PROCESSES AND PATHWAYS

Reversible H2 competition on parietal cells to decrease acid secretion

What is the mechanism of action of H2 Receptor Antagonists?

Irreversible H+/K+ ATPase inhibition leading to a 90-98 percent reduction in daily acid

What is the mechanism of action of Proton Pump Inhibitors (PPIs)?

Weak bases that react with gastric HCl to neutralize existing acid

What is the mechanism of action of Antacids?

Gel or paste that inhibits pepsin hydrolysis of mucosal proteins and increases prostaglandins and EGFs

What is the mechanism of action of Sucralfate?

PGE1 analog used for the prevention of NSAID-induced mucosal injury

What is the mechanism of action of Misoprostol?

Binds reversibly to K+ ions and blocks the H+/K+ ATPase pump

What is the mechanism of action of PCABs like Prazans?

Inhibiting NF-kB activity and modulating COX and LOX pathways in the GI mucosa

What is the mechanism of action of Aminosalicylates like 5-ASA?

Inhibit gene transcription of NO synthesis, phospholipase A2, COX-2, and NF-kB

What is the mechanism of action of Glucocorticoids in IBD?

Inhibit de novo purine synthesis leading to decreased lymphocyte proliferation

What is the mechanism of action of Purine Analogs like Azathioprine?

Binds to cyclophilin to inhibit calcineurin and decrease IL-1, IL-2, and T-cell activation

What is the mechanism of action of Cyclosporine?

Binds to soluble and membrane-bound TNF to block the inflammatory cascade and the NF-kB pathway

What is the mechanism of action of Anti-TNF agents like Infliximab?

Targets the A4 subunit to prevent the binding of inflammatory cells and their migration into tissues

What is the mechanism of action of Natalizumab?

Targets the A4/B7 subunit to block the interaction of leukocytes with gut vasculature

What is the mechanism of action of Vedolizumab?

Non-selective inhibitor of the JAK family including JAK1, JAK3, and TYK2

What is the mechanism of action of Tofacitinib?

Binds to sphingosine-1-phosphate (S1P) receptors to alter lymphocytic migration and sequester lymphocytes in lymph nodes

What is the mechanism of action of Ozanimod?

Disruption of the electron transport chain (ETC) in anaerobic bacteria and protozoa

What is the mechanism of action of Metronidazole?

Blocks K+ channels to decrease Cl- secretion and stool volume

What is the mechanism of action of Zinc in acute diarrhea?

Peripheral mu-opioid agonist that decreases intestinal transit

What is the mechanism of action of Loperamide?

Enkephalinase inhibitor that decreases stool output without affecting motility

What is the mechanism of action of Racecadotril?

Inhibits bacterial cell wall synthesis

What is the mechanism of action of Beta-Lactams?

Inhibits bacterial DNA gyrase and topoisomerase IV

What is the mechanism of action of Fluoroquinolones?

Binds to ergosterol and disrupts the cell membrane

What is the mechanism of action of Amphotericin?

Inhibits all 3 functions of HBV DNA polymerase

What is the mechanism of action of Entecavir?

Acyclic nucleoside phosphonate that inhibits reverse transcriptase

What is the mechanism of action of Tenofovir?

Host cytokine with antiviral, immunomodulatory, and antiproliferative actions that induces antiviral signals

What is the mechanism of action of Pegylated Interferon alfa?

Inhibits viral polymerase

What is the main role of Sofosbuvir?

Decreases cholesterol content of bile by reducing hepatic cholesterol secretion and stabilizes hepatocyte canalicular membranes

What is the mechanism of action of Ursodeoxycholic acid?

Reduces cardiac output and causes splanchnic vasoconstriction via Beta-2 blockade to lower portal pressure

What is the mechanism of action of Propranolol or Nadolol in varices?

Inhibits glucagon and other gut peptides to cause splanchnic vasoconstriction

What is the mechanism of action of Somatostatin or Octreotide?

Potent arterial vasoconstrictor used to reduce portal pressure in acute variceal bleeding

What is the mechanism of action of Vasopressin?

GLP-2 analog that stimulates mucosal epithelial growth and enhances fluid absorption

What is the mechanism of action of Teduglutide?

TPP cofactor for 6-keto acid decarboxylation

What is the mechanism of action of Vitamin B1 (Thiamine)?

Precursor to FMN and FAD for the electron transport chain

What is the mechanism of action of Vitamin B2 (Riboflavin)?

NAD+ and NADP+ precursor for DNA repair

What is the mechanism of action of Vitamin B3 (Niacin)?

Cofactor for prolyl and lysyl hydroxylase required for collagen crosslinking

What is the mechanism of action of Vitamin C?

y-carboxylation of glutamyl residues on clotting factors 2, 7, 9, 10

What is the mechanism of action of Vitamin K?

Establishes the resting membrane potential (RMP) and action potential

What is the primary mechanism of action of Potassium?

Regulating ECF volume, plasma osmolarity, and nerve conduction

What is the primary function of Sodium?

Inhibits HMG-CoA reductase and has antiplatelet effects

What is the mechanism of action of the nutraceutical Garlic?

Inhibits 5-alpha-reductase conversion of testosterone to DHT

What is the mechanism of action of Saw Palmetto?

Inhibits the 30S ribosomal subunit

What is the mechanism of action of Amikacin or Gentamicin?

Reactive intermediates damage bacterial DNA, ribosomal proteins, and cell wall synthesis

What is the mechanism of action of Nitrofurantoin?

Blocks early step of peptidoglycan synthesis

What is the mechanism of action of Fosfomycin?

Induces mild volume depletion to increase proximal Na and water reabsorption and passive Ca reabsorption

What is the mechanism of action of Thiazide Diuretics in preventing calcium stones?

Binds to oxalate in the intestinal lumen to prevent its absorption into the blood

What is the mechanism of action of Oral Calcium Carbonate in enteric hyperoxaluria?

Urine alkalization to prevent calcium oxalate formation

What is the mechanism of action of Potassium Citrate?

Urease inhibitor that decreases ammonia production and urine alkalinity

What is the mechanism of action of Acetohydroxamic Acid?

Inhibits PDE-5 enzyme to prevent the degradation of cGMP

What is the mechanism of action of Sildenafil or Tadalafil?

Stimulates adenylate cyclase to increase cAMP and decrease intracellular calcium

What is the mechanism of action of Alprostadil?

Blocks alpha-1 and alpha-2 receptors to relax smooth muscle and allow blood entry into the penis

What is the mechanism of action of Phentolamine?

Selective for Type 2 alpha-reductase to inhibit the conversion of testosterone to DHT

What is the mechanism of action of Finasteride?

Blocks alpha-1 receptors to relax the prostate and bladder neck and improve urine flow

What is the mechanism of action of Tamsulosin?

Pituitary desensitization via constant GnRH stimulation leading to decreased LH and FSH

What is the mechanism of action of GnRH agonists like Leuprolide?

Directly blocks GnRH receptors for immediate onset of testosterone reduction

What is the mechanism of action of GnRH blockers like Abarelix?

Competitive AR antagonist that inhibits nuclear translocation

What is the mechanism of action of Flutamide?

Blocks the CYP17 enzyme required for androgen biosynthesis in testicular and adrenal tissues

What is the mechanism of action of Abiraterone?

Inhibits protein synthesis by binding to the 50S subunit

What is the mechanism of action of Azithromycin?

Binds to the 30S ribosomal subunit

What is the mechanism of action of Doxycycline?

Stimulates mononuclear cells to release Interferon-alpha and cytokines

What is the mechanism of action of Imiquimod?

Negative feedback to the hypothalamus and pituitary to suppress FSH and LH release

What is the mechanism of action of Combined Oral Contraceptives?

Thickens cervical mucus, thins the endometrium, and reduces sperm transport

What are the mechanisms of Progestin in contraceptives?

Local sterile inflammation that impairs sperm viability

What is the mechanism of action of the Copper IUD?

Competitively blocks the conversion of plasminogen to plasmin to stabilize clots

What is the mechanism of action of Tranexamic Acid?

Suppresses ovulation and produces endometrial atrophy

What is the mechanism of action of Danazol in AUB?

Hypergastrinemia and increased risk of hip fractures

What happens when PPIs are used chronically?

Blackening of the tongue and stool

What happens when Bismuth preparations are used?

Sodium retention, hypertension, and hypokalemia

What happens when Carbenoxolone is used?

Toxic megacolon in the presence of fever or bloody stools

What is a dangerous consequence of using Loperamide inappropriately?

Ototoxicity and nephrotoxicity

What are the major side effects of Amikacin?

Tendon rupture and QT prolongation

What are major consequences of Fluoroquinolone use?

Lactic acidosis in severe hepatic decompensation

What is a major adverse effect of Entecavir?

Proximal tubulopathy and decreased bone density

What happens when Tenofovir (general) is used?

Flu-like symptoms, transaminitis, and neurotoxicity

What happens when Pegylated Interferon alfa is used?

Oligospermia and impaired folate absorption

What happens when Sulfasalazine is used?

Cushingoid symptoms like moon face, buffalo hump, and osteoporosis

What happens when Glucocorticoids are used chronically?

Bone marrow suppression and increased infection risk

What are dose-related consequences of Azathioprine?

Progressive multifocal leukoencephalopathy (PML) via JC virus reactivation

What is a severe consequence of Natalizumab use?

Increased risk of herpes zoster reactivation

What happens when Tofacitinib is used?

Disulfiram-like reaction when taken with alcohol

What happens when Metronidazole is used?

Bile salt-induced diarrhea

What happens when Ursodeoxycholic acid is used?

Increased risk for colorectal and small bowel neoplasia

What is a potential long-term consequence of Teduglutide?

Wernicke-Korsakoff syndrome and Beriberi

What happens when there is a deficiency of Vitamin B1?

Pellagra consisting of dermatitis, diarrhea, and dementia

What happens when there is a deficiency of Vitamin B3?

Flushing mediated by prostaglandins

What happens when high doses of Niacin are used?

Sideroblastic anemia and sensory neuropathy

What happens when there is a deficiency or excess of Vitamin B6?

Neural tube defects and megaloblastic anemia

What happens when there is a deficiency of Vitamin B9?

Ataxia and loss of proprioception due to myelin sheath dysfunction

What happens when there is a deficiency of Vitamin B12?

Scurvy with perifollicular hemorrhage and poor wound healing

What happens when there is a deficiency of Vitamin C?

Night blindness and Bitot spots

What happens when there is a deficiency of Vitamin A?

Teratogenicity in the first trimester

What is a consequence of Vitamin A toxicity?

Rickets in children and osteomalacia in adults

What happens when there is a deficiency of Vitamin D?

Neonatal hemorrhagic disease and Warfarin skin necrosis

What happens when there is a deficiency or rapid depletion of Vitamin K?

Sudden fatal arrhythmias and paralysis

What happens when there is an excess of Potassium?

Kidney stones and polyuria

What happens when there is an excess of Calcium?

Neuromuscular blockade and respiratory depression

What happens when there is an excess of Magnesium?

Osmotic demyelination syndrome

What happens when Sodium is corrected too rapidly?

Acrodermatitis Enteropathica

What happens when there is a mutation in the SLC39A4 gene affecting Zinc?

Villous atrophy leading to decreased drug absorption

What happens to the GI tract in severe PEM?

Increased free drug levels due to decreased protein binding to albumin

What happens to drug distribution in PEM?

Reduced hepatic enzyme activity and Phase 1 and 2 reactions

What happens to drug metabolism in PEM?