Page 286 - Review of Medical Microbiology and Immunology ( PDFDrive )

mebooksfree.com
mebooksfree.com
mebooksfree.com

mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com
mebooksfree.com mebooksfree.com mebooksfree.com transcriptase) of hepatitis B virus (HBV). It is used for the 275 mebooksfree.com
mebooksfree.com
CHAPTER 35 Antiviral Drugs
It is a reverse transcriptase inhibitor that acts by chain
treatment of chronic active hepatitis caused by this virus.
termination. It is approved for use in patients who have
developed resistance to other reverse transcriptase inhibi-
Entecavir
tors and in those who are starting treatment for the first
Entecavir (Baraclude) is a guanosine analogue that inhibits
time. It should be used in combination with other anti-
HIV drugs. The main adverse effects are liver damage,
lactic acidosis, and renal failure.
no activity against the DNA polymerase (reverse transcrip-
tase) of HIV. It is approved for the treatment of adults with
chronic HBV infection.
Nonnucleoside Inhibitors the DNA polymerase (reverse transcriptase) of HBV. It has
mebooksfree.com mebooksfree.com mebooksfree.com Retroviruses.” mebooksfree.com mebooksfree.com
mebooksfree.com
Unlike the drugs described earlier, the drugs in this group
Lamivudine
are not nucleoside analogues and do not cause chain ter-
Lamivudine is described in the section “Inhibitors of
mination. The nonnucleoside reverse transcriptase inhibi-
tors (NNRTIs) act by binding near the active site of the
reverse transcriptase and inducing a conformational
Telbivudine
change that inhibits the synthesis of viral DNA. NNRTIs
Telbivudine (Tyzeka) is a thymidine analogue that inhibits
should not be used as monotherapy because resistant
the DNA polymerase (reverse transcriptase) of HBV but
mutants emerge rapidly. Strains of HIV resistant to one
has no effect on the reverse transcriptase of HIV. It is useful
NNRTI are usually resistant to others as well. NNRTIs are
in the treatment of chronic HBV infection.
typically used in combination with one or two nucleoside
analogues.
Tenofovir
1. Nevirapine—Nevirapine (Viramune) is usually used
Tenofovir is described in the section “Inhibitors of
in combination with zidovudine and didanosine. There is
mebooksfree.com mebooksfree.com mebooksfree.com Retroviruses.” mebooksfree.com mebooksfree.com
mebooksfree.com
no cross-resistance with the nucleoside inhibitors of
reverse transcriptase described previously. The main side
Inhibitors of Hepatitis C Virus
effect of nevirapine is a severe skin rash (Stevens-Johnson
1. RNA polymerase inhibitors
syndrome).
Sofosbuvir
2. Delavirdine—Delavirdine (Rescriptor) is effective
Sofosbuvir (Sovaldi) is a uridine analogue that inhibits the
in combination with either zidovudine or zidovudine
RNA polymerase of HCV. It acts as a chain terminating
plus didanosine. The main side effect of delavirdine is a
drug. It is useful in the treatment of chronic HCV infection
skin rash.
caused by genotypes 1, 2, 3, and 4.
3. Efavirenz—Efavirenz (Sustiva) is effective in combi-
nation with zidovudine plus lamivudine. The most com-
mon side effects are referable to the central nervous Dasabuvir
Dasabuvir is a nonnucleoside inhibitor of the RNA poly-
system, such as dizziness, insomnia, and headaches.
merase of HCV. Its precise mode of action is uncertain as of
mebooksfree.com
mebooksfree.com
mebooksfree.com mebooksfree.com mebooksfree.com ritonavir (a booster of protease inhibitor activity). This mebooksfree.com
this writing. It is available in combination with ombitsavir
4. Etravirine—Etravirine (Intelence) is a second-
(an NS5A inhibitor), paritaprevir (a protease inhibitor) and
generation NNRTI useful in treatment-experienced
patients who have significant viremia. It is most effective
four-drug combination is called Viekira.
when given in combination with two protease inhibitors,
darunavir and ritonavir. The most common adverse
2. NS5A inhibitors
effect is a rash, and Stevens-Johnson syndrome has
Ledipasvir
occurred, albeit rarely.
Ledipasvir is an inhibitor of NS5A, an RNA-binding pro-
5. Rilpivirine—Rilpivirine (Edurant) is a second-gener-
ation NNRTI useful in treatment-naïve adult patients. It
HCV. Ledipasvir is available in combination with sofosbu-
is most effective when used in combination with either
vir (Harvoni) and is useful in the treatment of chronic
tenofovir or emtricitabine. The most common adverse tein required for the activity of the RNA polymerase of
HCV infection caused by genotype 1.
effects are depression and insomnia.
mebooksfree.com mebooksfree.com mebooksfree.com combination with dasabuvir (a polymerase inhibitor), pari- mebooksfree.com
mebooksfree.com
mebooksfree.com
Ombitsavir
Ombitsavir is another NS5A inhibitor that is available in
Inhibitors of Hepatitis B Virus
Adefovir
taprevir (a protease inhibitor) and ritonavir (a booster of
Adefovir (Hepsera) is a nucleotide analogue of adenosine
protease inhibitor activity). This four-drug combination is
called Viekira.
monophosphate that inhibits the DNA polymerase (reverse
mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com