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46 Cards in this Set

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types of pharmacodynamic changes that change drug effect w/o PK changes
additive, synergistic, antagonistic
4 categories/types of PK changes include
A - absorption
D - distribution
M - metabolism
E - elimnation
when used concomitantly, these two medications - and "interference with absorption" occurs
Atazanavir + PPIs/H-2 blockers
Atazanavir needs an ???? environment for proper absorption
acidic
PPI's are CONTRAINDICATED with what medication?
Atazanavir***

there is loss of absorption if administered together; pt should be counseled on this!
when Atazanavir is given with H2 blockers..how should the two be administered?
12 hours apart
interactions with HAART are more commonly PK or PD?
PK
****discuss metabolism of NRTIs and enfuvirtide (entry inhibitor)****
minimal of no CYP3A4 activity

absorption drug interactions occur (drug-drug interactions)
****NNRTI --- class effect regarding metabolism
ALL NNRTIs are substrates of cyp3A4
delavirdine aka Rescriptor -- is it an inducer or inhibitor of any CYP enzymes?
potent inhibitor of cyp3A4
efavirenz aka Sustiva -- is it an inducer or inhibitor of any CYP enzymes?
mixed inhibitor (10%)/inducer (90%) of CYP 3A4
nevirapine aka Viramune -- is it an inducer or inhibitor of any CYP enzymes?
potent inducer of CYP3a4
in regards to ALL protease inhibitors; what is the class effect regarding metabolism?
ALL PIs are substrates of CYP3A4
are PI's (as a class) inhibitors or inducers? of what CYP enzyme?
inhibitors of CYP3A4 (including other pathways)

some may act as inducers (PI vs. PI)

differ in interaction potency
what can be said about the metabolism of enfuvirtide (Fuzeon) - an entry inhibitor?
it does not significantly affect nor is affected by CYP450
CCR5 antagonist: Maraviroc -- is it a substrate, an inhibitor, an inducer???
its a substrate of CYP3A4

NOT an inhibitor or inducer
integrase inhibitor: raltegravir --- what can be said about its metabolism?
metabolized via glucuronidation

does NOT affect CYP450 3A4 pathway
what is the time frame of CYP450 inhibition?? (slow vs. fast)
inhibition occurs RAPIDLY, as soon as adequate concentrations of inhibitor are reached
what is the time frame of CYP450 induction?
peak effect occurs SLOWLY based on half-life of drug and time to synthesize new CYP450 enzymes
cyp450 inhibition leads to [increase or decrease] in drug levels? what about induction?
inhibition -- leads to increased levels

induction -- leads to decreased levels
list some antituberculosis meds that are a RED FLAG drug interaction with HAART meds
rifampin, rifabutin - potent INDUCERS of cyp3a4
list some azole antifungal meds that are a RED FLAG drug interaction with HAART meds
itraconazole, voriconazole, ketoconazole - INHIBITORS of cyp3a4
list some statins that are a RED FLAG drug interaction with HAART meds
simvastatin, lovastatin, atorvastatin -- 3A4 SUBSTRATES
list some anticonvulsant meds that are a RED FLAG drug interaction with HAART meds
carbamazepine, phenobarbital, phenytoin -- potent 3A4 INDUCERS
list some macrolide antibiotics that are a RED FLAG drug interaction with HAART meds
clarythromycin, erythromycin -- 3A4 INHIBITORS


exception: azithro - no effect
list some erectyle dysfunction meds that are a RED FLAG drug interaction with HAART meds
sildenafil, vardenafil, tadalafil -- 3A4 SUBSTRATES
list some benzodiazepines that are a RED FLAG drug interaction with HAART meds
midazolam, triazolam -- SUBSTRATES
why is methadone a RED FLAG drug interaction with HAART meds??
HAART causes decreased levels of methadone, which could trigger withdrawl symptoms
list some herbal remedies that are a RED FLAG drug interaction with HAART meds
st. john's wart, garlic supplements -- 3A4 INDUCERS
list some HAART combinations that should not be used together
PI + PI

PI + NNRTI


Tenofovir + didanosine/atazanavir
which two medications should not be given together due to concerns for LA, PN, pancreatitis, fatal acute renal failure???
didanosine + tenofovir

increased risk w/ buffered tab and even more so with enteric coated
Didanosine EC + tenovofir

when combined in pts weighing >60kg, what should be done in regards to dosing?
dosing of tenofovir (EC) reduced from 400mg to 250mg po qd
Didanosine EC + tenovofir

when combined in pts weighing <60kg, what should be done in regards to dosing?
no recommendations exist, but might want to reduce dose to 200mg po qd
rifampin vs. rifabutin effects on PIs...which one is more potent, which one is less?
rifabutin is LESS LIKELY to cause decreased PI/NNRTI levels
Rifampin is contraindicated with what antiretroviral class?
PI

when pts on PI therapy need rifamycin therapy, rifampin should be replaced by rifabutin and the rifabutin should be dose reduced!
what happens to statin levels with PI use?
statin levels are increased
which statin should be used in treatment of HIV pt dyslipidemia? and whY?
PRAVASTATIN

cleared via renal elimination, not liver

consider reduced dose of atorvastatin (if using it)

why not use simva/PI combo? fatalities reported
which statins should absolutely be avoided during HAART therapy?
simvastatin (zocor)

lovastatin (mevacor)
which two statins CAN be used concomitantly with HAART?
atorvastatin is safe at LOW doses (start at 10mg and titrate up according to response and tolerability)

PRAVASTATIN***
can rosuvastatin be used concomitantly w/HAART?
no. interaction is still seen with UNKNOWN mechanism

- its not metabolized through CYP450 3A4
are other agents (fenofibrates, zetia, niacin) okay to use with HAART?
YES
viagra interacts with which medications in HAART regimen?
PIs (esp ritonavir)

NNRTI (delavirdine - Rescriptor)
what happens during viagra + HAART interaction and what should be done about it?
Viagra AUC increased 2-11 fold depending on the PI involved

Start with 25mg, do not repeat dose for at least 48 hours

May consider increasing subsequent doses in 25mg increments for those not responding

Toxicity would include priapism, severe hypotension, visual changes

Similar dose reduction recommendations available for other available ED medications
St. Johns wort should be avoided with which HAART meds? why?
Concern for treatment failure, resistance, or both

Avoid SJW with PI and NNRTI
Garlic should be avoided with which HAART meds? why?
Cmax and trough decreased

Concern for treatment failure, resistance, or both

Avoid garlic supplements with PI and NNRTI
Maraviroc dosing changes according to the type of concomitant med given with it...
150mg bid (w/CYP3A4 inhibitors)

300mg bid (not strong inhibitors or inducers)

600mg bid (w/strong CYP3A4 inducers)