Mnemonics Flashcards
What are the cytochrome p450 inducers? (7)
"Ethel Booba take Phen-Phen and Refuses Greasy Carb Shakes" Ethanol Barbiturates Phenytoin Rifampin Griseofulvin Carbamazepine St. John's Wort/Smoking
What are the CYP450 inhibitors? (9)
"Inhibitors Stop Cyber Kids from Eating GRApefruit Q" Isoniazid Sulfonamides Cimetidine Ketoconazole Erythromycin Grapefruit juice Ritonavir Amiodarone Quinidine
What drugs display zero order elimination kinetics? (7)
WHAT PET
Warfarin Heparin Aspirin Tolbutamide Phenytoin Ethanol Theophylline
What type of inhibition is exhibited by the following:
Propanolol and Isoproterenol
Flumenazil and BZD
NE and terazosin
Competitive or Reversible inhibition
Potency (ED 50) decreases but maximal efficacy (Vmax) does not decrease
What type of inhibition is exhibited by the following:
Norepinephrine and phenoxybenzamine
Noncompetitive or Irreversible inhibitor
Maximal velocity (Vmax) decreases but not Potency (ED 50)
- also includes aspirin
What type of inhibition is exhibited by the following?
histamine and epinephrine
propanolol and thyroid hormone
Physiologic antagonism
- interacts with a DIFFERENT receptor that produces an effect opposite to the drug
What type of inhibition is exhibited by the following?
dimercaprol for lead poisoning
pralidoxime for organophosphate poisoning
sugammadex for rocuronium
Chemical Antagonism
- interact directly with the drug so it does not interact with or reach the receptor
What type of variation in drug response is exemplified by depletion of thiol cofactors in prolonged use of nitroglycerin, which is reversible by administration of glutathione?
Tolerance
- depletion of ESSENTIAL SUBSTRATES (not the receptor) due to continuous activation
- reversible by replenishing the substrate
- glutathione replaces the thiol cofactors
What type of variation in drug response is exemplified by the rapid decrease in responsiveness in drugs such as theophylline, salbutamol, nitrates, dobutamine
Tachyphylaxis
What drugs display tachyphylaxis?
MEDical students Love to watch CNN in HD
Metoclopromide Ephedrine Dobutamine LSD Calcitonin Nitroglycerin Nicotine Hydralazine Desmopressin
Type of drug response observed in the following situations:
aplastic anemia with chloramphenicol
cataracts with allopurinol
Idiosyncratic DR
This refers to the concentration of a drug at the receptor site. Except for topically applied agents, the concentration at the receptor site is usually proportional to the drug’s concentration in the plasma or whole blood at equilibrium.
Effective drug concentration
The volume at which the drug would need to be uniformly distributed to produce an observed blood concentration. Measured by the amount of drug in the body divided by plasma drug concentration.
Apparent Volume Distribution
- purely pharmacokinetic parameter with no direct physical equivalent (no units
- altered in liver and kidney disease (decreased protein -> decreased protein binding -> more free drug to bind to tissue -> increase Vd
A drug with a low volume of distribution would be more concentrated in which body compartment?
a. tissues
b. blood
c. extracellular space or body water
a. tissues - high Vd
b. blood - Low Vd
c. extracellular space or body water - medium Vd
Vd = drug conc in the entire body/drug conc in the blood
The condition in which the average total amount of drug in the body does not change over multiple dosing intervals. The rate of drug administration equals the rate of administration
Steady state concentration
- usually reached in 4-5 half lives
T/F Drugs that have zero order kinetics have constant half-lives.
False.
Drugs that follow zero order kinetics have no half lives because by definition their rate of elimination is CONSTANT.
Kidney disease decreases which of the following parameters? Vd or clearance?
Clearance
Clearance depends on the drug and the condition of the organs of elimination. For a drug that is very effectively extracted by an organ, the clearance is flow-limited. i.e. higher flow -> greater clearance.
Kidney diseases, especially nephrotic syndrome leads to decreased protein, thus decreasing proteins available for binding drugs -> MORE FREE DRUG -> inc Vd.
T/F A decrease in clearance will always result in increase in the half-life.
False
Half-life = (0.693 x Vd)/clearance
If the Vd is reduced along with the clearance, the half life may be unchanged.
Refers to the fraction of the administered dose that reaches the systemic circulation. Determined by computing the area under the plasma concentration curve.
Bioavailability
If a drug has a high Vd, how does it affect the loading dose and maintenance dose?
The loading dose would increase.
LD = (Vd x desired plasma concentration)/BA
- LD is NOT affected by clearance
- If the LD is very large, the dose should be given slowly to prevent toxicity i.e. Vancomycin
If a drug has low clearance, how would it affect the maintenance dose?
The maintenance dose would decrease.
MD = (clearance x desired plasma concentration)/BA
*MD is NOT affected by Vd
Phase 1 or Functionalization reactions convert the parent drug to a more polar product by unmasking or inserting a POLAR FUNCTIONAL GROUP. What are the 4 different types of phase 1 reactions?
a HORD of phase 1 reactions Hydrolysis Oxidation Reduction Deamination
T/F CYP450 enzymes are not highly selective in their substrates
T.
- Also they are called mixed-function OXIDASES
- found in high concentrations in the SMOOTH ER of the liver
- approximately 75% are metabolized by CYP3A4 or CYP2D6
What type of drug reaction involves conjugation of subgroups to -OH -NH2 and -SH functions on the drug molecule?
Phase 2 or conjugation reactions
Acetylation of isoniazid is a phase 1 or phase 2 reaction?
Phase 2 reaction, specifically, acetylation
*Phase 1 reactions: HORD - hydrolysis, oxidation, reduction, deamination
