Alternative Regimens Level

Efavirenz + (abacavir or zidovudine)/lamivudine

Nevirapine + zidovudine/lamivudine

Atazanavir/ritonavir + (abacavir or zidovudine)/lamivudine

FPV/r* (once or twice daily) + either [(abacavir or zidovudine)lamivu-

dine] or tenofovir/emtricitabine

LPV/r+ (once or twice daily) + either [(abacavir or zidovudine/lamivudine] or tenofovir/emtricitabine Saquinavir/ritonavir + tenofovir/emtricitabine

*Fosamprenavir calcium and ritonavir. tLopinavir and ritonavir (Kaletra).

The preferred NNRTI continues to be efavirenz, with nevirapine (Viramune) remaining an alternative option. Efavirenz now comes coformulated with two other NRTIs, emtricitabine and tenofovir, in a single pill (Atripla) to be taken once daily as a complete antiretroviral regimen, which has increased prescriptions for Atripla. Atripla is not recommended for pregnant women because of potential CNS malformations; Physicians

Table 17-4 Routine Laboratory Testing for HIV-Infected Patients

Laboratory Investigation

Comments

Confirmation of HIV seropositivity

Baseline assessment

CD4+ cell count Quantitative HIV RNA

Test every 3 months and after 2 weeks of changes in treatment

Antiretroviral resistance testing

With virologic failure

Complete and differential blood count Chemistry panel with liver enzymes Urinalysis Lipid profile

Glucose-6-phosphate dehydrogenase (G6PD)

Hepatitis B surface antigen (HBsAg); surface and core antibody Hepatitis C antibody

Anemia with zidovudine Glucose and lipids with protease inhibitors (PIs) Nephrotoxicity with indinavir Baseline testing as clinically indicated

Electroencephalogram Chest radiograph

As clinically indicated

Serologic test for syphilis Toxoplasma gondii antibody

As often as clinically indicated

Pap smear: cervical and anal for women and anal for men

Annual test indicated

Table 17-6 Antiretroviral Medicines

Generic (Brand)

Abbreviation

Nucleoside/Nucleotide Reverse-Transcriptase Inhibitors (NRTIs)

Abacavir (Ziagen)

ABC

Emtricitabine (Emtriva)

FTC

Didanosine (Videx)

ddI

Lamivudine (Epivir)

3TC

Stavudine (Zerit)

d4T

Tenofovir (Viread)

TDF

Zalcitabine (Hivid)

ddC

Zidovudine (Retrovir)

ZDV

Abacavir and lamivudine (Epzicom)

ABC + 3TC

Emtricitabine and tenofovir (Truvada)

FTC + TDF

Lamivudine and zidovudine (Combivir)

3TC + ZDV

Nonnucleoside Reverse-Transcriptase Inhibitors (NNRTIs)

Delavirdine mesylate (Rescriptor)

DLV

Efavirenz (EFV)

EFV

Etravirine (Intelence)

TMC-125

Generic (Brand)

Abbreviation

Nevirapine (Viramune)

NVP

Efavirenz, emtricitabine, and tenofovir (Atripla)

EFV + FTC + TDF

Protease Inhibitors (PIs)

Atazanavir (Reyataz)

ATZ

Darunavir (Prezista)

TMC-114

Fosamprenavir calcium (Lexiva)

FPV

Indinavir sulfate (Crixivan)

IDV

Lopinavir and ritonavir (Kaletra)

LPV/r

Nelfinavir mesylate (Viracept)

NFV

Ritonavir (Norvir)

RTV

Saquinavir mesylate (Invirase)

SQV

Tipranavir (Aptivus)

TPV

Fusion Inhibitor

Enfuvirtide (Fuzeon)

T-20

CCR5 Inhibitor

Maraviroc (Selzentry)

Integrase Strand Transfer Inhibitor

Raltegravir (Isentress)

Table 17-7 Antiretroviral Combinations to Avoid

Combination

Rationale for Avoidance

Atazanavir with proton pump inhibitors

Decrease in atazanavir absorption

Unboosted PIs with rifampin

Significant decrease in PI blood levels

Nevirapine in women with CD4+ >250 cells/mm3 or men with CD4+ >400 cells/mm3

Risk of serious and life-threatening hepatic events. Switching to nevirapine is possible once CD4+ count has increased beyond these levels with ART.

Efavirenz with itraconazole

Decrease in efavirenz blood levels

Abacavir in patients who are HLA 5701 positive

High potential for serious "abacavir hypersensitivity reaction"

Maraviroc in patients with dual/mixed or CXR4-utilizing virus

Because maraviroc is a CCR5 inhibitor, CXCR4-utilizing viruses respond inadequately or negligibly to treatment.

PIs, Protease inhibitors; ART, antiretroviral therapy.

must be cautious when prescribing efavirenz in fertile women because risk is highest during the first trimester. Nevirapine is not recommended in women with pretreatment CD4+ counts greater than 250 cells/ mm3 or in men with CD 4+ counts greater than 400 (level 2) because of a higher risk of serious hepatic events in these two groups (Table 17-7).

Both patient characteristics and physician preferences must necessarily be weighed when choosing between efavi-

renz and PIs. The preferred NRTI is emtricitabine coformu-lated with tenofovir, a one-pill-once-daily medication that has been compared with the other two coformulated NRTIs, lamivudine/zidovudine, and abacavir/lamivudine, because the former showed a better safety profile and virologic efficacy.

Once the antiretroviral regimen is selected, medication compliance becomes the most important factor in treatment success.

Table 17-8 Recommendations for Initiation and Discontinuation of Primary Prophylaxis of Most Common Opportunistic Infections (OIs)

OI

Initiation

Discontinuation

Drug of choice

PCP

CD4+ cell count <200 cells/mm3

CD4+ cell count >200 cells/mm3

TMP-SMX (Bactrim)

Toxoplasma gondii encephalitis

Seropositive for T. gondii and CD4+ cell count <100 cells/mm3

CD4+ cell count >200 cells/mm3

TMP-SMX (Bactrim) for PCP serves as primary prophylaxis. Suppressive regimen of choice for secondary prophylaxis is sulfadiazine plus pyrimethamine and leucovorin

MAC

CD4+ cell count <50 cells/mm3

CD4+ cell count >100 cells/mm3

Zithromycin, azithromycin

CMV retinitis

Primary prophylaxis is not routinely recommended; discontinuation of secondary prophylaxis can be considered in patients with a sustained response to HAART, defined as a CD4+ cell count greater than 100 to 150 cells/mm3 for at least 6 months.

Cryptococcus neoformans meningitis

Primary prophylaxis is not routinely recommended; discontinuation of secondary prophylaxis can be considered in patients with a sustained response to HAART, defined as a CD4+ cell count greater than 150 to 200 cells/mm3 for at least 6 months.

TMP-SMX, Trimethoprim-sulfamethoxazole; PCP, Pneumocystisjiroveci (carinii) pneumonia; MAC, Mycobacterium avium complex; CMV, cytomegalovirus.

An adequate response is expected between weeks 16 and 24 after initiation of ART. Other important factors for physicians treating HIV disease include close follow-up and monitoring of drug toxicities. Treatment success is defined as virologic suppression to undetectable HIV RNA (viral load) to the lowest detectable testing available (<48 copies/mL).

The wide use of HAART has helped decrease OI-related mortality in HIV-positive patients. OIs continue to cause morbidity and mortality for the following reasons:

1. Opportunistic infections are the main indicator of disease that drives many people who may be unaware of their HIV status to seek medical attention.

2. Highly active retroviral therapy may not be available to many patients for a variety of psychological and socioeconomic reasons.

3. Certain patients who are prescribed HAART may not experience virologic or immunologic response because of suboptimal adherence, pharmacokinetics, or unknown biologic issues.

Some OIs may cause a transient increase in viral load that may promote HIV disease progression and increase transmission. HAART becomes especially important to combat OIs for which specific treatments are unavailable.

Recommendations for the initiation and discontinuation of primary prophylactic medications are summarized in Table 17-8. Criteria to initiate or discontinue primary prophylaxis include the following:

1. Adequate CD4+ (immunologic) response.

2. The degree of virulence of the opportunistic agent. Thus the CD4+ cell count to minimize the risk of acquiring a specific illness will vary.

3. Other factors to consider in discontinuation of prophylaxis are the reduction of drug resistance, polypharmacy, drug to drug interactions, and cost.

Postexposure prophylaxis (PEP) of HIV infection in exposed individuals must be initiated within hours of exposure, if possible. The route of exposure may well be from mucous membranes, broken skin, or percutaneous route. The decision to initiate prophylaxis must be considered carefully because it is associated with potential morbidity and side effects. HIV testing must be performed at the time of exposure, at 6 and 12 weeks, and then 6 months later. Two-NRTI or three-drug (+ PI) regimens are recommended, depending on the severity of exposure.

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