Medication overdoses and toxicities: Pathology review
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Medication overdoses and toxicities: Pathology review
Prerequisite basic sciences
Prerequisite basic sciences
Supraventricular arrhythmias: Pathology review
Ventricular arrhythmias: Pathology review
Prerequisite basic sciences
Chest X-ray interpretation: Clinical sciences
Prerequisite basic sciences
ECG axis
ECG basics
ECG cardiac hypertrophy and enlargement
ECG cardiac infarction and ischemia
ECG intervals
ECG normal sinus rhythm
ECG QRS transition
ECG rate and rhythm
Coronary artery disease: Pathology review
Electrolyte disturbances: Pathology review
Heart blocks: Pathology review
Supraventricular arrhythmias: Pathology review
Ventricular arrhythmias: Pathology review
Prerequisite basic sciences
Anatomy clinical correlates: Anterior and posterior abdominal wall
Anatomy clinical correlates: Inguinal region
Anatomy clinical correlates: Other abdominal organs
Anatomy clinical correlates: Peritoneum and diaphragm
Anatomy clinical correlates: Viscera of the gastrointestinal tract
Appendicitis: Pathology review
Diverticular disease: Pathology review
Gallbladder disorders: Pathology review
GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review
Inflammatory bowel disease: Pathology review
Pancreatitis: Pathology review
Anatomy clinical correlates: Anterior blood supply to the brain
Anatomy clinical correlates: Cerebellum and brainstem
Anatomy clinical correlates: Cerebral hemispheres
Anatomy clinical correlates: Posterior blood supply to the brain
Amnesia, dissociative disorders and delirium: Pathology review
Central nervous system infections: Pathology review
Cerebral vascular disease: Pathology review
Dementia: Pathology review
Drug misuse, intoxication and withdrawal: Alcohol: Pathology review
Drug misuse, intoxication and withdrawal: Hallucinogens: Pathology review
Drug misuse, intoxication and withdrawal: Other depressants: Pathology review
Drug misuse, intoxication and withdrawal: Stimulants: Pathology review
Mood disorders: Pathology review
Seizures: Pathology review
Traumatic brain injury: Pathology review
Anatomy clinical correlates: Breast
Anatomy clinical correlates: Heart
Anatomy clinical correlates: Mediastinum
Anatomy clinical correlates: Pleura and lungs
Anatomy clinical correlates: Thoracic wall
Aortic dissections and aneurysms: Pathology review
Coronary artery disease: Pathology review
Deep vein thrombosis and pulmonary embolism: Pathology review
GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review
Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review
Anatomy clinical correlates: Viscera of the gastrointestinal tract
Gastrointestinal bleeding: Pathology review
Anatomy clinical correlates: Bones, fascia and muscles of the neck
Anatomy clinical correlates: Skull, face and scalp
Anatomy clinical correlates: Temporal regions, oral cavity and nose
Anatomy clinical correlates: Trigeminal nerve (CN V)
Anatomy clinical correlates: Vessels, nerves and lymphatics of the neck
Headaches: Pathology review
Anatomy clinical correlates: Anterior blood supply to the brain
Anatomy clinical correlates: Cerebellum and brainstem
Anatomy clinical correlates: Cerebral hemispheres
Anatomy clinical correlates: Posterior blood supply to the brain
Cerebral vascular disease: Pathology review
Anatomy clinical correlates: Female pelvis and perineum
Cervical cancer: Pathology review
Complications during pregnancy: Pathology review
Ovarian cysts and tumors: Pathology review
Sexually transmitted infections: Vaginitis and cervicitis: Pathology review
Urinary tract infections: Pathology review
Uterine disorders: Pathology review
Vaginal and vulvar disorders: Pathology review
Anatomy clinical correlates: Heart
Anatomy clinical correlates: Mediastinum
Anatomy clinical correlates: Pleura and lungs
Anatomy clinical correlates: Thoracic wall
Apnea, hypoventilation and pulmonary hypertension: Pathology review
Deep vein thrombosis and pulmonary embolism: Pathology review
Heart failure: Pathology review
Lung cancer and mesothelioma: Pathology review
Obstructive lung diseases: Pathology review
Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review
Pneumonia: Pathology review
Restrictive lung diseases: Pathology review
Tuberculosis: Pathology review
Drug misuse, intoxication and withdrawal: Alcohol: Pathology review
Drug misuse, intoxication and withdrawal: Hallucinogens: Pathology review
Drug misuse, intoxication and withdrawal: Other depressants: Pathology review
Drug misuse, intoxication and withdrawal: Stimulants: Pathology review
Environmental and chemical toxicities: Pathology review
Medication overdoses and toxicities: Pathology review
Prerequisite basic sciences
Shock: Pathology review
Prerequisite basic sciences
Anatomy clinical correlates: Arm, elbow and forearm
Anatomy clinical correlates: Axilla
Anatomy clinical correlates: Bones, fascia and muscles of the neck
Anatomy clinical correlates: Cerebral hemispheres
Anatomy clinical correlates: Clavicle and shoulder
Anatomy clinical correlates: Eye
Anatomy clinical correlates: Female pelvis and perineum
Anatomy clinical correlates: Heart
Anatomy clinical correlates: Hip, gluteal region and thigh
Anatomy clinical correlates: Male pelvis and perineum
Anatomy clinical correlates: Mediastinum
Anatomy clinical correlates: Pleura and lungs
Anatomy clinical correlates: Skull, face and scalp
Anatomy clinical correlates: Spinal cord pathways
Anatomy clinical correlates: Thoracic wall
Anatomy clinical correlates: Vertebral canal
Anatomy clinical correlates: Vessels, nerves and lymphatics of the neck
Anatomy clinical correlates: Viscera of the neck
Anatomy clinical correlates: Wrist and hand
Eye conditions: Inflammation, infections and trauma: Pathology review
Spinal cord disorders: Pathology review
Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review
Traumatic brain injury: Pathology review
Assessments
Medication overdoses and toxicities: Pathology review
USMLE® Step 1 questions
0 / 9 complete
Questions
USMLE® Step 1 style questions USMLE
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Transcript
Content Reviewers
A 19 year old young man named Cameron is brought to the emergency room by his father, who found Cameron vomiting next to a half-empty bottle of aspirin. Cameron tells you that he has a headache and is hearing a weird ringing noise. You decide to perform a blood test, which reveals that Cameron has metabolic acidosis.
Later that day, 32 year old Adaline presents in the emergency room due to nausea, vomiting, and slurred speech. Adaline reports that she has the flu and has been taking ibuprofen for the last couple of days. You notice that Adaline is very thirsty, and she also keeps going to the restroom to urinate. Her history reveals that she was diagnosed with bipolar disorder a few years ago, and is currently under treatment with lithium.
Based on their history and presentation, both Cameron and Adaline seem to have some type of medication overdose or toxicity. An overdose refers to taking too much of a substance, and can result in toxicity, which refers to how harmful that substance can be to the body.
Now, let’s go over some pharmacology basics. The therapeutic index, or TI for short, is a quantitative measurement of a drug’s dosing and its safety. For your exams, you should know that the TI is calculated as the ratio of the median toxic dose or TD50, which is the dose that causes a toxic response in 50% of the population, over the median effective dose or ED50, which is the dose that causes a therapeutic effect in 50% of the population.
Now, if the test question gives you a median lethal dose or LD50 for short instead of TD50, don’t panic! These two can be used interchangeably in the formula, but keep in mind that TD50 refers to human clinical trials, while LD50 refers to animal studies, and is defined as the dose that causes death in 50% of tested animals.
The important thing to note here is that medications with a wide therapeutic index are safer, since their toxic dose is much higher than their effective dose. On the flip side, medications with a narrow therapeutic index are more dangerous, since they have close toxic and effective doses.
Now, in contrast to the therapeutic index, there is the therapeutic window, which is defined as the range of blood concentrations at which a medication can give therapeutic effects while avoiding toxicity. The therapeutic window refers to any blood concentration of a given drug that’s between two parameters. The first one is minimum effective concentration or MEC, which refers to the minimum concentration that has therapeutic effects. The other one is minimum toxic concentration or MTC, which refers to the minimum concentration that has toxic effects. Everything between these two concentrations represents the therapeutic window.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Katzung & Trevor's Pharmacology Examination and Board Review,10th Edition" McGraw Hill Professional (2012)
- "Anticholinesterases and anticholinergic drugs" Continuing Education in Anaesthesia Critical Care & Pain (2004)
- "Paracetamol and fever management" Journal of the Royal Society for the Promotion of Health (2008)
- "Chemical and Mechanical Alternatives to Leech Therapy: A Systematic Review and Critical Appraisal" Journal of Reconstructive Microsurgery (2011)
- "Clinical Laboratory Medicine" Lippincott Williams & Wilkins (2002)
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