Question | Answer |
Medications that interact with warfarin | "ACADEMIC FACS"
Amiodarone
Ciprofloxacin/levofloxacin
Aspirin
Dicloxacillin
Erythromycin (Macrolides)
Metronidazole (Azoles)
Indomethacin
Clofibrates
Fibrates
Allopurinol
CYP 2C9 Inducers/inhibitors
Statins |
Amiodarone- drug interactions | -Digoxin
-Warfain
=decrease dose of digoxin or warfarin by 30-50% when starting amiodarone |
Digoxin- drug interactions | -increase in levels: likely due to decreased renal function
-toxicity more likely if potassium low
-P-gp substrate, narrow therapeutic range
-caution with drugs that lower INR: beta blockers, non-dhp CCBs, amiodarone, dexmedetonidine (Precidex), clonidine, opioids |
Grapefruit juice- interactions | inhibits CYP3A4
-simvastatin
-lovastatin
-nifedepine
-tacrolimus |
Lamotrigine and Valproate- drug interaction | severe rash |
MAOIS, Opioids- interactions | -avoid with serotonergic drugs- serotonin syndrome
-parkinson's drugs
-washout period for MAOIs: 14 days
-tyramine metabolism decreased with MAOIs: selegiline, rasagiline
-Serotonergic drugs: ephedrine, lithium, meperidine, levodopa, Dextromethorphan, cyclobenzaprine, triptans etc. |
Tramadol- drug interactions | -2D6 metabolized to active form
-diministed effect on 2D6 inhibitors (fluoxetine, paroxetine, or poor metabolizers of 2D6) |
Codeine- drug interactions | partial prodrug metabolized by 2D6
-ultrametabolizers, extensive metabolizers- OD risk
-2D6 inhibitors, poor metabolizers = diminished effect |
CYP450 enzyme inhibitors "BIGFACES.COM" | "BIGFACES.COM"
Bupropion
Itraconazole/ketoconazole/fluoxetine
Gemfibrozil
Fluoxetine/fluvoxamine
Amiodarone
Ciprofloxacin
Erythromycin/Clarithromycin
Sulfamethoxazole-trimethoprim
Clopidogrel
Omeprazole/Esomeprazole
Metronidazole |
CYP450 enzyme inducers | "PS PORCS"
Phenytoin
Smoking
Phenobarbitol
Oxcarbazepine
Rifampin
Carbamazepine
St. John's Work |
CYP450 enzyme inhibitors "G PACMAN" | "G PACMAN"
Grapefruit
Protease Inhibitors (ritonavir)
Azole antifungals
Cyclosporine, Cimetedine, Cobicistat
Macrolides (except azithromycin)
Amiodarone
Non-DHP CCBs |
Calcineurin Inhibiots- drug interactions | CYP substrates:
Systemic azoles
macrolides
rifampin
-nephrotoxic- avoid with aminoglycosides |
Fentanyl, Hydrocodone, Oxycodone, Methadone- drug interactions | CYP3A4 inhibitors = fatal respiratory depression |
PDE-5 Inhibitors- drug interactions | C/I with nitrates = severe hypotension
-decrease doses of alpha blockers with PDE5 inhibitors
-caution with CYP3A4 inhbitors- PDE5 inhibitors are substrates |
Quinolones, tetracyclines- drug interactions | Chelation risk, seperate from vitamins, electrolytes |
Statins- drug interactions | increased levels = increased muscle toxicity
-most are CYP3A4 metabolites: atorvastatin, simvastatin, lovastatin |
1 gallon | 4 quarts
3840 mL (approx)
3785 mL (exact) |
1 fluid oz | 30 mL (approx)
29.57 mL (exact) |
1 quart | 2 pints
960 mL (approx)
946 mL (exact) |
1 pint | 16 oz
480 mL (approx)
473 mL (exact) |
1 cup | 8 oz
240 mL (approx)
236.56 mL (exact) |
Use IBW for these drugs | -aminophylline
-theophylline
-acyclovir |
Use AdjBw (if obese) for these drugs | aminoglycosides |
Use TBW (if obese) for these drugs | -LMWHs
-UFH
-Vancomycin |
When calculating CrCl- which body weight to use? | Underweight: TBW
Normal: IBW
Overweight/obese: AdjBW |
Calcium+ Phosphate total should not exceed | 45 MEQ/L (precipitates) |
Hazard Ratio | Hazard rate in treatment group/ hazard rate in control group |
Sensitivity | 1- type II error(false negative) |
Specificity | 1- type I error (false positive) |
Relative risk reduction | 1- RR or (%risk in control- % risk in treatment)/ % risk in control |
Odds ratio | (disease present, exposed to treatment)(disease absent, unexposed to treatment)/ (disease absent, exposed to treatment)(disease present, unexposed to treatment) |
Number needed to treat | 1/(risk in control-risk in treatment group) or 1/ARR |
absolute risk reduction | %risk in control - % risk in treatment group |
Risk | # of subjects with unfavorable events in arm/ total # of subjects in arm |
Risk ratio | risk in treatment group/ risk in control group |
Anion gap | Na- Cl- HCO3 |
Calcium conversions | Carbonate: 40% elemental calcium
Citrate: 21% elemental calcium |
% ionization of weak base | 100/1 + 10^(pH-pKa) |
% ionization of a weak acid | 100/1 + 10^(pKa-pH) |
ANC | WBC X (%segs + %bands/100) |
Corrected calcium | Calcium reported (serum) + [(4-albumin)(0.8)] |
Vd Equation | amount of drug in body/ concentration of drug in plasma |
Cl Renal equals | Cl GFR + Cl secretion- Cl reabsorption |
Cl renal > Cl GFR | filtration + net secretion |
Cl GFR > Cl Renal | filtration + net reabsoprtion |
Cl renal = Cl GFR | filtration only |
Loading dose equation | desired concentration x Vd/F |
Ke equation | Cl/Vd |
Peak serum concentration equation | LD/Vd |
Clearance equation (extravascular) | absolute bioavailability x dose/ AUC |
steady state concentration equation | DR/Cl |
half-life equation | 0.693/Ke |
Clearance equation (IV) | dose/AUC |
clearance equation | rate of elimination/ concentration |
acute bioavailability equation | 100 X [(AUC extravascular)/(AUC intravascular)]x{(dose IV)/(dose extravascular)] |
Codeine- pharmacogenomics | consider testing CYP450 2D6
-ultrametablizers = toxicity risk |
Clopidogrel- pharmacogenomics | consider testing CYP2C19 genotype
-*1 allelle = fully functional
*2 and *3 = loss of function of alleles |
Trastuzumab- pharmacogenomics | HER2 protein overexpression- required for use |
Carbamazepine- pharmacogenomics | HLA-*1502
-test in Asian populations- increased risk of serious skin reactions |
Abacavir- pharmacogenomics | HLA-B*571
-if positive, increased risk of hypersensitivity |
Allopurinol- pharmacogenomics | consider testing HLA-B*5801
if positive, do not use- increased risk of SJS |
Phenytoin- pharmacogenomics | consider testing HLA-B*1502 in all Asain populations-incrased risk of SJS and TEN |
Azathioprine- pharmacogenomics | TPMT- low/absent activity = increased risk of myelosuppression |
Capecitabine- pharmacogenomics | consider testing DPD deficiency- increased toxicity risk |
Cetuximab- pharmacogenomics | KRAS- if positive, drug will not work |
Warfarin- pharmacogenomics | Consider testing CYP450 2C9*2/*3
-VKORC1 = increased bleed risk |
Thyroid function tests needed for these drugs | levothyroxine, armour thyroid, amiodarone, lithium, statins |
Drugs that cause severe skin reactions | allopurinol, lamotrigine, penicillins, phenytoin, piroxicam, sulfamethoxazole |
drugs that cause photosensitivity | carbamazepine, diruetics, methotrexate, retinoids, quinolones, st. john's wort, sulfa abx, tacrolimus, tetracyclines, voriconazole |
drugs that cause TTP | clopidogrel, ticlopidine |
avoid these drugs with peanut and soy allergies | progesterone (peanut), Clevidipine, propofol (Soy and eggs) |
hyperkalemia risk with these drugs | -aldosterone blockers- avoid NSAIDS
-ACEIs, ARBS, aliskerin, amiloride, triamterene, calcinuerin inhibitors, bactrim, cangliflozin, pentamadine |
ototoxicity risk with these drugs | salicylates, vancomycin, aminoglycosides, cisplatin, loop diuretics |
avoid these with drugs that have increased bleed risk | NSAIDs, SSRIs/SNRIs, ginko biloba, garlic, ginger, glucosamine, ginseng |