Clinical Toxicology Lecture 1 PDF

Al-Mustaqbal University College of Pharmacy 5th stage Clinical Toxicology Lecture: 1 Clinical Toxicology Initial Evaluation & Management of poisoned patient  Outline Human Clinical Toxicology ?...

Al-Mustaqbal University College of Pharmacy 5th stage Clinical Toxicology Lecture: 1 Clinical Toxicology Initial Evaluation & Management of poisoned patient  Outline Human Clinical Toxicology ? Related effect Approaches and Initial Evaluation Management Definitive care with poisoning Supportive Care and Monitoring 2  Clinical Toxicology This branch focuses on the effects of drugs and other chemicals on humans, particularly, but also on other animals. Its work is often involved with drug overdoses and other poisonings and determining the substance involved and its amount in the body. It typically coincides with other sciences like as biochemistry, pharmacology and pathology. Clinical toxicology deals with the adverse effects of agents such as drugs ,chemical, etc.  Approach to the poisoned patient All poisoned patients should be managed as if they have a potentially life-threatening intoxication(poisoning) , although they appear normal. The initial approach to the poisoned patient should be essentially similar in every case, irrespective of the toxin ingested. (regardless to toxin ) This approach can be termed as (Routine poison management) Clinical Toxicology 5th stage  Common poisoning Poisoning can result from exposure to a variety of substances, ranging from household cleaning products to pesticides. However, prescription and over the counter medications account for nearly one half of poisoning exposures. Clinical Toxicology 5th stage  Important Strategies ✔Treat the patient, not the poison", Promptly ✔Supportive therapy essential Maintain respiration and circulation – primary ✔Judge progress of intoxication by: Measuring and charting vital signs and reflexes TREATMENT OF ACUTE POISONING 1st Goal - keep concentration of poison as low as possible by preventing absorption and increasing elimination- 2nd Goal - counteract toxicological effects at effector site, if possible Clinical Toxicology 5th stage  Initial Evaluation & Management Evaluationinvolves??? Identification of agents-2 involved 1- Recognition that poisoning has occurred,,. Assessment of severity and-3 Management prediction of toxicity Management : is directed to the supportive care, prevention of poison absorption or enhancement of elimination , and when appropriate the administration of antidote. 7  Initial Evaluation (ABCDEs) Airway: Airways should be kept patent and any suspicion for obstructing material must be removed. The most common factor contributing to death from poisoning is loss of airway-protective reflexes with subsequent airway obstruction caused by: Flaccid tongue or Pulmonary aspiration of gastric contents. Clinical Toxicology 5th stage  Initial Evaluation (ABCDEs) Breathing: Evaluate respiratory rate and if available, oxygen saturation. If there is no oxygen monitor available but the patient has an elevated respiratory rate, consider supplemental oxygen. Clinical Toxicology 5th stage  Initial Evaluation (ABCDEs) Circulation: A prompt assessment of vital signs and hydration status is essential. 1. Check blood pressure and pulse rate and rhythm. 2. Begin continuous ECG monitoring 3. Secure venous access 4. Draw blood for routine studies 5. Begin intravenous infusion If the patient is hypotensive, normal saline or another isotonic solution is preferred Clinical Toxicology 5th stage  Initial Evaluation (ABCDEs) Disability (Neurological): A decreased level of consciousness is the most common serious complication of drug overdose or poisoning. In patients that are presented with seizures, it is important to check the blood sugar level. If the blood sugar level is < 72 md/dL, then administer 50ml of 50% dextrose IV Toxic seizures should be treated with IV benzodiazepines , Seizures refractory to benzodiazepines can be treated with barbiturates. Clinical Toxicology 5th stage  Initial Evaluation (ABCDEs) Exposure (evaluation of temperature): Consider the possibility of toxic syndromes associated with hyperthermia. Toxic levels of certain drugs can lead to significantly elevated body temperature. Clinical Toxicology 5th stage  Definitive care with poisoning 1. Try to identify the poison. 2. Accurate and complete history from sources other than patient (family, friends, pharmacist, & pill or bottles at the scene)(place where event occurs)). 3. Attempt to establish the time and amount of the ingestion. Clinical Toxicology 5th stage  Supportive Care and Monitoring Remember that acute poisoning is a dynamic illness and the patient’s condition may fluctuate over time. Therefore repeated examinations and ongoing clinical assessment and management are required. Clinical Toxicology 5th stage  Physical examination This may provide clues as to what the drugs ingested were. Important aspects of the examination include: Vital signs (PR, RR, BP, temp, O2 saturation if available) Neurological exam ( Pupil size, Glasgow Coma Scale (GCS), mental state, tone, reflexes, clonus, focal signs) Skin (colour, sweating absent/present) Dry mouth/salivation, bowel sounds, urinary retention Evidence of trauma Clinical Toxicology 5th stage  Risk Assessment An early, accurate risk assessment is the key to managing acutely poisoned patients. It enables us to predict the likely clinical course, potential complications, and to plan the management of the patient. Clinical Toxicology 5th stage  Risk Assessment 5 steps of a risk assessment: 1. Agent(s) Assess whether the ingested agents are likely to cause significant toxicity. 2. Dose(s) Calculate the dose taken in mg/kg body weight, use this information to predict likelihood of significant toxicity. Clinical Toxicology 5th stage  Risk Assessment 3. Time since ingestion This is important for determining the likely clinical progress of the patient, and to guide management. 4. Clinical features and progress Correlate the patient’s clinical features and progress with the dose taken and time since ingestion. 5. Patient factors (weight and co-morbidities) Consider individual patient factors that may put the patient at particular risk. Clinical Toxicology 5th stage  Investigations 1. Bloodsugar level 2. ECG – look for: - Rate (Bradycardia or Tachycardia) - Rhythm Clinical Toxicology 5th stage  Management The management of poisoning is directed towards 1- The prevention of further poison absorption 2- The increase of poison elimination 3- Use of an antidote (if appropriate) Clinical Toxicology 5th stage  Prevention of further poison absorption 1- Dermal Exposure *Remove all clothing. *Washing skin gently with soap and water for at least 30 minutes. 2- Eye Exposure *Washing conjunctiva with running water or normal saline for 20 minutes. *Solid corrosives should be removed by forceps. Clinical Toxicology 5th stage  Prevention of further poison absorption 3- GIT Exposure *Induction of emesis *Gastric lavage *Activated Charcoal *Cathartics *Whole bowel irrigation Clinical Toxicology 5th stage  Induction of Emesis Ipecac syrup: The safe method for induction of vomiting, should be given within 30 minutes of poison ingestion. Syrup of ipecac should no longer be used routinely as a poison treatment intervention at home. Clinical Toxicology 5th stage  Induction of Emesis Emesis Contraindications 1.Convulsions. 2.Corrosives. 3.Hydrocarbons 4.Coma 5.Less than 6 months of age (not well developed gag reflex) Clinical Toxicology 5th stage  Gastric Lavage Used in hospitals when emesis was failed or there was contraindication for it. Gastric lavage is effective in the first 4-6 hrs after ingestion. Technique: 1. An assistant with suction machine should be available. 2. Dentures, mucous, vomitus should be removed from patient's mouth. 3. Proper tube size to be selected according to the patient age Clinical Toxicology 5th stage  Activated charcoal Adsorption of a wide variety of drugs and chemicals. It is not digested; it stays inside the GI tract and eliminates the toxin when the person has a bowel movement. Adult dose is 1 gm/kg. Indications: (all of these must be met) Within one hour of time of ingestion Patient at risk of significant toxic effects Patient NOT at risk of airway compromise Clinical Toxicology 5th stage  Activated charcoal Contraindications: If an oral antidote is given Seizures, coma Corrosive ingestion Agent not bound to activated charcoal: Hydrocarbons, alcohols and corrosives (acids, alkalis) Clinical Toxicology 5th stage  Cathartics (Laxatives) These are substances that enhance the passage of material through GIT and decrease the time of contact between the poison and the absorptive surfaces of the stomach and intestine. a)Osmotic cathartics: increase osmotic pressure in the lumen, as Magnesium sulfate. b) Irritant cathartics: act by increasing motility, such as caster oil. Contraindications: GIT hemorrhage, Recent bowel surgery, Intestinal obstruction. Clinical Toxicology 5th stage  Whole Bowel Irrigation The goal of WBI is to clean GIT from non-absorbed ingested toxins. Polyethylene glycol electrolyte solutions are used. Indications ✔ Ingestion of a toxin that is known to be poorly adsorbed by a charcoal. ✔ Ingestion of massive amounts of drugs ✔ Ingestion of sustained-release or enteric-coated preparations ✔ Removal of ingested packets of illegal drugs (body packers). Clinical Toxicology 5th stage  Antidote A therapeutic substance used to counteract the toxic action(s) of a specific xenobiotic Antidotes are classified according to mechanism of action into: 1- Interacts with the poison to form a nontoxic complex that can be excreted e.g. chelators 2- Accelerate the detoxification of the poison: N-acetylcysteine, thiosulfate. Clinical Toxicology 5th stage Examples of Antidote Clinical Toxicology 5th stage  Antidote 3- Decrease the rate of conversion of the poison into its toxic metabolites: Fomepizole. 4- Compete with the poison for certain receptors: Naloxone. 5- Block the receptors through which the toxic effects of the poison are mediated: atropine. 6- Bypass the effect of the poison: O2 treatment in CO and cyanide toxicity. 7- Antibodies to the poison: digiband, antivenoms Clinical Toxicology 5th stage  Antidote Antidotes also can be classified into: 1- Physical 2- Chemical 3- Physiological Clinical Toxicology 5th stage  Antidote 1- Physical Antidotes Agents used to interfere with poisons through physical properties, not change their nature a) Adsorbing: the main example is activated charcoal. b) Coating: a mixture of egg & milk makes a coat over the mucosa. c) Dissolving: 10% alcohol or glycerine for carbolic acid. Clinical Toxicology 5th stage  Antidote 2- Chemical Antidotes a) Oxidizing: Amyl Nitrite is used in cyanide toxicity. b) Reducing: Vitamin C used for drugs causing Met-Hb. c) Precipitating: Starch, it makes blue precipitate with iodine. Clinical Toxicology 5th stage  Antidote 3- Physiological (Pharmacological) Antidotes a) Antagonism 1- Competitive Antagonists. 2- Non-Competitive Antagonism b) Chelating Agents Unite metallic poisons to form soluble, nonionizable, less toxic, and easily excreted chelates. e.g Dimercaprol (BAL) c) Antibodies (Immunology-based Antidotes) e.g. Digoxin Specific Antibody Fragment (FAB fragments, Digiband) Clinical Toxicology 5th stage  Enhancement of Poison Excretion 1- Forced Diuresis It is a simple method for some poisons. It is effect is increased with manipulation of urine pH. e.g. Fluid Diuresis, Osmotic Diuresis as mannitol 10%. Clinical Toxicology 5th stage  Enhancement of Poison Excretion 2- Dialysis By allowing toxic substances to pass through semi-permeable membrane depending on the concentration gradient. It is beneficial when renal function is impaired. a) Peritoneal dialysis b) Hemodialysis Clinical Toxicology 5th stage  Enhancement of Poison Excretion 3- Hemoperfusion Using equipment and vascular access similar to that for hemodialysis. The blood is pumped directly through a column containing an adsorbent material (either charcoal or resin). Clinical Toxicology 5th stage  THANK YOU FOR YOUR ATTENTION Clinical Toxicology 5th stage