Exam 1 Flashcards
Inadivir
HIV drug, St. Johns wart INCREASES metabolism via induction of CYP3A4
What are the three Xenobiotic receptors?
Aryl hydrocarbon (AhR), The pregnane X receptor (PXR), The constitutionally active receptor (CAR)
Most phase 1 rxns are performed by what?
CYP450 system
What CYP isoform is responsible for 30% of enzymes in the liver?
CYP450, CYP3A4 metabolizes approximately 50%
How many families of CYP450 proteins are there?
In humans there are 18 families
Of the 18 families of CYP450 proteins which are responsible for xenobiotics?
Families 1-3, others are mainly endogenous
Which three drugs are enzyme inducers for CYP450 enzymes?
Phenobarbital, Rifampin, Carbamazepine all INCREASE the synthesis of P450 isoforms
What induces the Xenobiotic receptor AhR? 2
PAH’s and TCDD
What induces the Xenobiotic receptor PXR? 5
Steroids, Hyperforlin, rifampin, phenobarbital and mifepristone
What induces the Xenobiotic receptor CAR? 2
Phenobarbital, phenytoin
Warfarin question for exam, what drug was give from 5 that would decrease plasma concentration via enzyme induction
look up
Indinavir
HIV drug, increased metabolism by induced CYP3A4 with St. Johns wort
Amiodarone
Anti arythmic, Inhibit CYP450
Cimetidine
HRT burn, Inhibit CYP450
Ketoconazole
Antifungal, Inhibit CYP450
Erythromycin
Antibacterial, inhibit CYP450
Cloremphenicol
Antibacterial, inhibit CYP450
Grapefruit juice has what effect on drug metabolism?
Inhibits CYP450 AND P-glycoprotein in the small intestine. Statin is an example, drinking grapefruit juice while taking statins can cause increased plasma levels of statins. Same effect with Felodipine (anti-hypertensive).
some drugs are actively transported back into the intestinal lumen by the P-glycoprotein, what two drugs are examples of this?
Digoxin-Hrt Failure
HIV-1 protease inhibitors
What is P-glycoprotein?
A drug transporter that can transport Digoxin and HIV-1 protease inhibitors to the intestinal lumen
What can inhibit the P-glycoprotein?
Macrolide antibiotics, resulting in increased serum levels of Digoxin
What is an example of a macrolide antibiotic?
Clarithromycin, results in inhibition of P-glycoprotiens and subsequent increased levels of Digoxin
What is the N-acetyltransferase 2?
NAT2 catalyzes the acytlation of isoniazid and other drugs, polymorphisms are present and pts treated with isoniazid can be either FAST (low blood levels) acetylators or slow (high blood levels) which are homogenous for AR allele of the enzyme.
What are Slow acetylators (NAT2 polymorphism) prone to?
Toxicity of drugs that are inactivated by acetylation
Felodipine
Anti hypertensive, Grapefruit juice decreases metabolism=high serum levels
Aromatic hydrocarbons in cigarette smoke, Cruciferous vegetables and chared foods and pesticides all have what effect of drug metabolism?
Induce enzyme metabolism.
Plasma concentration of a drug is determined by what three things?
Rate of” Input, distribution and elimination
What are the three most important Pharmacokinetic parameters?
Volume of Distribution, Clearance, Bio-availability
How do you define Volume of distribution?
amount of drug in body/Plasma concentration
conceptual volume of drug that would be needed to contain all of the drug in the body at the same concentration as in the blood.
What is the main purpose of Vd?
To determine the loading dose needed to quickly reach your target plasma concentration.
We know the dose we want to achieve by the therapeutic window
What is Clearance?
Rate of elimination of drug(amount/time)/Plasma drug concentration (amount/volume)
Total body clearance is the SUM of all clearance in the body
clearance is a constant for drugs that follow first order kinetics, and is directly proportional to the drug concentration.
What is rate of elimination?
CL x Conc. First order elimination
What is the equation for t1/2?
t1/2=(0.693xVd)/CL
How many half life’s to achieve steady state and eliminate the drug?
4 half lifes to reach steady state and another 4 to eliminate the drug.
What effect does doubling the infusion rate have?
It doubles the steady state concentration but DOES NOT change the half life, or the fact that we need 4 half lifes to reach steady state concentration Css
What three drugs exhibit zero order Kinetics?
Aspirin in high doses, Ethanol and Phenytoin, Only Phenytoin has clinical significance
What is needed for a rational dosage regimen?
Min therapeutic and min toxic conc. of a drug, Clearance, Vd of the drug
What is the therapeutic window?
The useful window between the min therapeutic conc. and the min Toxic conc. of the drug.
The peak must be below the toxic level and the trough above the therapeutic level
What is dosing rate at steady state?
At steady state, dosing rate is equal to rate of elimination which is equal to (CLxC)/F
How is maintenance dose calculated?
Maintenance dose= Dosing rate x Dosing interval
What is the equation for drug accumulation? (accumulation factor AF)
AF=1/Fraction lost in one dosing interval
AF predicts the ration of the Steady state to the peak concentration after the first dose.
When a drug is administered every half life what will the Css be?
The first peak times 2 and the trough at Css will equal the peak initially given. This means the AF is 2xthe first peak
What is the equation for loading dose with intermittent dosing?
LD= Maintenance dose x Accumulation factor
What is the time course effect?
The drug effect Vs Time
Enalopril
ACE inhibitor, popular for Hrt failure and hypertension
What are the examples of inhibitors of CYP450?
Cimetidine, Ciprofloxin, Ketoconazole, Clarithromycin, quinidine, Grapefruit juice
What are some exaples of INDUCERS of CYP450?
Rifampin (biggest), Phenobarbital, dexamethasone, carbamazepine, and Tobacco
What drug should not be given with sidenifil (viagra)?
Sidenifil should never be given with Nitroglycerin, since Sidenifil inhibits PDE5 preventing the breakdown of cAMP and Nitroglycerin increase Guanylate cyclase activity resulting in increased production of cAMP, when taken together the effect is remarkable.
What is the No effect dose?
Maximum dose at which specified toxic dose is not seen
What is a schedule 1 drug?
No accepted use, never can be used in clinical study.
What is schedule 2?
high potential for abuse but can be used and prescribed, no over the phone refills
What is schedule 3?
still potential for abuse but used and prescription must be re-written after 6 months or 5 refills
Schedule 4?
still potential for abuse but used and prescription must be re-written after 6 months or 5 refills. Difference from 3 is punishment if fund in illegal possession.
Schedule 5?
Same as any non-opioid drug, may be dispensed without prescription, unless state laws differ.
What are the three leading causes for Otitis Media?
H. influenzae, S. pneumonea, Moraxella cataralis
What are the most common cause of sinusitis and the types of presentations?
H. influenzae, S. pneumonea and
Acute 12 wks
recurrent acute 4 or more acute epis. in a yr
What is a clinical diagnosis of acute sinusitis?
- purulent nasal discharge ,
- nasal congestion + or facial pain or pressure
- bacterial infection suspected after 7 days if symptoms of purulent discharge, maxillary pain persist or symptoms worsen after initial improvement.
Pneumonia by exposure, Birds, Farm animals, ground water?
- Exposure to psittacine birds-Psittacosis (Chlamydophila psittaci)
- Exposure to parturient animals or birth products-Q fever (Coxiella burnetii)
- Exposure to water vapor and soil -Legionnaire’s (Legionella pneumophila)
Common bacterial causes of pneumonia
–Streptococcus pneumoniae (most common)
–Haemophilus influenzae (Non typable, COPD)
–Staphylococcus aureus including CA
-MRSA
–Chlamydophila pneumoniae (elderly)
–M. pneumoniae (crowding, child, yng adults)
–Legionella pneumophila (contaminated water soil disruption)
–Klebsiella pneumoniae (alcoholics)
–Pseudomonas aeruginosa
(immunosuppressed, chronic structural lung
damage → cystic fibrosis, bronchiectasis)
What are the laboratory findings of Legionares?
L. pneumophila 80% of human disease
–Aerobic gram negative rod
–Won’t grow in lab on routine media. Use buffered charcoal yeast extract.
–3 to 5 days to grow
•Attaches to respiratory alveoli and macrophage cells by pili
and is phagocytosed to enter cell.
•Intracellular pathogen than inhibits phagosome–lysosome fusion and evades destruction
What are the clues to diagnosing Lenionella?
•Clues to diagnosis –High fever > 39oC –Confusion –Diarrhea –Sputum findings on gram stain (3+ WBC no organisms) –Hyponatremia, hematuria –Failure to respond to Beta lactams
What are the charecteristics of Chlamydia and chlymidophila? Chlamydophila is the respitory one
–Obligate intracellular bacteria
–No peptidoglycan in cell wall
–2 distinct forms in growth cycle
•Elementary body= infectious particle and survives in extracellular environment. Entry into the cell is by phagocytosis
•Reticulate body is form in which multiplication occurs and lives in a membrane bound inclusion.
What is the most common org. for CAP?
Pseudomonas Aeriginosus.
–Non fermentive Gram negative aerobe, grows easily in lab. Green pigment and grape like odor. Oxidase positive.
Which are the Cholinergic fibers? What does that mean?
The cholinergic fibers are fibers that release AcH. They include:
All preganglionic fibers
All Parasympathetic post ganglionic fibers
All Somatic motor fibers to skeletal muscle
What are the adrenergic fibers?
They synthesize and release NE, they are most post ganglionic sympathetic fibers