Drugs Flashcards
Warfarin
Therapeutic Use, Mechanism of Action, Side Effects, Therapeutic Index, Metabolism, Pharmacogenomics, TDM
Therapeutic Use: Increases clotting time (anticoagulant) to prevent thrombi/stroke
Mechanism of Action: suppresses VKORC1 - reduces vitamin K regeneration - blocks carboxylation of coagulation factors
Side Effect: Increases bleeding if dose is too high
TI: ~1 - very narrow sweet spot
Metabolism: CYP2C9
Pharmacogenomics: CYP2C92/3 have reduced function - poor metabolizers need more days to determine if anticoagulation is stable & TDM via INR (international normalized ratio of patient prothrombin time - how long it takes to clot - adjust dose based on this number)
Pharmacodynamics: VKORC1 haplotype A - more sensitive to drug than wild-type G - higher risk of hemorrhagic activity
Dosage scheme depends on genetics of CYP2C9 and VKORC1
Benzodiazepines [-azepam + -azolam]
Diazepam [Valium]
Midazolam [Versed]
(Therapeutic Use, Mechanism of Action, Side Effect, TI, Metabolism)
Therapeutic Use: sedation, improve sleep, treat anxiety + muscle spasms
Mechanism of Action: allosteric activator of GABA-a receptors (binds b/w b+g subunits) - increase IPSP, increase Cl- current by increasing frequency of channel openings
Side Effect: over-sedation, dizziness, confusion, memory loss
TI: ~100+ (safer)
Metabolism: CYP3A4 hydroxylation [CYP2C19 helps with -azepams] (reduce 90% activity) & Glucuronidation (very water soluble and inactive form)
Sulfonylureas
Mechanism of Action
inhibit K-ATP channels, resulting in depolarized Vrest, allowing V-gated Ca channels to open and cause insulin secretion in pancreas and vasoconstriction in SMC
Minoxidil
Therapeutic Use, Mechanism of Action
Therapeutic Use: Treat HT
Mechanism of action: activates K-ATP receptors in SMC - hyperpolarized Vrest - v-gated Ca channels harder to open - more vasodilatation
Local Anaesthetics (Therapeutic Use, Mechanism of Action, and Special Characteristic)
Therapeutic Use: Localized pain reduction
Mechanism of Action: Block V-gated Na Channels by enhancing inactivation (preferential binding to inactivated state);
Use-Dependent Block: inhibition intensifies with use as more Na channels get inactivated after every AP (good for neurons that fire frequently - pain nerves + epilepsy); weak base than enters channel from cytosolic side through fenestrations
Tetrodotoxin (TTX)
Therapeutic Use, Mechanism of Action
Use: Eating pufferfish, should be just enough to make your fingertips tingle, POISON
Mechanism of Action: Potent Na Channel Blocker; acts like plug on EC side of channel (Pre-synaptic Transmission NMJ), also EC block on nicotinic receptor (Post-synaptic Transmission NMJ)
Drug Class: L-Type Ca++ Channel Blockers (Mechanism of Action, Therapeutic Uses)
Mechanism of Action: shorten cardiac AP plateau (phase II) = shorten AP
Use: treat angina, HT (inhibit SMC VC), Arrythmia
Drug Class: Na+ Channel Blockers (Mechanism of Action, Therapeutic Uses)
Mechanism of Action: Decrease/Attenuate depolarization upstroke (blunts rate of rise) - slows AP conduction through heart - prevents re-entry loops
Therapeutic Uses: local anaesthesia, arrhythmia, epilepsy/migraines
Drug Class: K+ Channel Blockers
Mechanism of Action, Therapeutic Uses, Side Effect
Mechanism of Action: impair repolarization in phase III - longer cardiac AP
Therapeutic Uses: arrhythmia
Side Effect: Drug Induced LQTS, pro-arrhythmic
Ondansetron (Zofran) and -setrons
Mechanism of Action, Therapeutic Use
Mechanism of Action: Competitive Antagonist at 5-HT3 Serotonin Receptors
Therapeutic Uses: Treat nausea + vomiting (that typically occurs because of cancer chemotherapy agents)
Zolpidem (Ambien)
Mechanism of Action, Therapeutic Use, Key Feature
Mechanism of Action: binds selectively to specific B[a]p sites involved in producing sleep
Therapeutic Use: help fall asleep
Allosteric Activator - reduces likelihood of receptor desensitization
Penicillin
Side Effect, Mechanism of Action, Excretion
Major Side Effect: blocks open GABA-a receptor channels - induces seizures!
Mechanism of Action: uncompetitive antagonist to activated GABA-a channels - CONVULSANT
Excretion: Tubular Secretion (through OATs, competing pathway with Probenecid causes prolonged penicillin activity - GOOD)
Strychnine
Mechanism of Action, Effect
Mechanism of Action: Post-synaptic inhibitor, competitive inhibitor of glycine receptors
Effect: causes excessive spasticity
Tetanus Toxin (Mechanism of Action, Effect)
Mechanism of Action: Pre-synaptic inhibitor, blocks glycine release
Effect: causes excessive spasticity
Memanite
Mechanism of Action, Effect
Mechanism of Action: binds to open NMDA channel (uncompetitive antagonist) and inhibits Ca2+ flow
Effect: May be used to treat Alzheimer’s and seizures
Acts like penicillin (uncompetitive antagonist)
Fluticasone [-son- and -one drugs]
Mechanism of Action, Effect
Mechanism of Action: activates glucocorticoid receptors to inhibit inflammatory response
Selective Serotonin Reuptake Inhibitors [SSRIs]
Mechanism of Action, Therapeutic Use
Mechanism of Action: blocks SLC6A4 serotonin reuptake SLC secondary active transporter
Therapeutic Use: anti-depressent (more serotonin lingering in synaptic cleft)
Grapefruit Juice [Furanocoumarins]
Mechanism of Action, Effect, Low vs. High F, Oral vs. IV
Mechanism of Action: Inhibit CYP3A4 + PGP, increasing bioavailability of drugs
Effect: Toxic elevations of drug in systemic circulation
Large effects on drugs with low F - bigger boosts possible
Only affects orally ingested drugs
Cimetidine [-idine]
Mechanism of Action, Key Feature, Metabolism Reaction, Problem
Mechanism of Action: Competitive Inhibitor (complementary shape) for H2 Histamine Receptor
Metabolized by S-oxidation
Inhibits many types of CYPs cause of drug:drug interaction toxic buildup
Desensitization: continual use causes GCPR receptor upregulation, over-inhibition suppresses internalization/degradation
Caffeine
Use, Mechanism of Action, Metabolism Reaction, Family
Use: stimulant
Mechanism of Action: competitive inhibitor (complementary shape to adenosine) of adenosine receptor at low doses (disinhibition of cellular functions)
Minor Mechanism: inhibits phosphodiesterases at higher doses (increase cAMP and signaling through pathway)
Metabolism: N-dealkylation to active metabolite or theophylline
METHYLXANTHINE FAMILY WITH THEOPHYLLINE
Theophylline
Use, Mechanism of Action, Metabolism Reaction, Family
Use: last resort to treat bronchiole disorders
Mechanism of Action: competitive inhibitor (complementary shape to adenosine) of adenosine receptor at low doses (disinhibition of cellular functions)
Minor Mechanism: inhibits phosphodiesterases at higher doses (increase cAMP and signaling through pathway)
Metabolism: N-dealkylation to inactive metabolite
METHYLXANTHINE FAMILY WITH CAFFEINE
Ethanol
Pathway, Problem
Pathway: EtOH - alcohol dehydrogenase oxidizes to - acetaldehyde (TOXIC drunk guy) - aldehyde dehydrogenase oxidizes to - acetate
Problem: Role in Acetaminophen toxicity - high ethanol induces CYP2E1, which can metabolize acetaminophen into toxic NAPQI
Polymorphisms: “Asian Glow” Chinese more likely to have enhanced alcohol DH and reduced aldehyde DH = toxic buildup of aldehyde causes facial flushing
Succinylcholine
Mechanism of Action, Metabolism
Mechanism of Action: prevents ACh excitation of skeletal muscle; depolarizing blocker - fastest known ACh blocker b/c you can overload dose and it’ll be degraded
Metabolism: Degraded twice via ester hydrolysis by pseudocholinesterases
Acetaminophen
Therapeutic Use, Mechanism of Action, Metabolism, Treatment for Metabolism Problems
Therapeutic Use: analgesic & antipyretic
Mechanism of Action: inhibits cyclooxygenases (housekeeping COX1 + painful COX2)
Metabolism: no phase I reaction because already hydroxylated, many possible pathways:
A. Sulfation to nontoxic inactivated form (LOW DOSES)
B. Glucuronidation to nontoxic inactivated form (LOW DOSES)
C. HIGH DOSES: CYP2E1 + CYP3A4 make NAPQI (reactive toxic intermediate electrophile kills hepatocytes) - metabolized again via GLUTATHIONE GSTs - requires glutathione
*If HIGH DOSE AND LOW GLUTATHIONE - NAPQI reacts with nucleophilic macromoleculs, triggering liver cell death
Treatment: N-acetylcysteine - complementary shape to glutathione, but less polar so it can diffuse through lipid bilayer (anti-inflammatory and antioxidant)