Drugs Block 3 Flashcards
Escitalopram
long-term tx for anxiety; slow/long-acting, targets serotonin reuptake transporters in brain; long t1/2, high Vd, even though high Cl, low serum-protein binding, 10 days to max effect. Metabolized by CYP1C9.
Alprazolam
acute-tx for anxiety; fast/short-acting; targets GABA receptors in brain; low Vd, short t1/2, lower Cl, high serum protein binding, time to peak effect only 1hr
Mannitol
an osmotic diuretic that increases urine flow, reduces drug reabsorption, increasing drug elimination.
***Gentamicin
nephrotoxic drug that reduces renal fxn and decrease renal elimination
Probenecid
reduces secretion of penicillin G and other anions, like furosemide, by competing for OAT/MRP transporters.
St. John’s Wort
an inducer of cytochrome P450 (3A4) and p-glycoproteins that promotes metabolism of drugs (cyclosporin, erythromycin). and therefore decreases plasma concentration these drugs.
Cimetidine
aka Tagamet; H2 receptor antagonist used to reduce acid secretion (to tx GERD) that also inhibits most CYP450’s; thereby inhibiting drug metabolism and therefore increasing plasma drug concentration. Also reduces hepatic blood flow which may affect drug clearance.
At high doses may have anti-androgenic effect; enlargement of breast tissue in males (gynecomastia) and spontaneous flow of breast milk (galactorrhea) in females; may induce confusion in elderly
Digoxin
a cardiac glycoside that has positive inotropic and negative chronotropic effects; mechanism of action is by blocking Na/K/ATPase; used to tx CHF, certain arrhythmias and tachycardia. Digoxin will decrease renal clearance of other drugs (quinidine, clarithromycin, ritonavir). It’s half life is 1/3 that of digitoxin.
Digitoxin
Same as digoxin but missing an -OH group, therefore less polar than digoxin; t1/2 is 3x a long as digoxin’s. No saturable binding to plasma protein.
Inulin
an indicator used to measure GFR; freely filtered in the kidney and neither secreted/absorbed. Also is not metabolized in the lumen or synthesized endogenously.
***Creatinine
Metabolite produced in skeletal muscle, is freely filtered and also slightly secreted in the tubule; can be used to estimate GFR, but will overestimate due to secretion.
PAH
Non-endogenous drug that is used to measure effective renal plasma flow; it is freely filtered and almost completely secreted so 90% of the drug is extracted in one pass!
Famotidine
aka Pepcid, an H2 receptor antagonist used to reduce acid secretion. Does NOT inhibit CYP450 like the other H2R antags do.
Omeprazole
H/K/ATPase inhibitor that is one of the most potent acid suppressors; used to tx GERD, ulcers, Zollinger-Ellison syndrome, an H. pylori infections; administered as a prodrug that is converted to its active form once inside the acidic compartment of parietal cells; supplied in delayed-release an enteric-coated formulas (protects against pre-absorption). Very few side effects, but may interfere with CYP450 metabolism of diazepam, phenytoin, warfarin, and cyclosporin.
Ranitidine
aka Zantac; an H2 receptor inhibitor that blocks acid secretion, used to tx GERD.
***Esomeprazole
aka Nexium, the S-isomer of omeprazole, also a PPI. Eliminated less rapidly with an increased half-life compared to omeprazole; therefore may have therapeutic advantage.
Diphenhydramine
aka Benadryl; an H1R antagonist used to treat/prevent allergic rhinitis and urticaria; used to tx atopic dermatitis for sedating and anti-pruritic properties. Also used to tx motion sickness (also a muscarinic antagonist)
Dimenhydrinate
aka Dramamine; an H1R antagonist used to treat/prevent allergic rhinitis and urticaria
Fexofenadine
aka Allegra, an H1 receptor antagonist that selectively blocks histamine-induced contraction of bronchiolar or GI smooth muscle; the active (a non-toxic) metabolite of terfenadine. Does not cross BBB.
Terfenadine
An H1 receptor antagonist used to tx allergic rhinitis, metabolized by CYP450; taken off the market because when taken with CYP450 inhibitors (grapefruit juice, cimetidine, ranitidine) the levels of terfenadine were toxic and lead to long QT and lethal ventricular arrhythmias.
Chloroquine
Used to tx/prevent malaria; highly lipophilic, super high Vd, high Cl, very long half life (214 hrs!!) resulting in drug accumulation and lots of side effects. High ion trapping in acidic vesicles.
*** reason the drug has a long t1/2 despite having a high clearance is its super high Vd.
Fentanyl
Analgesic often administered via transdermal patch due to high lipophilicity
Phenytoin
Anti-seizure medication; highly lipophilic so administered as the more soluble prodrug (Fosphenytoin) via IV, and later converted to active form. Substrate of CYP2C9. Nonsaturable binding to plasma protein. Non-linear PK in the therapeutic range.
Verapamil
L-type Ca2+ channel inhibitor used to tx angina, tachycardia, and A-fib; has high pKa, so remains in it’s charged (protonated state) at lower pH.