Exam 2 - HIV, STDs, Hepatitis Flashcards
HIV
..
Main monitoring of HIV
- CD4 cell count
- Viral load
CD4 count
Extent of destruction of immune system
Viral load
How extensive virus propagation is; goal is optimal viral suppression.
When is the optimal time to start HIV treatment?
Immediately upon diagnosis; want to minimize immune destruction.
Nucleoside reverse transcriptase inhibitors
- Backbone for HIV regimens
- 2 NRTIs + 1 other drug (typically)
-Based off of purine and pyrimidine nucleotides and nucleosides
- Stavudine (d4T) (Zerit)
- Zidovudine (AZT or ZVD) (Retrovir)
- Emtricitabine (FTC) (Emtriva)
- Lamivudine (3TC) (Epivir)
- Abacavir (ABC) (Ziagen)
- Didanosine (ddI) (Videx)
- Tenofovir (TDF) (Viread)
Nucleoside reverse transcriptase inhibitors
NRTI
- Backbone for HIV regimens
- 2 NRTIs + 1 other drug (typically)
-Based off of purine and pyrimidine nucleotides and nucleosides
- Stavudine (d4T) (Zerit)
- Zidovudine (AZT or ZVD) (Retrovir)
- Emtricitabine (FTC) (Emtriva)
- Lamivudine (3TC) (Epivir)
- Abacavir (ABC) (Ziagen)
- Didanosine (ddI) (Videx)
- Tenofovir (TDF) (Viread)
ADR Nucleoside Reverse Transcriptase inhibitors
NRTI
-Mediated by fact they’re not specific to only reverse transcriptase; can affect mitochondrial DNA and RNA synthesis.
Newer agents have less side effects: Abacavir, tenofovir, emtricitabine, lamivudine
ADR: lactic acidosis, fatty liver, pancreatitis, peripheral neuropathy
Before putting a patient on Abacavir, what do you have to test for?
Abacavir -
Pts with HLA-B5701; need to test for that, bc those patients will have a severe anaphylactic reaction.
Non-nucleoside reverse transcriptase inhibitors (NNRTI)
- MOA: Bind to reverse transcriptase and change the conformation so it can’t interact with viral RNA
- Regimens have 2 NRTIs + 1 other class, this could be that other class used.
-Delavirdine (DLV) (Rescriptor)
-Efavirenz (EFV) (Sustiva)
-Nevirapine (NVP) (Viramune)
MOST USED:
-Etravirine (ETR) (Intelence)
-Rilpivirine (RPV) (Edurant)
ADR:
- Rash, transaminitis,
- Single viral mutation can confer resistance to entire class!!!!! (except etravirine)
Protease Inhibitors
-MOA: Viral DNA is incorpoprated and cells are producing viral proteins. Meds will inhibit protease enzyme preventing virus from making mature proteins. Inhibit further HIV spread from cell to cell.
- Atazanavir (ATV) (Reyataz)
- Darunavir (DRV) (Prezista)
- Fosamprenavir (FPV) (Lexiva)
- Indinavir (IDV) (Crixivan)
- Lopinavir (LPV) (Kaletra w/ Ritonavir)
- Nelfinavir (NFV) (Viracept)
- Ritonavir (RTV) (Norvir)
- Saquinavir (SQV) (Invirase)
- Tipranavir (TPV) (Aptivus)
- Ritonavir - used for PK interaction for positive effects
- Ritonavir plus Darunavir
ADR:
-GI distress, increased lipids, glucose intolerance (diabetes), and altered fat distribution (“buffalo hump” when on PI for a long time).
-Metabolized in liver
Why is Lopenavir added to Ritonavir (Coletra)?
Ritonavir is a potent CYP3A4 inhibitor, by inhibiting CYP3A4, protease inhibitor drugs metabolized by it will go up.
Allows us to use less frequent dosing with medication. Increases levels and keeps them around for longer.
-Also done with cobicistat
What happens if you put a patient on simvastatin on ritonavir as well????
- CYP3A4 inhibitor
- Don’t mix with simvastatin. Can increase dose and cause myalgia.
Enfuvirtide (ENF) (Fuzeon)
- Fusion Inhibitor
- MOA: Inhibits HIV-1 envelope fusion to human cell. No activity against HIV-2, so won’t be used in Africa.
-Not given orally, its an amino acid. Given subQ.
-ADR: injection site reactions! Nodules can develop over time.
36-amino acid peptide
No oral administration
Given SC, injection site reactions very frequent
Pain, erythema, nodules
Maraviroc (Selzentry)
CCR5 antagonist
- Works on HIV-1 and 2. Blocks the CCR5 human receptor and not the virus.
- Can only use against the correct strain of virus
- Must do testing prior to starting therapy
ADR: rash and hepatotoxicity
Integrase Inhibitors
Raltegravir (RAL) (Isentress)
Dolutegravir (DTG) (Tivicay)
Elvitegravir (EVG) (Viteka)
»Coformulated with cobicistat, a CYP3A4 inhibitor to iincrease levels and dose drug less frequently.
- MOA: Bind to integrase and prevent viral DNA from being incorporated into chromosomal DNA.
- ADR: Rash, nausea, and headache (more recommended)
What NNRTI induce CYP3A4?
What class inhibits CYP3A4?
How does Rifampin impat drugs metabolized by CYP3A4?
- Some are on purpose (ritonavir). Most interactions occur through CYP3A4.
- NNRTI: Efavirenz, etravirine, and nevirapine induce CYP3A4
- Most protease inhibitors inhibit CYP3A4
- Keep interactions in mind with anti-TB drugs (Rifampin induces CYP3A4 and can make HIV drugs less effective)
- Food-drug interactions
- Some drugs require an acidic environment to be absorbed (don’t take with food, because it’ll increase pH of the stomach).
Initial HIV treatment should be managed with a minimum of ___ antiretroviral agents including a 2 NRTI backbone.
Give an example.
3
Protease Inhib. + 2 NRTI
- Darunavir (boosted by ritonavir)
- Tenofovir
- Emtricitabine
Integrase inhibitor + 2 NRTI -Raltegravir -Tenofovir -Emtricitabine recommended together, bc of truvada (combo pill).
NNRTI + 2 NRTI (less preferred)
- Efavirenz
- Tenofovir
- Emtricitabine
Adherence
- Major impact on resistance and ultimate success or therapy.
- Once you become resistant to a drug or class, you can’t use that drug again in the future, because the function is lost.
-Reasons for poor adherence: >Psychiatric illness >Substance abuse >Adverse effects - diabetes, weight gain >Unstable social circumstances - poor access to medical care
-Use combination formulations whenever possible
When dosing HIV meds, its important to use combination formulations whenever possible to increase patient adherence and decrease food interactions.
What combination therapies can you use?
-Efavirenz, Emtricitabine, and Tenofovir (Atripla)
- Elvitegravir, cobicastat, emtricitabine, tenofovir (Genvoya)
- Cobicastat - inhibits CYP3A4 to boost integrase inhibitor
-Emtricitabine, rilpivirine, and tenofovir (Complera)
Phenotype testing –
Who do you do this on?
Determines concentration of drug to inhibit growth by 50% replication of the virus (IC50). Concrete data on what it will respond to.
Results are compared to wild type virus
Provides resistance information for complex mutation patterns
Higher cost, slower turnaround
-More established patient that probably has more mutations
Genotype testing -
Who do you do this on?
- Checks for specific genetic mutations that are known to confer resistance to specific drugs
- Not as informative as phenotyping
-Pt with new onset, few mutations
HIV monitoring
Use genotype testing, monitor CD4 cell count, and viral load to determine if the drug regimen is effective or not.
Pt on a drug regimen:
- Viral load undetectable
- CD4 maintaining
- Over time, viral load is starting to increase.
What happened?
Could have had a mutation occur making regimen ineffective.
If they’re compliant, you know they have a new mutation and you have to switch over to a protease inhibitor or an integrase inhibitor. Need to have a reason to test.
How do you treat HIV in pregnancy?
Treat as if they were NOT pregnant:
- High viral loads in mom means baby will be exposed
- Need to suppress load as much as possible.
What drug CANNOT be used in pregnancy due to neural tube defects?
Efavirenz
-will effect early on in pregnancy
Frequently, HIV patients in intra-partum period, onset of labor to delivery, doctor will give mom and newborn _____________.
Zidovudine
- Prevents perinatal transmission
- Fetuses receive 4-6 weeks after birth
- AVOID BREASTFEEDING. Without immune system, HIV is more likely to have oral transmission. Normally, less likely bc AA are broken down.
When is chemoprophylaxis for HIV used?
Good for healthcare workers (postexposure prophylaxis) after high risk exposures.
-ADR: GI toxicity
Helpful to know HIV status of patient, if not possible go with worst case scenario.
Start as early as possible (1-2 hours).
Used to use tenofovir, now they recommend RATEGRAVIR for being better tolerated.
What combination therapy is initiated for chemoprophylaxis when exposed to HIV?????
Tenofovir, emtricitabine, raltegravir for 4 weeks.
Initiate ASAP to stop HIV cells from replicating and initiating infection.
What is used for pre-exposure prophylaxis?
Daily tenofovir / emtricitabine (Truvada)
-If pt knows they’ll be exposed, pre-exp. prophylaxis = “morning after pill”
When is pre-exposure using: Daily tenofovir / emtricitabine (Truvada) used?
2 NRTIs used daily.
Those at high risk:
- MSM
- Sero-discordant couples
- IV drug abusers
- Patients need to be seronegative prior to initiation
Evaluating treatment outcomes of HIV HAART:
-Baseline CD4 and HIV RNA load = tells propagation of virus
- HIV resistance test is recommended at initiation!
- Monitored every 3 months!!!! UNTIL HIV RNA is undetectable……
Why would you change a HAART regimen?
Reasons for changing regiment:
- Intolerable side effects
- Treatment failure (viral RNA > 200 copies/mL)
- Documented resistance to agents via testing
COMPLICATIONS OF HIV/AIDS
…
CD4 < 200
What are they at risk for?
What prophylaxis do you put them on?
Risk of PJP
BACTRIM
CD4 < 50
What are they at risk for?
What do you put them on?
Risk of Mycobacterium Avium Complex
MACROLIDES
Using CD4 count:
Lets us know what to use for prophylaxis.
Latent TB can be reactivated with low CD4 counts
Today, emphasis is placed on treating HIV infection and recovering CD4 count
Goals:
- Prevent exposure to opportunistic pathogens
- Vaccinate to prevent first-episode disease
- Chemoprophylaxis at certain CD4 thresholds to prevent first-episode disease
- Treat emergent OI
- Use secondary prophylaxis to prevent RECURRENCE
- Discontinue prophylaxis once immune recovery is sustained
**Prophylaxis used for chemo patients as neutrophils drop; put them on prophylaxis for same opportunistic infections
If you have a patient with a CD4 < 40, start on bactrim for PCP, and they get PCP. What do you do?
Treat the PCP and put them on Bactrim for secondary propylaxis.
If CD4 rebounds and is sustained, D/C prophylaxis.
Immune Reconstitution Syndrome (IRIS)
- Latent infection
- Do not have a good immune system to attack it
- Reconstituting immune system with HAART, CD4 count goes up and they can fight the infection.
- Inflammation starts, which can make them feel even worse.
-Can be treated symptomatically; antipyretics.