glucose.After resuscitation and stabilisation, attention can turn to identify the agents ingested using data from the history and physical examination.Although it is unlikely that a single abnormality detected on examination will help differentiate poisoning from other causes of illness, or indicate a specific toxin, a cluster of symptoms and signs in the same patient, known as a toxidrome, may be of considerable value in helping to identify a toxic agent.For example, an opioid toxidrome is characterised by impaired con- sciousness and, although a number of agents are associated with depressed consciousness, when this symptom is coupled with pin- point pupils, hypotension and respiratory depression, opioid poisoning is the most likely cause. The anticholinergic toxidrome (found with poisoning from drugs such as tricyclic antidepressants and antihistamines) includes tachycardia, dilated pupils, dry, warm skin, dry mucous membranes and urinary retention. Conversely, the cholinergic toxidrome, found after exposure to organophosphate and carbamate insecticides or nerve agents, includes salivation, lacrimation, urinary and faecal incontinence, emesis, abdominal pain, diaphoresis and small pupils.

Gut decontamination

There is no evidence that inducing vomiting with syrup of

ipecachuana(or “ipecac”) or performing a gastric lavage (ie, stomach washout),has any impact on the outcome of a poisoning.

Activated charcoal (AC) acts by adsorbing ingested substances and preventing their absorption from the gut into the systemic circulation. It is generally most effective if administered within one, or perhaps two, hours of ingestion. For overdoses of drugs that enter the enterohepatic circulation, such as carbamazepine, phenobarbitone, theophylline, quinine or dapsone, multiple doses of activated charcoal (MDAC) may be used, provided a patient’s bowel sounds are present.MDAC has    also    been   used   for overdoses of sustained release preparations.

Disadvantage  The main risk with AC is aspiration if a patient has an unprotected airway. If this occurs, administration of AC via a nasogastric tube, after the patient has been intubated, is indicated.

There are a variety of AC preparations available, including a sweetened version, but unfortunately none is able to prevent AC being a particularly unpleasant substance to drink.This makes its use, especially in paediatrics, difficult.

Dose    The usual dose of AC is 50g in adults and 1g/kg body weight for children under 12 years. When using MDAC, these doses are repeated four hourly, although smaller doses may be given more frequently if necessary.

Contraindication    It is best to avoid mixing AC with food, such as ice cream, to try to improve its palatability as this can reduce its adsorbent capacity.

Incompatibilities AC has a good adsorpive capacity for most drugs and chemicals, except for metals (eg, iron and lithium), alcohols (eg, ethanol, methanol and ethylene glycol), acids or alkalis.

Whole bowel irrigation (WBI) may be indicated where there has been ingestion of high doses of medicines such as iron or lithium tablets (which are not bound by AC), sustained release preparations or when treating “bodypackers” (i.e, those who swallow illicit drugs for smuggling purposes). WBI involves the oral administration of polyethylene glycol until the rectal effluent is clear. In the UK, the only suitable product is Klean-Prep.

Dose   The adult dose is 1.5-2L/hr, usually continued for two to six hours. In children aged six to 12 years old the dose is 1L/hr and in those nine months to six years old 500ml/hr. Klean-Prep can be made more palatable by chilling it. Administration via a nasogastric tube may be necessary.

Enhanced elimination of toxins

Severely poisoned patients are likely to require methods to increase the elimination of the toxin from the body. These will generally take place in an intensive care unit.

Urinary alkalinisation with sodium bicarbonate can increase the elimination of weak acids because it prevents the ionised drug being reabsorbed in the renal tubules. It is most commonly used in patients with moderate to severe aspirin poisoning.

 Dose In adults, the dose of sodium bicarbonate used is usually 1L of isotonic fluid (i.e, 1.26 per cent or 1.4 per cent) given intravenously over four hours.

Alternatively, 50ml boluses of hypertonic (8.4 per cent) sodium bicarbonate can be given, but this should ideally be administered via a central line, given the irritant nature of this preparation. In practice, a combination of the two regimens is often necessary to achieve adequate urinary alkainisation. The bicarbonate dose, regimen and dose-timing should be titrated to achieve a urine pH of 7.5–8.5.The urine pH should be checked at least hourly and patients should also have their blood gases monitored regularly to ensure that systemic alkalinisation is not occurring.

It is also important to monitor the serum potassium concentration closely and titrate potassium replacement accordingly — hypokalaemia will make it difficult to achieve alkalinisation. Once alkalinisation is achieved, the serum potassium is likely to fall in response to an increase in urinary potassium excretion.

Extracorporeal procedures such as haemodialysis and haemoperfusion are only used in patients who have been severely poisoned with a limited subset of drugs and chemicals — treatment of such patients should always be discussed with a poisons unit. Haemodialysis may be required in patients with severe aspirin, lithium, ethylene glycol or methanol poisoning. There are limited data on the use of haemofiltration as a method for toxin removal in the poisoned patient, but it may be required in patients with renal failure or a severe metabolic acidosis. Charcoal haemoperfusion may be used in patients with severe theophylline or carbamazepine poisoning, although drug clearance is similar to that with MDAC and so haemoperfusion is generally reserved for patients with life-threatening toxicity.

Antidotes

Some general aspects of antidote use include the importance of documenting a patient’s weight to ensure that a correct dose is used for dose-adjusted treatments such as N-acetylcysteine for paracetamol poisoning. Studies have shown that clinicians are poor at estimating patient’s body weight.

In addition, prescriptions for antidotes should be written using generic names, which helps avoid errors such as Parvolex (acetylcysteine) being read as Pabrinex (thiamine).

Role of pharmacists

The most important treatment measure for poisoning is prevention.Once a poisoning occurs it is important to be able to provide highly skilled supportive medical care.It is insufficient to focus only on simple first-aid measures, antidotal therapy or home remedies.

For treatment of poisoning pharmacist can do help to prevent poisoning and to improve treatment thereof.

Pharmacists direct and staff many regional poisoning centers.

They actually provide consultation to physicians treating poisoned patients to assure quality care.

1.      Undoubtedly,the most important role played by a pharmacist is in the area of prevention.This role,relative to poisoning prevention packaging of prescription drugs,was mentioned previously.However the role of pharmacist is particularly critical with regard to OTC products.

With prescription of medicines there is involvement of physicians who may provide prescription and precautionary advice.

2.  However,with OTC products the pharmacist is only the person who is in position to perform these functions.

The pharmacist can and should provide,explain and amplify directions for proper use of potentially toxic materials,bearing in mind that concern is for the safety of patient and for other household individuals.

Thus,dispensing of toxic medication provides an opportunity to warn the buyer about the hazards of leaving the material within reach un-suspecting children.

3.  In some instances it is warning labels on the products that pharmacist dispenses or to hand out patient information materials.The dispensing of drug also provides opportunity to inquire and give advice about facilities for safe storage.

Because of this contact the pharmacist can play personalized role in cautioning about prescription and commercial products.

4.  The pharmacist can do much to reduce aforementioned limitations of labeling.Although the public often may not read or appreciate precautions on labels,the effectiveness of latter are increased significantly if pharmacist takes time to explain them.

5.  The pharmacist also has a unique role to play in detecting product or labeling defects and an obligation to call to the attention of appropriate manufacturers or regulatory agencies potential labeling or product defects.

6.  Finally pharmacist can assist greatly in the educational efforts of community by distributing literature and by providing space for displays related to poisoning prevention.

Poison prevention education can be incorporated into many facets of community pharmacy practice. The approach to preventing an unintentional poisoning will likely vary from that of an intentional poisoning. However in both situations, prevention begins with the identification of high-risk patients.

7.  Pharmacists have a key role in ensuring the timely availability of any antidote that might be indicated and giving advice on treatment regimens and possible complications. Guidelines have recently been produced by the British Association of Emergency Medicine (BAEM) and the Guy’s and St Thomas’ Poisons Unit, which group the availability of antidotes by the urgency of clinical need. The antidotes held at each health care facility should be assessed to ensure that stock levels are appropriate when taking into account the epidemiology of poisoning in their local area. Regular expiry date checks should be carried out. The “Rarely used medicines” database run by London, Eastern and South East Specialist Pharmacy Services is a resource supporting pharmacy staff to obtain medicines quickly and easily, including antidotes, that are only stocked in small numbers of trusts across the area.There is also scope strategically to plan and rationalise antidote availability at a national level.

8.  Pharmacists working in emergency care need to be familiar with the management of common poisonings such as those caused by overdoses of paracetamol, antidepressants and hypnotics (eg, benzodiazepines). Key aspects of good patient management include:

●   Establishing a patient’s drug history from his or her medical notes, or from the patient (if appropriate), including over-the-counter medicines

●   Ensuring the appropriate prescribing of, and availability of, antidotes

●   Providing patient information

●   Supporting the continuity of medicine supply on discharge, where appropriate

Assisting medical teams in identifying the constituent ingredients of poisonous products and unidentified medicines is another main role for pharmacists. The TICTAC database(visual drug identification database covering medicines),is a useful resource for the latter.