Clinical Manual for Management of the HIV-Infected ... - myCME.com

6–70 | Clinical Manual for Management of the HIV-Infected Adult/2006
drugs should be avoided during pregnancy. HIV-infected
women in the United States are instructed not to
breast-feed, so there are usually no issues regarding TB
treatment of HIV-infected women during breast-feeding.
Treatment of pediatric patients
Children are often treated with a 7-month continuation
phase for a total treatment time of 9 months, although
there are no data on this issue. Some experts avoid
ethambutol in young children who cannot be tested for
the adverse event of color blindness; others consider the
risk so small with current ethambutol dosages that the
drug can be included safely. Treatment of children for
TB should be done in consultation with an expert.
Coordinating with Antiretroviral Therapy
ART and TB treatment must be coordinated for
both to be successful. Rifampin is a potent inducer of
cytochrome p450 enzymes and has clinically important
interactions with many medications, including certain
antiretrovirals and oral contraceptives. Rifampin
reduces the blood concentrations of nonnucleoside
reverse transcriptase inhibitors (NNRTIs) and protease
inhibitors (PIs), but does not affect nucleoside/
nucleotide reverse transcriptase inhibitors (NRTIs) or
the entry inhibitor enfuvirtide. Some NNRTIs and PIs
cannot be used with rifampin while other require dose
adjustment when coadministered (Table 3). Triplenucleoside
regimens can be administered safely during
rifampin treatment but are less potent than other firstline
antiretroviral (ARV) combinations. The safest ARV
combination to use with rifampin is a 2-drug nucleoside
backbone with efavirenz. Some clinicians increase the
efavirenz dosage to 800 mg/day because efavirenz blood
concentrations may be reduced 25% by concomitant
rifampin. Note that efavirenz is teratogenic; women
who take efavirenz should avoid pregnancy by using
birth control methods that use are not affected by
rifampin (preferably condoms plus injectable progestins
or condoms plus an intrauterine device).
Table 3. Interactions of Antiretroviral Medications with Rifampin or Rifabutin: Contraindicated Combinations and Dosage Adjustments
Rifampin
Nonnucleoside Reverse Transcriptase Inhibitors
Rifabutin*
Efavirenz** Rifampin dosage is unchanged; give efavirenz dosage of 600-800 mg No change in efavirenz dosage; increase rifabutin to
daily
450-600 mg 3 times daily
Nevirapine Generally not recommended; despite 25-50% reduction in nevirapine Use standard dosage of nevirapine;
levels, 2 small studies claim standard dosages are effective
rifabutin 300 mg daily or 3 times weekly
Delavirdine Never combine Never combine
Unboosted Protease Inhibitors
Ritonavir May be used at standard dosages; limited clinical experience Ritonavir at standard dosage;
rifabutin 150 mg alternate days or 3 times weekly
Amprenavir,
Never combine PIs at standard dosage; rifabutin 150 mg/day or
fosamprenavir
300 mg 3 times weekly
Atazanavir Never combine Atazanavir at standard dosage;
rifabutin 150 mg alternate days or 3 times weekly
Indinavir Never combine Increase indinavir to 1,000 mg every 8 hours;
rifabutin 150 mg/day or 300 mg 3 times weekly
Nelfinavir Never combine Increase nelfinavir to 1,000 mg every 8 hours;
rifabutin 150 mg/day or 300 mg 3 times weekly
Ritonavir-Boosted Protease Inhibitors
Lopinavir/ritonavir Lopinavir/ritonavir (3 caps twice daily) must be supplemented with Standard dosage of lopinavir/ritonavir;
(Kaletra)
additional ritonavir 300 mg twice daily; limited experience, not well decrease rifabutin to 150 mg alternate days or 3
tolerated
times weekly
Saquinavir/ritonavir Should not be used because of high rates of hepatotoxicity Standard dosage of lopinavir/ritonavir; decrease
rifabutin to 150 mg alternate days or 3 times weekly
All other ritonavir- Should not be used (adequate dosing regimens not defined) Standard dosage of PI/ritonavir; decrease rifabutin
boosted PIs
to 150 mg alternate days or 3 times weekly
Adapted from Updated Guidelines for the Use of Rifamycins for the Treatment of Tuberculosis Among
HIV-Infected Patients Taking Protease Inhibitors or Nonnucleoside Reverse Transcriptase Inhibitors.
Updated January 20, 2004. Nucleoside and nucleotide analogues are given in standard dosages
with either rifampin or rifabutin.
* If available, rifabutin may be substituted for rifampin when TB treatment and antiretroviral
therapy is combined.
** Avoid efavirenz during pregnancy or in women who may become pregnant on therapy. Both rifampin and
rifabutin significantly reduce estrogen and progestin levels for women on hormonal contraceptives; efavirenz
raises estrogen levels moderately. Two forms of birth control including one barrier method and either a mid-high
dose hormonal contraceptive or intrauterine device are most often recommended. Barrier methods are also
recommended for women who are infertile to reduce HIV transmission.