Toxicology Management Principles Quiz

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Questions and Answers

Which treatment is recommended for hyperkalemia caused by ACE inhibitors?

Oral potassium supplements

Hypertonic saline

I.V. calcium gluconate (correct)

Sodium bicarbonate (correct)

What causes malignant hyperthermia during anesthesia?

Increased Na+ release

Decreased muscle activity

Excessive muscle relaxation

Overstimulation of Ca2+ channels (correct)

Which condition is associated with hypokalemia?

Serum K+ < 3.5 mEq/L (correct)

Elevated serum K+ from diuretics

Hyperactivity causing low muscle K+

Kidney failure with high K+

What is the main treatment for severe hyperthermia?

Evaporative cooling Signup and view all the answers

What substance is a known cause of exertional heat stroke?

Amphetamine Signup and view all the answers

What is an expected consequence of severe hyperthermia?

Brain damage Signup and view all the answers

Which medication can be used to facilitate sweating in anticholinergic syndrome?

Physostigmine Signup and view all the answers

What is a significant complication of malignant hyperthermia?

Rhabdomyolysis Signup and view all the answers

Which antidote is used to treat respiratory depression caused by opioids?

Naloxone Signup and view all the answers

What characterizes chelating agents like dimercaprol and EDTA?

They form chemical chelates that are water-soluble. Signup and view all the answers

Which antidote is used to treat organophosphorus toxicity?

Pralidoxime Signup and view all the answers

Which medication is a treatment option for severe anaphylactic reactions?

Epinephrine Signup and view all the answers

What effect does vitamin K have in the treatment of coumarin-induced hemorrhage?

It increases blood coagulation factors. Signup and view all the answers

In which circumstances can seizures be induced?

By organophosphorus compounds and drug abuse overdose Signup and view all the answers

Which substance is used to detoxify acetaminophen and reduce liver toxicity?

N-acetylcysteine Signup and view all the answers

What is one role of sodium nitroprusside in medical treatment?

It treats hypertensive crises. Signup and view all the answers

What primary function does the peritoneum serve in peritoneal dialysis?

It serves as an in vivo semipermeable membrane. Signup and view all the answers

Which component is added to the dialysis solution for highly protein-bound chemicals?

Albumin Signup and view all the answers

What complication is commonly associated with hemodialysis?

Hypotension Signup and view all the answers

How does hemoperfusion enhance the elimination of toxins?

By utilizing a sterile column containing activated charcoal. Signup and view all the answers

Which of the following is a disadvantage of plasmapheresis?

It may result in the loss of some plasma proteins. Signup and view all the answers

What must the characteristics of chemicals be for effective hemodialysis?

Small molecular size Signup and view all the answers

What is a primary function of chemical antidotes in detoxification?

They react chemically to produce less toxic compounds. Signup and view all the answers

Which substance is a key component of the dialysis solution to create a hypertonic environment?

Glucose Signup and view all the answers

Which condition is NOT suitable for enhancing toxin elimination through forced diuresis?

The toxin is quickly metabolized in the liver. Signup and view all the answers

Which substance is commonly used to alkalinize urine?

Acetazolamide Signup and view all the answers

What is the primary purpose of dialysis in managing severe intoxication?

To facilitate the removal of toxins from blood using a semipermeable membrane. Signup and view all the answers

Which of the following factors does NOT aid in enhancing the elimination of toxins?

Chemical reabsorption by renal tubules. Signup and view all the answers

Acidification of urine is effective for promoting the excretion of which type of drugs?

Weak bases Signup and view all the answers

What is a key benefit of enhancing the elimination of a toxic agent via urine alkalinization?

Increases the excretion of weak acidic drugs. Signup and view all the answers

Which scenario would NOT typically require dialysis for toxin removal?

Severe opioid overdose. Signup and view all the answers

Which mechanism does alkalinizing the urine utilize to enhance elimination?

Increasing ionization of weak acids. Signup and view all the answers

Study Notes

Toxicology

Toxicology is the study of poisons and their effects on living organisms.
Management of toxicity focuses on enhancing elimination of toxins from the circulatory system

Principles of Management of Toxicity

Methods to enhance toxin elimination are employed when:
- The toxin is highly concentrated in the plasma compared to the organs.
- The toxin and its metabolites are readily excreted in urine.
- The toxin quickly detaches from plasma proteins.
- The toxin has a small molecular weight.

Forced Diuresis

Enhances excretion of drugs/metabolites through the kidneys.
Ineffective for chemicals reabsorbed by renal tubules (low concentration in urine)
Diuretics are used to increase urine output.
- Examples of diuretics include mannitol and furosemide.

Alkalinization of Urine

Promotes excretion of weak acids.
Increases ionization of weak acids, leading to "ion trapping" in renal tubules.
Examples of chemicals alkalinized by urine include: Na bicarbonate, acetazolamide, and weak acidic drugs such as salicylates, phenobarbitone, and methotrexate.

Acidification of Urine

Promotes excretion of weak bases.
Increases the ionization of weak bases, leading to "ion trapping" in renal tubules.
Examples of chemicals acidified by urine include ammonium chloride and ascorbic acid, and weak basic drugs such as amphetamine, quinine, and phencyclidine

Extracorporeal Techniques

Dialysis is an adjunct treatment for severely intoxicated patients.
Not necessary for toxins with specific antidotes (e.g., opioid toxicity with naloxone).
Ineffective for rapidly acting toxins (e.g., cyanide).

Dialysis Techniques

Chemicals diffuse through a semipermeable membrane from a higher concentration area (blood and interstitial fluids) to a lower concentration area (dialysis solution).
Peritoneal dialysis uses the patient's peritoneum as a semipermeable membrane for fluid and chemical exchange.
- Adequate peritoneal blood flow is crucial for its effectiveness.
- Dialysis solution typically contains sodium chloride, lactate, bicarbonate, and high glucose to make the fluid hypertonic.
- Albumin is added for protein-bound toxins.
- Complications of peritoneal dialysis include abdominal pain, protein loss, intraperitoneal bleeding, water and electrolyte imbalances, and intestinal, bladder, liver, and spleen perforation.
Hemodialysis uses an artificial semipermeable membrane (artificial kidney) to filter chemicals from the blood. The method is less effective for highly protein-bound chemicals that do not pass through the semipermeable membrane
Complications include infection, hypotension, and bleeding/clotting.
Hemoperfusion involves passing blood through a column containing activated charcoal or ion exchange resins to adsorb toxic chemicals.
It is more effective than peritoneal and hemodialysis due to a larger surface area.

Advantages of Hemoperfusion

Suitable for detoxifying lipid-soluble and high protein-bound chemicals.

Complications of Hemoperfusion

Trapping of WBCs and platelets.
Activation of the clotting system.

Plasmapheresis

A method to separate red blood cells from plasma.
Fresh frozen or treated plasma is mixed with red blood cells and returned to the body.
- Disadvantage: can cause patient's plasma proteins to be lost.

Chemical Antidotes

Chemical antidotes react chemically with the poison to produce less toxic compounds.
Example 1: Calcium salts react with oxalic acid to form a less soluble compound, which prevents absorption.
Example 2: Chelating agents (dimercaprol, deferoxamine, EDTA, penicillamine) bind to heavy metals, creating water-soluble complexes that are excreted in urine.

Receptor Antidotes

Receptor antidotes antagonize the receptor targeted by the poison.
Example 1: Naloxone (µ-receptor antagonist) is an antidote for opioid-induced respiratory depression.
Example 2: Atropine (M-receptor antagonist) is used to antidote organophosphate-induced cholinergic syndrome.
Example 3: Physostigmine (cholinesterase inhibitor) is an antidote for atropine toxicity.

Functional Antidotes

Functional antidotes oppose the physiological effects of the poison.
Example 1: Epinephrine is used to treat anaphylactic reactions to combat effects such as bronchial constriction.
Example 2: Vitamin K is used to reverse the effects of coumarin-induced hemorrhage, enhancing blood clotting factors.

Enzymatic Antidotes

Enzymatic antidotes work with endogenous enzymes to detoxify.
Example 1: N-acetylcysteine activates the endogenous glutathione (GSH) enzyme to detoxify acetaminophen.
Example 2: Pralidoxime reactivates acetylcholinesterase, which is inhibited in organophosphate poisoning.
Example 3: Ethanol is used to detoxify methanol by inhibiting alcohol dehydrogenase and reducing the formation of formic acid.

Supportive Treatments

Hypertension: Sodium nitroprusside and other vasodilators (e.g., nitroglycerin, calcium channel blockers) are used to treat hypertensive crises.
Anaphylaxis: Epinephrine, intravenous fluids, antihistamines, corticosteroids, and bronchodilators manage severe allergic reactions.
Seizures: Benzodiazepines (e.g., diazepam, midazolam) and phenytoin are treatments for seizures caused by toxins.
Electrolyte disturbances: IV calcium gluconate, sodium bicarbonate, diuretics, and polystyrene sulfonate are employed to correct abnormal electrolyte levels.
Hyperthermia: In cases of malignant hyperthermia, dantrolene is used to reduce Ca2+ release from the sarcoplasmic reticulum, thus relaxing muscles.
Exertional heat stroke: Treatment includes anticonvulsants, neuromuscular blockers, and evaporative cooling.
Anticholinergic syndrome: Evaporative cooling and physostigmine (a cholinesterase inhibitor) are used to stimulate cholinergic mechanisms and counteract hyperthermia.

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Description

Test your knowledge on the principles of managing toxicity in toxicology. This quiz covers methods for enhancing toxin elimination, including forced diuresis and urine alkalinization techniques. Understand how these principles apply to various toxins and their effects on living organisms.