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Body fluid compartments
Movement of water between body compartments
Acid-base disturbances: Pathology review
Diabetes insipidus and SIADH: Pathology review
Electrolyte disturbances: Pathology review
Renal failure: Pathology review
Acyanotic congenital heart defects: Pathology review
Adrenal masses: Pathology review
Bacterial and viral skin infections: Pathology review
Bone tumors: Pathology review
Coagulation disorders: Pathology review
Congenital neurological disorders: Pathology review
Cyanotic congenital heart defects: Pathology review
Extrinsic hemolytic normocytic anemia: Pathology review
Eye conditions: Inflammation, infections and trauma: Pathology review
Eye conditions: Refractive errors, lens disorders and glaucoma: Pathology review
Headaches: Pathology review
Intrinsic hemolytic normocytic anemia: Pathology review
Leukemias: Pathology review
Lymphomas: Pathology review
Macrocytic anemia: Pathology review
Microcytic anemia: Pathology review
Mixed platelet and coagulation disorders: Pathology review
Nasal, oral and pharyngeal diseases: Pathology review
Nephritic syndromes: Pathology review
Nephrotic syndromes: Pathology review
Non-hemolytic normocytic anemia: Pathology review
Pediatric brain tumors: Pathology review
Pediatric musculoskeletal disorders: Pathology review
Platelet disorders: Pathology review
Renal and urinary tract masses: Pathology review
Seizures: Pathology review
Viral exanthems of childhood: Pathology review
Adrenal insufficiency: Pathology review
Central nervous system infections: Pathology review
Childhood and early-onset psychological disorders: Pathology review
Congenital gastrointestinal disorders: Pathology review
Diabetes mellitus: Pathology review
Environmental and chemical toxicities: Pathology review
Gastrointestinal bleeding: Pathology review
GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review
Inflammatory bowel disease: Pathology review
Medication overdoses and toxicities: Pathology review
Obstructive lung diseases: Pathology review
Pneumonia: Pathology review
Psychiatric emergencies: Pathology review
Shock: Pathology review
Supraventricular arrhythmias: Pathology review
Traumatic brain injury: Pathology review
Ventricular arrhythmias: Pathology review
Congenital TORCH infections: Pathology review
Jaundice: Pathology review
Respiratory distress syndrome: Pathology review
Autosomal trisomies: Pathology review
Cystic fibrosis: Pathology review
Disorders of sex chromosomes: Pathology review
HIV and AIDS: Pathology review
Miscellaneous genetic disorders: Pathology review
Papulosquamous and inflammatory skin disorders: Pathology review
Anxiety disorders, phobias and stress-related disorders: Pathology Review
Developmental and learning disorders: Pathology review
Eating disorders: Pathology review
Mood disorders: Pathology review
Pharmacodynamics: Agonist, partial agonist and antagonist
Pharmacodynamics: Desensitization and tolerance
Pharmacodynamics: Drug-receptor interactions
Pharmacokinetics: Drug absorption and distribution
Pharmacokinetics: Drug elimination and clearance
Pharmacokinetics: Drug metabolism
Androgens and antiandrogens
Estrogens and antiestrogens
Miscellaneous cell wall synthesis inhibitors
Protein synthesis inhibitors: Tetracyclines
Cell wall synthesis inhibitors: Penicillins
Antihistamines for allergies
Non-steroidal anti-inflammatory drugs
Antimetabolites: Sulfonamides and trimethoprim
Cell wall synthesis inhibitors: Cephalosporins
DNA synthesis inhibitors: Fluoroquinolones
DNA synthesis inhibitors: Metronidazole
Miscellaneous protein synthesis inhibitors
Protein synthesis inhibitors: Aminoglycosides
Bronchodilators: Beta 2-agonists and muscarinic antagonists
Bronchodilators: Leukotriene antagonists and methylxanthines
Pulmonary corticosteroids and mast cell inhibitors
Anticonvulsants and anxiolytics: Barbiturates
Anticonvulsants and anxiolytics: Benzodiazepines
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Pharmacokinetics refers to the movement and modification of medication inside the body. Or more simply, it’s what the body does to the medication and how it does it.
Alright, so once the medication get administered, it first has to be absorbed into the circulation, then distributed to various tissues throughout the body; metabolized or broken down; and finally, eliminated or excreted in the urine or feces.
You can remember this as ADME - Absorption, Distribution, Metabolism, and Excretion.
Okay, let’s focus on the metabolism. This is the process of converting a medication into a less, or more active form. These forms are also known as metabolites.
So in most cases, metabolic reactions turn an active medication into a less active, or inactive metabolite, which is then ready to get excreted.
Some medications though, are administered in an inactive form, also known as a prodrug, which needs to be metabolized into an active form within the body before they can produce the desired effect. But even those medications will eventually need to go through further metabolism in order to get inactivated and excreted.
Now, all these reactions are broken down into two main phases: phase I and phase II.
This classification is somewhat misleading though. For some medications Phase II may occur before Phase I, while others may undergo only Phase I or only Phase II.
In any case, both phases take place primarily in the liver, and to a much lesser degree, in the lungs, kidneys, and the walls of the small intestine.
So, let’s zoom into a liver cell, also known as a hepatocyte.
Phase I reactions are typically carried out by a class of enzymes called cytochrome P450, or CYP450 for short.
These enzymes hang out mainly in cell compartments, like the endoplasmic reticulum and the mitochondria.
They are often abbreviated as CYP followed by a number, which indicates the family; followed by a letter for the subfamily, and then a number again for the form, like CYP3A4 or CYP2D6.
What these enzymes do is convert non-polar, lipid-soluble medications into slightly more polar, water-soluble metabolites through oxidation, hydrolysis, or reduction.
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